Exposure of the U.S. Population from Diagnostic Medical Radiation: Recommendations of the National Council on Radiation Protection and Measurements (NCRP report)

NCRP REPORT No. 100

EXPOSURE OF THE U.S. POPULATION FROM DIAGNOSTIC MEDICAL RADIATION

Recommendations of the NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASLIREMENTS

Issued May 1,1989 First Reprinting January 31, 1993 Natioml Councilon Radiation Protedh and Maasurwnents 7 9 0 WOODMONT AVENUE I Bethexh, MD 208l4

LEGAL NOTICE

This report was prepared by the National Council on Radiation Protection and Measurements (NCRP). The Council strive8 to pmvide accurate. complete and uaeful information in its reports. However, neither the NCRP, the members of NCRP, other persons contributing to or assisting in the preparation of this report, nor any person acting on the behalf of any of these parties (a) makes any warranty or repreaentation, express or implied, with respect to the accuracy, completeness or ueefulnees of the information contained in this report, or that the use of any information, method or ~ocessdisclosed in this report may not infringe on privately owned rights; or (b) assumes any liability with respect to the use of, or for damages resulting from the use of any information,method or prwms d i s c l d in this report, crndsr the Civil Rights Act of 1934, Section 701 et seq. as Mlended 42 USC Section et seq. (Title VIIl or m y other statutory or wmmon hw theory goveining iiability

National Council on Radiation Protection and Meammemat.. Exposure of the U.S. population from diagnwtic medical radiation: recommendstiom of the National Council on Radiation Protection and Measurements. a - ( N C R P report ;no. 100) p. "Issued May 1.1989." Includes index. ISBN 0-92600-1-0 1. Radiography, Medical-Health aspects-United States. 2. Nuclear medick+Health aspects-United States. 3. Radiation-Doaage. I. Title. 11. Series. PNLM: 1. Radiation Dosage. 2. Fhdiation Protection-standards-United S t a h . 3. Radiography-adverse effects. 4. Radiography-standards-United States. WN 650 N279eI RA 669.N363 1988 88-25316 363.1'79-dc 19 CIP

Copyright 0 National Councilon Radiation Protection and Meaaurementa 1989 All rights resenred. This publication is pmtected by copyright. No part of this public& tion may be reproduced in any form or by any means, including photocopying, or utilized by any information storege and retrieval syetsm without written permission from the copyright awner, except for brief quotation in critical articlea or reviews. Library of Congreas Catalog Card Number International Standard Book Number

Preface The NCRP has long mcog&ed the need for a clear assessment of the magnitude of doses from various souroes of radiation to which the population of the U.S. is ocpo9ed.In anticipation of the need to gather data for input into this process five as&sament committees, each a d h i n g a different source category, wem established, first in 1971 and then reestablished in 1986. NCRP reports assessing exposum from natural background, consumer products, and nuclear power gene ation have recently been published (NCRP, 1987%1987b. 1987~). This Report is concerned with the assessment of the radiation dose to the population from diagnostic medical and dental x-ray examinations and nuclear medicine examinations. Within these areas, the Report details data sources, numbers of examinations, population demographics, differential trends,absorbed doses, gonadal and genetically significant doses, and effective dose equivalents, as well as £ilm usage, dose reduction, and future trends for diagnostic radiology. This Report represents one source of information for the overall summary effort, NCRP Report No. 93, Ionizing Radiation Exposure of the Population of t h United States (NCRP,1987d). The International System of Units (SI) is used in this Report followed by conventional units in parentheses in accordance with the p d u r e set forth in NCRP Report No. 82, SI Units in Radiation Protection and Measwements (NCRP, 1985). This report was prepared by Scimtific Committee 44 on Radiation Associated with Diagnostic Medical Examinations. Serving on the Committee were: W.W. Burr, Chairman (1912-1976) Robert D. Maseleg, Jr, Chairman (1!#7~19%7)*

* D d Fnd A. Mettler, Jr., Chairman(1987-1988) Department of Radiology Universityof New Mexico JoeephS.Arearese Ceater for Devices and Radiological Health Rockdle, MD William W. Burr, Jr. Oak Ridge Associated Univemitiea Oak Ridge,TN

Aatolin Raventae Radiotherapy Section Martinez, CA

RobertO.Gmeon Thomas Jeffaraon U n i h t y Hospital PhhMpha, PA

hrsePeLSaeneer

Maws-

Bernard Shlaiea N u h Leetern Aaaociates Olney, MD

Battab Pacific Northweat Laboratoriee Richland, WA

MarvinR43~~&& Center for Devices and Radiological Health Rmkvilla MD University Hospital Cinciuuati, OH

iv

I

PREFACE

David L.Abernathy J. Lloyd Johnson Associates Northfield. IL

Advieow Members Ralph E.Bunge Centar for Devices and Radi01ogical Health Rockville, MD

Lynn A Selke Eaatmm Kodak Company Rochestep, NY

JameaG.Kedakea Univessity of Cincinnati Cincinnati, OH

NCRP S a r e m h t Tbomaa M. b a l

The Council wishes to express its appreciation to the Committee members, advisors and consultants for the time and effort devoted to the preparation of this RBport. Bethesda, Maryland June 15,1988

Warren K.Sinclair President

Contents .

1 Introduction ...................................... 1.1 overview ..................................... 1 2 Diagnostic Medical Radiation .................... 2. Concepts, 'Unitsand &aantitie!a ....................... 3. Diagndc Medical and Dental X-rayEmnminatione ....... 3.1 Data Sources ................................. 3 2 Equipment Availability and Film Usage ............ 3.3 Number and Thnds of Examinations ............... 3.4 Population Demographic9 ........................ 3 5 Diffmtial!lhmds ............................. 3.6 Exposure and Absorbed Dose .................... 3.7 Quality A s m e and Dose Reduction ............. 3.8 Gonadal and Genetidy Significant Dose ........... 3.9 Meau Active Bone Marmw Dose .................. 3.10 Somatic Doses and Effective Dose Equivalent ........ 3.11 Future Thnds in Diagnostic Radiography ........... 4 Nuclear Medicine .................................. 4 1 Introduction .................................. 42 Datasources ................................. 4 3 Number of Examinations ........................ 4 4 Population Demographics ........................ 45 Differential 'lhnds ............................. 4 6 Absorbed Dose in Nuclear Mediciae ................ 4.7 Gonadal and GeneticallyS i c a n t Dose ........... 4 8 Effective Dose Equivalent ....................... 5. sj........................................ Appendix A.Sample Calculation of Callective Effective Dose Equivalent ....................................... References ..........................................

.

The NCRP ...........................................

84

NCRP Publicatio~~ .................................... 91

Index ............................................... 102

1. Introduction 1.1 Overview

The use of radiation in medicine is m c q p k d as the largest manmade component of radiation expome to the United States population, second only to nahval backgrrrund as a source. The aim of this Report is to assess in detail the magnitude of medical diagnostic exposure and dose in the U.S. Medical radiation, for purposes of this Report, encompasses diagnostic radiology, dental radiography, and diagnostic nuclear medicine. Because of the special nature of radiation therapy (generally older age gmups and usrady with a diagnosis of cancer), radiation h m therapeutic sources will not be considered here. Once an exposure assessment is completed: (I) sources of radiation exposure might be compared, (2) problem areas may be identified, (3) possible benefit and detriment can be. estimated, and (4) if indicated, efforts may be mobilized for radiation dose reduction. Detriment from the use of medical radiation has not bean calculated since,in order to do this appropriately, one would need to balance the risk and benefits of the practice. Neither the data nor the methodology to accurately per form such an assessment are available at this time. From about 1930 until 1958, most radiation protection groups were predominantly interested in gonadal exposurea relevant to the risk of hereditary effects, and, t h f o r e , estimated what was termed a genetically significant dose (GSD). The major portion of the GSD from medical exposures is contributed by a few t w of examinations. Later, interest shifted to estimation of mean doses in otha tissues, particularly those regarded as more susceptible to the induction of carcine genic effects (ag., active bone marrow, t h p i d , lung, and female breast). For calculation of possible subsequent cancer induction, consideration of patient age at exposure was recognized to be important, but little medical demographic information existed concerning this parameter. It is very difficult to compare the risk of medical radiation with risks h m other sources of man-made exposure or h m natural background radiation. One problem is that such comparisons must, by nature, compare radiation of healthy versus sick populations. The effects of radiation are thought to depend upon the dose rate. total absorbed

dose, time over which the total dose is received, anem of the radiation, and the part of the body exposed. This Report examines the age distribution of population8 UM1e.r~ ing difterent medical diagnostic examinations and indicates that there are significant diffwces between the estimated potential risks when the collective effective dose equivalent is used compand with when a collective age and sex-weighteddose equivalent is used. Also examined are trends in the frequencies of various examinations and in the equip ment used. During the last decade, there have been many technological advances that have affected medical radiation exposures. New examinations are sometimes introduced to q l a c e older techniques. additional examinations may be performed, and examinations may be carried out with different types of imaging equipment. All of these factors may lead to an increase.or decrease in the absorbed dose. This Rerport reviews absorbed dosss to particular organs fmm various types of examinations. Absorbed doses from diagnostic x rays are expressed in gray (Gy) or as dose equivalent in si&s (Sv)since the value of the quality factor for photons is unity. Because there is considerable variability from study to study in modeling, computational techniques, and assumptions, mported f m quency and absorbed dosea for a given p d u r e often vary markedly. I t is useful to examiue the distribution of doses in a search for the causes of this substantial variation. Obviously such variation affects the p d o n of all estimates included in this Report. Where possible, causes of uncertainty have been identified. Final estimates of examination frequency, as well as collective and per caput doses, are felt to be accurate within plus or minus 25 percent. In summary, the the purpose of this Report is to review the currant status of population exposure to diagnostic medical radiation in the United States and to review trends in this exposure over the last myears. 12 Diagnoetic Medical Radiation Several factors set medinail exposue apart from other souroes of radiation expoam to the public: A. Medical expogure of an individual is deliberate rather than accidental or incidental to some other activity. The motivation of such exposum is to benefit that individual alone and not society in general. B. Except for some nuclear medicine pmxdures, exposure is not of the total body uniformly but is relatively confined to the area of

medicalin-t.

1.2 DIAGNOSTIC MEDICAL RADIATION

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3

C. In general, doses in diagnostic radiology are intermittent and given at a high dose rate while doses in nuclear medicine are d v e d at a relatively lower rate.but still at a high late compared with envhmmental sources, D. In diagnostic medical imaging procedures. the minimum expe sure is related to the number of photons necessary to obtein the diagnostic information required. Many examinations must be done with a certain irreducible dose to be of diagnostic value. While substantial dose reduction for a specific examination,is p e r a l l y not possible without technoIogical advances, adherence to good radiologic or nuclear medicine practice, and the use of modem equip ment and materials, make some dose control possible without decreasing associated benefits (NCRP, 1988). E. hrhaps the most significant diffemnce of diagnostic aqmtm h m other sources of radiation is the fact that the medically e x p o d population is highly selected, both in the sense that many of the exposed individuals are suffering from some form of illness and they are generally in the older segment of the population at large.

