Radiation Protection in Pediatric Radiology# (N C R P Report)

NCRP REPORT No. 68

RADIATION PROTECTION IN PEDIATRIC RADIOLOGY Recommendations of the NATIONAL COUNCIL O N RADIATION PROTECTION AND MEASUREMENTS

Issued November 1, 1978 - .- -- . First ~ e b r i n t i n July ~ 31, 1989 Second Reprinting April 30,1993 Third Reprinting June 30,1994 National Council on Radiation Protection and Measurements 7910 WOODMONT AVENUE / WASHINGTON, D.C. 20014

LEGAL NOTICE This report WM prepand by the National Council on Radiation Rotection and Meawemanta (NCRP). The Cormcil strives to provide accurate, complete and useful information in ita reporta However, neither the NCRP, the membem of NCRP, other pvsona contributing to or embting in the preparation of thin report, nor any pereon acting on the behalf of any of these parties (a) makes any warranty or representation, e x p m or implied, with respect to the accuracy, completeness or ueefulness of the information contained in thin report, or that the use of any information, method or prwem W o a e d m this report may not infringe on privately owned rights; or (b) acpumea any liability with respect to the use of,or for damagm d t i n g h m the uee of, any information, method or process d i s c l d in thin report.

Copyright 6 National Council on Radiation Protection and Mammmente 1981 AU rightansuved. This publication is protected by copyright. No part of thin publication m y be reproduced m any form or by any meam, including photocopying, or utilized by m y information storage and retrieval ayatem without written permission fmm the copyright owner, except for brief quotation in critical articles or reviewa. Library of Congmea Catalog Card Numbu 8180187 I n t u n a t i o d Standard Book Number 0-91339244-6

Preface The purpose of this report is to make available a source of practical information regarding the manner in which radiologic examinations in children should be conducted to reduce the radiation dose to these patients and those responsible for their care. The emphasis is on radiologic examinations as they affect children, although some additional material of more general interest is included for completeness. The report. is mainly for the use of pediatricians, radiologists, radiologic technologists, and other physicians and medical practitioners who order or use radiological methods in examining children. It is recognized that there are many approaches to the reduction of dose in the radiologic examination of children. The guidelines in this report are intended as assistance in the reduction of unnecessary radiation exposure and should not be construed as specific regulations. The Council has noted the adoption by the 15th General Conference of Weights and Measures of special names for some units of the Systeme International #Unit& (SI) used in the field of ionizing radiation. The gray (symbol Gy)has been adopted as the special name for the SI unit of absorbed dose, absorbed dose index, kenna, and specificenergy imparted. The becquerel (symbol Bq)has been adopted as the special name for the SI unit of activity (of a radionuclide). One gray equals one joule per kilogram; and one becquerel is equal to one w o n d to the power of minus one. Since the transition from the special units currently employed - rad and curie - to the new special names is expected to take some time, the Council has determined to continue, for the time being, the use of rad and curie. T o convert from one set of unite to the other, the following relationships pertain: 1 rad = 0.01 J kg-' = 0.01 Gy 1curie = 3.7 x 101Os-l= 3.7 x 10'' Bq (exactly).

/ PREFACE Serving on Scientific Committee 51A on Radiation Protection in Pediatric Rsdiology during the preparation of this report were: ANDREWK. POZNANSIU Chahm

iv

Radiologist in Chief Department of Radiology Children's Memorial Hospital Chicago, Illinois Members SColT DUNBAR Director of Radiology Children's Hospital Medical Center Cincinnati,Ohio ELEXMANGROSS~UN Director of Pediatric Radiology Duke University Medical Center Durham,North Carolina

JOHNA. KIRKPATRICK Radiologist in Chief Department of Radiology Children's Hospital Medical Center Boston. Mmaachusetts

WIUIAM MCSWEENI~Y Chairman of Radiology Children's Hospital National Medical Center Washington,D.C.

LEsrsR WE~SS Chairman of Pediatrics Henry Ford Hospital Detroit, M i c w

NCRP Seeretarkt - T'O~'EAS FEARON

The Council wishes to express its appreciation to the members of the Committee for the time and effort devoted to the preparation of this-report. Warren K. Sinclair President, NCRP Bethesda, Maryland December 1,1980

Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Objectives of Radiation Protection . . . . . . . . . . . . . . . . . . . . 1.2 Tissues at Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 A Common Sense Consideration of Risk . . . . . . . . . . . . . 1.4 Differences Between Adults and Children . . . . . . . . . . . . . . 1.5 Maximum Permissible Dose Equivalent . . . . . . . . . . . . 2. General Concepts of Reduction of Exposure to Medical Radiation in Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Should the Examination be Done? . . . . . . . . . . . . . . . . . . . 2.2 Training of Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Examination Rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Means of Minimizii Radiation Exposures from Exam. . lnations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Minimizing the Need for Repeat Examinations . . . . . . . . . 2.6 Diminution of Radiation Dose in Radiography . . . . . . . 2.7 Diminishing Fluoroscopic Dose . . . . . . . . . . . . . . . . . . . . . 2.8 Minimizing Radiation Outside the Area Examined . . . . 2.9 The Pregnant Girl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Gonadal Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Means of Gonadal Protection . . . . . . . . . . . . . . . . . . . . . . 4. Protection of Personnel and Parents . . . . . . . . . . . . . . . . 4.1 Immobilization of Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Fluoroscope Design and Radiation to Personnel . . . . . . . 4.4 Eye Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Monitoring Dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Pregnant Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Immobilization of Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Methods of Immobilization . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Equipment Consideration in Pediatric Radiology . . . . . . 6.1 Radiographic Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Imaging Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CONTENTS

6.3 Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Fluoroscopic Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Cineradiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7 Computed Tomography (C.T.) . . . . . . . . . . . . . . . . . . . . . . . . 6.8 Dental Radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 . Special Problems of Mobile Equipment . . . . . . . . . . . . . . . . 7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Radiography in Operating Rooms . . . . . . . . . . . . . . . . . . . . . 7.3 Mobile Fluoroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix A .Doses from Various Examinations in Pediatric Radiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix B .Method for Estimating Selected Organ Doses for Projections Commonly Used in Pediatric Radiology . . Appendix C .Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ................ References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The NCRP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NCRP Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

43 43 44

46

46 48 50 50

52 52 55 65 111 114 122 128 139

Introduction 1.1

Objectives of Radiation Protection

The major objective of radiation protection is the protection of people exposed, future generations, and the maintenance of the collective dose to mankind as a whole a t a low level, while still allowing the necessary activities from which radiation exposure may result. Protection is required to minimize somatic and hereditary effects. Somatic effects are those that become manifest in the exposed individual. Hereditary effects are those that become manifest in the exposed individual's subsequent progeny. Of these effects, there are two types that are considered The first is stochastic, for which the probability of an effect occurring, rather than its severity, is regarded as a function of dose without apparent threshold. Non-stochastic effects are those in which the severity varies with the dose and for which a threshold may occur. Hereditary effects and, at the doses of interest here, most somatic effects are stochastic. Carcinogenesis is the chief somatic effect at low doses and, therefore, is a significant reason for maximal radiation protection. Other clinically significant somatic effects of postnatal irradiation require doses far greater than those usually involved in medical diagnostic radiology. Another somatic effect of concern in radiological practice is teratogenesis as a consequence of the examination of pregnant women with resultant exposure of the embryo or fetus in utero. This effect may be a low threshold phenomenon or stochastic in nature. The goal of radiation protection is to prevent detrimental, non-stochastic effects and to limit the probability of stochastic effects to levels deemed acceptable. In medical applications of radiation, the decision about the acceptability of the level of risk is usually dependent upon the potential benefit that the patient may derive from the study. The problem with this approach is that it is very difficult to quantitate the benefit; therefore, a qualitative judgment must be made. In general, the following criteria should be considered for the use of medical diagnostic radiation: 1) When a new diagnostic imaging procedure using ionizing radiation is introduced, it should produce a benefit that is expected to outweigh the risk from irradiation. 1

2) Exposure should be kept to the minimum necessary to gain the needed diagnostic information. 3) The recommended maximum permissible dose limits for the general public or radiation workers do not apply to the patient's radiation dose from medical procedures. There is no maximum permissible dose for medical radiation. 4) The exposure to other individuals in the vicinity of the patient being examined should be kept as low as reasonably achievable and should not exceed the limits recommended by the NCRP (NCRP, 1971).

1.2 Tissues at Risk

In the past, much concern was given to the concept of critical organs and tissues, particularly the gonads and active bone marrow. Recent evidence suggests that other tissues may also be susceptible to the induction of cancer and that some, particularly the female breast, have a higher risk of radiogenic cancer than does the bone marrow. The risk factors will be discussed in connection with each tissue. Most of the data available for risk estimates deal with mortality from cancer. In some situations other riskti, such as benign tumors of the thyroid, may be important. Estimates of risk mortality are available (ICRP, 1977, UNSCEAR 1977, and NAS 1972) (Table 1.1). According to TABLE 1.1-Radiogenic N-

cancer mortcrl3y risk estimates for low-LET radiations (Deathaper 10' persons per rad) ICRP (1977) UNSCEAR (1977) BEIR (NAS 1972)'

RiaL per 106 per red

Risk per 106 per rad

Bone Cancer Lung Cancer Thyroid Cancer Breast Cancer

25

5-15 10 (Japan) 60

Leukemia

20

20-50

5

2-5

20

25-50

5

100-125 (in utero)

W Other Cancers All Cancers

45 250 (in uterolb 50 (G9Y ) ~ 25 (10 y)b

+

2.0

50

100

Rink per 10" per rad

100 2w250 (in utero)

250 (in ~ t e r o ) ~ 30 (G9 Y ) ~

150 (10 + vlb

'BEIR eatimates (NAS. 1972). were originally given an deaths per 10' persons per year per rem. They are converted to deaths per 106 person per rad since we are dealing with I radiation. They are mukiplied by duration of the plateau region (period of manifeet excess incidence) to obtain the figures given in this table. Age at the time of radiation exposure in parenthesis.

1.2

TISSUES AT RISK

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NCRP Report No. 64 (NCRP, 1980) the effect of x radiation at very low doses and/or dose rates may be smaller than the linear projections given in the other reports cited above, perhaps % to %o of those values.

1.2.1

Bone Marrow

The active bone marrow is the tissue at risk for radiation-induced leukemia. Data from studies on populations irradiated as the result of the atomic bomb explosions at Nagasaki and Hiroshima, as well as data from patients who have received radiation therapy, suggest that the risk of death from leukemia is approximately 20 to 50 deaths per lo6 per rad. The incidence of radiation-induced leukemia reaches its peak within a few years after irradiation and returns to pre-irradiation levels after about 25 years (ICRP, 1977).The risk appears to be about twice as great after irradiation of children as it is after irradiation of adults, and the risk after in utero irradiation is probably even higher. Impairment of the bone marrow function is not a significant factor in most forms of diagnostic radiology since an exposure of 2000 R given during radiation therapy over a lifetime does not appear to impair the hemopoietic function (ICRP, 1977).

1.2.2

Breast

During reproductive life, the breast seems to be among the body tissues more susceptible to radiogenic cancer. The risk factor for breast cancer is of comparable magnitude to that for leukemia. The mortality risk estimate given by the ICRP (1977) is 25 per lo6 persons per rem; UNSCEAFt (1977) gives values of 10 per lo6 persons per rem from Japanese data and 60 per lo6 person per rem from other data for females. The risk in children before maturity is not known. Boice et al. (1979) suggest that girls 10-19 years of age have the greatest risk of breast cancer based on the best available human epidemiological data. For doses in the usual diagnostic range, this predicted excess risk from radiation is stitl very small as compared with the risk of spontaneous (nonradiogenic) breast cancer.

1.2.3

Thyroid

There is a greater chance per rern of radiation induction of thyroid cancer than of leukemia. However, since thyroid cancer is usually controllable, the overall mortality is much less than that from leukemia. ICRP (1977) gives a risk of 5 per lo6 person per rem for thyroid cancer mortality. The absolute risk of thyroid nodularity is 12.3 per

lo6 person per rem per year and the absolute risk of thyroid cancer in children is 4 3 per 1$ person per rern per year (Maxon et al., 1977).

Other Organs Some of the risks of death for various organs are given in Table 1-1. ICRP (1977)and UNSCEAR (1977)give the overall lifetime mortality risk from cancer as about 1 per LO4 per rem of whole body irradiation. Therefore, a large population would be needed to detect any increase in incidence of cancer for the dose levels used in diagnostic radiology. Since the overall risk of fatal cancer is only 1 per 10' per rem or less, it is not surprising that in a follow-up study of 1,480children who had multiple cardiac fluoroscopies, no increase of cancer was found (Birch and Baker, 1960).Obviously, one would need a much larger population to detect any increase in incidence of cancer for the dose levels used in those examinations. 1.24

The main concern in irradiation of the gonads is the hereditary (genetic) effects on the descendants. The human gonads have a low sensitivity to the induction of cancer. Impairment of fertility is also not a concern for the exposure levels used in diagnostic radiology since it does not occur as a result of doses less than 300 rads in young women (ICRP, 1977). This is much larger than doses used in diagnostic radiology. Similarly, although sperm count may be depressed temporarily by an absorbed dose of 25 rads delivered a t a high dose rate, the absorbed dose rate required to cause permanent sterility is larger by at least one order of magnitude (ICRP, 1977). Ash (1980) reportd similar data. It appears that at low doses and/or dose rates the frequency of dominant and sex-linked disorders, as well as chromosomal diseases, increases in direct proportion to the dose, although there are few substantiating data available at low doses in man. The genetic defects resulting from paternal radiation are more often dominant mutations and unbalanced translocations, whole chromosomal trisomies are more commonly the result of maternal radiation (Lewis,1975).The mortality risk of hereditary disease within the first two generations following the radiation of either parent is considered to be about 4 x 1W'per rem (ICW, 1977).

1.2 TISSUES AT

1.2.6

RISK

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5

Lens of the Eye

Cataracts have been described as a result of x irradiation to the lens of the eye. According to the ICRP (1977),a cumulative total dose to the lens of 1500 rads over the occupational lifetime is below the threshold for production of any lens opacification that would interfere with vision. A single dose of 200 rads could produce cataracts, but with fractionation of exposures, higher doses are required (Merriam and Focht, 1957; Schenken and Hageman, 1975).

1.2.7

Fetus

Fetal radiation is a concern both in pregnant adolescents undergoing radiologic examination and in pregnant mothers or female personnel who are in the room while a child is examined. The probability of inducing structural malformation or growth retardation is greatest during the period of major organogenesis. In humans, organogenesis probably starts at 12 days after conception (3-4 weeks after the last menstruation) and extends through the 10th week post-conception (12th week post-menses). For doses less than 10 rads, it is unlikely that an increase in incidence of structural malformations would be detectable in patient populations. In humans, the natural incidence of congenital malformation is about 9.0 per 100 live births and the incidence of all birth defects is approximately 10.5 per 100 live births (UNSCEAR, 1977). Risk estimates of 5 x per rad for malformations in mouse embryo have been reported for high doses on the 8th day of pregnancy (the end of the first trimester or of organogenesis in the mouse) (UNSCEAR, 1977). Data to allow risk estimates to be made for human fetal doses encountered in diagnostic radiology are unavailable. Experimental results also indicate that irradiation of the embryo during the pre-implantation period in humans (3rd and probably 4th week post-menstruation) does not result in malformations, but can lead to very early (asymptomatic) embryonic death for sufiiciently high doses. Although causal relationship is still in question, it appears that increased risk of leukemia and other childhood cancer is associated with diagnostic irradiation in intrauterine life. According to NAS (1972), the number of deaths per lo6 person per year per rem is one in children over ten years of age, two in children 1-9 years of age, and 25 in utero at the time of irradiation. If the examination can be postponed until after the duration of the pregnancy without compromising the health of the pregnant woman, this should be done [NCRP Report No. 54 (NCRP 1977b)I. If postponement is not feasible, modification of the examination for dose

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1.

INTRODUCTION

reduction to the fetus should be accomplished to the extent it does not compromise its value. For example, the number of films for the study may be diminished. The recommendation of NCRP Report No. 53 (NCRP, 1977a) is that for occupationally exposed pregnant women, the dose-equivalent limit for the embryo or fetus should be 0.5 rem during gestation. This is the same as the maximum permissible dose-equivalent limit recommended for the non-occupationally exposed individual member of the general public, except that it is for 9 months rather than for a year.

1.3

A Common Sense Consideration of Risk

Radiation certainly is not our only risk in l i f e m a n y other risks exist. A one in a million risk of death has been attributed to 400 miles of travel by.air, 60 miles by car; smoking % of a cigarette; 1% minutes of rock climbing; 1%weeks of typical factory work in Great Britain; or 20 minutes of being a man aged 60 (Pochin, 1978). It is also important to remember that radiation is only one of many' agents that can cause genetic mutations or congenital malformations. Others include certain chemicals, viruses, other microorganisms; and high body temperatures can also produce these effects. In most cases the cause is unknown. Thus, the presence of a genetic defect or malformation does not mean that it was caused by irradiation of the parent, since approximately 3-4 percent of all infants born in the United States show some abnormality, even when neither parent has received any radiation other than natural background. We are consbntly exposed to natural radiation from cosmic sources; from terrestrial radionuclides in earth, rocks, water, and materials derived from the earth; and from natural radionuclides within the body. The amount of natural background radiation to which individuals are exposed varies with the altitude, soil composition, etc. For example, the natural background radiation dose in Denver is approximately 45 mrem per year greater than in much of the rest of the United States (NCRP, 1975). These doses can be contrasted with the average dose to the lungs from a chest radiograph which, in children, is less than 5 mrad and is significantly lower in the infant. Details of the amount of background radiation in the U.S. are presented in NCRP Report No. 45 (NCRP, 1975). The goal of radiation protection in medical diagnostic applications of radiation is to obtain the needed information with the lowest radiation dose to the patient and others exposed. Even though the

1.5 MAXIMUM PERMISSLBLE DOSE EQUIVALENT

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7

dose required for many radiological examinations is relatively small and may be less than the annual background rate, because of the minute possible risk there is an advantage in limiting it to a minimum, but not to the degree that this constraint interferes with the acquisition of the information needed. In considering radiation doses in individual applications of radiation, the maximum effort should be expended to minimize the dose in high dose studies such as cardiac angiography, where doses up to 90 rads may be given to the skin of the chest (Ardran et al., 1970). It is very important to consider which portion of the body is irradiated. For example, well collimated beams to the chest result in such a minute amount of radiation dose to the gonads as to be of practically no heritable genetic significance. Similarly, consideration of the dose resulting from an examination is important. At first glance, 50 radiographs of a newborn infant within a few weeks may seem excessive and cause some anxiety until one recognizes that the total dose delivered to the bone marrow with these 50 films is usually under 0.15 rad, and only a fraction of the active bone marrow is irradiated. When considering radiation protection in children, greater attention should be given to those examinations in which the critical organs are exposed directly as compared with examinations where they are outside of the primary radiation field, such a s in examination of the extremities.

1.4 Differences Between Adults and Children The longer life expectancy of children results in a greater potential for manifestation of possible harmful effects of radiation. Also,children may be more ,sensitiveto leukemogenesis by a factor of about 2 (Beebe et al., 1978). However, the radation doses used to examine children are usually smaller than those employed in adults. For example, a frontal chest radiograph in a newborn may be done with an entrance skin exposure of less than 5 mR, while for an adult the study may require 50 mR to obtain a diagnostic image. Motion is a greater problem in children and requires adjustment of technique so that it can be minimized. 1.5

Maximum Permissible Dose Equivalent

The NCRP and the ICRP have recommended maximum permissible dose-equivalent limits for occupational and non-occupational exposure

other than background and medical (patient) exposure (NCRP, 1971; ICRP, 1977). The judgment of these organizations is that these limits are set well below what is considered a significant risk. These limits are not applicable to medical radiation where the radiation exposure is expected to result in net health benefit for the patient.

2.

General Concepts of Reduction of Exposure to Medical Radiation in Children 2.1

Should t h e Examination be Done?

The most effective way of providing radiation protection for patients is to avoid unnecessary radiological examinations. To ensure this goal, adequate clinical information should be available to the radiologist before an examination is done, particularly one that involves relatively high exposures such as a fluoroscopic examination. Although it is usually impractical to prescreen the consultation requests for all examinations to determine their appropriateness, prescreening certainly should be done in any fluoroscopic or complex study. Also, if an examination appears inappropriate to the technologist, it should be brought to the attention of the radiologist; and if the radiologist considers it inappropriate, he has the responsibility to discuss the matter with the referring physician, to cancel the procedure or to possibly modify the examination to one of lower risk or suggest an alternative study. A proper consultative relationship between the referring physician and the radiologist will ensure the continued education of both in the efficacy of radiologic imaging procedures and their appropriate use. In making the decision as to whether an examination will be beneficial to the patient, the referring physician should consider whether it will contribute materially to a diagnosis, whether it will increase the confidence of diagnosis, whether it will affect decisions on other diagnostic tests that may need to be done, whether it will aid in evaluating the planning and/or the efficacy of appropriate treatment. Examinations of children done for research purposes must be carefully evaluated for possible gain vs. risk to the child. Informed consent must be obtained from the parents in these cases. The dose should be kept as low as possible, particularly if the gonadal area and bone marrow are exposed. Thus,hand radiographs often can be obtained in children with less concern than examinations of the pelvis. The deci-

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2.

GENERAL CONCEPTS OF EXPOSURE TO RADIATION

sion concerning the safety of any research procedure should be made on an individual basis and should be evaluated by a review committee of the institution.