2. Concepts, Units and Quantities I t is important to define various units and quantities that wiU be used throughout this Report. In 1928, the International Commission on Radiation Units (ICRU)proposed the roentgen (R)as the exposure unit. The definition of the roentgen was changed slightly in 1938 (ICRU, 1938). The m t g e n is the amount of x or gamma rays that p d u c e s a given amount of ionization in a unit of air; 0.000258 coulomb per kilogram (Ckg)or 1.0 electrostatic unit (ESU)in 0.001293 g of air. This is a unit of "exposm" in air and not "absorbed d w " in tissue; in addition, it is not applicable to high energy x-rays (greater than 3 MeV)or to particulate radiations. The rad was proposed in 1953 (ICRU, 1971)and applies to absorbed energy or dose. The md is defined as 100 erglg of tissue (or other absorbing material). A new international system (SI)unit is now in use, the gmy (Gy); 1 Gy (1joule of energy absorbed in each kilogram of absorbing material)is equivalent to 100 rad, and 1rad equals 10 mGy This unit is not restricted to air and can be measured in other absorbing media (NCRF! 1985). The radiation units defined above relate only to physical parameters. A unit that reflects biologic response and could be used to compare effectsof different radiation8 would be extremely useful; toward this ad,a unit of "dose equivalence" was derived, the rem An SI unit called the sieuert (Sv)has replaced the rem; 1Sv equals 100 rem,and 1 rem equals 10 mSv. A review of international units for application in radiation protection and measurements was presemted in NCRP Report No. 8 2 (NCRP, 1985). Exposures and doses from radiographic studies are I.eportedin many different ways. The easiest relevant measurement to make is expasure "freein-air" at the position whem the skin would be located (entrance skin exposure);however, such a measwement cannot be exactly related to absorbed skin dose. Another quantity often reported is entmnce skin dose, which is calculated from entranm skin expomre (ESE)and includes backscattered radiation. This dose is usually the highest of any point in the body. 'lb calculate the absorbed dose at a given depth in tissue. the beam quality must be known. The traditional unit for measumment uf radioactivity has been the curie (Ci3.7 x loa0disint8grationsls). I t has been replaced by the SI unit, the b e c q m t (Bq). The becquerel has units of reciprocal second

2. CONCEPTS. UNITS AND QUANTITIES

1

5

and is equal to one disintegration every second; 1 Ci therefore equals 3.7 x 101°Bq. Many concepts have been derived specifically for use in radiation protection. The absorbed dose in tiseue, measumd as energydeposited in a gram of tissue, is not d y useful in predicting the severity of the effects unless other factors are taken into account. W o major factors are the quality factor of the radiation Q, and the product of all other modifying factors, N. Thus, the dose equivalent, H, is g i m by the equation H = DQN where D is the absorbed dose (ICRU,1976,1980). Absorbed dose is usually defined as the mean absorbed dose in an organ or tissue. Of course,this repmwnts a simplification of the actual situation When an organ or individual is irradiated, the dose is not uniform throughout the volume of the organ but can be rather inhe rnogeneous. The simplification is acceptable based on the assumption that the detriment will be the same whether the organ is uniformly or non-uniformly irradiated.At absorbed doses of 1 Gy (100 rad) or less, the mean dose to an organ or tissue (where the irradiated portion is repmentative of the whole organ or tissue) is an accepted quantity (ICRP, 1969). For low doses of radiation delivend to a population, one may choose to express a collective dose equivalent (S). In a given population, this is defined as S=H,P,. In this equation, H, is the dose equivalent in the whole body or any specif~edorgan, and P,represents the number of members in the exposed subgroup. In an attempt to compare detriment from irradiation of a limited portion of the body with the detriment from irradiation of the total body, the International Commission on Radiological Protection (ICRP, 19'77)has derived the concept of effective dose equivalent (HE), which utilizes weighting factors (w,) for the relative risks associated with irradiation of various tissues. The effective dose equivalent VI,) is calculated as C wJZT where w, is the weighting factor for an organ and HT is the dose equivalent in that organ. The weighting factors recommended by the ICRP for use in calculating effective dose equivalent are shown in mble 2.1. As defined by the ICRP, the weighting factors an? nominal values for an average adult. Thus, application of the effective dose equivalent may be limited in medical situations where the patient &-tics may be significantlydifferent from the average.

6

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2.

CONCEPTS,UNITS AND QUANTITIES

T ~ L2.1E Weightingfactors for &dating effective dose equivalent for selected tissues (ICRP,1977) ?Tseue

Weighting Factor (w,)

Gonads Breast Red Bone Marrow

0.25 0.15 0.12 0.12 0.03 0.03 0.30

Lung Thyroid Bone Surface Remainde~

to .In calculation of the HEfor the remaining organs. the value of 0.06 is &ed each of the five organa or tissues mcaiving the higheat dose equivalents among the remaining tissues. If the gastrointestinal tract is irradiated. the stomach, small intine, upper large intesthe, and lawer large intestine am treated es four separateorgans.

The mean per caput active bone m w dose is occasionally calculated as an indicator of somatic effeds, particularly leukemia In general, this concept suffers from the uncertahtiea h u t the actual distribution of active bone marrow in various age groups and, them fore, it is usually calculatedonly for adults. The gemtically signrgnr@utt dose (GSD) for a population is used as a measure of genetic detriment to be expe&d, defined as "the dose to the gonads which, if given to every member of the population, would by the produce the same genetic detrimant as the actual doses &ved various individuals" (UNSCEAR, 1972).

3. Diagnostic Medical and Dental X-ray Examinations 3.1 Data Sources Data were reviewed on the frequency of diagnostic examinations. including conventional medical radiographs, and fluommpy, specialized medical imaging p d u r e s , dental radiographs, and nuclear medicine. For purposes of this report, the terms examination and procedum are used interchangeably. For many e o n s , the projection of the x-ray beam has been speci£ied (e.g., a chest examination or procedure may include multiple projedi011s, such as posterioranterior, antarior posterior, and lateral). This information is much more useful for dosimetric purposes than simply the number of views obtained without refemce to beam M o n . As much relevant tissue dose information as possible has been included. No new m y s were performed by the NCRF! Extensive review of published surveys and some unpublished but publicly available data sources were utilized. Comprehensive s u r veys of population exposures and doses from medical radiation are complicated and -ive; therefm, limited surveys of £requencies of certain pmcedures are more common. For example, surveys of numbers and types of computed tomography (CT)or ultrasound p m c d m s provide useful public health information but are also of interest to commercial manufacturers of related equipment and supplies. Them f m , these surveys are performed by several private companies and financially supported by manufacturers. Results of these surveys are not typically published in the open literature, but some of that kind of information has been obtained and is induded in this Report. Following is a description of the major studies utilized in this Report: A. X-ray Exposum Studies (XES).The United States Public Health Service (USPHS),in 1964 (XES 64) and 1970 (XES 70), surveyed x-ray exposwe to the total United States population (FDA, 1966, 1973). These surveys provided information on the hquency of diagnostic medical and dental x-ray examinati011s, the amount of x-ray earposure, machine technical parameters, and age and anthropometriccharacteristics of patients d v i n g examinations. Information gathered in the 1970 X-ray Exposure Study has somewhat more statistical dkbility

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3. DIAGNOSTIC X-RAY EXAMINATIONS

than the 1964 data due to a larger survey sample size. The X-ray Exposure Studies of 1964 and 1970 were populatiombased surveys done on a household basis and included only the civilian population. Individuals were asked to remember x-ray examinations. Follow-upinformation on individuals d v i n g x-ray e x ~ t i o nwas s obtained from the facility where the examination was performed. This included the number of films taken, projections, technique factors, and machine parameters. Data concerning dosimetry were obtained h m a dosimetry package sent to the facility where the x-ray examination was performed. The XES provide data on diagnostic medical irradiation only and not on ultrasound or nuclear medicine. Since that time, the USPHS has performed only m o limited ~ studies. B. Johnson Associates Survey. Comprehensive data on 1973.1979, frequency we^ collected by J. and 1980 diagnostic imaging p&um Lloyd Johnson Associates (Johnson and Abernathy, 1983). This was done using a stratified random sample of U.S.short-term general care hospitals and from selected office practices. The 1980 sample included 378 hospitals and physicians' offices. The authors estimated that the survey mflects about 90 percent of total diagnostic imaging proce dures. I t was conducted by mail questionnaire and is a facility-based. not a population-based, survey. C. Radiation Experience Data (RED 1).In 1980 and 1981, the Bureau of Radiological Health (BRH), now the Center for Devices and Radiological Health, conducted a hospital-based survey of mdiological procdures. The RED 1 study was based upon a stratified random sample of 81 U.S. short-term general care hospitals. The survey is unique in that it collected patientspecific records. This a l l d detailed analysis, not only of types of specific p d m , but also, of age and sex of patients having each prucedure (FDA, 1985). Initially, the BRH investigators had hoped to obtain computerized records from the sample hospitals. In about onehalf the cases this was not possible, and it was necessary to code and keypunch radiology department log books for computer processing. E m in those hospitals that provided computerized data, them was no standardization of p m cedure codes, and each code had to be translated into a standard RED code. The data include not only conventional x-ray procedures, but also nuclear medicine, u l m u n d , and computed tomography. Only the 1980 data have been published; they have been included to the greatest possible extent in the current report. Since it is hospital based, this survey differs from the XES studies which are population based. I t contains data on numbers of p d m but does not contain patient eqxmre or dose data as the XES did. Since the RED 1 study p d to be expensive,it was conducted only in 1980 and 1981.

3.1

DATA SOURCES

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D. Radiation Experience Data (RED 2). In 1982, the BRH conh-acted with a commercial company to obtain radiologic t e n d data,

and this effort was designated RED 2 to differentiate it from the survey the BRH itself had p h o u s l y conducted. RED 2 data differ from RED 1 in that the hospital sample size was increased from80 to 500,but they include no age or sex information on patients having the procedw. The data were collected by mail survey and were derived from summaries of hospital radiology department worklaads. The 500 hospitals in the survey group are not statistically mdomized; however, they include a fairly wide representation of type of hospital size, and geographical location. The number of x-ray, nuclear medicine and ultrasound pmmdures of various types are provided for the first and third quarter of each year and can be extrapolated to the entire U.S. population on an annual basis. The survey alsoincludesthe type andquantityafx-ray contrast mate rial used. Some general data are available h1981.Mom detailed data have been obtained for 1982 and 1983,including data on digital sub* tion angiogmphy and nuclear magneticresoname imaging. E. Nationwide Evaluation of X-ray Ikends (NEXT).Dosimetry data are available from the 1970 XES study and, more recently, in the form of the NEXT program. This program is canied out in cooperation with about 40 state radiation health programs and includes exposure data fmm hospitals and outpatient facilities (Johnson and Goetz, 1986).The expome data were obtained for the following x-ray examination cate gories (amongothers): Lateral skull Abdomen or KUB (kidneys,mters,bladder) RefmPde pyelogram Thoracic spine (AP) Cervical spine (AP) L u m b o s d spine (AP) Full spine (AP) Measurements are made for a "standard patient" exposure. These data are available on an annual basis from 1973 through 1981.The data are useful in d e t . any significant changes in expoam due to trends that may have occufied in those particular procedures since the 1970 XES study and may be of some assistance in assessing the possibility of extrapolating the 1970 XES exposure data for other examinations through 1981. The study also permits calculation of radiation doses for selected examinations to certain body organs. The disadvantage of the NEXT study is that it is limited in the number of procedures examined and only refers to variation in exposure for a "standard patient".

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3. DIAGNOSTIC X-RAY EXAMINATIONS

An attempt was made to iden* other sources of data, even thaugh they might be quite limited, in ordex to allow validation of at Least some of the points in the RED and NEXT studies.The pssibility of u* ing gowmmental health programs such ae M e d i m and Medicaid was also invwtigated; hawevea, only data concerming the total e t u r e of fun& far radialogy could be obtained, and no specific information mceming the number of procedureg was available. Private insuranc~ compauim were also contacted to investigate whether specific statistical information collceming frequency of x-ray examinations might be available on an individual state basis. U n f e a t a l y , such data did &st, but weae unobtainable by the NCRI? Since RED 1 and RED 2 data are mncamed only with procdres performed in hospitals, an attempt was made to estimate the percent of radiography performed in outpatient f d t i a . Film manwtve contacted concerning (1)the total amount of film sold to hospitals versus outpatient facilities, (2)the film size and quantity sold to these facilities,and (3)the annual U.S.consumption of x-ray film. Only data csoncesning the last point could be obtained. Oaxwicmally,professional organhitions maintain specific relevant information. Both the American College of Radiology and the American Chiropractic Association provided such data on x-ray usage.

3.2 Equipment Availability and Film Usage Data an the number of 0pedima.ldiagnostic x-ray machines wem supplied by individual state radiation control programs and compiled by the U.S.Food and Drug Administration. Thenumbers of diagnostic radiographic x-ray machines at t h y e a r intervals are shown in Wle 3.1.These data indicate that them has been a considerable increase in the number of dental x-ray machines (expressedboth in absolute numbers and on a per caput beeis), while there has been a relatively smaller increase in thenumber of medical machines. The amount of medical x-ray film sold in the United States annually from 1963-1982is shown in a b l e 3.2. Them has been a steady increase in annual film sales with an increase of approximately 57 percent between 1970 and 1980. The W0bna.n Report (Wolfman, 1986) is a comprehensive survey of sales in the entire photographic industry and lists annual total U.S. salesof x-ray films by size and number.

3.3 NUMBER AM) TRENDS

TABLE3.1-DiaRnoJtic

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.em9 mqchines in the United Statss.

'b Year

Dental

Medicalb

1969 1972 1976 1978 1981

103,000 (0.61) 126.000 (0.60) 146,000 (0.68) 172,000 (0.77) 204,000 (0.89)

101.000 (0.50) 110,000 (0.53) 116.000 (0.63) 123.000 (0.55) 127,000 (0.66)

*Datasupplied by Ctmter far M c e a and Radiobgieal Health, FDA. USPHS. . bAbout 50 percent are hospital based and 60penrzmt ere outside of hospitals.

.

( ) indicates number of machines per 1,000 population.

TABLE 3.2-Estimaladannurrl nted~Wx-my fibn sales in the United sinde6 Year

Sheeta (Millions)

3.3 Number and T h d a of F

'

Sheets Per Capita

tiom

'Mle 3.3 shows the percentage mix of inpatient and outpatient diagnoe tic x-ray -0119 performed in hospitals on an aMual basis. Esti-

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3. DIAGNOSTIC X-RAYEXAMINATIONS

mates of the type and number of hospital x-ray examinations performed in 1964.1970 and 1980 am given in Wle 3.4. The annual number for dental radiogtaphic p d u r e s is hin nble 3.5 while that for c h h p d c and podiatry examinationsis given in nble 3.6. The total number of diagnostic medical x-ray examinations in the U.S. is the sum of those performed in and outside of hospitals. The number of radiographic examinations performed outside of hospitals is difficult to assess but was derived b m several sources as already outlined. The 1980 National Ambulatory Care Survey (McLemoreand Koch, 1982) indicates that, of a total of 575 million office visits to physicians, 45 million (7.8 percent) d t e d in the ordering of an x-ray examination. Some of these wem performed in hospitals and some in an office setting. Johnson and Abernathy (1983) indicate that about 50 percent (22 million) an? performed outside of hospitals. Data h m the ACR Manpower Survey (ACR, 1982) indicate that in 1980 about 16 million (9 percent) x-ray examinations were performed in radiologists' offices. The total number of medical diagnostic x-ray examinati011s in 1980 was estimated to be about 180 million, divided as follaws: hospitals (short-and long-term),141million (78percent);radiologists' offices, 16 million (9 percent); other physicians' offices, 7 million (4 percent); podiatrists, 6 million (3 percent); and chiropractors, 10 million (5.6 percent). These numbers are felt to be accurate within plus or minus 20 percent with the major portion of uncertainty arising b m the determination of the number of examinationa performed in physicians offices.

TABLE 3.3-Source

ofpatients having diagnostic mdiogmphic prvcedums in

U S hospitalsa Wrmnt

Year

Inpatient

Outpatient

1970 1976 1976 1977 1978 1979 1980 1981 1982

65 60 69 68 68 69 69 60 60

35 40 41 42 42 41 41 40 40

Bata from the American Hospital Association

3.3 NUMBER ANDTRENDS

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TABLE 3.4-Hos~ibolx-myexaminations (in thousad¶)in the UniM S W s Year Examination

1964.

Skull Head CT BodycT Chest (radiographic) Abdomen Otidney;ureters,bladder) Biliary Lumboeacralwine U P P GI Barium enema p y e l m

Pelvis Heed and neck (excludingskulI1 ExWtiea UPF

Lower Other 'lbtal (rateper 1,000 population)

1970b

1-

2.600

3,600

3.700 1,wI

21.800 2.800 2.000 1.700 3.200 2.300 2,300 1,300 2,000

32,600 3,000 3,000 2.200 4,200 3,400 1,500 3,600

62,900 6.700 3.500 4.200 6.500 3,800 4.200 1,200 6,500

5,000 6,300 5,300

6,000 6,900 9,000

12.800 16.700 9.100

68,500

81,700

132,400

(310)

(410)

(580)

-

-

2,800

600

1Fmm FDA 1966, estimated from the number of film used by type of examination in hoepitale. bFDA, 1973. cFDA. 1985.

Tmm 3.6-Dentd x-my e m m h t h n s in the United Stuted

Year

X-rayc?xAminetinn~ (inmillions)

Filma (inmilhom)

Examhatiom per 1,000

population

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3. DIAGNOSTIC X-RAY EXAMINATIONS

TABLE 3.6-Number Year

of diagnostic chimpmctic and podiatry ewminations (in th~wMds)

Chiropractic

-tub

aData from American ChiropracticAssociation. bDatafrom Kumazawa et d,1984.

In the United States, there was a substantial increase in the £te quency of dental examinations per 1,000 population from 1970 to 1982 ('Igble 3.5), although the rate of inmaw was not as rapid as in Great Britain (Wall and Kendall, 1983) w h m the frequency doubled between 1970 and 1981. Thm was an average of 1.6 dental visits per person annually for the total United States population (Mamy et al, 1982). The number of exposures per patient declined somewhat as a d t of replacement of the full mouth series by panoramic pmcedures. In 1970, approximately 6 percent of all dental x-ray examinations in the United S t a b were pantornographic; this number rose to an estimated 18 percent by 1982. In 1982, the annual dental examination rate was 456 per 1,000population. Estimates of the numbem of various diagnostic x-ray examinatio~m in the U.S. and of the averall total are shown in 'Igble 3.7 for 1964,1970 and 1980. The 1980 estimates in Bble 3.7 are compiled from all available sources and include short-term and long-term hospitals, all physiciax~~' and dentists' offices, federal facilities, podiatrists and c b praetors. Examinations of the chest extremities and lumbar spine 8coount for 67 percent of the total. Adding examinatioxw of the abdomen (kidney,ureters,bladder, or KUB),gallbladder, and upper gastrointestinal tract bring the total to 83 percent. The annual fmpency of medical x-ray examinations of 790 per 1,000 population is mid-range when comparison is made to some other developed countries,e.g., 1,016 for Canada in 1980 (UNSCEAR, 1982). 820 for France in 1981 (Bene dittini et al, 1983). 836 for the Federal Republic of Germany in 1978, 494 for Sweden in 1979 (UNSCEAR, 1982), and 496 in the United Kingdom in 1983(Wallet al, 1986).

T ~ L3.7-Estimated E totalnumber ofDiagnostic z-my pnmdams in the United States, 1964=1w

Number of examinatiom(thousands) Examination

skull Other head and neck Cervical spine

Heat CT

MY a" Chest (radiographic) (photofluorogrpahic)

M-

Abdomen (kidneys,ureters, bladder) Biliary Thoracic spine Lumbar spine Full spine Upper gastrointestinal Barium enema

W w

hlvis Hip Upper extremity (arm)

-ex-tYw) other ntalmedical Dental lbtaldiagnostic x-ray

examinations

163,000(870p

aFbm Mettler, 1987. bIncludee podiatry and chiropractic. C( ) refers to frequencyper 1,000 population. ' "ons has The use of both medical and dental diagnostic x-ray hmased substantially since 19'70,even without the inclusion of podiatry ' and c h h p d c "om Wles 3.5 and 3.7). During this decade, medical radiographic erraminatians in hospitals have m d by 62 percent and total examidions by an a t e d 38 percent, while the U.S. population i n by only 11 pemmt. 'I'he major incseases have ocrwred m examinations of the elderly The number of dental radiographic

"ons~creased51percentduringthesameperiod.~some extent,thisfindingof~utilizationwasvalidatedby anaammpa-

nyingin~insalesafdcalx-rayfilmofaboutM)~t.Thisis not an exact codation since a small ftrrction of medicalx-ray £h is used by v e b k a h m and because the film per examination ratio may be changing WdY.