2.1.1

Examinations of Questionable Value

Although it is apparent that some radiologic examinations have low yields of detected abnormality, while others have high yields, the clinical indications for a specific examination cannot be definitely determined at this time. No general rule can be made since there may well be different indications depending on the population studied. The following list of examinations of low yield are guidelines and should not be considered absolute and may not be valid in all situations. (1) Excretory urograrns for evaluation of failure to thrive when there are no additional clinical or laboratory findings. (2) Voiding urethrograms for evaluation of failure to thrive when no other clinical or laboratory findings are present. The voiding urethrograrn gives a relatively high dose to the gonads. Particular care should be taken that this examination not be used indiscriminately. (3) Barium enema for evaluation of abdominal pain in the absence of other clinical or laboratory findings. (4) Routine fluoroscopy of the heart. Very rarely will specific cardiac diagnoses be made by cardiac fluoroscopy. (5) Routine reduction of fractures under fluoroscopy. (6) Radiographs of the paranasal sinuses for evaluation of fever when there are no localizing sinus symptoms. (7) Radiological examinations of the skull after injury when there are no localizing signs and symptoms. Bell and Loop (1971) found that without signs or symptoms the yield of fracture was very small, but by using the same clinical criteria, De Smet et al. (1979) showed a much higher incidence of fracture. However, even when a fracture is found, this affects the clinical management very little unless the fracture is depressed (Roberts and Shopfner, 1972). Fractures in children correlate very poorly with cerebral complications. Harwood-Nash et al. (1971) found that fracture occurred in less than one-half of children with extradural hematoma; subdural hematoma occurred twice as frequently in traumatized children without associated skull fracture than in those with a fracture. (8) Preoperative chest radiograph. This is still a somewhat controversial issue and again illustrates that what is true in one institution may not necessarily obtain in another. Sagel et d.(1974) found no clinically significant findings in 521 patients who had routine chest

2.1

SHOULD THE EXAMINATION BE DONE?

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11

radiographs on admission or preoperatively. Conversely, Sane et al. (1977) in a prospective evaluation of 1500 preoperative chest radiographs, in children, found that in 3.8 percent of the cases surgery was either postponed or cancelled or the anesthetic technique altered as a direct result of the roentgenographic identification of unsuspected abnormalities.

2.1.2

Factors to Consider When Deciding.to Perfonn A Radiological Examination

When deciding whether to perform a radiological examination, one should also review any previous films available from within or outside of the institution. They may contain sufficient information to obviate the need for additional radiological examinations. The decision on whether to use previous films will be somewhat dependent on the quality of these studies and on their timing and availability. Occasionally, an additional study must still be done because it is important to make a diagnosis promptly so that the patient can be treated without delay. Radiological examinations should be performed only when requested by a practitioner who feels that the examination will benefit the patient and not simply on request of the child or his parents. There are situations where a practitioner caring for a patient performs his own radiological examinations. Generally speaking, this self referral for radiographs should be discouraged. A physician doing his own radiographs may increase the number of unnecessary examinations. Another consideration in the determination of whether a radiological examination should be performed is whether a diagnosis can be made in some other way. For example, a lower dose or non-radiographic examination, such as ultrasound, sometimes may be substituted for a high dose radiation study. Determination should be made by the radiologist whether a repeat examinaton is really needed. In deciding to repeat a film or an entire study, one should consider whether these repeat films will yield significant new information or simply produce an aesthetically improved image. In larger radiology departments, methods should be instituted to avoid duplicate examinations caused by erroneously written duplicate requests. The use of a card file which lists all of the examinations and dates for each patient can avoid this problem. The use of a computer is another possible solution. The timing and proper sequencing of the radiological examinations are also important in decreasing the need for repeat studies. For

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2.

GENERAL CONCEPTS OF EXPOSURE TO RADIATION

example, if an excretory urogram is needed in the newborn and it is done on the first day, inadequate studies will often result because of immature renal function and the examination may have to be repeated. On the other hand, if the clinical situation is such that the examination can be postponed until several days or a week after birth, a much better study will be obtained. Alternatively, if an examination is needed in the first few days of life, an ultrasound or nuclear medicine study may be substituted.

2.2

Training of Personnel

Although the general radiologist is usually knowledgeable about radiological techniques, it is important that he or she recognize that examinations in children are different from those in adults. Not only do different techniques need to be used, but different diagnostic possibilities occur so that the examination must be modified accordingly. For example, when performing a colon examination in a middle-aged or elderly adult, cancer must be excluded no matter what the indication is for the study. As a result, the examination is usually done with meticulous preparation, careful fluoro6~0py,and multiple spot films in order to visualize the flexures and the sigmoid. In a child, in many instances, a much more limited study can be done. For example, if the purpose is to exclude malrotation, preparation can be eliminated and only brief fluoroscopy and one or a few films are required to determine the location of the cecum. There are many physicians and other practitionera who are not radiologists who use x rays. These include cardiologists, orthopedists, urologists, gastroenterologists, dentists, podiatrists, osteopaths, and chiropractors. High radiation exposures are often due to inadequate knowledge of basic radiological physics or an appreciation of the biological effects of x rays. To ensure efficacious use of radiation and to avoid high-dose radiography, non-radiologists as well as radiologists who use radiation should have formal training in x-ray techniques, radiation physics, and radiation protection as a part of their residency training. Competence in these areas should be certSed by their appropriate specialty board. Radiological technologists should also have training in pediatric radiology. In departments where a large number of children are examined, selected radiology technologists should be used so that . .they will develop expertise in handling these children Proper matmmmg of children during examinations and development of appropriate techniques in handling children will rlimininh radiation exposure to the

2.4 MINIMIZING RADIATION EXPOSURES

/

13

children and to other individuals (see subsequent sections). The lack of availability of experienced personnel may result in increased dose per examination and a higher incidence of inadequate studies which may require repeat examinations.

2.3

Examination Rooms

In any radiology department that examines a sificant number of children and has several radiographic rooms, a room should be set aside where all or most of the children are examined. This room should, when possible, be staffed with technologistswho are trained to do pediatric examinations. By setting aside a special room, various devices, gadgets, etc. can be readily available for the expeditious and safe radiological examination of children. A discussion of equipment consideration is found in Section 6 of this report. 2.4

Means of l' '

' '

g Radiation Exposures fiom Examinations

Beside reduction of unnecessary examinations as previously described, other factors that are important in decreasing radiation exposure include using a minimum number of films per examination, minimizing the need for repeat examinations, diminishing the dose per film, and diminishing fluoroscopic dose. In determining the number of views necessary for a standard examination, a compromise must be made. The more films that are obtained, the more likely it is that additional information will become available and a correct diagnosis can be made. However, with each additional film, the additional diagnostic yield diminishes asymptoti&Y-

The radiological examination of children should be tailored as much This is not possible for all examinations, but should be done particularly in procedures which result in a large dose to the child. The follow-up examination may be abbreviated without affecting the information desired. For example, excretory urognuns done simply to determine persistent caliceal dilation may be limited to two or three exposures using the information from the first examination to determine the time for maximum information yield. The use of films of the contralateral extremities for comparison is often unnecessary (Merten, 1978). Comparison vie- should be obtained mainly in cases of interpretative difhculty with radiographs of the injured extremity. as possible to the clinical problem.

14

2. GENERAL CONCEPTS OF EXPOSURE TO RADIATION

/

2.5

W

'

' '

g the Need for Repeat Examinations

The two most frequent causes of retake examinations in hospitals for adults are incorrect exposure (too black or too light a film) and improper positioning. Respiratory and other motion is a third cause (Burnett et d.,1975; Mazzaferro et d., 1974). In children, motion is often a more common cause than in adults; it accounted for about 12 percent of repeats in Der Vartanh's (1978) study (Table 2-1). Another observation bn Der Vartanian's study is the greater incidence of repeats by student technologists as compared with fuIly trained ones. This increase is expected and illustrates the importance of experience in decreasing unnecesmy radiation exposure. Since children are often incapable of remaining immobile for a radiological examination, methods that minimize motion w i l l decrease the need for repeat studies. These means include immobilization (which will be d k u s e d subsequently), establishing rapport with the patient, and the use of very short exposure times. To make the latter possible, the room with the highest capacity (kW) generator available should be selected as the one in which children are examined. The use of mobile equipment should be avoided when possible since the generators usually are small and it is difficult to use short enough exposure times and have a diagnostic image. When several mobile units are

.

~

student TecFhwl+ Combined 12.6 9.6 10.5 31.4 17.3 21.5 12.4 11.7 11.9 40.3 43.4 42.5 1.5 2.9 2-5 1.8 15.0 11.1 100 100 100

Technique Positioning Motion

E.posun MkIlaneous Total N (film expoeed) N (6hs) reueated) -

-

-

-

Technique-includes gds, cone and fogging e m . Motion-includes breathing d patient movem~lt Expmue-indudee improper netting of hV aod mAa Fhmshg-indudes fogging, pmcesor jam. Miecellaneowtincludescatheter problems-automaticilhu c b q p (mold of th- am urws due to radiographic unit failure lather than technique.) 'Data supplied by N. Der-Vartanian,RT, The ~oe&lal for !3i& chikhn, Toronto, Ontuio. Canada.

2.5 MINLMIZING REPEAT EXAMINATIONS

/

15

available, the ones with the largest capacity should be used when radiographing children. Correct exposure and processing are as important in pediatric radiology as in the study of adults as far as reduction of radiation exposure is concerned. Proper exposure is probably more difficult to gauge in children because of the great range in patient size. Underexposure and film mal-development decrease available information content and may result in repeat studies, thus increasing radiation exposure to the patient. Over-exposure increases radiation dose and decreases the information content. Generally speaking, the technical factors involved in examining children are different from those for adults and technique charts based on the size rather than age of children are particularly useful. Automatic exposure control is one solution to obtaining optimum exposures in children. However, this technique is often difficult to use in children because of the characteristics of much of the equipment that is available today. Automatic timing will not work satisfactorily if the detection chambers are larger than the portion that needs to be radiographed or if the patient is moving away from the detector. Also, the generator must be capable of ultrashort exposure times (around 3 milliseconds) for automatic exposure and it must have very short interrogation times (the time delay between the initiation of the exposure by closing a contactor and the actual start of the emission of x rays by the machine). A quality control program is needed to maintain quality of processing (Gray, 1977; HEW,1977) and constant output of the radiographic unit (Hendee and Rossi, 1979, 1980). Although processing errors were a very small factor in repeats in Der Vartanian's study (Table 2-I), the low incidence of this problem is probably related to the fact that tight quality control already exists in that hospital. The radiographic machine should have relatively little variability in the amount of output when certain kV and mAs levels are used. Thus, the control readings must accurately and consistently reflect the exposures generated and the machines must be checked a t regular intervals to ensure that this Occm. Clothing, bandages, diapers, etc. often produce artifacts on the radiograph which obscure informational detail. The smaller the child, the more significant the artifacts caused by the garments. Certain of the new fire-resistant gowns have a considerably greater opacity than conventional clothing. For these reasons, in young children, all clothing should be removed from the body part to be examined whenever possible. Proper bowel preparation for examination can also minimize the need for repeat studies. This is particularly true for excretory urograms

16

/

2. GENERAL CONCEPTS OF EXPOSURE TO RADIATION

and some barium enemas. Examination of a colon because of bleeding should not even be started if the colon is poorly prepared, as the examination will need to be repeated. The key to minimizing the number of repeat studies is to use radiological technologists trained in pediatric radiography when possible. This is because many of the errors that lead to repeat studies are under the technologists' control and can be avoided with the use of proper techniques by skilled personnel. The training of the technologists should be an on-going process. The technologist should have the opportunity to see the radiograph immediately after processing, thus providing an instant self monitoring which assists in maintaining the quality of the examination. This radiograph also should be evaluated for quality with the radiologist who will interpret the study.

2.6

Diminution of Radiation Dose in Radiography

Generally speaking,the hlghest kilovoltage technique possible that will result in an acceptable diagnostic examination should be used. This w i l l generally result in a lower dose to the patient. However, high kV examination should be avoided in examining the newborn chest, in bone radiography,and when iodinated contrast media are used because of loss of radiographic contrast. Scattered radiation with high kV technique is more penetrating, so that the doses to areas of the body outside of the x-ray beam area may be greater. With chest radiography, the dose to the gonads may increase as the kV is increased, although the bone marrow doae to the area irradiated will decrease. For example, for a PA radiograph of the chest of an adult patient using x rays with a 1.5 m m aluminum half value layer, the dose (in mrad) to the u t e m is 0.03 percent of the entrance skin exposure (in mR).It is 0.12 percent at 2.5 m m of aluminum and 0.45 percent at 4 mm of aluminum half value layer (Rosenstein, 1976). The entrance skin exposures to the chest, however, are less for higher kV, so that the actual increase in absorbed dose due to scattered radiation is not as much as might be expected from the relative percentages. In the examination of very small infants there is little ecattered radiation. Therefore, a Bucky diaphragm or a stationary grid is usually not necessary. By not using gJads, a 3-6-fold saving in radiation exposure can be accomplished. Various intexdjirq screens are available for radiography. Although eome of the faster screens can significantly niminish the radiation, the information content dimini.shes (resolution decreases and quantum

2.7 DIMINISHING FLUOROSCOPIC DOSE

/

17

mottle increases). There is no total agreement in the radiological profession and there is insufficient evidence in the literature to determine which film-screen combinations are optimal for the examination of children. This subject is discussed further in Section 6. 2.7

Diminishing Fluoroscopic Dose

Potentially, fluoroscopy can give much larger doses of radiation to the patient than radiography. The dose depends directly on the fluoroscopy time, which is often a function of operator skill. Fluoroscopy should be used only if conventional radiographs cannot satisfactorily give the information required. Simple anatomical information can be obtained more satisfactorily with radiography and hence with a lower dose to the patient. Generally speaking, fluoroscopy should be used primarily to study dynamic phenomena rather than anatomical detail. In some rare situations, fluoroscopy may be used for locahzation of anatomical findings if rotation of the patient may enhance its perception or, very occasionally, for choosing a proper radiographic projection. When performing fluoroscopy, it is extremely important to obtain the cooperation of the child before the examination is commenced. This is particularly important in examining young children who may not understand clearly what is required of them. Instructions to a child on how he should hold his breath or what positions he should be in should be given before fluoroscopy so that no fluoroscopic time will be wasted. When using fluoroscopy, special care should be taken to avoid exposing the patient unnecessarily. The fluoroscope should be approximately centered on the area in question by external observation rather than by having the fluoroscope turned on and finding the area in question fluoroscopically. During fluoroscopy, the smallest possible beam area should be used for the information required. The use of a small beam area decreases radiation exposure to the patient, decreases scatter to surrounding individuals, and results in a better image. There are other ways in which fluoroscopic dose can be minimized that involve reducing the fluoroscopy time. For example, when waiting to see the duodenal bulb fill, or to see movement during reduction in intussusception, the fluoroscope can be flicked on for a fraction of a second at relatively long intervals until the necessary information is obtained. Having the elapsed time visible to the fluoroscopist is a useful reminder to keep it as short as possible. Alternatively, recording the duration of fluoroscopy may also be useful. Fluoroscopic time will

18

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2. GENERAL CONCEPTS OF EXPOSURE TO RADIATION

vary considerably with different patients and with types of exarninations that are performed. It depends very much on the complexity of the study and no predetermined maximum fluoroscopy time can be considered proper for a specific examination. However, a waning device that indicates when a preset time has been exceeded should be utilized. Another way to minimize fluoroscopic time is through the use of videotape, whereby a complex fluoroscopic phenomenon can be reviewed as many times as desired without re-exposing the patient. An alternative recording device is the video disc. With this device, a high quality fluoroscopic image can be maintained statically on the television screen after a very short exposure; or alternatively, in situations where changes are occurring slowly, the x rays may be pulsed, for example, once per second while maintaining an image on the screen until the next pulse. Video discs are particularly useful in the operating room where processing facilities are not readily available and where fluoroscopy is used as a substitute for radiography - for example, in hlp nailing (Grollman et al., 1972; Zatz et al.,1974). As in radiography of very small infants, grids are not necessary during fluoroscopy since the amount of scatter is so small. Removing the grid during fluoroscopy of small infants will diminish the radiation exposure to the patient several-fold. During fluoroscopy the shortest possible patient-to-image intensifier distance should be used. Most image intensifier fluoroscopes today have an automatic compensation so that when longer distances are used, a higher radiation dose is given to the patient. Also, the larger distances increase the radiation dose to the observer. An increase in the distance of the detector from the patient will also increase motion and penumbra blur. One of the causes of a relatively larger radiation dose in fluoroscopy is related to automatic brightness control. This mechanism normally allows proper balancing of radiation output to the thickness of the part examined. When there is a very opaque object in the middle of the field, such as a very filled urinary bladder in voiding cystourethrography, the radiation dose can rise to the maximum of the unit giving a dose rate of 5-10 rad min-I. Since one is interested in the region around the radiopaque bladder, one should establish the radiation output in a region where there isn't any contrast medium and switch to manual brightness control to maintain this level when the fluoroscope is centered over the contrast filled structure. Another approach is to avoid having a radiopaque structure fill up the center, or a large part of, the fluoroscopic screen. In this way, radiation dose can be minimized. Another method of reducing fluoroscopic dose involves installation of a variable aperture iris (Rossi, 1978).

2.8 MINIMIZING RADIATION OUTSIDE THE AREA EXAMINED

/

19

When performing cine radiography, the cine rate should be kept to the minimum necessary for particular examinations. Although some examinations may require 60 frames/second, others may be diagnostically acceptable at 7% or 15 frames per second.

2.8

Mi

'

' '

g Radiation Outside the Area Examined

Proper collimation is important in reducing dose to the patient by decreasing the volume irradiated and decreasing scattered radiation. It is not enough to collimate to the size of the film in radiographing small body parts (e.g., infant chests); it is important to collimate just to the anatomical area of interest. Manual override of automatic collimators must be used to match the area examined. Evidence of collimation should be apparent on most films by the presence of a clear rim of unexposed film. Setting incorrect limits on the collimator may exclude areas of interest from the radiograph. Therefore, use of collimation requires proper knowledge of external landmarks by the technologist. Alignment of the light localizer of the collimator should be checked regularly. This is particularly important in the radiography of infants for whom small fields are used. Even small discrepancies between the radiation beam and the light beam may mean that the area of interest may be partially excluded from the area exposed. The use of immobilization in certain patients will allow the use of smaller fields since the child will not move with respect to the x-ray beam. In some examinations which result in relatively large radiation doses, such as angiograms, marking the opposite comers of the collimator light on the patient's skin at the time of the preliminary film may be useful to determine the correct position when adjustments are made for the serial film run.

2.8.2

Shielding

Gonadal shielding will be discussed further in Section 3. Careful positioning of the patient is important so that the gonads are not irradiated when areas remote from the gonads are filmed. For example, in making hand radiographs, if care is not taken, the patient may be positioned in such a way that the direct beam exposes the gonads. This type of positioning should be avoided (see Figure 2.1).

20

/

2. GENERAL CONCEPTS OF EWOSURE TO RADIATION

GONADAL DOSE RATIO 17

a

0,5mR

1

6

0.03 mR

Fig. 2.1. Protection of the patient by positioning. Reducing the beam aize and repositioning so that the gonads lie outside the x-ray beam and are shielded - the patient by the patient%own body can effect *large reduction in pnad dose.The dose magnitude is represented by the volume of a cube beneath each drawing (FromKeane and Tikhnov,

Eyes. In tomography of the mastoids or cranium,a relatively large dose to the eyes can result. This can be reduced 20-30 fold simply by using a PA rather than an AP projection (Berger et d,1974). With appropriate practice and patience, most children can be examined in the PA projection. In situations where the PA projection cannot be employed, eye shields can be used with multidirectional tomography, but not with linear tomography (Krohmer, 1972; Dobrin et al., 1973). During pneumoencephalography and cerebral angiography, a high dose may also be given to the lens of the eye; and in certain situations, lead goggles or glasses can significantly reduce this radiation dose without affecting the informational content (Bergstrom et al., 1977a, 1977b; Uttleton et al, 1978). Thyrod. Shielding of the thyroid is not practical in most radiologic exarnbtions. In the chest it is not possible, since visualization of the airway in the neck is often important. Thyroid shielding may be of some value in dental radiography (See Section 6.8 Dental Radiography) Breast. Since the breast in females is considered slightly more sensitive to the induction of cancer than the bone marrow. there may be some value to minimiziqj this dose in examinations where girls receive repeated radiation to the breast, such as with a scoliosis series. The breast can be shielded in the lateral view either by appropriate

-

2.9

THE PREGNANT GIRL

/

21

collimation, which may not always be possible, or with the use of a shadow shield, which can be placed on an I.V. stand or collimator. The breasts cannot be satisfactorily shielded in the AP view. Dose can be diminished if a PA rather than an AP view is used, but this may produce a diagnostically less satisfactory image.

2.9

The Pregnant Girl

The simplest practical way to ascertain the possibility of pregnancy is to ask the time of the last menstrual period in all adolescent girls in whom the abdomen is directly irradiated. If there is a question, the possibility of pregnancy should be further evaluated by careful review of history and, if necessary, further evaluated by ultrasound or pregnancy testing. In the consideration of a request for radiologic examination of a pregnant girl in whom there will be direct irradiation of the fetus, a detennination should be made whether the examination can be postponed until after delivery or to the second or third trimester. If the examination should still be done, additional care should be taken to minimize radiation dose to the fetus if possible. Examinations of extraabdominal portions of the body, such as skull or chest, can be done without significant risk if proper collimation is used, since the dose to the uterine area from these examinations is extremely small. See NCRP Report No. 54 (NCRP, 1977b) for a further discussion of the factors involved.

Gonadal Protection It is recognized that x rays may produce mutations in germ cells and that this phenomenon may have no dose threshold. Small gonadal doses to individuals from diagnostic radiological procedures may involve little genetic risk to the progeny of those individuals. However, small doses to the gonads of the population as a whole will affect the genetic pool. Thus, gonadal protection is indicated if it does not com~romisethe information to be gained from a radiological examination. Gonadal shielding should not be used as a substitute for collimation, but it should be used in addition to it. A considerable reduction in gonadal dose may be accomplished if the gonads are kept out of the direct beam (Figure 3.1). A gonadal shield should be used if the direct beam is close to the gonads (about 5 cm or closer) and if the use of the gonadal shield will not obscure important diagnostic information. Figure 3.2 illustrates the decrease in radiation exposure to the testes by using a specific shaped contact testicular shield. The saving in radiation may be 95 percent if the gonads are in the primary beam. When the gonads are more than 5 cm from the edge of the primary beam, the dose to the testes behind the shield is about the same as if they were not shielded (HEW, 1975;HEW, 1976).