16

1

3. DIAGNOSTIC X-RAYEXAMINATIONS

Data on medical diagnostic imaging p d u m mere published pmviously by Johnson and Abemathy (1983).The overallnumber of pmadutw estimated in the present report for 1980 is greater than that estimated by o h authors (Johnson and Abemathy, 1983; FDA, 1985).The reason for this discmpancy is that the p-t nqort includes gmups such as longterm hcspitals, federal agencies, family practtimem, podiatrists, c h b praetors, and dentists which wem variably or not at all included in @ow studies. Inclusion of such groups is impoptant since data from the American (2himp&c Association indicate that,in 1982, ~ r a c t o r s performed about 10.millionx-ray examinations of the spine. Ultrasound and nuclear medicjne examhiion p d m wexe not included in the previous tables but are included in latm d o n s . The attempt here was to compare only 1980 x-rayutilization with the 1964 and 1970 XES (FDA, 1966, 1973) data As Johnson and Abernathy (1983) pointedout,thegmwthof~osticI.ediolagyhasincludedmosttypesof examinatom and has not been limited to the newer modalities such as computed tomography If ultmsound and computed tomography are replacing moE conventional radiographic proad-, a sigtllfcant tmnd was not obvious on a national basis in 1980, although a resurvey now may show such changes. It has always been difficult to accumulateextensivedata on the national utilization of x-rays. The 1964 and 1970 XES studies wem household surveys that were both extensive and expensive. Both studies wem c m ducted with a high level of statistid pmckion, but no such survey has been done since then, and it is unlikely that any such survey will be n?peatedintheforeeablefutam.ThepresentReportmakesuseof diverse sources of data, which w t m not callected in the same manner nor by the same gmup. W o r e , the present estimates cannot be as m t e as the 1964 and 1970 data, but they are useful nevertheless. Estimates, based on the available data sources, have taken into account the sample size, type of study, and statistical validity. As an example, although the 1970 X E S study was the most valid overall national survey stathtically, it included small sample sizes in certain areas of the United States. For chimpmtic radiology, thm wem only 89 responses m the entire survey. Thus, the data from the American chimpractjc Asmiation M survey have been used p r e h t i a l l y The 1980 hospital-baseddata (Wle 3.4) are mare valid statistically than the data obtained fmm physicians' offices. Hospital data h m the several sources vary by about 5 percent, while outpatient estimates vary between sources by up to 20 percent. Thus, while the best estimate of total medical radiography in the U.S. is 180 million pmcedwes, the true number may be anywhen? between 170 and 210 million procedures. TEmeliness of data pmsentation is also of concern.Unfatmatel~1980

3.4

POPULATION DEMOGRAPHICS

1

17

data were amundated from January of 1980 until January of 1981, and then had to be collected, oollated and analyzed. This p m s took another 2 to 3 years.The 1980 data are valuable because the only other reasonably complete national data set dates back to 1970. Incmmbg utilization of cliagnwtic medical radiographic om has occurred while the number of medical x-ray machines per 1,000 of population has mnained almost constant. This reflects mom efficient utilization of existing machines. At the same time, the number of radie graphic examinations performed per dental machine decl.eased due to a marked haease in the number of operatingdatal machines. In summary,bebetween 1970 and 1980 there was an increase in the fmpency of almost all typesof diagnosticladiographic examinations. The rate per 1,000population of medical radiogmphic ' &ns hcmased by about 18percent while the totalnumber i n & by 32 percent. Both the mte and total number of dental radiographic examinations increased by about 40 to 50 percent.

3.4 Population DeJlqpphics

The diffemnces between age groups mxivinghospital medical diagnostic radiologic examinations in 1970 and 1980 are shown in lhble 3.8, which shows that in 1980,over onefourth of all medical x-ray examinations were received by persons 65 years of age and older. This Thisding is in marked contrast to the 1970 data in which only 15 percent of examinations wem performed in the 65 and over age group. One might suppose that this shift is due to the inmasing age of the U.S. population, but data from the U.S. Census Bureau indicate that the percentage of the U.S. population over the age of 65 has inmased only from 10 to 11 percent between 1970 and 1980 Wble 3.9).

Percent (examinatio~w in thousands)

18

1

3. DIAGNOSTIC X-RAYEXAMINATIONS

TABLE 3.9-Am distribution of tlie dotd lasidsnt U S mubtion fin thowam#

< 15 16-29 30-44 45-64 >64

65,948 (31) 40,147 (21) 35.607 (19) 38,383 (20) 18.127 (9)

57.938 (28) 49,414 (24) 34.545 (17) 41,981 (21) 20,107 (10)

61,270 (23) 62.126 (27) 43,672 (19) 44,481 (20) 25,708 (11)

.Data from U.S. Census Bureau. ( indicntespmamt d total population for that year.

?gble 3.10 indicatesthe sex and age distributicm of persam having same common The m c m h g use of x-ray examinations in the elderly may d e c t the ecanomic climate of the 1970s.The increased use of

. ..

suchfnraminationsshouldnotnecessarilybe~edas~~or detrimmtaLIndeed,uaeafdiogmphic~mthisagegmup carriea essentially no genetic risk and certainly less carcinogenic risk than exposme of yaungez persons. The benefits obtained frcrm radiographs of this older and gemally lees healthy age p u p have pbably outweigld the possible detrhent hm addiradiation arpowue,although spe cificdataunthis aspect aredifficult toobtain.

The rapidrise m diagnoetic x-ray pmcedm mandates an ev&atian of the possiile amixibution of new khniques, espe&dy certain specijic

pcdms. The new modalitiesmay provide better diagnostic information than those pmAcusly available and may, tlxdore, mplaca them Such an c=au@e is a dec3ease in the number of radionuclide brain scans with the advent of computed tomography (CTlof the head. Another possiity is that a new technique may augment diagno&c informatian plwided by exbtingpFoceQlresand,themfoae,dtmaninaeasemthetatalnumber

of~ulwperf~Ammbinatonofbothisalso~le.In general although then? has been a rapid rise in new h a g b g techniques, these account for only a s d portion of the total number of procedures. Conmtional mdmgmphy continues ta account for over 90 percent of 811

.-

Specific ambaths of studiee used f a imaging a c a b i n body prat CP systamcnegraqwdtogetberd.JraminedsF!qlbmtianyinthe~ ~Tbedatain~tablesreplresa?tan~~dynamicsituatjaaL

TheriseinusageofthemwmmodaWesshouMaotbeccm&uedtomean

3.6 DIFFERENTIAL TRENDS

Heed. sku4 neck Male FemaCe Both Chest

Male Female

Both UppergastrointeatiMl Male

Female Both CholecJrstography Male Ebmale Both Bnrium enema Male Female Both Intrayenm urography Male Female Both

LUmbOeacralspine Male Female Both Extremities Male Female Both MammWwhy Male Female

Both C

a m Male Female Both All x-rays Male Female Both

p

u

~

~

~

I

19

20

1

3. DIAGNOSTIC X-RAYEXAMINATIONS

[email protected],the risemI.nunbersofsuchpmc&mmay s i m p l y ~ e ~ o f u s e d t h modalitymthe~Hmweqsome~I$atedto~dose ~aainaease,are~evidgntandare~t hthelast~etherehasbeenrapidqansimofbothdigitald mtemmtional technologies. Digital t,dmology in this context lefers to the recording of transmitted photons on an image i n t m d k or other such -tor rather than on film. This pmm~sallows computer manipulation of theimagesandthistechnol~hasfaundwidespreaduseinvaseular radiology but it can also be used for other examinations. Interventid technology mfers to a number of tmhniques in which radiology is used to guide the dialogist or other physician m a semhrgical diagnostic or therapeutic p d m . Examples of such pmcdures are phement of drainage catheters,needle biopsy of various Molls, catheter placement for infusion of pharmaceuticals, and balloon catheter placement for occlusion or dilitation of blood vessels.Most of these procedures lequire lengthy periods of fluoroscopy and may result m high absarbed doses to the patient as well as the operator. Although data on the hqumcy of such p d m are not available at this time, there rue some data on the k b e d doses h m these pmcedm. Evans and Mettler (1985)c?Kllmirred the bends in use of computed tomography in the United States during the peiiod 1981 to 1983.'Ibtal scans as det,embd by questionnaire i nfiom 2,337,000in 1981 to 4,303,000in 1983.'IBble 3.11 indicates that in 1983computed tomography (CT)was used 63 percent of the tirae for head imaging and for body (particularly abdominal) scanning,37 percent of the time. As expect4 the dative amount of body scanning is i n c a m m to head CT.The rate of haease of CI' use slowed markedly, with the incl.ease over the previous year being 53 percent fmm 1981 to 1982 and 21 percent from 1982 to 1983. Since 1982,nuclear magnetic monauce imaging (MRI) has has become available In MRI, images am generated by using radio waves and mag netic pulses,and no ionizing radiation is involved.l3esent.l~the maim use of magnetic resonance appears to be for brain and spinal and imaging, but no numerical data exist yet on the frequency and availabiity of such . . -ns. Spinal cord imaging procedures doubled bebmm 1970 and 1980. The, intanduction of water soluble contrast agents may be partially rqmmible. M t e the limited data on CT scans of the spine, such scans appear to have had a significant impact on the number of mydograms. It should be noted that, in many instances, CI' is performed befare or immediately after a myelogmm, especially if water soluble contrast agents am used. Thus,the procedures may pmve to be additive in number.

3.6 DIFFERENTIAL TRENDS

TABLE3.1 1-Computed

1

21

twnogm~hyrcse(l

Numbea of examhtkna (int h o u d I Examination

Hsad spine

MY ?btal

1981 1.755 69 623 2,337

1982 (75) (3) (22)

--

(100)

1983

2.481 141

(69)

960 3,682

(27) (100)

(4)

2712 425 1,166

(631 (10) (27)

4,303

(100)

- -

'From Evens and Mettler (1985). ( ) indicate percent of examiuati01~9.

The number of hospital ultmmmd pmcedum (another modality that does not involve ionizing radiation) hmaaed h m fewer than 200,000 in 1973 to 4.5 million by 1979 (Wle 3.12). The number aLnost doubled behem 1979 and 1982. The largest proportion of examhatiions are gallbladder, obstetrical, and mspedied abdominal categories.All areas have sh~~withtheexception0fneonatal~ul~Thistype of amnimtion inmmd rapidly in 1980 and 1981 as a substitute for cranial CI'and now has stabilized. Skull x-rays have i n d siwe 1970 (W3.13). The rate per loo0 fmm 18 in 1970 to 30 in 1980. A s one might expect, p o p ~ o increased n there has been a substantial demase in radionuclidebrain scans due to the availability of CI'head scanning. Mammography has been a subject of scientific scrutiny and public awareness since the late 1960's. Between 1970 and 1980, m a n m e graphy i n d fivefold However, only about one percent of the female population h had mammography during each year. The data are shown in n b l e 3.14. The number of cardiac imaging p d m using x-rays has been affected not only by advances in cardiac nuclear medicine but also by echocardiography Qtble 3.15 presents a Feview of available data Unfor tunately, there are no data on cardiac x-ray contrast p d m before 1973. The number of diagnostic cardiac catheterizations more than doubled between 1973 and 1980. Echocardiographydoes not appear to have caused a significant change in use of other p d m s . Radionuclide blood pool studies and myocardial ischemia studies increased .rapidly from 1981 to 1982, while radionuclide infarct scanning decreased slightly. Gore et d (1987)have compared the use of diagnos; tic procedures in patients with acute myocardial infarction in 1975 and ' 1984. Although the clinical characteristics of the patient population did not change, the physician practice patdid, resulting in a marked I increase of diagnostic procedures in the two years as follows radionu1 clide ventriculography 2.6 to 52.7 percent, coronary arteriography 3.1

1

1

22

3. DIAGNOSI'IC X-RAYEXAMINATIONS

to 9.8 percent, and pulmonary artery catheterization 7.2 to 19.9 per cent. The possible impact of new treatment modalities such as coronary angioplasty or pharmaceutical infusion is as yet unknown. TABLE 3.12-Hospital ultmclourPdpx&m

by a M d o ~ s i rIfn s thouscmdsl

Neonatal head Thyroid Gallbladder Liver & biliary hact hdspleen -9

mvis obstetrical Softti8sw Head & neck v a s c u k m Heart Aorta (abdominal) MpIleralveS3eh

Abdomend RetaQpeiitoneJIl other

( ) indicates percent of total.

&JohnsonAmxiaka data bRED 2 data %categary inctudeg breast and male reproductive organa. *Abdominalcabgory for 1979 aad 1980 date indudes eomeothar categariessuch as gallbladder.

'1Malredi~hicchestx-rayshave~~17oper1,ooOpapulation in 1964 to 240 in 1970 and 280 in 1980. How muchof this haease is duetotheaband~tdpho~~hic&hniqumisI.mlmcrwn. When chest x-ray examinations are considered by year, there is no significant diffgence in the rates per 1,000population for 1964,1970and 1980. In 1980, radiagraphic chest x-rays accounted for 40 p a m t of hospital radiographic pxxmdms ampad to 40 percent in 1970 and 37 percent in 1964. Ahhugh ultmmd pmmdms became adable in the early 1970s

-

andnownumbmmoaethanane-thirdofthermmbeaofawominalmedical jmW&% "ons,therehasbeeoanodecreaseinuppeagastmh~nal examinations or barium enemas. In fact, the number of such p m h i n the United States has i n m a d i n spiteoftheuseof ultrasod AWo~(=Tasof1982appearedtohawlittleimpactanthsotbertwo

TABLE 3.1 %-Estimates of United Sdndps hosdtnl head exwnkhn8 (En Year

Examination Source

1964

1970

-

-

1972 0

2,623

3.616 48

-

Heedf.3

Skull Pneum~e~lcephalogram

-

Ftadionuclidebrainscan

-

121

Radjonuclidecktemogmm

Year Hospitals offim

1964 63 13 66

nt.1

-

1978


-

-

-

1.610

1,646

-

-

1.260 12

-

1973

-

-

-

1980

19701

1979b

1980b

1-

199

910 210 1.120

1,000 260 1.260

1.247

41 246

1982

2,700 2,481 4,700 6,700 4 229 1,164 1,176 812 16 13

eXES data bJohnsonA s m i a h data cRED 1 data (hospitalsonly).

TABLE 3.16-Esiint&~ Examination

of hospital&

imogingpmcdum fin h w a m W

Year 1972 1973 1980 1981 1982

A n s i ~ o g r e p h yand coronary ~ W ~ P P ~ YEchocardiography 0 Radionudideblood pool 11 Radionuclideinfarct scan 2 Radionuclide scan p e r f w i o n l thallium ~ 0

200

604 424 1.400 25 - 320 - 680 148 228

-

409

-

498

140 302

ltible 3.16 compares various b i i imaging procedures. Several W d s are apparent. The rate of performance of oral cholecystogmm peaked or at least stabilized in 1979 and 1980. There has been substantial growth in biliary ultrasound,which may be responsible for the lack of growth or decrease in oral cholecystograms observed in 1982. Intravenous cholangiography has been steadily declining since 1970. The recent development of hepatobiliary radiopharmaceuticals has been msponsible for a resurgence in nuclear biliary scanning and a d m in the number of oral cholangiogmm.

24

1

a. DIAGNOSTIC X-RAYEXAMINATIONS

Hospital renal imaging procedures were reviewed to ascertain whether renal ultrasound, CT or radionuclide scanning had an effect on intravenous pyelograms. Them was a fourfold i n ~ e a sin e the number of radionuclide renal scans between 1972 and 1982. This may reflect an increase in the number of Fenal transplant studies or may repmmt a difference in reporting between RED 2 and Johnson's data Ftenal ultrasound usage is inmasing somewhat, but these newer modalities have had little effect in reducing the rate of intravenous pyelograms betwean 1970 and 1982. Pelvic x-rays are important because of the gonadal dose that they may cause. Pelvic CT examinations i n d between 1981 and 1982 (Table 3.17). Mvic imaging procedures were specifically considered, with the expectation that radiological examinations of the pelvia might have decmsed with widuse of non-obstetrical pelvic ultm sound. Some surveys,however, are of limited value in this lespect since they include examinations of the hip and pelvis in the same category. .'Zb date therehas been no convincing evidence of a d e ~ e a s in e pelvic x-ray examinations due to the use of nm-obstetrical pelvic ultrasound.

TABLE 3.16-7hd9 in United Stntes hospital bibhry i m a g r m a g r n g p rh o cthowMdPp ~s

Year

-

Opaative chohlgiognun

Endoscopic retrogradechobgkgmn T-tube cbolangiogram

-

-

-

38

-

271 44 104

'From Mettler et al. 1985.

TABLE3.17-Hospibnlpelvic imagingpdunes (in thoYear Wvic x-ray WvicCT Mvic ultraaoundd

aXES data bRED 1data cRED2 data dobstetricd excluded.

1964.

1,233

1970. 1,400

1980b 1,200 29

889

1982~ 905 71 844

3.6 EXPOSURE AND ABSORBED DOSE

1

26

3.6 Exposure and Absorbed Dose The distribution of exposure or absorbed dose in a patient resulting from a diagnostic x-ray examination depends upon (a) the amount of incident radiation, (b) the location and direction of the incident beam, and (c)the attenuation of the beam in the body. The amount of incident radiation depends upon exposure at the skin entrance and the size of the radiation field. "Exposure" for an examination is sometimes reported " b i n - a i r " (ie., without the body present) or it may be given as skin surface exposure (with the body there). Alternatively, the absorbed dose in soft tissue at the surface may be reported. The ratio of the exposure on the body to that "bin-air"for examinations that give a major contribution of radiation induced detriment is about 1.2 to 1.4. The quotient of the absorbed dose in soft tissue to the exposure at the skin surface is about 0.92 for all radiation qualities of interest here. Some authors have reported results in energy deposited in a given organ rather than average energy deposited per unit mass. In such circumstances, comparing results is difficult and it would be worthwhile to unifv methods of exp~ssionin the litera-. While the average absorbed dose in a given organ of the body depends upon all the factors given above, some consolidations are possible when considering relative distribution of absorbed dose in the body If the physical characteristics of the beam (tube potential, tube current, radiation field size, location, and filtration) are the same for a series of exposures, the relative absorbed dose distribution is independent of the amount of incident radiation. Approximate but adequate constancy is also obtained for a range of patient sizes for a particular type of examination. While the exposure at the body surface for a given type of examination for adults may range wer a factor of up to 40, the dative absorbed dose is usually considered to be adequately constant. It should be noted,hawever, that relative absorbed dose distributions change markedly with age, especially for children and infants. Data concerning trends and variability of exposures in the United States are available from the Nationwide Evaluation of X-ray W d s (NEXT)program (Johnson and Goetz, 1986). Histograms for composite data from 1982 to 1983 are shown in Figure 3.1 and indicate a rathex wide distribution of such exposures. Similar distributions of exposure have been found in England (Shrimpton et d , 1986) and Italy (Padovani et ab, 1987). With the advent of rare earth mand faster meen-fihn combhations, one might exp& that the mean expmre at skin entrance would be decreasing; However, the NEXT data suggest that,in spite of technologi-

26

I

3. DIAGNOSTIC X-RAYEXAMINATIONS

d achtwm. these has been littlechamgem exposum Wle 3.18 comparw data for 1973 and 1981 far selected types of e o n s and indicates that, although far some types a demwa has been observed,in other ~theskin~hasactuallyincreased,Overall,~~aee isled~conchKlethat~and~beddosesfarspecific~jeo tions in conventional radiography in the United States may not ham changed ajgdkmtly in the United States W 1970. Absorbed dam m various organ^ are needed in cuder to cakdate the eftective dase equivalent The organs of intarst usually indude thymid, actiw bone mamm, lungs, female bma& and gonads. Organ doses for a standard patient for a limited number of examinations amdmtd in tbe United States can be derived fmm NEXT pl.olgram data (Figure 3.2). A Monte Carlo axnputea tahique and a mathematically chmi'bed an* pomorphic phantom have been develaped and can be used to calculate tissueair rat& for selected organs (k&tnin, 1976).Dmder et al. (1984) calculated organ doses for x-ray diagnosis by utdizing Monte Carlo methods for both male and female phantoms designed aocording to ICRP ~cepersons.Whiletherearesome~cesmorgan~reported bythe~eau~mostare~.WWiththesetechniques.onecanderive mean absorbed dosea in a number af organs, norxmbd to a unit of expoam meastlled "&in-air" mder diffiesent aditions of beam quality a n d f i e l d S i z e . T h e s e p l w i d e i n f ~ h f ~ ~ ~ ~ , ~ ~ lung, breast, ovary and testi~. Average beam qualitiss, enbmce e.xpomw,

andnumberoftibnsusedformostdiagnosticmedical~examiLaws and Ftmmshb (1978)are m t e d in lhbh 3.19.

nations repeated by

TABLE 3.10-Mean e x p w a at skin entnmceper fibn in the United Stntas f a g X lPja

Examination(project)

19'73

1981

Chest (PIA)b

0.43 6.86 16.04 16.79 17.06 19.46 6.24 4.02

0.52 4.98 16.18 12.86 7.36 16.64 6.24 1.81

w

o

(lridw%llmht%bladder) ~ e s a d e ~ ~ ( A / p ) c Thomcic apine ( A / P ) e

Abd-

Lullbar spine

mC@=(M'F Feet ( D m .2.68 x 10, Clkg = 1 R.

bP/Arefersto postmior (back)to anterior (front)beam projection (ie,the x-ray beam enbra the Poetapior portion of the body and exib anteriorly). refers to anterior to paeteaior beam projection. d D Prefersto dored (topof foot) to pedal (bottom of foot) beam projection.