3.1

Indications

Testicular shielding should be used in most examinations of the pelvic area and in most abdominal examinations where the symphysis pubis is seen and when the shield will not interfere with the information to be gained from the study. For example, in cystourethrogkaphy the gonadal shield will interfere with proper visualization of the urethra; when performing a barium enema, it is very inconvenient to use the gonadal shield. Testicular shielding generally should be used in examinations of the lumbar spine, abdomen, pelvis (except when the pubis needs to be evaluated), hips, sacrum and coccyx, excretory urograms, small bowel, 22

3.1 INDICATIONS

Fig. 3.1. Effect of technique on gonad exposure in abdominal radiography. The magnitude of the gonad dose in each method is represented by the volume of a cube. Restriction of the x-ray beam area,optimum choice of exposure factors, and good

processing reduce the gonad dose by a suhdantial amount (From Keane and T i o v , 1975).

upper femur, etc. Testicular shielding can also be used when performing examinations using mobile equipment. Shielding of the ovaries is much less effective than that of the testes. A saving of only about 50 percent may be possible with the ovaries in the direct beam (HEW, 1975).Another problem with ovarian shielding is the fact that in many examinations the ovaries overlie important pelvic structures, such as ureters, bladder, colon, etc., which are often the subject of clinical interest and therefore cannot be shielded. Also, the site of the ovaries is very difficult to determine in the child. It appears that the ovaries are hlgher and more lateral in children than in adults. Fochem and Pape (1962) in 200 salpingograms found that in only 5.5 percent of adult women the ovaries were above the minor pelvis, and none was found below the margin of the symphysis (Figure 3.3). In infants and children, however, higher sacral, pelvic, or even perilumbar position was common (D'Angio and Tern, 1967; Fochem and Pape, 1962) (Figure 3.4). Therefore, the entire sacrum, minor pelvis, and probably the lower lumbar region and part of the pelvic bone should be shielded in young females when ovarian shielding is indicated. The size of the pelvic portion of the shield is very dependent on patient size, and it requires considerable experience on the part of the

24

/

3. GONADAL PROTECTION

Test mditiom: SFD: 40 inches kVp: 80 kilovolts peak Field site: 14x17 Inches AP pmibctim

o----o No shieldin; e---

-2

Contact shisMinl

.O +2 +4 +6 +B Distance Betwem Ed;e of Firld and Gonad Site (in mtiantcrs)

+ 10

Fig. 3 3 . Male gonad exposure as a fundion of distance between the edge of the xray field and the location of the gonads (From HEW,1975.1976).

radiological technologist to choose the proper size of the shield. Too large an ovarian shield can obscure the area of interest. In hip radiography, for example, it is easy to obscure the hip joint with the gonadal shield, in which case additional films may be required, giving more radiation to the patient than if the shield had not been used. When the gonadal shield is too small. the ovaries will not be shielded. Although ovarian shielding cannot be used in most examinations, it can be used in a portion of a film series. For example, in the erami-

3.1

INDICATIONS

/

25

FLg. 1.3. h t i o n of the ovarim in 200 women and girls. The location of the ovaries over the mcrum was mainly in girls (From Fochem and Pape, 1962).

0

= RT.

-

LT e@ Ovaries in one infant 0

Fig. 3.4. Loeation of the orarics in children (Rom I Y W and Te€& 1967).

26

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3. GONADAL PROTECTION

nation of the hips when A P and frog-leg view are obtained, one of the films can easily be shielded without diminishing significantly the information obtainable. Another example of the use of ovarian shielding is in studies such as follow-up of Perthes disease or scoliosis, where all of the follow-up films can be taken with ovarian protection. Technologists should be trained to gauge adequately the size of shield that should be used.

3.2

Means of Gonadal Protection

A shield of at least 0.5 mm lead equivalent should be used. There are a number of methods of gonadal protection, each of which has advantages and disadvantagesand situations in which it can or cannot be used. The three main types of gonadal shields are the contact shields, the shadow shields, and the shaped contact shields.

3.2.1

'

Contact Shields

Contact shields are the simplest and cheapest to use. They are simply pieces of lead or lead rubber, or even such objects as lead gloves which can be placed over the gonads (Figure 3.5). Specially-designed contact shields have been described by Abram et al. (1958), Ardran and Kemp (1957), Bretland (1959), Godderidge (1979), and Schwartz et al. (1960). For ovarian protection the size and shape of the shield is very important as it needs to correspond to varying pelvic sizes. The shields devised by Godderidge (1979) are probably more appropriate for children because of the higher and wider distribution of the ovaries, but are somewhat difficult to use without obscuring important parts of the pelvis. The contact type shields are most useful when a patient is lying supine, as they are easily dislodged and difficult to position when the patient is lying in oblique or lateral position, or if the child is sitting or standing. In small children, contact gonadal shields should be taped directly to the skin. Ln older children, this is more difficult because of lack of patient cooperation due to modesty and social factors. A female gonadal shield should be placed so that its lower margin is at the symphysis pubis which is readily palpable in most girls (Figure 3.5). The upper margin of the shield should cover the pelvic inlet and extend up to the superior marpin or the sacrum or higher. In the male, the contact shield should simply cover the testes. The upper end of the contact shield is usually placed at about the level of the symphysis.

3.2 MEANS OF GONADAL PROTECTION

/

27

i , --Fig. 3.Sa Typical location of contact ganadal shield on a girl. Taping the shield in place pennits more secwe positioning (Pomanski,1976).

Fig. 3.Sb. Typical location of contact gonadal shield on a boy (Poznanski1976).

3.2.2

Shadow Shields

A shadow shield is radiopaque and is placed between the x-ray tube and the patient, but is not in contact with the patient. It may be on a stand which is placed on the radiographic table (Hodges et al., 1958) or it may be attached to the collimator (Whitehead and Grifiith, 1961; Epstein, 1960). Its location with respect to the gonads can be determined by the shadow it casts in the light of the beam of the light localizer. Some of the commercial varieties of shadow shields allow the use of varying size shields that can be inserted at will into the beam. Shadow shields can be used in the neonatal intensive care nursery where a small lead cut-out can be placed on top of a closed incubator (Hernandez et aL, 1978) and its position adjusted over the gonadal area by the shadow cast by the light localizer. In film examination of scoliosis in the upright position, the shadow shield placed on an intravenous stand is convenient to use (Poznanski, 1976). The shadow shield can be used in the sterile field since it is not in contact with the patient. It is somewhat easier to use in the upright position than contact shields; however, slight patient motion will move the shield to an improper position. Immobilization of the child helps to prevent this. Another advantage of shadow shields is a social one, in that no item is placed in contact with the genital area and the gonadal area does not need to be handled. However, even here palpation of the pubis is necessary to determine proper position of the shield in girls.

3.2.3

Shaped Contact Shields

Shaped contact shields are available for use in boys (HEW, 1975; Brown et al., 1971; Godley, 1973). They consist of a cup made either of lead or lead rubber which can be placed directly around the testes or, altematively, a lead cup that can be placed in an insert within a pair of specially-designed undershorts or athletic supports. Several commercial versions of the latter are available, either with washable or disposable undershorts, and these come in a variety of sizes (Figure 3.6).

The advantage of shaped contact shields is that the patient can be moved into various positions without rearranging the gonadal shield. Thus, these shields can be used during fluoroscopy where the other types are relatively ineffective. The difficulty with some of these shields is that female radiological technologists may be hesitant to place them on the patient (Brownet al., 1971). The underpants with the shield have the advantage that they can be put on by cooperative patients obviating the social problem. Another disadvantage is that their use is somewhat more time consuming and they are more expensive to use than either the shadow shield or contact shield. Care

3.2 MEANS OF GONADAL PROTECTION

Fig. 3.6.

/

29

Examples of shaped contact shields for boys (From Poznanski, 1976).

also has to be taken that underpants of a proper size are used. If the pants are too large, the shield moves away from the testes during patient movement. The shaped contact shield is used mainly when multiple projections are used;for example, in spine films with oblique views or in excretory urography. It may be used sometimes in fluoroscopy as well. Other methods for male gonadal shielding have been suggested. Krepler et al. (1977) used a specially-shaped contact shield together with a sheet of lead under the testes to decrease radiation backscatter. 3.2.4

Discussion

Generally speaking all of the gonad shields, when used properly, will offer some protection to the gonads. The choice of the type of gonadal protection is less important than the decision to use one. Even with the proper use of the various shields, there may be some interference with the examination. For example, in radiography of the pelvis, the pubis may be obscured and thus the shield should not be used in the evaluation of fracture. The lower-most portion of the bladder also may be excluded by the shield so that care has to be taken that these shields are used intelligently. They should be avoided in certain clinical situations where important anatomical portions may be excluded. Many times a decision on whether to use a shield has to be made by the radiological technologist. Therefore, education of the technologist in the matter will help in its proper use.

4.

Protection of Personnel and Parents 4.1

Immobilization of Patients

Some form of restraint is often necessary in the examination of the infant and toddler. When possible, mechanical means of immobilization should be used rather than having parents or employees hold the child. Although mechanical methods of immobilization are useful for the examination of the infant, these are often not very practical for the toddler. When a child must be held because of the impracticality of other means of immobilization, it should be done by a parent if possible rather than by an employee. If hospital employees are consistently used to hold patients, their exposures should be carefully monitored. Preferably, these employees should be rotated so that individuals do not receive excessive doses. In any case, whoever holds the child should be properly protected with leaded aprons and gloves.

4.2

Shielding

Leaded aprons or shields should be used by anyone who is in the radiation exposure room when the patient is examined. The type of lead apron will depend on the type of task an individual may perform. If the back of the individual must be repeatedly turned toward the patient, a wrap-around apron should be used. Distance is very effective in radiation protection, and individuals who do not need to be near the patient for support should be as far away as possible since the radiation from scatter will diminish approximately according to the inverse square law. Thus, a t 3 meters, the dose will be approximately 1/9th that a t 1meter. In the fluoroscopy of infants, the volume irradiated is much smaller than that in the adult or larger child so that the amount of scattered radiation is also much smaller. Lead gloves should be used when the hands are in the radiation field or very near to it. Even then, the hands should not be in the direct beam, but rather in the beam that has been attenuated by the patient. 30

4.4

EYE PROTECTION

/

31

Care should be taken that no other part of the operator is in the direct beam, that the operator is irradiated only by scattered radiation, and that proper protection against this scattered radiation is used. Leaded aprons and leaded gloves should be checked periodically for their integrity and a record kept of the results.

4.3

Fluoroscope Design and Irradiation of Personnel

In fluoroscopy with an under-table tube and above-table image intensifier, the scattered radiation to the fluoroscopist, particularly the head and neck, is diminished if the intensifier is very close to the patient and if a lead curtain is positioned between the patient and the fluoroscopist. The dose to the fluoroscopist from scatter in such an arrangement is least when he is directly opposite the intensifier or fluoroscopic screen. If the fluoroscopist is not in line with the lead curtain, the dose to his eyes and neck may increase significantly. In over-the-table tube/under-table intensifier systems, shielding of the operator or other personnel is much more difficult (Figure 4.1). There may be more than 2.5 times the amount of scatter to the eyes of the operator (Wholey, 1974). Similarly, doses to technologists may be 4 times greater with the over-table tube (Stacey et al., 1974). Scattered radiation is much more difficult to control. Various fixed shields can be used to help diminish this radiation (Eubig et al., 1978), but are difficult to maintain. Fluoroscopy using remote control units will significantly diminish radiation dose to the radiologist. Several special pediatric remote control fluoroscopy units are now commercially available, but are not widely used in the United States. U- or C-arm fluoroscope units present an even greater problem in radiation protection since it is more difficult to use fixed additional shielding for scattered radiation. However, with the use of shields the exposure to the eyes was reduced from 8.8 to 3.4 mR per examination and to the thyroid from 10 to 2.7 mR per examination in the study of Balter et al. (1978).

4.4

Eye Protection

The radiation exposure to the eyes of the fluoroscopist is very small when examining small children since the scattered radiation itsel€is relatively small. However, even in angiography or angiocardiography

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4.

PROTECTION OF PERSONNEL AND PARENTS

Exposure per hour

6

I

Exposure per hour mR1h 80kV 0.5mA Phantorn.5 thickness 200rnm

I

Fig. 4.1 a Radiation field during fluoroscopy. Standard over couch tube (From Bergstrom et al., 1977a). 4.1 b. Rediation field during fluoroscopy. Standard under couch tube (From Bergstrom et aL,1977a).

where larger doses usually result, these doses are well below those doses which produce cataracts. In adult cardiac catheterization,Rueter (1978) found the average exposure to the eyes of the operator per procedure to be 20 mR with considerable variability. This exposure

4.6 PREC~ANTPERSONNEL

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33

should be considerably lower in angiography of infants and small children. Eyeglasses with lenses containing lead will offer some protection to the fluoroscopist from scattered radiation when doing high dose studies, such as angiography (Bergstrom et aL, 197711; Littleton et al., 1978). As previously mentioned, various shields are also useful.

4.5

Monitoring Dose

Some form of radiation dosimeter is now requited in most states for individuals occupationally exposed to radiation. This usually is in the form of a filmbadge. In individuals who perform angiograms or other high dose studies, an additional monitor worn above the apron will give a dose measurement which is closely related to that received by the eye or thyroid (Rueter, 1978). In this situation, therefore, there may be an advantage to wearing two monitors, one under the apron for bone marrow dose and one above the apron to represent eye and thyroid dose.

4.6

Pregnant Personnel

Care should be taken to minimizethe radiation exposure to pregnant personnel in the fluoroscopic room. The maximum dose permitted to the fetus is 0.5 rad during gestation. (Thisis associated with a maternal exposure (R) several times greater than 0.5.) If proper protective devices are used in a pediatric radiological practice, the dose to pregnant radiologists, technologists, or parents will be several magnitudes smaller than 0.5 rad. This is true even if the individual is in the fluoroscopic room or does mobile examinations, so that these activities can usually be maintained. Examination of the employee's previous radiation record will determine whether the exposure received is likely to be below 0.5 rad and thus may be used as a guideline in determining whether such an employee should be permitted in fluoroscopy or to do mobile studies. For further discussion of this topic see NCRP Report No. 53 (NCRP, 1977a).

5. Immobilization of Children 5.1

Indications

Children not old enough to follow instructions to remain in a constant position are difficult to radiograph. Mechanical methods of immobilization are often useful in ensuring that the films are obtained in the proper projection and that motion is minimized. With mechanical means of immobilization, proper collimation is easier to achieve since there is less chance that the child will move out of the radiation beam. The use of immobilization devices also tends to improve the quality of examination, thus decreasing the need for repeat studies. The use of mechanical means of immobilization rather than parents or personnel to hold the child lessens the radiation exposure to these individuals. With proper techniques, immobilization can be simple, easy to use, and not traumatic to the child. Mechanical immobilization is used most frequently in infants where it has most value. Mechanical immobilization may not be necessary in the study of the premature and other very sick infants who do not move much. It may be very difficult in the premature infant because of problems in maintaining a sterile environment. In some of these situations, holding of the baby by personnel during exposure may be necessary. Because of the slight scatter in these studies, this represents little hazard (see also Section 6). Toddlers are the most difficult group to examine because it is difficult to use conventional immobilization techniques. One has to establish rapport and gain cooperation of these children. This may be time-consuming, but it is worthwhile. Sedation or anesthesia are sometimes needed, particularly for studies where exposure times or examination times are long, such as in tomography and computed tomography; or in situations where significant discomfort may occur, such as in angiography. In older children, the use of some immobilization device to support or steady an extremity may be of value even in a cooperative child. 5.2

Methods of Immobilization

There is no single optimal means of immobilizing infants for radiography. Many have been described in the literature since the 1920s 34

5.2 METHODS OF IMMOBILIZATION

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35

(Abraham, 1928;Abramson, 1928; Bowen, 1932;Chartres, 1967;Darling, 1978; Davis, 1967; Den Boer and Fedderna, 1978;Fortner, 1958; Geissberger, 1939; Harvey, 1942; Hedig, 1931; Kohn and Koiransky, 1931; Labrune, 1973; Lassrich et al., 1978; L'Heureux and Dopking, 1974; Miller, 1952; Pigg, 1961; Pornanski, 1976; Schuster et at.,1974; Shurtleff, 1962;Vezina, 1970;Wood, 1934).Many additional methods used in children's hospitals are not published. The methods described in the subsequent pages are intended as illustrations of some techniques that have been proved satisfactory. They are not necessarily the only ones. Many of the methods of immobilization use some sort of immobilization board to which a child is attached. This may be a simple board (Miller, 1952; Poznanski, 1976) (Figure 5.1) or a board with a ring attached to either end, such as the octagon board (Vezina, 1970) (Figure 5.2). These boards can be homemade according to published plans (Pmanski, 1976) and some are commercially available. One convenient method is to attach the infant to the boards by means of Velcro straps (Pornanski, 1976) (Figure 5.1). These pennit insertion and removal of the child very quickly, which speeds up the examination. Alternative methods of attachment include the use of elastic (Ace) bandages or adhesive tape. The bovds used should be made of relatively homogenous and radiolucent materials. One quarter inch tempered masonite, smooth on both sides and sealed with clear lacquer, is a convenient material that is readily available, casts no radiographic pattern, and is quite radiolucent. Plexiglas or plywood of the same thickness can also be used, but the Plexiglas is somewhat more opaque and the plywood occasionally shows some grain pattern on radiographs when used in studies made a t very low kilovoltage for small babies. The boards used should be smooth, readily washable, and have no cavities so that barium can be easily washed from them. The board can be angled in various positions by the use of angles, blocks, or wedges. The octagon board, which is commercially available, can actually be placed in 8 different positions; and with a drive mechanism (Figure 5.2)it can be placed at any desired angle.' For examination of the hands and feet, plastic sheets which compress the hands or feet and are held by weights or other devices will facilitate examinations of these parts (Figure 5.3).One-sixteenth inch acetate sheet is a useful material for this purpose, since it is flexible and will not shatter. Boards do not necessarily have to be used. The method used a t the Children's Hospital Medical Center in Boston is simply to attach the

'A commercial power driven cradle is aLao available (Spectnun).

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5.

IMMOBILIZATION OF CHILDREN

Fig. 6.1. Immobilization of a child by meam of an immobilization board (From Poplaneki 1976).

5.2 METHODS OF IMMOBILIZATION

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37

Fig. 6.2. immobilization of a child using the octagon board (From Pornanski, 1976).

Fig. 5.3.

Immobilization for a hand radiograph (From Pornanski, 1976),

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5. IMMOBILIZATION

OF CHILDREN

Fig. 5.4. Immobilization of an infant by means of adhesive tape, sandbags, and compression bands.

infant to the radiographic table by means of adhesive tape, sandbags, and compression bands (Figure 5.4). Special immobilization devices have been developed for chest radiography. Depending on the preference of the radiologist and technologist, a method may be chosen which functions in the supine or the upright position. The University of Michigan-Henry Ford Hospital chair offers a convenient method of immobilizing a child in the upright position (Poznanski, 1976) (Figures 5.5 and 5.6).The child is held in the chair by Velcro straps and the chair can be rotated in various oblique projections. There are also some commercially available devices for chest radiography.

\

METHODS O F IMMOBILIZATION

Fig. 5.5. University of Michigan-Henry Ford Hospital chair immob-g the upright position (From Poznanski, 1976).

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39

a child in

Care has to be taken when using immobilization methods so that the circulation to the extremities is not diminished. Good visibility of the toes and hands during the examination is important and they should be checked periodically. One should be certain that the straps do not obstruct the airway and are not applied over the mouth or nose or neck. Compression straps placed around the chest or abdomen should be loose enough so that they will not limit respiration, but tight enough so as to hold the child securely. When straps are used, additional methods of protection should be available so that the child will not fall out of the device. Abrasion to

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Fig. 6.6.

5. IMMOBILIZATION OF CHILDREN

UniveRity of Michigan-Henry Ford hospital chair i m m o b i i g a child in

the upright position.

the skin from the straps can be avoided if care is taken in applying the straps so that the rough surfaces do not touch the bare skin and the straps are not too loose. In any method of immobilization, excessive flexion of the neck should be avoided as this can cause difficulty with respiration. Generally speaking, commonly used methods of immobilization are safe when used in a thoughtful, knowledgeable manner.

6. Equipment Considerations in

Pediatric Radiology 6.1 Radiographic Unite

In a radiographic room used for children, the control panel should offer easy visibility and auditory contact between the M d and the technologist. This is important with children as it helps to establish rapport, increase the child's cooperation, and thus may decrease the need for repeat studia A three-phase, twelve-pulse generator and control system capable of a t least 600-800 milliamperes with linear output characteristics in a range of 50 through 120 or 150 kV is recommended. It should have timing circuitry that is able to provide radiographic exposure times as ahort as tiuee milliseconds and automatic exposure control circuitry accurate to 6 milliseconds. Separate rotor and exposure controls are important in examining children so that the exposure can be obtained within milliseconds of the time the exposure switch is activated. To permit this rapid start of x radiation output it is essential that a generator have a short interrogation time. This is particularly important in chest radiographs so that films can be obtained in the desired phase of respiration. Automatic exposure control, if available, should have a fast response because of the short exposure times used. Detectors should be of appropriate size and arranged in a proper codiguration for pediatric patients. Otherwise, the detectors should not be used at all because they will not afford the advantages of proper exposure and may allow the patient to be exposed u n n d y .

6.2

6.2.1

Imaging System

Film-Screen Combinations

There is no consensus among radiologists about what &-screen cornbibations are ideal tor pediatric radiology. The dower film-screen 41

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6.