8.8 EXPOSURE AND ABSORBED DOSE

I

27

The results of the Monte Carlo calculations for organ doses account only for the primary radiation and radiation scattered within the patient. The contniutionof radiation scatted from the machine filter, collimator, and the air betwean the x-raytube and the patient is usually not included. When the organ of inlies within the primary beam, this external contributian d y accounts for more than 1 percent of the values Wed. Howerver, when the organ of inter& is several antimeters outside the primary beam, the contribution from external scab k may increase the organ dose by as much as 25 to 50 percent. The contribution to the effective dose equivalent by organs outside the beam is usually small. For standard male and female patients, tables of Monte Carlo calculati011s that pmvide dose information for various organs from selected aaminations are available (Rosenstein, 1976; Drexler et d,1984; Shrimpton et d,1986).

Fig. bl. Exposum at akin entrauce, all states,1982-1983. (a)PIA cheat plrojectione; (b) abdomen (kidneys. untteas, bhdder),AIP; (c) h d m e a d spine, AIP;end (dl dental bitewing (at a m tip) (fmmJohneon and Goetz, 1986).

28

1

3. DIAGNOSTIC X-RAY EXAMINATIONS

TABLE3.19-Avemge beam qualities entmnce erposmq and number of filmP used for

Chest

Skull

CervicalSpine

Ribs

AP PA LAT OBL AP PA LAT OBL AP PA LAT OBL

AP PA LAT OBL

Shoulder (one)

AP

PA LAT OBL AP Thoracic spine PA LAT OBL Cholecystogram AP PA LAT OBL AP Lumbar spine PA LAT OBL Upper gaetaointestina1 AP PA LAT OBL Abdomen (kidneys. AP ureters, bladder) PA LAT OBL AP Barium enema PA LAT OBL

3.6 EXPOSURE AND ABSORBED DOSE

BmnodiB Rujatim L u m b o s d spine

Intravenous P ~ W -

Pelvie

Hip

Full Spine ~chiroprrtctdc) Mammoizraphyd

Rojdcnb

(HVL,mmm

1

29

Entrance Avcaagermmbard 7 &pep(CkgxlWP F'mjech lMal

AP PA LAT OBL

2.40 2.35 2.65 2.54

2.35 5.04 8.98 4.14

1.21 0.08 1.43 0.70

3.4

AP PA LAT OBL AP PA LAT OBL AP PA LAT OBL

2.47 2.53 2.59 2.59 2.39 240 2.64 2.61 2.36 1.80 2.44 2.30

1.54 1.14 1.36 2.36 1.41 0.79 3.46 3.72 1.16 1.11 2.34 2.39

4.51 0.20 0.04 0.70 1.04 0.02 0.13 0.14 1.21 0.01 0.76 0.07

5.5

AP &ocaudal mediolateral

3.50

0.72 2.5 2.5

1.0 1.0 1.O

1.0 2.0

e

1.3

2.0

.From Laws and Roeenetein 11978),with exception of mammography bAF! A n ~ P o s t a r i o r ,PA, RmbxiorAnteriar; LA'I: lateral; OBL. oblique (fluoros copy not included). 52.58 X l(rC/kg-1R *The U.S.population x-ray eurvey (FDA,1973)did not adequately repmsnt curremt usage of mammography as a diagnostic modality The HVL!e and entrauceexposures in current mammography vary according to technique. These conditim were choeen as repmaentative for the purposes of thie NCRP Rep&. 'Not specified

The effect of patient size on doses received in diagnostic radiology was studied by Maillie e t al. (1982).The thickness of the patient is more important at low potential or voltage, and the average entranw dose from radiographs taken on individuals of various thicknesses may differ by as much as a factor of four or five. As the peak voltage is raised, the variation in entrance dose due to body thickness is reduced by a factor of about two. Of course, the thickness of the irradiated part is not the only factor that influences the dose to various organs. For example, a taller person will have some organs displaced farther from the din=ct x-ray beam than a shorter person. It is much more difficult to calculate organ dosea when fluoroscopy rather than radiography is used. The reason is that automatic bright-

30

1

3. DIAGNOSTIC X-RAY EXAMINATIONS

ness controls are often used for fluoroscopic Puruninatiw. d t i n g in changes in the exposure rate and beam quality as the beam is moved Thus, even when exposum parameters are known and exposure thea recorded, the uncertainty in the absorbed doaes from fluoroscopy is larger than that for radiography. Absorbed dose calculations in fluoroscopic emminations also present other unique problems due to the continuous changes in beam dime tion, field size, and positioning during the course of an examination. standard radiographic procedums, matters such as the incident

V p e of Examlnatlon/RoJectlonCoder CH SK AB RP TS CS LS FS

Chert, P/A Skull, Lateral Abdomen, KUB, A/P Retrograde Pyelogram, A/P Thorack Splne, A/P Cervkal Splne, A/P Lumboracral Splne, A/P Full Splne, A/P

Fig. 32. Mean argan dosea. 1982-1983(fmmJohnson and Goetz, 1986).

3.6 EXRXUIE AND ABSORBEDDOSE

1

31

exposure aide of the patient are straightforward, but during fluom scopic~examinationsthe incident and exit sides of the patient are often changmg. In general fluomscopic procedures result in much higher doses to individual patients than most other typea of standard radiographic examinations. Rawley et d (1987)have reported on the median exposum times for variow flumscopic muminations in England. They report the followiqg barium swallow, 180 seconds; barium meal, 180 seconds; and barium enema, 160 seconds. Little diffemm in time was noted in A t i o n to the sex of the patient; however males combtmtly d v e d higher absorbed dosea due to larger body size. Longar screep ing times of 337 seconds for a barium enema and 240 seconds for a barium meal am qorted by Padwani et d (1987)in Italy, Fluoroscopy times for commy angiograms are usually on the order of 10 to 20 minutes (Amiel et d, 1979).Cascade et d (1987)have m t l y reported exposures and fluo~oscopytimes for the Atively new technique of percutaneous transluminal amnary angioplasty. In this technique, fluomcopy is utilized to monitor the p r o p s of a balloon catheter introduced in order to dilate one or more stenotic coronary arteries. When only one stenosis was dilated, fluoroecopy time was 36 minutes with a skin dose of 0.6 Sv. When two stenoses wem dilatd, fluoroscopy time was 61,minutes and patient skin dose was 1.3 Sv.Similar data were reported by Faulkner et d (1986). Several authors have investigated the effect of variation in equipment design on patient dose. 'Ible (1985)indicated that machines with the tube placed over the table often give substantially higher doses (particularly to the male gonads) than those with the tube under the table. Zeck and Young (1983)pointed out that very high radiation levels can be associated with C-arm fluoroscopes. In general, the minimum source-skin distance for a C-arm device is 30 cm. Spacers are normally used to maintain this distance but are some times removed and not replaced. If the patient is then positioned dose to the tube, the entrance skin exposure rates will be much higher than those usually calculated. Fetal doses fmm diagnostic examinations have not been reviewed in this Rsport. However, such issues have been addressed in a previous Report of the Council (NCRP, 1977). The dose in& in pediatric x-rayexamination8 is of in-t since, in many circumstanm, a large portion of the child's body is induded in the primary beam. 'Zbtal body and organ doses fmm Monte Carlo calculations in pediatric examinations are presented by Rosenstein et clr (1979)and in NCRP Report No. 68 (1981).Radiation doses to neonates intensive care wem cxami.ned in Great Britain by Robinson and Dellagrammaticas (1983).These babies are of particular

concern since they may receive relatively large numbers of radiographs compared to adults, and such studies often include fluoroscopic examinations and CT scans.The mean active manow dose from all examinations was found to vary inversely with the birth weight. Overall, childran with lower birth weight received more examinations. Leibavic and Fellows (1983), reporting on pediatric angiocardiography, noted that these p d m prwide the highest exposum per examination of any diagnostic p d u r e , and that as much as 25 percent of the exposure from such examinations was contributed by manual "test" exposums to adjust the technique. The average exposure r a b in the posterior-anterior (PA) projection for cine filming was 1.4 x 10" Clkg (55 mR) per second and in the lateral projection, 4.2 x Ckg (162 mR) per second Fluoroscopy exposure rates were approximately one twentieth of this. Mammography. An organ dose of special intamst is that to the female breast. Skin exposures to the breast during mammography in the United States have been reported by Bates and Demidecki (1979). These data were collected by a joint project at 27 screening centers. The results show ( a b l e 3.20) a substantial d u c t i o n in exposures and tissue doses during the course of this project. Additional recent data are presented in NCRP Report No. 85 (1986) and by Rosenstein et d (1986). In 1985, the Center for Devices and Radiological Health mnducted a NEXT mammography project in cooperation with the Conference of Radiation Control Program Directors. About 40 percent of randomly surveyed facilities utilized xeroradiography with an average glandular absorbed dose for one view of about 4.0 mGy. For smeedfilm with grid and screenl£ilm without grid techniques, the values were about 1.25 and 0.7 mGy, respectively. Practical recommendations to improve radiation protection in clinical mammography have been published (NCRP, 1986).Breast compression is particularly important not only to improve contrast and irnpmve sharpness by p m n t i n g motion, but also to reduce absorbed dose. Firm compression of the breast can reduce absorbed dose by 25 to 50 percent. An analysis of data from some 60 mammography installations throughout the United States (Shrivastava, 1980) s h d that the choice between xerographic and film-sawn receptors is the most critical factor affecting breast dose, follawed by the choice of half-value layer and target material. Use of film-screen receptors result in only 20 to 35 percent of the absorbed dose delivered by xeromammography.

3.6 EXPOSURE AND ABSORBED DOSE

1

33

TABLE 3.20-hemge cnmiooaudal m a n m q q h y skin erposunes in the unidedsidesand doses sf bra^ thick brea9t.rsportfordreBZWscreeningcen~ Xemx Imegereceptol

let yser

l%mm€sm

4th year

1st year

4th year

h j e c t averege

let yeer

4th year

skinenexposure(C/kg)b

8.51x 101 %&Q x lW 3.61 x 101 1.50 x 101 8.51 x 101 P53x 101 Dose to "gland" at 3 cm depth (mGyp 4.9 3.5 1.O 0.4 4.1 2.7 .After Bates and Demi& (1979). b258x l(r Clkg = 1 R. e l mGy = 0.1 red.