EQUIPMENT IN PEDIATRIC RADIOLOGY

combinations, in general, produce a more detailed image with less quantum mottle than the faster systems, but they do this in association with increased radiation exposure to the patient. The fast film-screen combinations, although inherently producing a less detailed image with good quantum mottle, can, when there is motion, produce a better quality image than the slow systems since shorter exposures are required and motion blur will therefore be less. The matter is further complicated by the availability of rare earth phosphors which generally permit 2-3 times lower radiation doses than conventional screens for the same amount of spatial frequency information a t certain kVp levels (Wagner and Weaver, 1976). The decrease in radiation may be eightfold if more quantum mottle is acceptable. These rare earth screens, however, have two disadvantages: they cost 2-3 times more than conventional screens and they have a greater kV dependence. This makes them more difficult to match to presently available generators, particularly when phototiming is used. At low kilovoltage, around 5060 kV, where many neonatal films are obtained, the saving in radiation is smaller than at higher kilovoltages. There appears to be no single system that is ideal for each examination since some examinations require much less detail visualization than others. There is probably an advantage to using more than one film-screen combination and thus be able to tailor the detector to the particular examination. For example, the fastest film-screen combination could be used for the evaluation of the healing of hctwes; scoliosis; bone age studies; progress of many orthopedic conditions, such as Legg Perthes disease, dislocation, slipped capital epiphyses, and limb l e ~ g t hdetermination For these examinations, a high speed rare earth film-screen combination could be used without loss of the information of interest. The difficulty in using systems with different sensitivities is the increased chance of using inappropriate techniques or of loading a cassette with improperly matched film. Also, it is more difficult to use different speed systems with automatic timing. There is a lack of agreement on whether chest radiographs and detailed bone radiographs are satisfactory with the new rare earth intensifying screens (Godderidge, 1980; Wesenberg et d,1977). In some of these examinations, the mottle may be quite disturbing when using a high-speed rare earth system. Although nonscreen films have been useful in the past for evaluation of the hand, for small erosions, or subperiosteal resorption, present mammography film-screen combinations offer comparable detail a t a lower radiation dose. Xeroradiography generally is associated with 6-10 times higher radiation dose than screen film (Wolfe, 1969; Scott et ad.,1978; Rosen-

field et aL.,1978; Bryant and Julian, 1978) and should not be used routinely. It is sometimes of value in evaluating soft tissue changes, particularly in the airway or in searching for slightly radiopaque or radiolucent foreign bodies, such as wood (Woesner and Sanders, 1972). Cassettes with graphite fronts have lower absorption than conventional materials. When used in situations of low kilovoltage and radiography of small parts, such as an infant chest, they can reduce the radiation exposure to the patient by 25-50 percent (Budin, 1980; Shuping et at., 1980).

Since scattered radiation varies with the volume irradiated, no grids are needed for radiography of small infants.When radiographinglarger +ts, grids may be necessary to reduce scatter. Ideally, lower ratio grids should be used for low kV studies. In most modem equipment, grids are interchangeable without requiring hand tools. A rapidly moving grid is necessary in pediatric use because of the short erposure times that are often required. Alternatively, stationary fine line grids canbeused.

6.4

Processing

Proper processing of radiographic films, cine, and fluoroscopic spot films is very important in dose reduction. Goldman (1977) showed that in one institution the number of retakes increased proportionately with greater variation in processing. .Underdevelopment can lead to over-exposure in two ways: on a short-term bas& repeat studies will be required since films will be too light; in the long term, underdevelopment will be compensated for by the technologist by giving larger exposures to the patient. Over-processing usually increases fog and may make the examination unsatisfactory. Manual processing is generally more subject to error than automatic processing, since it often results in marked variability in development. If manual processing is employed, sight development should be avoided and great care must be taken to provide proper temperature, replenishment, and time in the developer and fixer. Automatic procesora should be carefully maintained by properly trained individuals and should be monitored daily by routine freshly

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6. EQUIPMENT IN PEDIATRIC RADIOLOGY

exposed sensitometric strips (Poznanski and Smith, 1968) so that the density remains within a constant preassigned range. Pre-exposed strips should not be used since, even after three days, the strips may lose their sensitivity to development changes (Vucich and Goldman, 1977). Density changes may be due to alterations in developer temperature, faulty replenishment, chenical contamination, changes in the pH of solution, or alterations in film transport speed. By charting the sensitometric strips on a daily basis, trends in processor malfunction can be detected and separated from the normal daily variation. Replenishment rate is usually set for an average mix of films. When pediatric films are processed, there generally will be a greater number of smaller films than in the case of films of adults, and therefore a lower replenishment rate may be appropriate in certain situations. Other ways to avoid factors affecting processing include making certain that proper safelights are present in the darkroom-filter type, the bulb wattage, and distance should be as recommended by the manufacturer for the type of film being used-and that the film is never stored in areas of high temperature or where it can be exposed to radiation. For example, cassettes should not be left in locations in radiographic rooms or on top of processors where extra heat may cause fogging. An automatic processor that has not processed a film for 20 minutes should be "primed" with a film to ensure that the cross-over rollers are properly wetted when the patient film goes through

6.6

Fluoroscopic Equipment

Conventional fluoroscopes without image intensifiers should not be used in the examination of children They provide less diagnostic information and, in practice, also give higher radiation dose to the patient. Image intensifiers are available in several sizes. For smaller children, the 6-inch units are preferable, but in dealing with a mix of children, including those of adult size, Winch units may be necesllary. Image intensifier tubes are also available with dual or triple modes (allowing the use of two or three field sizes), but smaller intensifier units sometimes produce a better image than the gmaller mode of the dual or triple tubes and may use a lower amount of radiation than the combined tube. Cesium iodide image tubes have the advantage of providing superior detail and do not appear to have the relatively rapid 1- of inteneibi-

6.5

FLUOROSCOPIC EQUIPMENT

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45

cation that was seen with.the older tubes. Although the image intensifying tube system using mirror viewing may be acceptable, attached closed circuit television systems coupled to the image intensifier have the advantage that the image may be videotaped for use in critical evaluation and re-evaluation of fluoroscopic findings without further radiation exposure of the patient. The minimum amount of filtration in a fluoroscopic unit is mandated by regulations of the Bureau of Radiological Health (BRH). However, additional filtration in fluoroscopy may be of value in decreasing radiation (Villagran et al., 1978). A filter of 0.1 mm of molybdenum reduces the exposure to the patient by a factor of 2 or 3 for the same information content (Heinrich and Schuster, 1976).However, this filter reduces the tube output about two-fold and thus interferes with the ability to examine larger patients. Hence, it may not be practical in all situations. Generally, the larger the amount of radiation used in an image intensifier system, the more scintillation-free is the image. A compromise has to be reached in the balance between image quality and altering the iris diaphragm or "f" stop of the television camera lens. The wider the diaphragm opening (lower "f" stop), the more light is available to the camera and the less radiation is needed. A variable iris diaphragm would offer an advantage as it would pennit use of different levels of radiation for different clinical situations (Rossi et al., 1978). In many units, the x-ray output of the tube is controlled by a feedback mechanism. Thus,if the "f" stop number is very high, a scintillationfree image is produced at the cost of much greater radiation. This quality of image may not be necessary in most situations. When the camera aperture is wide open (lowest "f" stop number), the radiation needed is much lower, but the image may be objectionable because of the excessive scintillation and camera lens aberration. Again, a compromise must be reached. Some of the more modem machines have a mechanism to fluoroscope with automatic brightness control at low, medium, or high dose rates This flexibility is a significant advantage in the examination of children. Spot films obtained by photographing the output phosphor, such as can be done with 70,90, 100, or 105 m m spot films, may require only about one-fifth the amount of radiation of conventional filming, although when compared with fast rate-earth screens, this advantage is smaller. Using these photofluorographic spot films has the advantage of not only reducing the radiation dose to the patient, but also of shortening the exposure time, thus decreasing motion blurring. The information lost in these spot films as compared with the conventional ones is only slight. Another advantage of the photofluorographic spot

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6. EQUIPMENT IN PEDIATRIC RADIOLOGY

film is that it can be obtained instantaneously a t a specific desired time which gives a greater chance to capture a desired phase of a rapidly changing phenomenon. In many commercially available units, these fluorographic spot films can be made individually or in a rapid sequence, so that multiple exposures are obtained as long as the exposure switch is in the on position. The rapid sequence method should be used only when it is needed for a specific purpose, such as capturing a rapidly moving structure, e.g., the upper esophagus. Use of this mode routinely for all filming will increase unnecessarily the number of films obtained and, therefore, unnecessarily increase the radiation dose to the patient.

6.6

Cineradiography

Cine systems should be pulsed so that the radiation exposure only occurs during the time that the camera shutter is open. Cine chould be operated a t a minimum rate necessary for the information desired. In most situations, 16 mm filming is adequate and should be used since 35 mrn usually requires a larger radiation dose. However, for cardiac examinations many physicians stiU prefer 35 mm film. In cardiac angiography, as in radiography, a balance must be reached between radiation dose and image quality. For optimal quality, a 35 mm camera is recommended. The report of the Intersociety Commission for Heart Disease Resources (Judkins et al., 1976) recommends that a t least 20 p a d per cine frame should be used when the cine is viewed a t a t least 24 frames per second, while photofluorographic spot film fluorograms should receive 100 p a d image input per frame. The measurements are a t the input plane without a grid imposed between the sensor and the input plane. The aperture of the lens in the cine camera should be open as much as possible to decrease radiation. The limiting factors are the increase in scintillations as the aperture is opened and the decreased image quality when the lens is wide open. As a result, the cine camera lens should be closed to a t least one "f" stop above the maximum aperture.

6.7

Computed Tomography (CT)

The same basic principles of radiation protection hold in computed tomography (CT) as in conventional radiography. Particularly with modern CT units, the radiation dose to the patient is comparable to

6.7 COMPUTED TOMOGRAPHY (C.T.)

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47

conventional radiography (Shrivastava et al., 1977; McCullough and Payne, 1978;Bassano et al., 1977;Brasch et al., 1978). As in conventional dlming, proper indications should be present for performing computed tomographic examinations. As is true for all radiological procedures, CT should be done under the supervision of a physician who has experience in radiation protection and knowledge of the implications of radiobiology. Also, as in conventional studies, the examination should be tailored so that the minimum number of scans should be obtained to give the necessary radiological information. In most cases, collimation is very good in modem CT units so that there is very little radiation outside of each scan. Thus,more scans simply mean that a larger volume of the patient is irradiated, not that the area studied receives a greater dose, unless overlapping scans are obtained. Increasing the number of scans in CT is equivalent to increasing the field size in conventional radiography. It differs from conventional tomography where each additional scan gives additional radiation to the same area. The dose to the area irradiated in computed tomography is similar to that received from conventional examinations. There is considerable variation among the different scanners. The surface doses in abdominal scans in children ranged from 0.39 to 5.60 rads in the study of B m h et al. (1978).With modern scanning, the doses are comparable with those received from an excretory urogram where 4 films may give 0.5 rad (Webster et al., 1974) [although the mid-body dose for excretory urethrography is smaller than that given in CT]. The dose in CT is less than that given in a renal arteriograrn where 1.5 minutes of fluoroscopy and 20 f h will give 11.6 rads (Webster et al., 1974).The dose to the head in cranial or brain scans is comparable with that received in conventional skull radiography and significantly less than in cerebral angiography (Webster et al., 1974). Because high kilovoltage is used in computed tomography, scattered radiation will be greater than with most conventional radiography of the same region. Dose values near the scanner are about 1-2m a d / slice a t 1 meter from the scan circle (McCullough and Payne, 1978). Therefore, an individual restraining a child may receive more radiation than in radiography, so mechanical restraining devices may be more important. Also, the dose to remote organs may be greater. For example, in CT of the head, a study of a 10 kg child will give a skin dose of 1.3 rads, a dose to the thyroid of 310 mrad, and to the gonads, 30 mrad (Bhave et al., 1977). These doses are higher ~ h a nthe dose (less than 1 mrad) that is usually absorbed by the gonads with a routine skull series. As in conventional radiology, the radiation dose from scattered

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6. EQUIPMENT

IN PEDIATRIC RADIOLOGY

radiation to organs outside of the field will be proportionately greater in smaller children since these organs will be nearer to the scattering area. For example, in a head scan the dose to the thyroid is 70 mrad in a 40-cm tall child and 40 mrad in a W-cm tall child. The gonadal doses for the same two heights will be 11 and 4 mrad, respectively (Bhave et d,1977). CT units that permit very short exposure times have an advantage for children where motion is a greater problem than it is in adults

6.8

Dental Radiography

Dental radiography in children presents many of the same radiation protection problems as were considered previously for medical pediatric radiography. Some typical exposures in dental radiography are given in Table A.4, Appendix A. As in pediatric radiology generally, it i s important that proper rapport with the child be established so that cooperation may be obtained (Bean and Isaac, 1973).It is also important that the individual taking the films is familiar with radiographic techniques, particularly in children, so that the incidence of repeat films can be minimized. Quality control techniques are equally applicable in dental radiography as in medical radiography. Particularly, much attention must be paid to optimal processing and quality control, since processing in dental radiography is usually manual (Overend, 1976). High-speed screens can be used in panoramic radiography and cephalography, with consequent decrease in radiation to the child (Reiskin et aL, 1977).There is some loss of image quality when much faster film-screen combinntions are used, and a trade-off h a to be made between the radiation and the information available on the film. The choice of kilovoltage will also affect the radiation received by the patient. The higher the kilovoltage, the lower the radiation dose and the shorter the exposure time, with consequent minimbation of motion. However, contrast decreases at higher kilovoltagee, and a compromise must be reached on the optimal kilovoltage to be used. In dental radiography, the greatest concern of radiation protection is the radiation to the thyroid and perhaps the salivary glands. When using modem dental radiographic equipment, there is relatively little bone marrow or gonadal irradiation. The thyroid dose can be diminished by thyroid shielding, both in cephalometry and in panoramic radiography (Myers et ol., 1978;Block et ol., 1977).The reduction is greater in cephalometric radiography, where it can be from 50 percent

6.8 DENTAL RADIOGRAPHY

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49

to 85 percent. There are some problems in shielding the thyroid of

dchildren when using the standard thyroid shields, which are too large for small children. These, however, can be cut down to appropriate size for the smaller patients, so that they do not obstruct the view of important structures. For example, a thyroid shield sometimes may interfere with the vhdization of the lower border of the mandible. Gonadal shields or aprons over the gonads are of relatively little value with modern, tightly collimated dental radiography equipment. However, they do help in making the patient aware that there is concern with radiation protection. Pointad cones on dental radiographic units give a larger radiation dose to the patient than do the parallel-shielded cones that are now available in new dental machines (Weissman and Sobkowski, 1970). The pointad cones also irradiate a much larger area, with consequently greater thyroid irradiation. In children, smaller field sizes can be used than in adults. As in conventional radiography, the field size should not exceed the size of the film, since radiation outside the film does not add to the diagnostic information. In panoramic radiography, field size can be diminished by decreasing the height of the beam, this will significantly diminish the dose to the thyroid and adjacent organs. As in medical radiography, it is important that the dental radiographs be obtained for valid indications (White and Tsamtsouris, 1977). Generally, dental films should not be obtained in children on a purely routine basis, but only if some benefit from the radiographs is expected (Valachovicand Lurie, 1980).The frequency of filming should also be tailored to the clinical situation. For example, children with much decay may need more frequent radiologic examinations than children who do not have this problem. The number of views obtained should also be tailored to the clinical needs. Irradiation of personnel may also be a greater problem in pediatric dental radiography than in radiography of older patients. It is important that, whenever possible, film holding devices be used. These devices eliminate the need for the patient to hold the film packet with his hand and they help in positioning and stabilizing the film. If someone else must hold the film, this individual should not be an occupationally exposed person (radiation worker) and should be properly shielded.

7. Special Problems of Mobile Equipment 7.1 General Studies performed with mobile equipment have a greater potential than standard studies for unnecessary radiation exposure of personnel and other patients. If care is not taken, greater radiation exposure to the patient may also occur from examinations with mobile x-ray equipment. When selecting a mobile unit for use in pediatric radiology, one should choose a unit with the greatest possible output. In examinations with mobile units there appears to be a greater variability in exposure since other variables are introduced, such as variation in distance from the tube to the patient, which is harder to maintain constant than is the case with fixed radiographic units. Similarly,line voltage variation in patient rooms may be great when a mobile unit is used, affecting the output of the machine. Capacitor discharge or rechargeable units have the advantage that they are not affected by line voltage fluctuations although some of them have the problem of different output depending on the amount of charge stored. In neonatal nurseries, potential radiation exposure of personnel from use of mobile equipment is usually not as great as in radiography of larger children, since only a very small volume is irradiated with very little scatter. For example, in a typical neonatal intensive care nursery with 5 patients, if each infant received two AP films, the dose at a distance of one foot from any infant will always be less than 70 p a d (Pornanski et ale, 1974). Thus,if an employee was in the nursery all year long on an eight-hour shift, but was always more than one foot away from any infant being radiographed, the maximum dose to such an employee would be less than 18 millirad, which is a small percentage of background radiation (100 mrad). In a neonatal intensive care nursery, leaded aprons should be worn if a nurse or aide is within one foot of the patient being radiographed, but the leaded aprons may be omitted if the nurse or aide is more distantly located. Also, there is no need for the nurse or attendant to leave other infants unattended in the nursery when radiographs are being made. When the primary beam is directed horizontally, care must be taken not to aim the beam a t any other patient or individual in the room; or, alternatively, a 60

7.2 RADIOGRAPHY

IN OPERATING ROOMS

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51

shield should be used behind the infant being radiographed so as to intercept the entire primary beam beyond the patient. Because no good method of immobilization has yet been developed for use on a premature infant in an incubator, the infant ofen must be held for the exposure. The individual holding the infant should keep

Fig. 7.1. Examples of shielding utilized in horizontal beam radiography in which an individual is required to hold the infant.

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7. SPECIAL PROBLEMS OF MOBILE

EQUIPMENT

his hands well out of the primary beIn horizontal beam radiography, the beam often must be aimed at the individual holding the infant which is not acceptable in most other forms of radiography. However, this produces no significant dose to the holder when radiographing premature infants if a 0.5 mm lead apron is worn or if a shield is placed between the cassette and the individual holding the infant (Figure 7.1). bdiography of older patients using a mobile unit produces much more scatter, and much greater care has to be taken for personnel or other patients in the nearby area. It is important to remember that because of the inverse square law, distance often provides the best protection. Thus,at 30 cm the radiation exposure is approximately 100 times that at 3 m. In using mobile x-ray equipment, the radiologic techonologist must wear an apron and, if possible, stand a t least 2 meters from the patient (NCRP, 1976). The beam should not be pointed at other patients or personnel in the vicinity. Other children in the room should be protected by aprons or other shields if they are within 3 meters of the child being radiographed.

7.2

Radiography in Operating Rooms

At the present time, explosive anesthetics are rarely used in children. When radiography is necessary during operative procedures, non-explosive agents should be used. In this way, conventional mobile units can be used rather than the explosion-proof ones in which light localkers may not be available. Light localization and collimation are particularly important in the operating room where positioning may often be very difficult, where the n o d anatomic landmarks are not usually palpable, and the film cassette is partially covered by drapes. Care must be taken that the primary beam is perpendicular to the film in the operating room, particularly when a grid is used. If this is not the circumstance, a signiiicant decrease in film density will occur and repeated etudies will be necessary.

7W

Mobile Fluoroecopy

Potential radiation hazards are particularly diflicult to control when mobile fluomopic units are used (Kockum et ul., 1958). Generally, mobile fluoroscopy produces larger amounts of radiation than does radiography. The units are d y in a "C" configuration and have relatively few means for protection 6om scattered radiatioa The uee

7.3 MOBILE nUORqSCOPY

/

53

of mobile fluoroscopic equipment should be kept tf! a minimum. If used in the operating room in orthopedic procedpres or for foreign body localization, it should be used with a video disc or other image storage device, when possible. Otherwise, excessixg 'ff)$ation may be delivered to the patient and the surgical team. If these stprage devices are not available, films should be substituted for fluoroscopy.

APPENDIX A

Doses from Various Examinations in Pediatric Radiology Table A.l presents maximum skin doses for diagnostic x-ray examinations for children of ages 1, 5,10 and 15 years. The term maximum dose refers to the maximum dose obtained with the techniques used in the author's institution (Webster et al., 1974) and certainly could be exceeded if different technical factors were used. Table A.2 presents mean whole body doses for the same examinations and ages (Webster et aL, 1974). Tables A.3a-A.3c present gonadal doses for children of ages 6 months. 1and 12 years (Webster et aL. 1974). Table A-4 presents some typical skin entry exposures received in dental radiology (Valachovic and Lurie, 1980).

56

/

APPENDLX A

TABLE A.l-Maximwn skin doses in x-ray exatninafions (rad).'

1. Cerebral Studies Radiography, skull mries, 5 films Biplane cerebral angiography. 48 flIm Fluoroscopy. 6 min 2. Angwcomlwgraphy Biplane serial radiography, 40 films Cineradiography 35 mm. 60 fps,"60s Fluol-oscopy, 30 min 3. Kuhey, Ureters, Bladder Intravenous pyelography. 4 films Renal angiography, 20 films AP Fluoroscopy. 4 rnin Cinecystourethrography, 16 mm, 7% kk 1.6 min Fluorascopy, 2 min 4. Chest Radiography, PA and lateral Puhonary &ography, 30 films A P Fluoroscopy, 1.5min 5. Liver Radiography. abdomen AP film Abdominal angiography, 30 films' Fluoroscopy, 5 min 6. Bone Cervical spine. AP and lateral Dorsal or lumbar spine. AP and lateral Pelvis, AP and lateral 7. Obstetrics Obstetric abdomen

0.3 8.4 3

0.7 11.4 4.8

0.9 12.0 7.2

1.8 2.8 24

3.3 4.2 36

5.7

02 1.4 32 0.8 22

0.3 3.0 4.8 1.3 3.0

0.05 3.0 1.2

0.03 0.05 0.07 6.4 10.2 15.9 1.8 2.6 3.3

0.05 2.1 4

0.08 0.18 0.25 4.5 15 23 6 8.5 11

0.05 03 0.1

0.1 0.4 0.15

6.6

51 0.5 4.8 6.8 2.1 4.3

0.1 0.9 0.3

1.1

13.2 9.6 7.2 10.6 66

0.75 7.5 8.8 2.7 5.2

0.15 1.6 0.45

Fetal dose 1.0 Pelvimetry Fetal dose 4.0 The term maximum refers to the marimurn with the techniques wed in the authore' institution and certainly could be exceeded if different technical factors were used (From Webster et ah, 1974). RameS per m n d Magnification technique for 1 and 5 years.

/

APPENDIX A

57

TABLEA.2-Mum who&-bodydoses in x-ray emmh&ona (rad)? AGE m YEARS X - I ~ YEmmm~nax

1. cerebrcrl studies Radiography, eeriea, 6 61ms Siplaw cerebral angiography,48 films Fluoroscopy,6 min

1

5

0.02 0.04 0.6 0.65 0.W 0.05

10

15

0.04 0.04 0.5 0.4 0.07 0.08

2. AngiOcdgr4phy

Biplane selid radbp~aphy, 40 filme

Cinerndiogmphy.35 mm, 60 kb 60 .a Fluomscopy.30 min 3. K M ,Ureter%,Bladder htravenous pyelography.4 t i h a Renal mgiopnphy,20 films AP 4 min F'~uoroecopy, ~inecyatourethrography, 16 mm,7%Mb 1.6 min Fluomecopy,2 min 4. Chest Radiography,PA and lateral Pulmonary arteriogaPhy,30 filmsAP Fluoroscopy,15 mia 5. Liver Radbpaphy,abdomen, AP film Abdominal angimhy,30 hC Fluomxopy,5 min 6. Bone Cemcal spine, AP md Lateral Doreal or lumbar spine. AP and Lateral Pelvis,AP and lateral 7. Obstebics Obstetric abdomen

Pelvimetry 'From Webeter et aL (1974). Rames per second M a g d h t i o n technique for 1 and 5 years.

0.13 0.08 0.26

0.22 0.27 0.25 0.08 0.08 0.08 0.5 0.6 a6

0.03 0.03 0.15 0.04 0.1

0.04 0.06 02 0.06 0.15

0 . 0.06 02 0.06 0.15

0.07 0.06 0.2 0.06 0.15

0.W 0.005 0.008 0.007 0.6 0.8 09 03 0.05 0.07 0.08 0.08 0.005 0.015 0.03 02 0.4 1.2 0.2 0.25 0.3

0.03 1.3 0.3

0.006 0.015 0.015 0.015 0.02 0.07 0.15 0.15 0.01 0.03 0.05 0.05

Fetal dose 1.0 Fetd d m 2.0

58 /

APPENDIX A

Abdomen

Pelvia

37" oblique

11

66

50

40

Lateral

13

64

50

40

Anteroposterior

10

50

10

40

Lateral

12

64

10

40

Anteroposterior

7

52

25

40

Anteroposterior with plaster

8

64

25

40

Upshot

' From Aspin (1965). Target-Film-Distance.

7.5

60

25

40

max. min. max. min. max. min. max. min. max. min. ma%. min. max. min. max.

43 5.7 95 4.4 44 0.92 14 1.1 12 23 35

39 44 48 55

42 86 100

68 &d 7.2 10 16 18 24 27 31 37 38 46

TABLE A.3b-Gonadal dose in a 4-year-old child (mrad/film)." Thickness (cm)

kVp

Skull

Anteroposterior

15

76

Lateral

13

Sinuses

Waters Lateral Towne's Law Anteroposterior (co-operative patient) Anteroposterior (unco-operative patient) Lateral

19 12 16 13 9

Mastoids

56 90 68

Cervical spine

Field

10

40

72

10

40

90

56

10 10 10 10 25

30 30 30 30 40

9

64

10

40

10

66

10

40

9

70

10

40

Odontoid (moving jaw)

13

76

75

40

Anteroposterior

13

58

10

72

Postero-anterior

13

58

10

72

Lateral

20

77

10

72

Anteroposterior

12.5

49

50

40

37' oblique

13.5

64

50

40

min. max. min. max. min. min. min. min. min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max.

Projection

Odontoid (still jaw)

Chest

Thoracic spine

8

T.F.D.b (in.)

Reeion

mha

Size

Male 0.040 0.088 0.034 0.081 0.030 0.0054 0.085 0.036 0.035 0.16 0.022 0.10 0.0096 0.060 0.030 0.1 1 0.25 0.42 0.096 4.8 0.019 1.3 0.097 4.7 0.098 0.51 0.20 1.1

Female 0.075 0.18 0.058 .0.16 0.073 0.015 0.16 0.052 0.071 0.8 0.053 0.41 0.03 1 0.31 0.072 0.34 0.53 1.4 0.39 3.2 0.44 3.4 0.64 4.3 0.58 3.8 1.O 7.3

\

%

8

E

*

Lateral Lumbar spine

Full opine

Pelvie

70

50

40

min.

Antemposterior

11

52

50

40

max. min.

37O oblique

15

73

50

40

max. min.

Lateral

20

78

50

40

max. min.

Anteropoaterior Anbropoabrior

Abdomen

19

9 plaster

11

57,

200

72

13

69

200

72

max. min. max.

min. max. min. max. min. max.

Antempoatenor

11

56

10

40

Lateral

20

&

25

40

Anteroposterior

11

60

25

40

Antaropoetenor in plater

13

72

25

40

min.

upehot

11.5

68

25

40

min. max.

pin. max. max.

a

h r n A s p i (19661. Target-Fi-Distance.

0.2 1 1.O 3.3 75 11

230 14 62 110 120 180 190 1.2 18 6.6 23 55 62 70 78 95 110

1.3 6.0 41 47 140 150 81 100 77 82 89 94 11 12 73 92 33 35 37 42 56 64

%''8

m

u2 52

*

62 /

APPENDIX A

Lumbar spine

Full spine

Abdomen

Pelvis

Lateral

25

82

75

40

Anteroposterior

14

58

75

40

37' oblique

18

79

75

40

Lateral

28

94

75

40

Anteroposterior

14

63

200

72

Anteroposterior in plaster

16

75

200

72

Anteroposterior

13

60

25

40

Lateral

27

98

25

40

Anteroposterior

14

66

25

40

Anteroposterior in plaster

16

80

25

40

Upshot

14

78

25

40

'From Aspin (1965). Target-Film-Distance

min. max. min. max. min. max. min. max. min. max. rnin. max. min. max. min. max. min. max. min. max. min. max.

0.33 0.88 3.2 15 12 28 6.3 16 140 150

200 220 5.4 60 5.2 28 75 84 83 96 127 136

0.48 1.6 72 100 240 270 110 140 89 96 110 120 35 35 69 74 38 45 57 62 65 72

5z

5 X

%

61

/

APPENDIX A

TABLEA.4-Same typical skin enby c q m w r e s in dental radwlogv..' Qpe at eramination

S i e molar periapical film (long. lined. open ended cone) Paralleling technique: 70 kVp 90 kVp 70 kVpC Paralleling technique with beam-guiding device: 90 kVp National average. U.S., 1970. per intraoral film National average. U.S.. 1978. per intraoral film Panoramic film Conventional film-screen combition Rare earth film-screen combination Lateral cephalometxic film Conventional Nm-ecreen combination Rare earth Nm-acreen combination

'h o r n Valachovic and Lurie (1980). Total exposure to patient.

'With samarium filtration.

7SY 600 310 264 210 910 500 4500-6000

1000-3oO 103 5-20

APPENDIX B

Methods for Estimating Selected Organ Doses for Projections Commonly Used in Pediatric Radiology Rosenstein et al. (1979) developed tables that give an estimate of the radiation dose to various organs for radiographic examinations commonly performed in infants and small chiIdren. The data are available only for newborn, 1 year olds, and 5 year olds. The tables (Tables B1-B20) give the dose in mrad per R entrance exposure. To use these tables, one needs the half value layer of the radiation used and the entrance exposure (in air).

Eetimating Exposure Rate and HVL If these two factom are not known, they can be estimated from the kVp, mA, filtration, and source to skin distance. NCRP Report No. 54 (1977b) illustrates how this can be done. The estimated expoAure rate in air (mR/mAa) as a function of kVp and total aluminum filtration at 40" (1 meter) from the x-ray source can be obtained from Figure B.1 for single phase equipment. For three phase, the values need to be multiplied by a fador of 1.85. Ifa distance other than 40" is used, an inverse square law correction must be made. The half-value layer in mm of aluminum (HVL), if unknown, may be estimated from Table B.21a for full-wave rectified potential x-ray machines; and from Table B.21b for threephase and conatant potential equipment. If the filtration and HVL are not known, for calculation purposes m e a total filtration or a HVL of 2.5 mm of aluminum. 65

66 /

APPENDIX B

Newborn 1-year 5-year

(2)

Ovaries

Thyroid

Newborn I -year 5-vear

(490) (270)

Active Bone Marrow

Newborn I-year 5-vear

57 26

Lunga

Newborn 1-year 5-year

142 14

Total Body

Newborn 1-year 5-year

297 155

+

(410) 1240)

' 'See Note 2 for explanation of values in parenthesis, page 106 See Note 4, page 107

33

+

,

(490) (270) 73 35

23

' From Rosenstein et al. (1979). See Note 1, page 106

(2)

+ +

(66) 15 188 97

155 21 326 181

+ + (410) 1240) 44 35

(56) 27 213 122

(2)

+

(490) (270) 78 37 193 27 345 192

+ + (410) (240)

22 19 18

48 42 (56) 29

6.5 10 8.7

229 132

0.5 0.5 0.5

m

TABLE B2-AP SKULL-organ dose (mrad) for 1 R entrance exposure (free-in-air).' SID AND FIELD SIZE

REFERENCE PATIENT

Sow-to-image receptor distance (SID) (centimeters [inches]) Field size at image receptor (centimeters [inches]) Collimated to film size #I Collimated to film size 6 2

Newborn

I-year old

5-year old

102 [40]

102 [40]

91 [36]

ORGAN DOSE (mrad/R) BEAM QUALITY (HVL. mm At) -+

2.0

Film

COLLIMATION -r

#1

3.0

2.5

Film #2

Film #1

Film #2

Film #I

Film #2

Maximum coefficient of variation (I)

Testes

Newborn I-year 5-year

+ +

+ +

+ +

+ +

+ +

+ +

2.0 SO 9'0

EEI 8PZ

861

MI ZCZ

fa

'681

LOI OOZ

LOE

191 PLz

'(6161) ' I D l a u!avuasoH wold. 901 a8wd 'I WON a s ,

marc-9 ma&-1 UlOqMaN

9'0 VI

w F l W0.L

k o m ~ auog a ~ y q

L'I

70 /

APPENDIX B

Active Bone Marrow

Newborn I-year byear

+

+ +

+

Newborn I-year 6-year

(130)

(130) (90)

(130)

Newborn I-year bvear

32

50 35

43

Newborn 1-year 5-vear

17

60 27

23

+

+

+ +

(130)

(130)

(130) (90)

+

(90) 68

46

48

35 26

72 51

26

76

78

47

40

9.0 6.4

-

Total Body

Newborn 1-year 5-y~ar

155

h m Rosenstein et al. (1979). * See Note 1, page 106 See Note 2 for explanation of values in parenthesis, page 106

''

195 106

180

226 124

192

24 1 131

0.5 0.4

m

TABLE B4-LAT SKULL-organ dose (mad) for I R entrance exposure (free-hair).' SID A N D FIELD SUE

REFERENCE PATIENT

I-yearold

Newborn

5-year

old

Source-to-image receptor distance (SID) (centimeters [inches]) Field size at image receptor (centimeters[inches]) Collimated to 1% size +1 Collimated to film size #2 ORGAN DOSE (mrad/R)

BEAM QUALITY (HVL, mm Al) -r COLLIMATION -r

Newborn 1-year

2.0

3.0

2.5

Maximum coefficient

Fi

Film

Film

Film

Film

Fi

of

#1

62

61

62

#1

#2

variation (46)

+ +

+

+ +

+

+ +

+

Newborn I-year 5-vear

Ovaries

Newborn I-year 5-vear

+ +

+

+

(460)

(300)

+ + (460)

(380) 322

(300)

+ +

+ +

+ +

(460)

(380) 364

(380)

(300)

425 -

Newborn 1-year 5-vear

35 28

Lung

Newborn 1-year 5-year

16 9

Total Body

Newborn 1-year 5-year

240 166

Active Bone

Marrow -

-

48 39

47 35 -

'From k n s t e i n et 01. (1979). * See Note 1, page 106 'See Note 2 for explanation of values in parentheeie, page 106

'

34 26

46 38

21 10 196 107

23 15 268 I92

24 16 227 125

--

13 20 7.4 -

51 38

0.9 1.5 0.6

29 17

9.3 12 5.4

239 133

0.4 0.5 0.2

-

27 18 278 203

74 /

APPENDIX B

Newborn 1-year 6.vnar

+

Thyroid

Newborn 1-year 6-vear

509

509

540

640

585

685

6.0

Active Bone Marrow

Newborn 1-year 6-year

20

W

28

71

30

76

1.2

Lungs

Newborn I-year 5-vear

41

234

54

287

63

30 1

4.1

Total Body

Newborn I-year 5-year

98

204

115

240

124

264

0.3

(3)

From Roeenetein et 01. (1979). See Note 1, page 106

' 'See Note 2 for explanation of vduea in parenthesis. page 106 +

* See Note 4, page 107

+

(3)

+

(3)

TABLE B G L A T NECK-or--

dose (mrad) . , .lor 1 R entrance exmsure (free-in-air).' SID AND FIELD SIZE

REFERENCE PATIENT

1-year old

Newborn

Source-to-image receptor diatance

5-year old

Not Applicable

(SID) (centimeters [inches]) Field aim at image receptor (centimetere [inches]) Collimated to body part Collimated to Nm eize

Not Applicable

ORGAN DOSE (mrad/R)

BEAM QUALITY (HVL,mm Al) -r F h #I

COLLIMATION -P

Newborn 1-year 5-year

2.5

2.0

+

Maximum coefficient

3.0

Film

Film

Film

Film

Film

12

#1

#2

#l

#2

+

+

+

+

+

of variation (2)

Newborn

Newborn 1-year 5-year

(370)

(470)

(370)

(470)

(370)

(470)

Newborn 1-year S-year

24

60

32

81

35

87

Lunge

Newborn 1-year S-year

32

156

40

212

45

24 1

Total Body

Newborn 1-year bvear

93

204

108

238

117

254

Active Bone Marrow

'From R o e e ~ t e i net af. (1979). +

See Note 1, page 106

' 'See Note 2 for explanation of values in parenthesis, p w e 106

15

0.3

w

TABLEB7-AP CHEST-organ dose (mrad) for 1 R entrance exposure (free-in.air).' SID AND FIELD SlZE

REFERENCE PATIENT -

Newborn

5-vear old

1-veer old

-

Source-to-imagereceptor diatance (SID) (centimeters [inches]) Field size at image receptor (centimeten, [inches]) Collimated to body part Collimated to film size ORGAN DOSE (mrad/R)

BEAM QUALITY (HVL, mm Al) -, COLLIM ATION +

Testea

2.0 Body Newborn 1-year 5-year

part

Body part

Film aize

(7)

(14)

(7)

+

+

+

+

3.5

3.0

2.5 Film size

part

Film size

(14)

(7)

(14)

+

+

+

Body

+

+ +

Body part

Film size

+

+

Max.

CV(%)*

P'O

S&&

192

P'O

P'O

CSI

1'1

-9

Z'Z L'Z 9'E

9S9

LZI

&'I 9.1 El 0'9 UP •

.

088

(&I

088

(Z)

LOI aaud ' s a n p ~(AD

9'29 PSS oC9

999 9% OE9

SSZ OPZ 682

EZC ZPE PES

ELZ OZE IOS LES LW 019

m9 0W 208

OLL S8S LSS

OLL SBS LS8

COI FII 691

121 I01 91I

OPI ZZI 881

(€1 (CZ)

'

(0s)

(2) (61) (9)

(El (CZ)

m

IlZ LZZ PLZ LC9 ZZB 019

88 Z6 III 099 0W Z08

u o ! p p ~j o quaprg~ao~ urn~xem j o uo~qwuw~dxa i o j p WON aas 901 aawd 'msaqquarsd s a n p j o uo!~sm[dxa i o j z WON aas 901 aasd '1 aqoN aas '(6L61) 70 Id u!Weuwo?J '"OU, LLZ LPP SSP O&S

MI OPZ SPP OEE

IS

6z1

69

PB

60s Z89

60(;

Z89

(2) (61) (9)

(EZ) (

)

(61) (9)

rear(-g rear(-1 uloqfiaN

@OR

.

,, +

WO.L

rear(-9 rear(-1 uloqmaN rear(-9 rear(-1 woqfiaN real-9 rear(-1 uioqmaN mar(-g rear(-I UloqMaN

fi-N auoa a~!vv P!oJ~.L

s a p ~ o

TABLEB&PA CHEST-organ dose (mmd)for 1 R entrance exposure (free-in-air).' SID AND FIELD SIZE REFERENCE PATIENT

Source-to-image receptor distance (SID) (centimeters [inches]) Field size at image receptor (centimetern [inches]) Collimated to body part Collimated to film size

Newborn

1-yearold

5-year old

183 [72]

la3 [72]

183 [72]

ORGAN DOSE (rnrad/R) BEAM QUALITY (HVL, mm Al) -r COUIMATION -r

Testea

2.0

Newborn 1-year 6-vear

2.5

Film

size (18)

Film

(3)

+

+

3.5

3.0

Body part

Body part

size

Body part

Film size

(3)

(18)

(3)

(18)

+

+

+

+

+ +

+

+

Body part

Film

+

+

size

Max.

CV (8)'

.

Newborn 1-year 5-vear Thyroid

Newborn 1-year 5-year

Active Bone Marrow

Newborn 1-year 5-year Newborn 1-year 5-year

524 478

568

Lungs

Total Body

Newborn 1-year 5-year

257 218

476 311

488

578 567 526 292 252 213

630

687 540 537 357

no

610 613

691 638

634

661

311

568 384 326

268 257

'From h x e ~ t e i net aL (1979). See Note 1. page 106

' ' See Note 2 for explanation of values in parenthe&, +

'.b

page 106

See Note 4 for explanation of maximum coefficient of variation (Max. CV) values, page 107

632

262

660

2.3 2.7 2.3

332

0.3 0.4 0.4

(1)

+

XPO~

q d

t9) wd

ane

+ +

+

(1) (8)

I

q d

'WN

ans

.(%)AD

w d LPOH

9.c

(1)

+

'

+

+

md Xpoa

w d

(9)

(8)

ans

0' &

pi0 mar(-9

Q'z

+ (8)

ans

wd

+ (9)

marl-g maL-1 "JoqmaN

'=-=&

Zred Lpoa

0'2

p10 mar(-1

NOIIVWITIO~ uI?vnb ~ v a

+

+

(wrmu '?AH)

a

"JoqfiaN IN3LLVd 33N3XBdaEI

azrs a - 1 3 ~aNv ars w ' ( l ! ~ - ~ ~ - a~neodxa i + ~ J ) 23UDJ?UJ

I

JV7-48 n 7 e v ~

10)(PVJW) i+sOpU V % ~ O - J S ~ H ~

Newborn 1-year 5-year

(5) (13)

Thyroid

Newborn 1-year &year

(410) (380)

Active Bone Marrow

Newborn 1-year SY ear

(60) (40)

(5) (13) (10)

(60) (40) (19)

(5) (13) (10)

(60) (40) (19)

(600) (480)

(410) (380) 440

(600)

(410)

(600)

(480)

(380)

(480)

440

510

510

102 83

160 101

146 120 93

225 147 111

173 150 132

281 182 153

Lunge

Newborn 1-year 5-year

591 544

655 551

695 629 600

776 664 538

720 706 592

831 730 626

Total Body

Newborn 1-year &year

244 184

433 268

296 231 185

520 333 246

320 257 225

563 370

'From Rusenstein el al. (1979). ' See Note 1, page 106 See Note 2 for explanation of values in parenthesis, page 106 See Note 4 for explanation of maximum coefficient of variation (Max.CV) values, page 107

''

294

(10)

560

138

612

230

(19)

560

16 21 17

162

1.O 1.3 1.2

616

2.2 2.4 2.2

298

0.3 0.4 0.4

TABLEBl-?'o REFERENCE PATIENT

CHEsT-or~wt - dosc fmrad) . . for . I R entrance e.wodure {free-in-air).' SID AND FIELD SIZE

Source-to-imagereceptor distance (SW) (centimeters[inches]) Field size at image receptor (centimeten,[inch-]) Collimated to body part Collimated to film size

5-yur old

Newborn

I-yearold

Not Applicable

Not Applicable 21 x 30 (8.3 x 11.81 28 X 36111 X 141

ORGAN DOSE (mrnd/R) BEAM QUALITY (HVL, mm Al) -D COLLIMATION -,

3.0

2.5

Maximum

3.6

Body

Film

Body

Film

Body

Film

Part

eize

P b

aim

Part

niza

coefficient of variation (Q)

Te8tea

Newborn 1-year 5-year

(4)

(18)

(4)

(18)

(4)

(18)

TABLE B11-AP KIDNEYS-orm - dose (mrad). .for 1 R entrance emosure (free-in-air).' SID AND FIELD SIZE

REFERENCE PATIENT

Source-to-image receptor distance (SID) (centimeters [inches]) Field size a t image receptor (centimeters [inches]) Collimated to body part Collimated to film size

Newborn

1-year-old

11 X 8 [4.3 X 3.1)

16 X 14 [6.3 X 5.5) 25 X 20 [lo X 81

25 X 20 [lo X 81 ORGAN DOSE (mrad/R)

BEAM QUALITY (HVL, mm Al) -+

2.0 Body Part

COLLIMATION -+

5-year-old

2.5 Film size

Body Part

Maximum

3.0 Film size

Body Part

Fi size

coefficient of variation (%)

-

Ovaries

Newborn I-year 5-vear

( 12)

Newborn 1-year 5-vear

(8) (12)

(4 )

(110) (19) (20)

(40) (150) (70)

390 (210) 270

(40) (150)

(8)

(4)

(70)

(110) (19)

(20) 560 (210) 370

(8 (12) (4)

(110) (19) (20)

47h

(40) (150) (70)

580

*,llb

(210) 400

40 32.11b

Thyroid Active Bone

Marrow

Total Body

Newborn 1-year 5-year

(6) (2) (1)

(60) (5) (2)

(6) (2) (1)

(60) (5) (2)

(6) (2)

Newborn 1-year 5-year

39

149 67 50

54 52 39

206 98 73

57 57

Newborn 1-year 5-year

178 38 29

491 158 129

201 48 39

552 179 155

214 51

Newborn 1-year 5-year

100 97 85

346 174 149

114 114 101

389 20 1 175

' From Roeenstein et a/. (1979). 'See Note 1, page 106 ' See Note 2 for explanation of values in parenthesis, page 106 '.'See Nob 4, page 107

'

(1)

(60) (5) (2) 214 104 78

1.6 1.6 1.5

44

620 206 182

3.5 3.9 4.1

122 121 109

411 216 187

0.5 0.4 0.3

44

TABLEB12-AP

B L A D D E R - ~ ~ ~ ~(mrad) ~ ~ O for ~ ~I

REFERENCE . PATIENT -

- - --

R entrance exposure (free-in-air).'