Breast phantoms have been utilized to assess absorbed dose fmm various imaging systems. Computation of individual dose is, of course. dependat upon b m t size, adiposity, and other technical factors but, for ~sisafde~t,oneneedstoIm~)~the~breastsizeand composition for the popukion of intarest. At the m t time, research continues into altemath methods for k t imaging such as thernqpphy, u l a m h y , -on. computed tomogmphy, heavy ion mammography, magnetic resonance imaging, and digital x-ray mammography. With the pmsible exmption of u l m m h y , none of the other techniques appears to have had any impact on the fmquency of -hy. The use of grids in mamme graphy ha. also been advocated to irnpmve image quality and reduce scatten?dradiation Kirkpatrck (1985)measured the effect of use of such grids on patient dose and showed that, althoughthem was a gain in image quali~abwxbeddoseswereappmxhatdythreetimeshighe.rwiththe use of grids. Computehed ?bnwgm.phy Absorbed doee fmrn the newer teclmh gies, such aa as,is also a matter of conmm The maximum dose to the sldn from a CI' scan can be as high as 560 mGy (56 rad), although in Wcal use, the entrance skin dcrses are mostly about 60 mGy (6 4.The dose distribution within the body fmrn (;T is markedly diffemnt fmm that of conventional radiography (Evans and Metth, 1985).In most d k g r & phy, the dose is highest on the incident side and lawest at the exit poiut; with CI',the dose is loweat in the center ofthe body. The effectivedose equivalent and absorbed dose fmrn various pmcedum have been derived by Stieveet clL (1977)and Dmcler et aL (1984). The x-ray beam of a CT unit is usually highly collimated, but the q e may bein ornear the primary beamin scansofthe brainor faceand the d o s e t o t h e ~ a f h e y e i s o f ~ ~ ~ f o r ~ t i o n p ~ o n purposes. Lurid and Halaburt (1982)and h n h o l z et aL (1983)indicated

34

1

3. DIAGNOSTIC X-RAY EXAMINATIONS

for~CI'that,althou&~~and~tpositim~scnne effectqmntheabsoPbeddoeemthelensoftheqe,the~testdoseaare those~whthescanisdanewiththegantryangulateddmd m relation to t h e o r b i b m e a t a l ( ~ l i n eIn . this cirauastance,theeye isincludsdmtheprimarybeam.Thispoeitioningfactorcausedthedoseto thelensoftheeyetoincreasebyaf~of~tofaurcom~to standardorbibmeatalecans.Dosestotheleasoftbeeyeframcranial ~omputedtamograph~ cuemtherangeoftheabsdeddosehvmothen pmmhea Ishemood et a1 (1918)pmvided absorbed doses to the lePls aa fdkrws: orbital hypocyclcidal t a m e , 120 mGy (12 red); petmus boare tmogqhy, 100 mGy (10 rad); ambd a n g i w phy, 5(1100 mGy (5-10md); ,20 mGy (2 rad) and skull emmkdon, 15 mGy (1.5red). Dental m g m p h y Radiath cloeea fnnn dental x-ray examinations we1e~~detailmthe1982~oftheUNS(=EAR(UN~ 1982).OvwaR, the mliationexpoam?from dental filmsmay be demashg slightly. The United States Nationwide Evafuation of X-ray sends (NEXT)survey~thatthemeanexposumatskinen~frnm dental bitewin@;postehr films was 1.79 x l W C/kg (695 mR)m 1973 and 0.86 x lo4 C/kg (334 mR) in 1981. The exposum fmm cephalometric examhatiam inmased hm.6.71 x 10" C/kg (26 mR)m 1913 to 16.0 x 10" C/kg (62mR)m 1981.

3.7 Quality Amunmce and Dose R d u c t h Quality asianancemay bedefined as anoqgmhdeffortbythe staff a Wty to ensure that the appmpriab diagnostic images

pducedbythefacility areofdfSently highqualitytoprodeconsi4 h t l y adequate diagnostic informath at the lowest possible cost and with the least possible expcsm of the patient to mhtkm. A quality assuranoe program includes, h f o r e , many amponents, ranging h m machinecalhatimtostaffand~educah~~&ts are~inthefallowirlg~hs. Stieve et aL (1985)and o h m repeatedly emphasize that training p n gramsintheuse,caliion, audqualityassuranceofx-rayequipmentm aneiwntialpart dauydoeenxbctkmpmgram. Inmanyofhpractices mtbeUnitedStates,x-ray ' " am performed by persons with little or no formal training m the uses d x-rays or x-ray pmtection. Cohen (1985)attempted to genep.alize and assessthe h&tsfmm quality assur ance prqgrams. He estimated that a quality assurance p q r a m will lead to areQlctionof50~tmthemeanwhole~dose~hthrn diagnostic d o g y (for dedoped axmtries) fmm apprmdmatey 1.0

3.7 QA AND DOSE REDUCI'ION

1

35

m G y (100 rmad) to 0.5 m G y (60mred)pryear Amport of NCRP ~tific~~7Oon~tyassurancein~laclialogyis available (NCRP, 1988). The judicious use of radiographic examinations and eliminatcm of rn productive examidions also qmsmts an area foa potmtial population dose reduction This area has been the topic of seveial cent WHO mporh (1983, 1986). Amw of emphasis in this regard have mted about the e£ficacy of saeening or pmopemh chest x-rays, skull films after head trauma,pwmployment chest or lumbar spine and dnatians of the genisystan a d sinuses in children (Gustafssan, 1980;Gustafsson and Morbmmq 1983). Do' ' ' c ~ c a n b e a s i g d i m n t c a u s e o f ~ ~ b e d dose variation. F'adwani et al (1987)has m t l y s b some limitati011s of the Monte Carlo methods when they are used to determinje abmbed doses to various organs as a d t of medical practice. Monte Carlo methods assume good pmctice (eg,excellent collimation). In his survley m northeast Itals~,he found major dii%mmm betwem the absoAbed dose to organs calculated by Monte Carlo methods versus those measured u& ing t h e r m o ~ddosimeters. t Actual testicular doses, for example, were higher by factms of 4 to 60 than Monte Carlo calmlatiom would suggest. Similar findiugs were Feported for absorbed dose to the breast

andthyroid The voltage and radiation output of x-ray machines wme studied by Henshaw (1985)and M y et al(1985),who observed variatiam b m the dekdvoltagerangiugfmm 5 to20perc8ntor mole-andavemghg appmxhately 10 percent. Belletti et al (1985)malyzed causes of mpeat films. One of the mom significant mdts was again the d h a q m c y

between~andselectedpeakdtage'Rsnto~percentofthe x-ray mdmes examined we.re found to have a ten percent cliffamce b e h e n the set and measured values of peak volOf all films that neededtoberepeated,wer50percmtweredueto~ora9t.e;rrposure. Most umatkfactory films wexe due either to variations of the voltage produced by unstable generatars, incorm3 choice of e i h volor cummt or malfunctions in film pmcedng. In most instituticms m the U.S.,estimated =take rates are in the range of thFee to seven percent and W p m pmbably contribute about fivepercent to the population dose. In computed tomography, them is a tradeoff betwem image naise and radiation b All c a l d m used by the computer to construct the image are limited by the statistical nature of the detxted p h o h . Several attempts have been made to due the dose through technical m&c& tions. Dose mduction can be achieved by collectkg data only during a portion of the scan. More mentl~~, Stantanand %ti& (1983)have devised a method that collects data over the entire scan but eqmm the Fegian of

36

I

3. DIAGNOSTIC X-RAY EXAMINATIONS

intaest to a highex dose than other anatomical struwithin the scan vohune. This step is acmmphhed through the use of a variable thickness fil~d~peakreductiiansofupto80percentateclaimedfwMscans. M d e y and Zilkha (1984)discussed v a r i m methods to reduce ladiaton d o s e i n t h e m a n a g e m e n t o f i n ~ l e s i o n sthat amclinically followed by the use of computed tomography but they did not provide any quautitative dose reduction factor. McCunough (1980)suggested that the p e ~ farmanceof&(;T-be-edandcheckedindtoensurea typical level of performance and to provide a baseline value for a pragram of quality assurance. Items normally tested include slice geomeby, patient dosage, &actual behavior, and contrast detail perfonname C!dhatioa of the x-ray beam to conform to the body portion of intenst is extmaely important in dose reduction. Many older machines have a cirwlar x-ray beam while f ilm is rectangular. Johnson and Goetz (1986) have Feported that a change fmm circular collimation to m h n g u h callimation or positive beam limitation has resulted in a deaease in the beam area to film area ratio from over 3 to about 1.1between 1964 and 1983.The situalim is somewhat diffem~twith fluoroscopy. In this case, the cdhatars rue usually xwhxygh while the image intensifier is circular. If the operatawishes to use the whole of the c k d a r image, there is about 25 pemst additionalunnecessary radiation. Digital radiographic and angiographic systems rue being instaUed in many hospitals.The amtrast mlution of such imtmmntation is primar ily limited by quantum mottle (non-unifompattern of light due to fluctuation in the number of photons).Rimkus and Bailey (1984)indicate that the number of ' ,did levels of gray imaged (mtrast d u t i o n ) will significantly affect the radiation dose As an example, if 128 meaningful visual shades of gray on an image I.equire a certain dose to the patient, simply raising the level of canbast mdution to 256 shades of gray will increase the dose by a factor of 5 to 10. However,such contrast resolution is d y needed for diagnwis and this is, therefore, an area whm urine sary dose can be avoided. Some of the possible methods of dose reduction and their quoted dose reduction factorsrn summarized in W l e 3.21.

3.7 QA AND DOSE REDUCTION

1

37

TABLE 3.21-Somep~dbSties j6rcdlectiuo dose equiwlent & d o n inImdiad+sticuse~

Reduaiw

Waf w m

Action

u w

RBfemca

factor

Eliminate medically 1.2

unnecesear~d~

Proper M o p h g of film

1.1-1.3

Cohen(1985)

Russell andckmicbd (1987)

Inbuductiooof @ty Radiography

mlaogram(genm

2.0

Cohen(1986)

Damase in rejected filmsthmugh quality m p r ~ g n r m

1.1

Oalliniet d (1985)

Pmpmio and Blnirhart (1986)

Mcari8 and Young (1984)

Beam dimation Incressiagpeakkil~~~Iltage Use of rare earth screens IncFeasingfiltration Rare earth filtration

1.6-3 1.6 2-4 1.7 2-4

Newlin (1978)

Change fmmP ~ ~ to chestradiography Use of carbon fiber materials Replemmeut of CaWO, screws with spot film technique Entrence expame guidelines Gonadal shielding

U

~

Wiahowaki (1983) Wiatxww8ki (1983)

'Ifmdall and Washburn (1987)

10 2

Y

Muetafa and Kuris (1986) Huf- and Russell (1986)

4 Kuhn(l986) 1.5 Laws and Roam&& (1980) lo0 (to

fKmads) .