Newborn

SID AND FIELD SIZE I-year-old

Not Applicable

Not Applicable

-

Source-to-image receptor distance (SID) (centimeters [inches]) Field size a t image receptor (centimetera [inches]) Collimated to body part Collimated to Nm size

BEAM QUALITY (HVL,mm Al) +

102 [403

ORGAN DOSE (rnrad/R) 2.0 2.5 Body Part

COLLIMATION +

5-year-old

Film size

Body part

3.0

Film size

Body Part

Film size

Maximum coefficient of variation (%)

Testes

Newborn 1-year 5-year

( 1,070)

( 1,070)

( 1,070)

( 1.070)

( 1,070)

( 1,070)

6.0

Ovarieu

Newborn I-year 6-year

270

270

370

370

400

400

Thyroid

Newborn 1-year &year

+

+

+

t

+

+

Newborn 1-year 6-year

33

44

49

62

53

68

(1)

(1)

(1)

(1)

(1)

(1)

Active Bone Marrow

w

1.6

Newborn I-year 6-year

Newborn Total Body 1-year 79 111 6-year 'h r n Roeenntein el al (1979). 6ee Note 1, page 106 'See Note 2 for explanation of vduea in parenthesis, paEe 106

'

11

94

131

100

140

28

0.3

TABLE B13-PO BLADDER-organ dose (mrad) for 1 R entrance exposure (free-in-air).' S I D A N D FIELD SIZE

REFERENCE PATLENT

Newborn

Source-to-imagcreceptor distance (SID) (centimeter8 [inches])

1-yearold

&year old

102 [40]

102 1401

16 x 16 [6.3 x 6.31 20 x 26 [8 x lo]

22 x 22 [8.7 x 8.71 26 x 30 [lo x 121

Not

Field rim at imyle receptor (centimeters [inches]) Collimated to body part Collimated to film aize

Applicable

ORGAN DOSE Imrad/R)

BEAM QUALITY (HVL,rnm All+ COLLIMATION-, Teatea

Newborn l-year 6-year

2.0

2.6

3.0

Body Part

Film

Body

Film

Body

Film

(850)

(860) 800

(8M))

(850) 900

(850)

(860)

960

950

800

size

Part 900

cite

Pw

size

Maximum coefficient of variation (%) 10 12

E'O t.0

L91 ZIZ

+ + OLB

92

(092)

ZZ

PI 1 ZZI

+

+ (092) OLB

991 661

+ + (WZ)

WE

-

LO1 €11

+

-

+

PC1 ZL1

+ +

-

(092) 09Z

(OSz) 0%

08 86

+ +

maX-g maX-1 "JoqA'JN

-

(092) 09Z

maAq mart-1 WoqmaN mart-g maX-1 Wc"4maN

PWU oa)RW

TABLEB14-AP ERECTABDOMEN-organ dose (mrad) for 1 R entrance exposure (frcc-in-air).' S1D AND FlELD SIZE REFERENCE PATIENT Newborn 1-yearold 5-yearold Some-to-image receptor distance 10.2 [MI (SID) (centimeten, [inches)) Not Not Field aize at image receptor (centimetere[inches]) Applicable Applicable Collimated to body part 23 X 30 [9.1 X 11.81 28 x 36 [I1 x 141 Collimated to f h size

ORGAN DOSE (mred/R) BEAM QUALITY (HVL, mm A])+

2.6

2.0

Body part

Maximum

3.0

cwflicient of

nize

Z

Nm aim

B p 2

'?"" am

(50)

(160)

(so)

(1W)

3eb

370

a00

4aO

11

Film

Testes

Newborn I-year 5-year

(50)

(150)

Ovaries

Newborn 1-year byear

270

270

370

,

variation

(%I

Y5t w

Thyroid

Newborn 1-year 5-year

(5)

(5)

(6)

(6)

(6)

(5)

Active Bone Marrow

Newborn l-year 5-vear

57

74

83

110

89

116

Lunge

Newborn l-year 5-vear

118

175

137

220

151

233

3.3

Total Body

Newborn l-year 5-vear

159

!206

189

242

202

269

0.3

' R o m Roeenatein el al. (1979).

+ See Note 1, page 106

() See Note 2 for explanation of values in parentheeia, page 106 Onb

See Note 4, page 107

TABLEB I ~ - A P A B D O M E N - O-~ R ~dose Irnmd). .for I R entrance exposure (bee-in-air).' SID AND FIELD SIZE

REFERENCE PATIENT

Sxrce-to-image receptor distance (SID) (centimeters [inches]) Field sine at m e receptor (centimeters [inches)) Collimated to body part Collimated to hlm aim

Newborn

1-year old

Syear old

102 [40]

102 [40]

102 [40]

ORGAN DOSE (mrad/R) BEAM QUALITY (HVL, rnm A l b

20

MY

C0UIMATION-r

Part

Film size

910 (1,070) (1,070)

Te~m

Newborn 1-year 5-year

86 (105) (125)

Ovaria

Newborn 1-year 5-year

390 270 270

390

270 270

MY part

144 (105) (125)

560 370 370

Maximum

3.0

2.5

Film size

1,OOo

(1,070) (1.070) 660 370 370

caflicient

:

Film size

152 (105) (125) 680

400 400

of variation (%I

1,120 (1,070) (1,070)

23,4.7b 32,t? 30,6~

580 400 400

11 11 11

ZI1 191 QZZ

9'1

EZI GZ L6t

L9

96)

a

06Z

W

961

,O'E'E'S JE'W ,L'E'VS

6EZ 9OE 61P

ZOZ OIZ 9ZZ

992 6Z6 OW

Z'O VO VO

SI

97

06 ZII LEI

101 0)I

11Z

881 961 ZIZ Lt 8P 99 &S 001 LC1

LO1 e m 't WON aaS
891 L91 981 6&

S9 69 16

69 66 691

X ! 6)

LZZ 6CP

.

marc-9 maX-1

wOqmaN nd-9 maK-1

W*aN meKq me&-I WOgfiaN

82 8Z

sz

OOP

00)

08Z

082

(oo)

(om)

an8

(%I UORBUBA

(Lr) (091)

(Opt)

q91'PP q-21'SC

OPI

OPI

e

3'

092

Wd

lua!3gjaoo

ired Apoa

MZ OZ6 (mr) 011

OIZ (OW) ans

v!d

09Z OZC (ocr)

OII (1)) (SOI)

WZ 002 ( 1 OP

Oa (OW)

Wd

~POB

an8

rn 0' z

O'C

--W

OZZ OBZ

(om) OP (LH (SOI)

lrsd ~POB O'z

maXg rsaX-I "~oq*e~ maX-q ma&-1

-A0

ww.L

IL10qrYL3N

-

-NoLLv~n'I03

+(IV

?AH)

m n bm a

(H/PW) 3SOa NVDHO

[ovl ZOI p ~ marl-9 o

m

3

..(+-q.aaJI

"Joq*aN

PP mx-I

tot1 zor

[wlzor 3ZIS (l'I3ldQNV OlS atnsodxa w u v ~ u a

tl-q~url BIalaWlueD) (ms) =wslp

e-q--w

J X # U V d a3N3IIWm

I

A O (~p m t ~asop ) UV~O-N~J~O vd--g~a ( I ~ V 81UVJ,

Thyroid Active Bone

Marrow

Total Body

Newborn 1-year 6-year

(2) (6) (1)

(20) (14) (9)

Newborn 1-year 6-year

190 148 135

276 185 149

Newborn 1-year 6-year

46 37 35

414 224 96

62 51 47

459 259 126

67 56 51

499 283 143

5.6,1.7~ 5.5,1.6b 5.4

Newborn 1-year 6-year

190 170 161

379 264 206

218 199 192

427 305 242

232 213 206

451 327 259

0.3 0.2 0.3

From ~080llllteifIel a!. (1979).

+ See Note 1, page 108

0 See Note 2 for explanation of values in parenthesis, page 106 See Note 4, page 107

(20) (14) (9) 361 249 207

(2) (6) (1) 259 214 197

(20) (14) (9) 376 266 225

* *

(2) (6) (1) 247 197 183

. 1.O 1.O 1.1

TABLE B ~ ~ - L A T A B D O M E N - O ~dose ~ C ~(mmd) I for I R entrance exposum (free-in-air).' SlD AND FIELD SIZE

REFERENCE PATIENT Newborn

I-vaar old

6-vear old

13 x 14 l6.l x 6.61 20 x 25 [B x 101

18 x 21 [7.1 x 8.31 26 x 30 [lo x 121

21 x 31 [8.3 x 12.21 28 x 36 [11 x 141

Source-to-image receptor distance (SID) (centimeters [incheel) Field size at hsge receptor (centimeter8 [ichee]) Collimated to body part Collimated to film .&a

ORGAN DOSE (mrad/R) BEAM QUALITY (HVL,mm All+

.

Maximum

3.0

coefficient of variation (I) ~~

Ovarim

Body

(lso) (430) 420 300

Dart

Newborn 1-year 5-year

(300) (70) (130)

(480) (240) (180)

(300) (70) (130)

(m) (lea)

(3oO) (70) (130)

Newborn

(M) 270

(430) 270 190

(430) 430 230

(430) 430 230

(430) 420 300

Body D& -

Testes

Film size

Film size

Body

1-year &year

190

-

(240)

Film size

art

~~

-

-

(480) (240)

20,12~ 44.16~ 46 23 30 30

Newborn l-year 6-vear

(3)

Thyroid Active Bone Marrow

Newborn l-year bear

161 107 83

216 136 90

198 150 111

280 182

Newborn l-year bear

74

Lunge

32 30

522 232 70

Total Body

Newborn l-year 5-sear

199 152 134

359 226 158

(30) (10)

(3)

+

+

From Roeenatein el al. (1979).

+ See Note 1, page 10g

() See Note 2 for explanation of valuer in parentheab, page 106 a'b

See Note 4, page 107

(30) (10)

'136b

in

208 152 125

295 196 132

1.1 1.2 1.4

87 43 35

587 267 87

86 54 46

628 293 101

6.0J.5~ 5.6,1.6~ 5.6

224 179 157

403 26 1 186

239 190 169

425 280 198

0.3 0.3 0.4

(3) (3)

+

.

(30) (10)

+

(3) (3)

+

+

a

W

TABLE B l S A P PELVIS-or~m - dose fmradl. .kr I R entrance ex~osure(free-in-air).' SID AND FIELD SIZE

REFERENCE PATIENT

Source-to-image receptor distance (SID) (centimeters [inches]) Field size at im-e receptor (centimeters [incheel) Collimated to body part Collimated to film size

Newborn

1-year old

5-year old

15 X 15 c5.9 X 5.91 25 X 20 [lo X 81

21 X 21 18.3 X 8.31 30 X 25 [12 X lo]

28 x 25 [11.0 x 9.81 36 X 28 [I4 X 111

ORGAN DOSE Imrad/R) -

BEMI QUALITY (HVL., mm N)-D

2.0

'2

COLLIMATION-

Teatea

Newborn I-year 5-year

910 (1.070) (1,070)

Ovaries

Newborn 1-year 5-vear

390 270 270

F@

Body

maze

Part

910 (1.070) (1,070) 390 270 270

1,000 (1.070) (1,070) 660

370 370

Maximum

3.0

2.5

F$n

an?

Body Part

1,000 (1,070) (1,070) 660 370 370

1,120 (1,070) (1,070)

F+ 8l.m

1,120 ( 1,070)

(1,070)

580

680

400 400

400 400

coefficient of variation (%)

4.7 6.0 6.0 11 11 11

Thyroid Active Bone Marrow

Newborn I-year 5-year Newborn 1-year 5-war -

Lunge

Newborn 1-year 6-year

Total Body

Newborn 1-year 5-year

18 (6) (2)

212 166 140

" From Rosenstein et al. (1979).

+ See Note 1, page 106

O See Note 2 for explanation of values in parenthesis, page 106

46 (13) (4)

299 220 159

24 (6) (2) 236 192 165

-

60 (13) (4)

332 249 186

26 (6) (2) 249 204 175

66 (13) (4) 351 267 199

10 15 25 0.5 0.4 0.4

*

2

z

TABLE Bl9-AP HIP-organ dose (mrad) for I R entruce exposure (bee-in.ai.)." .

REFERENCE PATIENT

,

5?

m

SlD AND FIELDSIZE

Newborn

I-yew old

5-yearold 102 [40]

Not

Not

Applicable

Applicable

Source-to-imagereceptor dintance (SID) (cantimetere[inchea])

Field size at image receptor (centimeters [inches]) Collimated to body part Collimated to film size

13 x 19 [6.1 x 7.61 20 X 25 [8 X 101

ORGAN DOSE ( n i r a d / ~ i BEAM QUALITY (HVL, mm All+

MY

COLLIMATION-.

Testes

Ovaries

2.0

mart

Newborn 1-year Cyear

(420)

Newborn 1-yea) &year

(1W)

2.5

Film size

Maximum

3.0

2

size

'

BS

coefficient

Film urn

of

variation

($1

. .

(1,070)

(420) . .

(210) :

: (160)

1

0

(420)

(1.070)

(210)

(160)

(210)

13,~~

22

Newborn

Thyroid

1- yea^

+

+

+

+

+

+

Active Bone

byear Newborn 1-year 5year

21

29

31

42

33

46

Lur~rs

Newborn 1-year byear

(1)

(2)

(1)

(2)

(1)

(2)

Total Body

Newbom 1-year 6-year

52

93

62

Marrcnr

From h n m t e i n et 41. (1979). + See Note 1, page 106 () See Note 2 for explanation of values in parentheeie, page 106 b.' See Note 4. m e 107

111

66

119

1.9

32

0.3

TABLE B!20-PO HIP (ONEJ-organdose (mrad) for I R entrance exposure (frec-hair).' SID AND FIELD SIZE

REFERENCE PATIENT

Newborn

1-yew old

I-year old

lOZ [40]

102 [40]

10 x 16 [3.9 x 6.31 20 x 25 [8 x 101

13 x 22 15.1 x 8.71 20 x 25 [8 x lo]

Source-to-imagereceptor distance (SID) (centimetern [inches]) Not

Field size at image receptor Applicable

(centimeters [inches]) Collimated to body part Collimated to film size

ORGAN DOSE (mrad/R)

BEAM QUALITY (HVL,mm A])+ C0LLIMATION-r

Testes

Ovaries

2.0 MY

Part

Newborn 1-year 5-year

(9oo) (780)

Newborn 1-year 5-year

(140)

(2so)

2

2.6 MY par(.

Muimum

3.0

Film

size

coefficient

MY Part

P!m 1u0

(m)

(m)

(9oo)

(780)

(9oo) (900)

(m)

(900)

(780)

(%lo)

(420) (240)

(280) (140)

(420) (240)

(280) (140)

(4.20) (240)

of variation (%)

14 12

29 22

Thyroid Active Bone

Mamow

Newborn 1-year &year

+ +

+ +

+ +

+

+

+ +

+ +

Newborn 1-year &year

37 10

73 21

50 16

103 34

57 19

110 36

1 1

9 1

2

11 2

3 1

15

71

184 85

83

213 101

89 67

224 108

*

Newborn 1-year

Total Body

Newborn 1-year Byear

5-year

52

From RoeeMtein et al. (1979).

+ See Note 1, puge 106 ()

See Note 2 for axplanation of valuea in parenthesis. page 106

1

62

2

1.6 2.2

20 26 0.3 0.3

106

/

APPENDIXB

TABLE B2la-Half-value layers as a fwcctwn of /ii&ation and tubepotential for dioanosricunicsa Puk Potential (kVp)

Total

Flitration

mm Al

30

40

50

80

70

80

90

10

110

120

" For full-wave rectified, single phaee, potential. Daived &om Hale (1966) by interpolation and extrapolation. .

.

TABLE B2lb-Halfivakrc layer cur a function bftubepotential for three-phnse m?nera&Ta

2.5.

23

2.4

2.7

3.1

8.0b

2.3 2.6

2.6

3.0

2.9

3.2

3.3 3.6

3.5"

3.3 3.6

3.6

3.9

4.3

4.0

4.0 4.3 4.6

- 5.0 - -

4.6

Estimated from NCRP (1968) and Kelley and Trout (1971). FrOm KeUey and h u t (1971).

TECHNICAL N

m ON TABLE ENTRIES

Note 1. The symbol + in the table indicates no 'detectable contribution to organ dose was observed. Note 2. A table entry in parenthesis 0 indicates that the coefficient of variation was large in relationship to the differences in the mrad/R values as a function of HVL.Therefore, the trend for mrad/R as a function of HVL could not be resolved. Values given are the average of the rnradm values obtained for all the indicated HVL conditions. Note 3. The values for active bone marrow and total body given in mrad/R can be converted to integral dose per roentgen (g-rad/R) for each reference pediatric patient by multiplying

APPENDIX B

/

107

by the following factors: Active bone marrow

Total body

Newborn l-year old 5-year old

Note 4. The symbol in the maximum coefficient of variation (%I column indicates the maximum coefficient of variation was greater than 50 percent. The maximum coefficient of variation is the largest value obtained for any of the data in the row. Typically the coefficients of variation for all values in the row were about the same magnitude as the maximum. When this is not the case. the superscriptbin this column indicates that the first value given is for the field size collimated to the body part and the aecond value given is for the field size collimated to the film size. Note 6. The coefficient of variation is a measure of the reproducibility of the organ dose calculation, using a Monte Carlo dosimetry technique (see Rosenstein, 1976). Coefficient of variation (in percent) = 100 x one standard deviation organ dose - -

Calculating Organ Doee By inverse square extrapolation, determine the exposure rate (mR/mAs) in air (i-e., without backscatter factor) at the source-skin distance (SSD) used (i.e., at the point where the primary beam enters the patient). Multiply the result by the total mAs used and expteS8 the results in roentgens by dividing by 1,000. k o m Tables B.1-B.20, the dose in mrad per R entrance exposure for specific projections can be determined for testee, thyroid, bone m m w , lungs, and total body. For a specified HVL, the tables give

data for collimation to film size and/or to limited body parts for the newborn, 1-year old and Byear old. Using these tables, the absorbed dose to the organ of interest can be determined by multiplying the selected value mrad/Ft by the calculated entrance exposure in R.

Example Calculate absorbed dose to the ovaries, active bone marrow, and thyroid fiom an AP chest x-ray in a 5-year old girl. The factors are:

- source to film distance 72 inches - tube potential setting 80 kVp (3phase generator) - total filtration 2.5 mm A1 - tube current 500 mA - exposure time = 0.012seconds (The exposure rate was memured a t 80 kVp to be 2.12 mR/mAs)

To Calculate Exposure Rate If It Ie Not Known (1)To estimate the exposure rate use Figure B.l a t 80 kVp and 2.5 mm A1 filtration. The graph shows a value of 5.9 &/nub a t 40

inches. (2)Since 72" distance was used, this is corrected using the inverae square law. Exposure rate at 72" = 5.9 x (40/72)* 1.82 mR/rnAs. (3) To convert to 3 phase, multiply 'by conversion factor of 1.85. Three phase exposure rate = 1.82 x 1.85 = 3.37 mR/mAs. A difference such as that illustrated here between calculated and measured values is not uncommon so it is best to use a measured exposure if availble. However, the calculated values would still give useful information within 30 to 50 percent of the measured value.)

-

To Calculate Organ Dosee Using the measured expormre rate of 2.12 mR/& (1) Actual exposure for the settings used = mA X time x m R / b 500 x 0.012 x 2.12

-

APPENDIX B

/

109

FILTRATION ( m m Al Fig. B.L Ehpmm rate in air (at 1 m from the x-ray source) as a function of total filtration for vnriow values of tube potential Values are for full-wave recti6ed single phme equipment (for 3 phase multiply by 1.85) (From McCullough and Cameron, 1970).

-

= 12.72 mR or approximately 13 mR

0.013 R. (2) If we aswune a 1 inch distance between patient and film and the source to film distance was 72" and the patient was 5" thick, the source to skin distance (SSD) = 72 - (5 + 1) = 66 inches. (3) The exposure in air at the skin is calculated using the inverse square law. W u r e in air at SSD = 0.013 R x (72/6612 = 0.015 R.

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APPENDIX B

(4) h m Table B.21b using 80 kVp and 2.5 q m Al total filtration, the HVL = 2.7 mm A1 (measured HVL was 2.5 mm AZ). (5) From Table B7 at 2.5 mm A1 HVL with collimation to body part the doses to various organs of a 5-yearold girl are:

Ovaries

Active Bone Marrow Thyroid Therefore, the doses in this example will be

Dose to Ovrviea = 2 x 0.015 = 0.03 mrad Active Bone Marrow = 88 x 0.015 = 1.3 mrad Thyroid = 650 x 0.015 = 9.8 mrad

(If calculated exposure rates rather than meaaured expowve rates had been used, these doses would be 0.015, 2.1, 15.6 mrad which, although less accurate, still give a general idea of the dose).

APPENDIX C

Glossary absorbed dose: The quotient of dZ by dm where dZ is the mean energy imparted by ionizing radiation to the matter in a volume element and dm is the mass of the matter in that volume element, i.e., the absorbed dose, D = dZ/dm. The special unit of absorbed dose is rad, 1 rad = 0.01 J kg-'. angiography: Radiography of blood vessels after injections of a radioopaque material into an artery. automatic exposure control (phototiming): A method for timing radiographic examinations, the duration of the exposure being controlled by the amount of radiation which reaches a radiation-sensitive detector after it has passed through the patient. collimator: An arrangement of shielding material designed to define the dimensions of a beam of radiation. cone: A deyice used to indicate beam direction and to establish a minimum source-surface distance. It may or may not incorporate a collimator. It may be conical or cylindrical in shape. dose equivalent: A quantity used for radiation protection purposes that expresses on a common scale for all radiations, the irradiation incurred by exposed persons. It is defined as the product of the absorbed dose and certain modifying factors. The unit of dose equivalent is the rem. See rem. energy imparted (integral dose): The total energy absorbed from ionizing radiation in an irradiated region in a phantom or animal. It is frequently obtained by integrating the absorbed dose with respect to mass throughout an irradiated region. It may be stated in joules per kilogram or gray. expoeure: A measure of the ionization produced, in air by x (or gamma) radiation. It is the sum of the electrical charges on all of the ions of one sign produced in air when all electrons liberated by photons in a volume element of air are completely stopped in air, divided by the mass of the air in the volume element. The special unit of exposure is the roentgen (R). fluoroscopy: The observation of the internal featwes of an object by means of the fluorescence produced on a screen by x rays tmmn&d through the object. 111

112

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APPENDIX C

half value layer (HVL) (exposure): The thickness of specified material which attenuates the beam of radiation to an extent such that the exposure rate is reduced to one half of its original value. In this definition the contribution of all scattered radiation, other than any which might be present initially in the beam concerned, is deemed to be excluded. image quality: An inexact and indefinableterm relating to the fidelity with which all the characteristics of an image (not only its shape) approach an agreed conventional representation of the object producing it. kerma: The total initial kinetic energy of all of the directly ionizing particles ejected by the action of indirectly ionizing radiation per unit mass of specified material. kilovolt (kV): A unit of electrical potential difference equal to 1,000 volts. kilovolts peak (kVp): The crest value of the potential difference of a pulsating potential generator. When only one-half of the wave is used, the value refers to the useful half of the cycle. maximum permissible dose (MPD): The maximum dose equivalent that the body of a person or specific parts thereof, shall be allowed to receive in a stated period of time. milliampere (mA):One thousandth of an ampere, a unit of electric current. milliampere-second (mAs): The numerical product of the milliamperage multiplied by the exposure time in seconds. noiae: A colloquial expression referring to the fluctuations resulting from the quantized and random nature of natural processes, for example the emission and absorption of x-ray or light photons. output: A measure of the radiation beam produced by a radiation source. It is usually stated as the exposure rate or absorbed dose rate at an appropriate calibration point under a closely defined set of conditions. quantum mottle: The irregular density variation on a radiograph due to the random variation in x-ray intensity over the surface of the intensifying screen. rad: The unit of absorbed dose: One rad is 0.01 joules absorbed per kilogram of any material. (Also defined as 100 ergs per gram.) radiography: The observation of internal features of an object by means of an image produced on photographic film by radiation transmitted through the object. rem: The unit of dose equivalent. For radiation protection purposes in this report, covering x and gamma.radiation, the number of rems may be considered equal to the number of rads or roentgens.

GLOSSARY

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113

resolution: In the context of an image system, the output of which is finally viewed by the eye, it refers to the smallest size or highest spatial frequency of an object of given contrast that is just perceptible. The limiting resolution is the resolution for an object consisting of black and white area, viz., of unit contrast or depth of modulation. roentgen (R): The special unit of exposure for x and gamma rays. One roentgen produces 2.58 x lo-' coulombs per kilogram of air. scattered (secondary) radiation: Radiation that, during passage through matter, has been deviated in direction as a result of a collision or interaction and may have had its energy diminished. screen-film system: A combination of an intensifying screen in intimate contact with an x-ray film utilized to increase the density on the fiLm or, as is more usual in practice, to allow a smaller x-ray exposure to be used than would be required to give the same film density without the screen. sensitivity: The reciprocal of the exposure for a given image quality. skin dose: The skin dose (surface dose) is the radiation delivered at the skin. It is the sum of the dose from the incident radiation plus the dose from the backscatter radiation. unsharpness: A measure of the inability of the image to reproduce faithfully the boundary of a given contrast. x-ray film characteristic curve: A graph of film density versus the logarithm of the x-ray exposure. x-ray tilm contrast: The slope of the x-ray film characteristic curve.

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WOOD, H.C.,JR (1934)."A frame for holding infants upright during roentgenography,"Am. J. Roentgenol. 31, 396. ZATZ, L. M., F'INSTON, R. A., and JONES,H. H. (1974). "Reduced radiation exposure in the operating room with video disc radiography," Radiology 110,475.

The NCRP The National Council on Radiation Protection and Measurements is a nonprofit corporation chartered by Congress in 1964 to: 1. Collect, analyze, develop, and disseminate in the public interest information and recommendations about (a) protection against radiation and (b) radiation measurements, quantities, and units, particularly those concerned with radiation protection; 2. Provide a means by which organizations concerned with the scientific and related aspects of radiation protection and of radiation quantities, units, and measurements may cooperate for effective utilization of their combined resources, and to stimulate the work of such organizations; 3. Develop basic concepts about radiation qumtities, units, and measurements, about the application of these concepts, and about radiation protection; 4. Cooperate with the International Commission on Radiological Protection, the International Commission on Radiation Units and Measurements, and other national and international organizations, governmental and private, concerned with radiation quantities, units, and measurements and with radiation protection. The Council is the successor to the unincorporated k c i a t i o n of scientists known as the National Committee on Radiation Protection and Measurements and was formed to carry on the work begun by the Committee. The Council is made up of the members and the participants who serve on the seventy Scientific Committees of the Council. The Scientific Committees, composed of experts having detailed knowledge and competence in the particular area of the Committee's interest, draft proposed recommendations. These are then submitted to the full membership of the Council for careful review and approval before being published. The following comprise the current officers and membership of the Council: President Vice Pres&nt S e c r e w ond T i e w e r Assistazl Secretcuy

Assistant Treasurer

WARREN K . SINCLAIR HYHERL.FRIEDEU W . ROGERNEY ROBERTF. FARON ~ R O L 0. D WYCKOFF

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Members

SEYMOUR ABRAHAMSON S. JAMESADEWEIN ROY E. ALBERT EDWARDL. ALPEN JOHN A. AUXIER WILLIAMJ. BAIR JOHND. BOICE JR. V I ~ P.R BOND HAROLD S. BOYNE ROBERTL. BRENT ANTONE BROOKS REYNOLDF. BROWN MELVINW. CARTER GEORGEW. C A S ~ RANDALLS. CA~WELL ARTHURB. CHILTON STEPHEN F. CLEARY GERALDDODD PATRICIAW. DURBIN MERRILEISENBUD THOMASS. ELY BENJAMING. FERRIS DONALDC. RJZCXENSTEIN R~CHARD F. F ~ R HWER L. ~ U E D E L L ARTHURH. GLADSTEIN ROBERTA. GOEPP BARRYB. GOLDBERG ROBERT0. GORSON DOUGLASGRAHN ARTHURW. GUY JOHN H. HARLEY JOHN W. HEALY Lours M. HEMPELMANN,J R JOHN M. HESLEP GEORGEB. HUTCHISON SEYMOUR JABLON A. E w m m m JAMES

BERNDKAHN JACOBK A ~ E R JAMES G. KEREIAKES EDWARDB. LEWIS THOMASA. LINCOLN RAY D. LLOYD CHAR- W. MAYS ROGER0.MCCLELLAN JAMESMCLAUCHLIN CHARLESB. MEINHOLD MORTIMER M. MENDELSOHN DADEW. MOELLER A. ALANMOGHWI PAULE. MORROW ROBERT D. MOSELEY,JR. JAMES V. NEEL ROBERT J. NELSEN FRANKPARKER ANDREW K. POZNANSKI NORMAN C. RASMUSSEN WILLIAM C. REINIG C H E S R. ~ F~ICHMOND HARALDH. Ross1 ROBERTE. ROWLAND EUGENEL. SAENCER LEONARDA. SAGAN WARRENK. SINCLAIR JOHNB. STORER ROYC. THOMPSON JAMES E. TURNER ARTHURC. UPPON JOHN C. VILLIWRTH GEORGEL. VOELZ NIEL WALD E ~ w W. m WEBSTER GEORGEM. WILKENING MCDONALDE WRENN

Honorary M t m b a n LAURIS~ON S. TAYLOR. Honoray President

EDGAR C. BARNES C~uu.B. BWW~RUP A u s r m M. B R U E ~ P. COWAN FREDBR~CK ROBLEYD.EVANS

PAUL C. Horn;= GEORGEV. LEROY KARLZ. MORGAN RUSBELLH. MORGAN HERBERTM.PARKER

EDITR H. QUXMBY WILLIAMG. RUSSW JOHN H. RUST J. NEWELLSTANNARD HAROLD0.WYCKOPP

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Currently, the following Scientific Committees are actively engaged

in formulating recommendations: Basic Radiation Protection Criteria Medical X-Ray, Electron Beam and Gamma-Ray Protection for Enup to 50 MeV-Equipment Performance and Uae. Incineration of Radioactive Waste X-Ray Protection in Dental OFfices Standards and Measurements of Radioactivity for Radiological Use Radiation Protection in the Use of Small Neutron Generators High Energy X-Ray Dosimetry Administered Radioactivity Dase Calculations Maximum Permissible Concentrations for Occupntional and Non-Occupational Exposures Waste Disposal Biological Aspects of Radiation Protection Criteria Radiation Resulting from Nuclear Power Generation Industrial Applications of X Rays and Sealed Sources Radiation Associated with Medical F . tions Radiation Received by Radiation Employees Operational Radiation Safety Instrumentation for the Determination of Dose Equivalent Apportionment of Radiation Exposure Surface Contamination Radiation Protection in Pediatric Radiology and Nuclear Medicine Applied to Children Conceptual Basis of Calculations of Dose Distributioll~ Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Radiation Bioassay for Assessment of Control of Intake of Radionuclides Experimental Verification of Internal Dosimetry Calculations Internal Emitter Standards Human Radiation Exposure Experience Dosimetry of Neutrons from Medical Acceleraton, Radon Measwements Priorities for Dose Reduction Efforts Civil Defense Environmental Pathways Quality Assurance and Accuracy in Radiation P r o w i o n Measurements Biological Effects and Exposure Criteria for Ultrasound Biological Effects of Magnetic Fields Microprocessors in Doairnetry Efficacy Studies Buality Assurance and Measurement in Diagnostic RadiDlogy

In recognition of its responsibility to facilitate and stimulate coop eration among organizations concerned with the scientific and related

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aspects of radiation protection and measurement, the Council has created a category of NCRP Collaborating Organizations. Organizations or groups of organizations that are national or international in scope and are concerned with scientific problems involving radiation quantities, units, measurements and effects, or radiation protection may be admitted to collaborating status by the Council. The present Collaborating Organizations with which the NCRP maintains liaison are as follows: American Academy of Dermatology American Association of Physicists in Medicine American College of Radiology American Dental Association American Industrial Hygiene Aswciation American Institute of Ultrasound in Medicine American Insurance Association American Medical Association American Nuclear Society American Occupational Medical Association American Podiatrj Association American Public Health Association American M u m Society American Roentgen Ray Society American Society of Radiologic Technologists American Society of Therapeutic Radiologists Association of U.niversity Radiologists Atomic Industrial Forum College of Ameiican Pathologists Federal Emergency Management Agency Genetics Society of America Health Physics Society National Bureau of Standards National Electrical Manufacturers Association Radiation Research Society Radiological Society of North Ami!rica Society of Nuclear Medicine United States Air Force United States Army United States Department of Energy United States Department of Labor United States Environmental Protection Agency United States Navy United States Nuclear %g&tory Cammission United States Public Health Service

The NCRP has found its relationships with these organizations to be extremely valuable to continued progress in its program.

The Council's activities are made possible by the voluntary contribution of time and effort of its members and participants and the generous support of the following organizations: Alfred P. Sloan Foundation Alliance of American Insurers American Academy of Dental Radiology American Academy of Dermatology American Association of Physicists in Mediiine American College of Radiology American College of Radiology Foundation American Dental Association American Industrial Hygiene Association American Insurance Association American Medical Association American Nuclear Society American Occupational Medical Association American osteopathic College of Radiology American Podiatry Association American Public Health Association American Radium Society American Roentgen Ray Society American Society of Radiologic Technologists American Veterinary Medical Association American Veterinary Radiology Society Association of University Radiologists Atomic Industrial Forum Battelle Memorial Institute Bureau of Radiological Health CoUege of American Pathologists Edison Electric Institute Edward MallinckrodL Jr. Foundation Electric Power Reseerch Institute Federal Emergency Management Agency Genetics Society of America Health Physics Society James Picker Foundation National Association of Photographic Manufacturers National Bureau of Standards National Cancer Institute National Electrical Manufacturers Association Radiation Research Society Radiological Society of North America Society of Nuclear Medicine United States Department of Energy United States Environmental Protection Agency United States Navy United States Nuclear Ftegulatory Cornmisoion

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To all these organizations the Council expresses its profound appreciation for their support. Initial funds for publication of NCRP reports were provided by a grant from the James Picker Foundation and for this the Council wishes to express its deep appreciation. The NCRP seeks to promulgate information and recommendations based on leading scientificjudgment on matters of radiation protection and measurement and to foster cooperation among organizations concerned with these matters. These efforts are intended to serve the public interest and the Council welcomes comments and suggestions on its reports or activities from those interested in its work.

NCRP Publications NCRP publications are distributed by t h e NCRP Publications Office. Information on prices and how to order may be obtained by directing a n inquiry to: NCRP Publications 7910 Woodmont Avenue Suite 800 Bethesda, MD 20814-3095 The currently available publications are listed below.

NCRP Reports No.

Title

Control and Removal of Radioactive Contamination i n Laboratories (1951) Maximum Permissible Body Burdens and Maximum Permissible concentrations of Radionuclides in Air and in Water for Occupational Exposure (1959) [Includes Addendum 1 issued in August 19631 Measurement of Neutron Flux and Spectra for Physical and Biological Applications (1960) Measurement of Absorbed Dose ofNeutrons, and of Mixtures of Neutrons and Gamma Rays (1961) Stopping Powers for Use with Cavity Chambers (1961) Safe Handling of Radioactive Materials (1964) Radiation Protection in Educational Institutions (1966) Dental X-Ray Protection (1970) Radiation Protection in Veterinary Medicine (1970) Precautions i n the Management of Patients Who Have Received Therapeutic Amounts of Radionuclides (1970) Protection Against Neutron Radiation (1971) Protection Against Radiation from Brachytherapy Sources (1972) Specification of Gamma-Ray Brachytherapy Sources (1974) Radiological Factors Affecting Decision-Making i n a Nuclear Attack (1974) Krypton45 in the Atmosphere-Accumuhtion, Biological Significance, and Control Technology (1975)

NCRP PUBLICATIONS

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Alpha-Emitting Particles in Lungs (1975) Tritium Measurement Techniques (1976) Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies U p to 10 MeV (1976) Environmental Radiation Measurements (1976) Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities (1977) Cesium-137 from the Environment to Man: Metabolism and Dose (1977) Medical Radiation Exposure of Pregnant and Potentially Pregnant Women (1977) Protection of the Thyroid Gland in the Event of Releases of Radioiodine (1977) Instrumentation and Monitoring Methods for Radiation Protection (1978) A Handbook ofRadioactivity Measurements Procedures, 2nd ed. (1985) Operational Radiation Safety Program (1978) Physical, Chemical, and Biological Properties of Radiocerium Relevant to Radiation Protection Guidelines (1978) Radiation Safety Training Criteria for Industrial Radiography (1978) Tritium in the Environment (1979) Tritium and Other Radionuclide Labeled Organic Compounds Incorporated in Genetic Material (1979) Influence of Dose and Its Distribution in Time on DoseResponse Relationships for Low-LE T Radiations (1980) Management of Persons Accidentally Contaminated with Radionuclides (1980) Radiofrequency ~lectrorna~netic Fielcls-Properties, Quantities and Units, Biophysical Interaction, and Measurements (1981) Radiation Protection in Pediatric Radiology (1981) Dosimetry of X-Ray and Gamma-Ray Beams for Radiation Therapy in the Energy Range 10 keV to 50 MeV (1981) Nuclear Medicine-Factors Influencing the Choice and Use of Radionuclides in Diagnosis and Therapy (1982) Operational Radiation Safety-Training (1983) Radiation Protection and Measurement for Low-Voltage Neutron Generators (1983) Protection in Nuclear Medicine and Ultrasound Diagnostic Procedures in Children (1983)

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NCRP PUBLICATIONS

Biological Effects of Ultrasound: Mechanisms and Clinical Implications (1983) Iodine-129: Evaluation ofReleases from Nuclear Power Generation (1983) Radiological Assessment: Predicting the Transport, Bioacc u m u l a t i o n , a n d Uptake by M a n o f Radionuclides Released to the Environment (1984) Exposures from the Uranium Series with Emphasis o n Radon and Its Daughters (1984) Evaluation of Occupational and Environmental Exposures to Radon and Radon Daughters in the United States (1984) Neutron Contamination from Medical Electron Accelerators (1984)

Induction of Thyroid Cancer by Ionizing Radiation (1985) Carbon-14 in the Environment (1985) SI Units in Radiation Protection and Measurements (1985) The Experimental Basis for Absorbed-Dose Calculations in Medical Uses of Radionuclides (1985) General Concepts for the Dosimetry of Internally Deposited Radionuclides (1985) Mammography-A User's Guide (1986) Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields (1986) Use of Bioassay Procedures for Assessment o f Internal Radionuclide Deposition (1987) Radiation Alarms and Access Control Systems (1986) Genetic Effects from Internally Deposited Radionuclides (1987)

Neptunium: Radiation Protection Guidelines (1988) Public Radiation Exposure from Nuclear Power Generation in the United States (1987) Ionizing Radiation Exposure of the Population of the United States (1987) Exposure of the Population in the United States and Cam& from Natural Background Radiation (1987) Radiation Exposure of the U.S. Population from Consumer Products and Miscellaneous Sources (1987) Comparative Carcinogenicity of Ionizing Radiation and Chemicals (1989) Measurement of Radon and R a h n Daughters in Air (1988) Guidance on Radiation Received i n Space Activities (1989) Qmlity Assurance for Diagnostic Imaging (1988) Exposure of the U.S. Population from Diagnostic Medical Radiation (1989)

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Exposure of the U.S. Population from Occupational Radiation (1989) Medical X-Ray, Electron Beam and Gamma-Ray Protection for Energies Up to 50 MeV (Equipment Design, Performance and Use) (1989) Control of Radon in Houses (1989) The Relative Biological Effectiveness ofRadiations ofDifferent Quality (1990) Radiation Protection for Medical and Allied Health Personnel (1989) Limit for Exposure to "Hot Particles" on the Skin (1989) Implementation of the Principle of A s Low As Reasonably Achievable (AL.AXA) for Medical and Dental Personnel (1990) Conceptual Basis for Calculations of Absorbed-Dose Distributions (1991) Effectsof Ionizing Radiation on Aquatic Organisms (1991) Some Aspects of Strontium Radiobiology (1991) DevelopingRadiation Emergency Plans for Academic, Medical or Industrial Facilities (1991) Calibration of Survey Instruments Used in Radiation Protection for the Assessment of Ionizing Radiation Fielcls and Radioactive Surface Contamination (1991) Exposure Criteria for Medical Dugnostic Ultrasound:I. Criteria Based on Thermal Mechanisms (1992) Maintaining Radiation Protection Records (1992) Risk Estimates for Radiation Protection (1993) Limitation of Exposure to Ionizing Radiation (1993) Research Needs for Radiation Protection (1993) Radiation Protection in the Mineral Extraction Industry (1993) Binders for NCRP reports are available. Two sizes make it possible to collect into small binders the "old series" of reports (NCRP Reports Nos. 8-30) and into large binders the more recent publications (NCRP Reports Nos. 32-118). Each binder will accommodate from five to seven reports. The binders carry the identification "NCRP Reports" and come with label holders which permit the user to attach labels showing the reports contained in each binder. The following bound sets of NCRP reports are also available: Volume I. NCRP Reports Volume 11. NCRP Reports Volume 111. NCRP Reports Volume IV.NCRP Reports

Nos. Nos. Nos. Nos.

8, 22 23, 25, 27, 30 32, 35,36, 37 38,40,41

1

NCRP PUBLICATIONS

Volume V. Volume VI. Volume VII. Volume VIII. Volume IX. Volume X. Volume XI. Volume XII. Volume XIII. Volume XIV. Volume XV. Volume XVI. Volume XVII. Volume XVIII. Volume XIX. Volume XX. Volume XXI. Volume XXII.

NCRP Reports Nos. 42,44, 46 NCRP Reports Nos. 47,49,50,51 NCRP Reports Nos. 52, 53, 54, 55, 57 NCRP Report No. 58 NCRP Reports Nos. 59,60, 61, 62, 63 NCRP Reports Nos. 64,65,66,67 NCRP Reports Nos. 68,69, 70, 71, 72 NCRP Reports Nos. 73, 74, 75, 76 NCRP Reports Nos. 77, 78,79, 80 NCRP Reports Nos. 81,82, 83,84, 85 NCRP Reports Nos. 86,87,88,89 NCRP Reports Nos. 90,91, 92,93 NCRP Reports Nos. 94, 95, 96, 97 NCRP Reports Nos. 98,99,100 NCRP Reports Nos. 101, 102, 103, 104 NCRP Reports Nos. 105, 106,107, 108 NCRP Reports Nos. 109, 110,111 NCRP Reports Nos. 112,113,114

(Titles of the individual reports contained in each volume a r e given above.) No. 1

NCRP Commentaries Title Krypton-85 in the Atmosphere-With Specific Reference to the Public Health Significance of the Proposed Controlled Release at Three Mile Island (1980) Preliminary Evaluation ofcriteria for the Disposal of Transuranic Contaminated Waste (1982) Screening Techniques for Determining Compliance with Environmental Standurds-Releases of Radionuclides to the Atmosphere (1986), Revised (1989) Guidelines for the Release of Waste Water from Nuclear Facilities with Special Reference to the Public Health Significance of the Proposed Release of Treated Waste Waters at Three Mile Island (1987) Review of the Publication, Living Without Landfills (1989) Radon Exposure of the U.S. Population-Status of the Problem (1991) Misadministration of Radioactive Material in MedicineScientific Background (1991) Uncertainty i n NCRP Screening Models Relating to Atmospheric Transport, Deposition and Uptake by Humans (1993)

NCRP PUBLICATIONS

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Proceedings of the Annual Meeting No. 1

Title

Perceptions of Risk, Proceedings of the Fifteenth Annual Meeting held on March 14-15, 1979 (including Taylor Lecture No. 3) (1980) Critical Issues in Setting Radiation Dose Limits, Proceedings of the Seventeenth Annual Meeting held on April 8-9, 1981 (including Taylor Lecture No. 5) (1982) R a d i a t i o n Protection and New Medical Diagnostic Approaches, Proceedings of the Eighteenth Annual Meeting held on April 6-7, 1982 (including Taylor Lecture No. 6) (1983) Environmental Radioactivity, Proceedings of the Nineteenth Annual Meeting held on April 6-7,1983 (including Taylor Lecture No. 7) (1983) Some Issues Important i n Developing Basic Radiation Protection Recommendations, Proceedings of the Twentieth Annual Meeting held on April 4-5,1984 (including Taylor Lecture No. 8) (1985) Radioactive Waste, Proceedings of the Twenty-first Annual Meeting held on April 3-4,1985 (including Taylor Lecture No. 9) (1986) Nonionizing Electromagnetic Radiations and Ultrashnd, Proceedings of the Twenty-second Annual Meeting held on April 2-3, 1986 (including Taylor Lecture No. 10) (1988) New Dosimetry at Hiroshima and Nagasaki and Its Implications for Risk Estimates, Proceedings of the Twenty-third Annual Meeting held on April 8-9,1987 (including Taylor Lecture No. 11)(1988) Radon, Proceedings of the Twenty-fourth Annual Meeting held on March 30-31, 1988 (including Taylor Lecture No. 12) (1989) Radiation Protection Today-The NCRP at Sixty Years, Proceedings of the Twenty-fifth Annual Meeting held on April 5-6, 1989 (including Taylor Lecture No. 13) (1990) Health and Ecological Implications of Radioactively Contaminated Environments, Proceedings of the Twentysixth Annual Meeting held on April 4-5,1990 (including Taylor Lecture No. 14) (1991) Genes, Cancer and Radiation Protection, Proceedings of the Twenty-seventh Annual Meeting held on April 3-4,1991 (including Taylor Lecture No. 15) (1992)

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Radiation Protection in Medicine, Proceedings of the Twenty-eighth Annual Meeting held on April 1-2,1992 (including Taylor Lecture No. 16) (1993) Lauriston S. Taylor Lectures No. 1

Title

The Squares of the Natural Numbers in Radiation Protection by Herbert M. Parker (1977) Why be Quantitative about Radiation Risk Estimates? by Sir Edward Pochin (1978) Radiation Protection-Concepts and Trade Off's by Hyrner L. Friedell (1979) [Available also in Perceptions of Risk, see abovel From ''Quantity ofRadiationnand ''Dose" to "Exposure" and "Absorbed Dose"-An Historical Review by Harold 0. Wyckoff (1980) How Well C a n W e Assess Genetic R i s k ? Not Very by James F. Crow (1981) [Available also in Critical Issues in Setting Radiation Dose Limits, see abovel Ethics, Trade-offs and Medical Radiation by Eugene L. Saenger (1982) [Available also in Radiation Protection and New Medical Diagnostic Approaches, see abovel The Human Environment-Past, Present and Future by Merril Eisenbud (1983) [Available also in Environmental Radioactivity, see above] Limitation and Assessment i n Radiation Protection by Harald H. Rossi (1984) [Available also in Some Issues Important in Developing Basic Radiation Protection Recommendations, see abovel Truth (and Beauty) in Radiation Measurement by John H. Harley (1985) [Available also in Radioactive Waste, see abovel Biological Effects of Non-ionizing Radiations: Cellular Properties and Interactions by Herman P. Schwan (1987) [Available also in Nonionizing Electromagnetic Radiations and Ultrasound, see above] How to be Quantitative about Radiation Risk Estimates by Seymour Jablon (1988) [Available also in New Dosimetry at Hiroshima and Nagasaki and its Implications for Risk Estimates, see above] How Safe is Safe Enough? by Bo Lindell (1988) [Available also in Radon, see above]

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Radiobiology and Radiation Protection: The Past Century and Prospects for the Future by Arthur C. Upton (1989) [Available also in Radiation Protection Today, see above] Radiation Protection and the Internal Emitter Saga by J . Newel1 Stannard (1990) [Available also in Health and Ecological Implications of Radioactively Contaminated Environments, see abovel When is a DoseNot a Dose? by Victor P. Bond (1992) [Available also in Genes, Cancer and Radiation Protection, see abovel Dose and Risk in Diagnostic Radiology: How Big? How Little? by Edward W. Webster (1992)[Available also in Radiation Protection in Medicine, see abovel Science, Radiation Protection and the NCRP by Warren K. Sinclair (1993) Symposium Proceedings The Control of Exposure of the Public to Ionizing Radiation in the Event ofAccident or Attack, Proceedings of a Symposium held April 27-29, 1981 (1982)

NCRP Statements No. 1

2

Title "Blood Counts, Statement of the National Committee on Radiation Protection," Radiology 63, 428 (1954) "Statements on Maximum Permissible Dose from Television Receivers and Maximum Permissible Dose to the Skin of the Whole Body," Am. J. Roentgenol., Radium Ther. and Nucl. Med. 84, 152 (1960) and Radiology 75, 122 (1960) X-Ray Protection Standards for Home Television Receivers, Interim Statement of the National Council on Radiation Protection and Measurements (1968) Specification of Units ofNatura1 Uranium and Natuml Thorium, Statement o f the National Council on Radiation Protection and Measurements (1973) NCRP Statement on Dose Limit for Neutrons (1980) Control of Air Emissions of Radionuclides (1984) The Probability That a Particular Malignancy May Have Been Caused by a Specified Irradiation (1992)

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Other Document. The following documents of the NCRP were published outside of the NCRP Report, Commentary and Statement series: Somatic Radiation Dose for the General Population, Report of the Ad Hoc Committee of the National Council on Radiation Protection and Measurements, 6 May 1959, Science, February 19,1960, Vol. 131, No. 3399, pages 4 8 2 4 8 6 Dose Effect Modifying Factors I n Radiation Protection, Report of Subcommittee M-4 (Relative Biological Effectiveness) of the National Council on Radiation Protection and Measurements, Report BNL 50073 (T-471) (1967) Brookhaven National Laboratory (National Technical Information Service Springfield, Virginia)

The following documents are now superseded andlor out of print:

No. 1

NCRP Reports Title

X-Ray Protection (1931) [Superseded by NCRP Report No. 33 Radium Protection (1934) [Superseded by NCRP Report No. 41 X-Ray Protection (1936) [Superseded by NCRP Report No. 61 Radium Protection (1938) [Superseded by NCRP Report No. 131 Safe Handling of Radioactive Luminous Compound (1941) [Out of Print] Medical X-Ray Protection Up to Two Million Volts (1949) [Superseded by NCRP Report No. 181 Safe Handling of Radioactive Isotopes (1949) [Superseded by NCRP Report No. 301 Recommendations for Waste Disposal ofPhosphorus-32and Iodine-131 for Medical Users (1951) [Out of Print] Radiological Monitoring Methods and Instruments (1952) [Superseded by NCRP Report No. 571 Maximum Permissible Amounts o f Radioisotopes i n the Human Body and Maximum Permissible Concentrations in Air and Water (1953) [Superseded by NCRP Report No. 221 Recommendations for the Disposal of Carbon-14 Wastes (1953) [Superseded by NCRP Report No. 811

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Protection Against Radiations from Radium, Cobalt-60 and Cesium-137 (1954) [Superseded by NCRP Report No. 241 Protection Against Betatron-Synchrotron Radiations Up to 100 Million Electron Volts (1954) [Superseded by NCRP Report No. 511 Safe Handling of Cadavers Containing Radioactive Isotopes (1953) [Superseded by NCRP Report No. 211 Radioactive-Waste Disposal i n the Ocean (1954) [Out of Print] Permissible Dose from External Sources of Ionizing Radiation (1954) including Maximum Permissible Exposures to Man, Addendum to National Bureau of Standards Handbook 59 (1958) [Superseded by NCRP Report NO. 391 X - R a y Protection (1955) [Superseded by NCRP Report No. 261 Regulation of Radiation Exposure by Legislative Means (1955) [Out of Print] Protection Against Neutron Radiation Up to 30 Million Electron Volts (1957) [Superseded by NCRP Report No. 381 Safe Handling of Bodies Containing Radioactive Isotopes (1958) [Superseded by NCRP Report No. 371 Protection Against Radiations from Sealed Gamma Sources (1960) [Superseded by NCRP Reports No. 33,34 and 401 Medical X-Ray Protection Up to Three Million Volts (1961) [Superseded by NCRP Reports No. 33,34,35 and 361 A Manual of Radioactivity Procedures (1961) [Superseded by NCRP Report No. 581 Exposure to Radiation i n an Emergency (1962) [Superseded by NCRP Report No. 421 Shielding for High-Energy Electron Accelerator Installations (1964) [Superseded by NCRP Report No. 511 Medical X-Ray and Gamma-Ray Protection for Energies up to 10 MeV-Equipment Design and Use (1968) [Superseded by NCRP Report No. 1021 Medical X-Ray and Gamma-Ray Protection for Energies Up to 10 MeV-Structural Shielding Design and Evaluation Handbook (1970) [Superseded by NCRP Report No. 491 Basic Radiation Protection Criteria (1971) [Superseded by NCRP Report No. 911 Review of the Current State ofRadiation Protection Philosophy (1975) [Superseded by NCRP Report No. 911 Natural Background Radiation in the United States (1975) [Superseded by NCRP Report No. 941

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Radiation Protection for Medical and Allied Health Personnel (1976) [Superseded by NCRP Report No. 1051 Review ofNCRP Radiation Dose Limit forEmbryo and Fetus i n Occupationally-Exposed Women (1977) [Out of Print] Radiation Exposure from Consumer Products and Miscellaneous Sources (1977) [Superseded by NCRP Report No. 951 A Handbook of Radioactivity Measurements Procedures, 1st ed. (1978) [Superseded by NCRP Report No. 58,2nd ed.1 Mammography (1980) [Out of Print] Recommendations on Limits for Exposure to Ionizing Radiation (1987) [Superseded by NCRP Report No. 1161

NCRP Proceedings No. 2

Title Quantitative Risk i n Standards Setting, Proceedings of the Sixteenth Annual Meeting held on April 2-3, 1980 [Out of Print]

Index Abdomen, 56-63,92-96 gonadal dose. 58-63 radiation dose, 56-57 Abdomen AP. radiation dose. 94 Abdomen. erect AP, radiation dose, 92 Abdomen, lateral, radiation dose, 98 Abdomen PA, radiation dose, 96 Absorbed dose. 111 Angiography, 56-57,111 abdominal, radiation dose, 56-57 Automatic exposure control, 15, 111 Background radiation, 6 Benefit-risk relationship, 1 Bladder. 8&91 Bladder AP,radiation dose, 8@-89 Bladder, posterior oblique, radiation dose.

Dental radiography, 48.49,M indications, 49 radiation doses, typical, 6 4 thyroid protection, 48 Dentists, 12 Distance as protection. 30 Dose equivalent, 111 Duplicate examination. 11

90-91

Bone marrow. 3.65 dose tables, 65 risk of radiation. 3 Breast, 3. 19 risk of radiation. 3 shielding, 19 Bucky diaphragm. 16 Cancer risk. 2-5 bone marrow, 3 breast. 3 fetus, 5 general. 2 other, 4 thyroid. 3 Cartinogenesis, 1 Cardiac angiography, 46 Cardiologists, 12 Cataracts. 5 ~ephalometricfilm, radiation dose, 64 Cerebral anmoaraohv. - . - - radiation dase, 5657

-

Chest, gonadal dwe. 58-63 Chest AP, radiation dose, 78-79 Chest, lateral, radiation dose, 82-83 Chest PA. radiation dose, 80-81 Chest. posterior oblique, radiation dose

84-85 Child-adult differen-

conduct of examinations, 12 radiation risk, 7 Chiropractors, 12 Cineradioa;raphy, 19.46 Chromosomal disorders. 4 Clothing, 15 Collimation, 19 Collimator, 111 Comparison views, 13 Computed tomography, 46.47 indications, 46 radiation dose. 47 scattered radiation, 47 Cone. 111 Congenital malformations, incidence, 6 Contact shields. 26

7.12

Energy imparted. 111 Excretory urogram, radiation dose, 56-57 Exposure,111 Eyes, 19.31 protection of fluonwcopist, 31 shielding, 19

Failure to thrive, 10 Fertility impairment, 4 Film processing, quality control, 15 F i screen combination, 16.41-42 choice, 41 non-screen film. 42 rare earth, 42 Filtration, 45, 106 half value layer tables, 106 molybdenum, 45 Fluoroscopy, 10, 17-18, 31-33, 44-45, 52, 111

brightness control 18 C-arm, 31

140

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INDEX

cooperation of the child, 17 definition, 11 1 equipment, 31 eye protection, 31 filtration. 45 grid, 18 image intensifier sizes, 44 indications, 17 mobile units, 52 monitoring dose, 33 molybdenum fdtration, 45 operating room, 18 over the table tube, 31 photofluorographic spot f h s , 45 questionable indications, 10 scattered radiation distribution, 32 spot films. 45 television, 45 time, 17 under table tube, 31 variable aperture iris, 18 variable iris diaphragm, 45 video disk. 18 video tape, 18 Fracture reduction, 10 Gastroenterologists, 12 Gonadal dose, 20.23 beam size effects, 23 effect of patient position, 20 Gonadal protection see Gonadal shielding Gonadal shielding, 22, 26,28-29 contact shields, 26 indication. 22 interference with examination, 29 methods, 26 shadow shields, 28 shaped contact shields, 28 Gonadal radiation doses, selected examination, 58-63 Gonads. 4.22 risk of radiation, 4 shielding general, 2 Grids. 16.18.43 fluoroscopy. I8 Half value layers, 106.112 definition, 112 as function of tube potential and filtration, 106 Hereditary effects. 4 chrornasomal, 4 mortality, 4 sex linked, 4 dominant, 4 Hip AP,radiation dose, 102

Hip, posterior oblique, radiation dose. 104 Image intensifier, 44 cesium iodide, 44 size, 44 type?44 Image quality, definition, 112 Imaging systems, 41,42 film screen combinations, 41 xeroradiography, 42 Immobilization board, 35 Immobilization of children, 34.38-40 chest radiography, 38 indications, 34 methods, 34 precautions, 39 risks. 39-40 ~ndicationsfor medical radiations, 1 Indications for radiologic examinations,911 abdominal pain, 10 benefit to patient, 9 factors affecting decision, 11 failure to thrive, 10 fluoroscopy for fracture reduction, 10 preoperative chest, 10 questionable examinations. 10 research, 9 skull injury. 10 Intensifying screens, I6 Kerma. 112 Kidneys AP, radiation dose, 86 Kilovolt (KV) 16, 106,112 half value layer-tables, 106 Lead aprons. 30 Lead gloves. 30 Leukemia, 3 Lungs, dose tables, 65 Mastoids. gonadal dose. 58-63 Maximum permissible dose, 2,7,112 d e f ~ t i o n 112 . not applied to medical radiation. 2 Mobile equipment, 50-52 barriers. 51 neonatal intensive care, 50 scattered radiation. 52 variability in exposure, 50 Natural radiation, 6 Neck AP, radiation dose, 74 Neck. lateral. radiation dose, 76 Neonatal intensive care nlusery, 28.50 gonadal shielding, 28 mobile examinations, 50

radiation dose from scatter. 50 Noise, 112 Obstetrics. radietion dose. 56-57 Octagon board, 35 Operating room,mobile equipment, 52 Organ radiation doses, 65, 107 calculation methods, 107 estimator methods, 65, 107 Orthopedist$l2 Osteopaths, 12 Output, 112 Ovarian shielding, 23-25 indications, 23 location of ovary, 23.25 size of shield, 23 Ovaries, 23,65 dose tables, 65 location, 23 Panoramic film, radiation dose. 64 Pelvis, gonadal dose, 56-63 Pelvis AP. radiation dose, 100 Photofluorographicspot films,45 Podiatrists. 12 Pointed cones, 49 Preparation for examination. 15 Pregnancy, 21 determination, 21 modification of examination, 21 Pregnant personnel. 33 Preoperative chest, 10 Previous films, 11 Processing x-ray film, 43-44 automatic. 43 manual, 43 priming procesor, 44 Proper. 43 replenishment rate. 44 sensitometric ships. 44 Q u d t y control, 15 exposure, 15 ,-P 15 program, 15 Quantum mottle, 12 Rad, 112 Radiation d o e , 46.47,50,55-105 abdomen, 56-57 abdomen AP, 94 abdomen erect AP,92 abdomen lateral. 98 abdomen PA, 96 angiocardiography,56,57 angiography abdomen, 56-58 bladder AP, 88

bladder po6terior oblique, 90 bone marrow tables, 65 cardiac angiography, 46 cephalometric film. 64 cerebral angiography, 56-57 chest, 56.57 chest AP, 78 chest lateral, 82 chest PA, 80 chest, posterior oblique, 84 computed tomography, 47 dental-typical, 64 excretory urogram. 56-57 gonadal doses from selected examinations, 5&63 hip AP, 102 hip posterior oblique, 104 lodneys AP,86 kidney ureters, 56.57 l u n p t a b l e s , 65 neck AP, 74 neck, lateral, 76 neonatal intensive care nursery. 50 obstetric, 56.57 organs, methods of estimation, 65 ovaries-tables, 65 panoramic film,64 pediatric radiology, 55 pelvis AP, 100 skin doses, table, from selected eurminations. 56 skull, 56-57 skull AP,68 skull. lateral, 72 skull PA, 70 spine, 36-57 testes--tables, 65 thyroid-tables. 65 total body-tables. 65 Tomes view, 66 whole body doses from selected examinations, 57 Radiation dose reduction, 9, 13-14, 16-19. 31,48 clinical information, 9 collimation, 19 comparison views, 13 consultation, 9 dental radiography, 40 distance, patient to detector, 18 eyes of fluoroscopist, 31 fluoroscope design, 31 fluoroscopy, 17 kiIovoltage. 16 number of views, 13 patient, 9 repeat examinations,14

shielding, 19 tailored eramination. 13 video disk, I8 video tape, 18 Radiation effects, 1, 3-5 breast, 3 bone marrow. 3 carcinogenesis, 1 embryo, 5 eye, 5 fetus, 5 gonads, 4 hereditary, 1,4 lens of eye, 5 non-stochastic, 1 other organs, 4 pregnancy, 5 somatic, 1 stochastic, 1 teratogenesis, 1 thyroid, 3 Radiation exposure per mAs, 109 Radiation protection, 1,6,9,'22, 30, 48,W children, 9 dental radiography, 48 distance, 30 goals 1,6 gonads, 22 medical radiation, 9 mobile units.50 objectives, 1 parents, 30 personnel, 30 Radiation risk, 2-7 BEIR (NAS1972), 2 breast, 3 child-adult differences, 7 bone marrow,3 cancer, 2 common sense considerations, 6 embryo, 5 eye, 5 fetus, 5 gonads, 4 ICRP 1977,2 pregnancy, 6 thyroid. 3 UNSCEAR 1977,2 Radiography, 112 Radiologic equipment, 30-31, 34, 41, 4446,48,50,109 computed tomography, 46 dental radiography, 48 film screen combinations, 41 filtration. 45 fluomscopic, 44 fluoroscopic units deeign. 31

image intensifiers. 44 immobilizations devices, 34 lead aprons and gloves. 30 mobile, 50 output mR/mAs, 109 processors, 41 radiographic units. 41 shields, 30 spot films, 45 variable iris diaphragm, 45 Radiologic examinations, 9-11. 1516.21. 34-35,48 benefit to patient, 9,11 duplicate, 11 feet, 35 film screening combination, 16 grids, 16 hands, 35 immobilization, 34 i n d i c a t i o ~ Indications e for intensifying screens. 16 pregnant girl, 21 preparation, 15 questionable value, 10 repeat, 11 research, 9 self referral, 11 teeth, 48 timing, 11 Radiologic examination rooms,13 Radiologic technologist, 12, 16,31 Radiologist, 31 eye protection. 31 protection. 31 Radiology, indications. 1 Rem, 112 Repeat examinations. 11.14.19 causes, 14 collimator. 19 exposure problems. 14 indications, 11 minimizing need, 14 motion. 14 positioning, 14 respiratory motion. 14 Resolution, 113

Retakes see Repeat examinations Research, 9 Risk, 6,39 chemicals, 6 driving auto, 6 immobilization devices, 39 other than radiation. 6 radiation-see Radiation risk Roentgen, 113 Roentgens per mAs, 109

INDEX Scattered radiation. 16, 32, 47, 113 computed tomography, 47 definition, 113 fluoroscopy. 32 Screens, dental radiography, 18 Screen-film system. 113 Self-referral of radiologic examinations, 11 Sensitivity, 113 Shadow shields, 28 Shaped contact shields, 28 Shielding, 19, 22.30.34 breast. 19 dental radiography, 49 eyes, 19 general, 19 gonads, 22 leaded aprons, 30 thyroid, 19 Sinuses, gonadal dose, 58-63 Skin radiation dose. 56, 113 selected examinations. 56 Skull, 10,5663 gonadal dose, 58-69 injury, 10 radiation dose, 56-57 Skull AP, radiation dose. 68 Skull, lateral, radiation dose, 72 Skull PA. radiation dose. 70 Sperm count. 4 Spine, 56-63 gonadal dose. 58-63 radiation dose, 56-57 Spot films,45 Sterility, 4 Stochastic effects, 1

1

143

Tailored examinations, 13 Television systems, 45 Testes--dose tables, 65 Testicular shielding. 22. 24 dose as function of distance from shield, 24

indications, 22 Thyroid, 3, 19,48, 65 dose tables, 65 radiation dase in dental radiography, 48 risk of radiation, 3 shielding, 19 Thyroid protection, dental radiography, 48 Total body-dose tables. 65 Townes view, radiation dose, 66 Training, 12. 16 Tube potential see Kilovolt

Variable aperture iris,18 Variable iris diaphragm, 45 Velcro straps. 35 Whole body radiation doses, selected examinations. 57 Xeroradiography, 42 X-ray equipment see Radiologic equipment X-ray film processing see Processing x-ray f h