Use 6 C T bpogmmor scout view Acoustic @a1 related to Qse rate

Pehrimegy

F

l

v

6-10 1.3

Suramoi et aL (1984) A n h n and Mattarm

Fkplammt of iwsereen 2-5

techniques

Variable~irisonTVcamera

High and low dose switching Radiologisttechnique

Digital Radiography

Deaease in contrast mlution Umof-eYatem

Computed tomography

M

v

h

y

Gantry angulation to d u d e e~efnJmprimarybm In-screenS

Optimal mm&

3 1.5 2-10 2-3 2

Cuwau and 'lhyl~ (l986k

Rowlgr et d (1987) Leibwic andCaldimtt 11983) Leibovicam-lCa&ott (1983) Rowley et d (1987)

Rimkus and Baily (1984) Rlmkus andBaily(1984)

2-4(toeye) Kronhdzetd(l983) 2-6 NCRP (1986) 1.3-1.5 NCRP (1986) 3 H m et d (19'79)

Filtaatim ~roleofpmpatraininginradiationpmeectioniaextmdyim~t. Doeereduction factQs remlthgfrcm this me probably large but are difficult to quantitate.

38

I

3. DIAGNOSTIC X-RAY EXAMINATIONS

38Gonadal and (hne&dy SignifcantDose

For estimates of possible detriment to tofuture g e m d h q two quantj. ties am often reported. These are gonadal dose and genetically sigifhnt dose (GSD). The gonadal dose is the calculated dose to the testes or waries h m a given ' lation in either an individual patient o ra "standard" patient. The GSD is defined as that "dose which,if given to every member of the population, would produce the same genetic detriment as the actual doses received by the various individuals" (UNSCEAR. 1972).The GSD is a weighted dose caIculatedon the basis of the number of p d u ~the ~ ganadal , dce, and the age distribution of the population mpmd (particularly the number of chiMren expected among that age population). Analysis of the GSD from diagnostic radio logic can be helpful in designing dmbgks for m b h h b g radiation dose to thepopulation It also has been used to estimate possible detriment h m a spedjc practice and,to a limited exkmt, allows diagM>4 tic radiology to be compared to o k radiation sauroes such as nuclear medicine and natural diaticm expome, The GSD was estimated from population data of the U.S. Cenwls Bureau Age and sex distributions for radiologicalpmceduxw performed in hospitak are given in W o n 3.4 of this Repcnt The age and eex buti ions for.pmaxhuwperformed in private practice were assumed to be the same as those for hospitals sine no other information was d able. The relative child e q e d m q for a given examination was calculated from the live birth rate for each age and sex grmp having that examhation. FkMve child expectancy d e r s to the plobability of a persun of a given age and sex having offspring in futuFe years. Live birth rate data wen?. obtained b m the National Center for Health Statistics (NCHS, 1981).The total frequency uf examinations uf each type p e r f d in the United States is givenin Section 3.3. The gonadal doses for various exmiaatioas were d to be thoae reported in 1970 by the Bunmu of Radiological Health O A , 1976). The calculation does not include any redudion for p d a l shielding, even though such shielding is often provided fop some typesof exmi&hm. The formula used f a calculation of the GSD was: D; = dj' Nj'm Wj'W where 'ion of tb D; = amtribution to the GSD from class Q) specifiedsex (*), 4' = the mean gonad doee per individual undergoiag class U) earamination, NjW/N = the dative number of cmmkdians per caput per year, and WiiW = the relative future child exp&auq of the individual undergoing class G ) ' "a

~~

3.8 GONADALAND GSD

1

39

3.22 idicah the gonadal doe, relative fiwpency, dative chiM enrpectancy, a d GSD fur each sex and -on type. The expaam of males acctnmts far appXim&dy o n e m of the GSD and theexposum

TABLE 3.B--1-3

Sen

Male

indudedin mlculation o f g m d d y significant the fir1983 bs~andereaminahbnEYpB0

Mean Relative Relative oonadalDoseChild pGy~mrad) ( x l e a ) E

ExamHead&&

10 (1)

160 (15)

0.57 0.31 0.47 0.16 0.38 0.65 0.70

970 (97)

36

0.31

10 (1) 1,750 (175)

28 17 11

0.22 0.17 0.20

0.1 (0.011 5.1 (0.61)

2.070 (207)

18 11 3

0.24 0.13 0.21 Male'Ibtal

8.9 (0.89)

-

2.160 (218) 6.000 (600)

.

-

40 298 23 69 I8 106 119

Chest cewicalspine Lumberepk Hipslpehris . upperLmvrexmmitiea

OSDfor Exanl'Ijrpe PGY( m d )

-

0.9 (0.09)

-

19.3 (1.93) 41.0 (4.10)

-

12.5 (1.25)

Abdomen (ldneya,

ureterS.bu Upper gastrointestinal Bdllovid

Bariumeanuna Gall bladder Irltravenou~pyde

-

gram

H d a '

-

Bodym

-

-

Fermals Head&& -Spine Hipalpelvis Upper extremities ~

~

t i Abdomen (kklneye.

ureters,bladdB) 2,210 (nu Uppergtlstmb~ endSmanbawel 1,710 (171) Bariumenema 9,030 (903) Gall bladder 780 (78) IntTavelloua pyel6,880 (5881

-

HdCT

W

Y

~

-

-

98 (9.8)

-

35

0.38

29.4 (2.94)

39

0.26 0.17 0.14

17.3 (1.73) 39.9 (3.99) 2.1 (0.21)

0.N 0.33 0.21 Female'lbtal

23.6 (2.35)

56

-

-

26 72 103

7.210 (721) 2,100 (210) a

-

0.41 0.21 0.30 0.21 0.21 0.15 0.41

no

-

e

32

10 (1)

chest ~ s p i z r e

10.5 (1.06)

22

26

19

20 13 3

0.6 (0.06)

-

84.8 (8.48) 11.0 (1.10)

-

-

-

209 (20.9)

(-1 indicates less than0.01 pGy. ' -ti typea which are usuaIly hdudedin the eategoly of 'Thae em a number of "atbere"whichhavenotbeemhchddinthis?gble.Inch&moftheeemayhmasathe GSD by 10 to 20 percaat.

40

I

3. DIAGNOSTIC X-RAY EXAMINATIONS

of females for appmimately tsvethirds of the GSD. The largest amtributars to the GSD ate -tiom of the hips and pelvis of males and ammhatinnn of the lumbar spine and barium enemas offemab. The total annual GSD is estimated to be about 300pGy (304. As m pwious studies (FDA,1976),the GSD contribution from dental x-ray examinations has not been included, lxcawe it is so small than 1 pGy (0.1 mrad)]. The genetically significant dose from dental radiography in wen-aped countries appears to r e p m t about 1/10,000 of that frommedical diagnostic diogmphy It is expectd that gonadal shielding would have a datively small e f k t on the GSD. Gonadal shielding is applicable to the male only and, thus, would only affect about onethird of the GSD. It is aLw unlikely that gonadal shielding is being used in mom than 20 parcent of examinations in the U.S. Thus, if gonadal shielding were taken into account, it might &ce the estimated GSD by only 6 to 7 percent. Thisis offset by the fa& that horoscopic @on9 of radiographic examhations wem neither included in previous nqxrh of the GSD nor in the pment calculatians. Inctusionofthefluorr>scopic~wouldcertainlyraisetheestimateof the GSD. Another factor that has not been accounted for in the calculation in this regard is that collhnation and canelation of the beam to field size have improved over the last decade (Figure3.3)(Johnson and Goetz, 1986), and this alone would lower the gonadal doses, particularly for the male. The genetically significant dose was calculated to be 0.17 mGy (17 mrad) in 1964 and 0.2 mGy (20mrad)in 1970 (FDA, 1976).Utilizing the same methodology and gonadal doses for this leport, the 1980 GSD value has been calculated to be appmximately0.3 mGy (30mad). Another difhmce between the pl.esent results and thm obtained by the FDA (1976) for the 1970 GSD estimate is that the mom mxmt calculatiansinclude a larger number a.lumbar spins and full spine examinalkm due to more accurats identifidon of the number of chhpractic radiogqhic p m c e d ~ being ~ ~ performed. In* of these chiropwctc data h89 raised the GSD estimate by about 20 percent. It is not m p i s i n g that the GSD has irscreased in the last decade even though a larger pescentage of the alder population is A v i n g radiological -0119. As mentioned earlier, the number of exambtions per formed over the last decade inutwed by appmxhmbdy 32 pemnt, which tmrdatm wd with the calculated estimate of a 50 percent increase in the GSD during the same time period. In ~-y, the genetically dgrdbnt d m to the U.S. poplation from diagnostic radiologic ptocechules has i n m a d ap-tely 50 perrent over the last decade. It is edmated to be about 300 pGy (30 mrad). Appmximately twr,thkds of this is due to emposure of females,

3.9 MEAN ACTIVE BONE MARROW DOSE

1

41

with the largest pmporticms due to examinaticms M v i n g the a W o ~ pelvis, and lumbar spine

F9g. 3.3 Mean ratio of beam area @A) to film area @A).chest. P l k 1964-1983 (h Johnson and Goetz. 1986).

3.9 Mean Active Bone Marrow Dose Estimates mpublished of the mean active bone marraw dose to the adult population by Shleien et a1 (1978).who calculated that the mean active bone marrrrw daee b diagnostic radiology was 0.83 mGy (83 mrad) m the U.S. m 1964, and that it had haeased to 1.03 mGy (103 mrad)in 1970. The survey methods and datasources far then& and frequency of p m c d m in di€femnt age gmups for 1980 have been d m i abow. In theabsmoeofnaticmally~~activebonemanrrw~~ 1980 for various examinations, the 1970 doses have been used The cantniuticms to the mean adult active h marnrw dose fmn qecXc emmbaticms w m calculated by e&b&g the number of

42

I

3. DIAGNOSTIC X-RAY EXAMINATIONS

of eech type performed on adults (adult -on rate)and &@dying this by the mean actiw bone marraw dose for that exmidian. Data fmm the U.S.Census Bureau indicate that,in 1980,Eilmillion members of the U.S population wem less than 15 years of age. This component of the population has not ham induded in the calculation of the adult active bone marmwdose. From'information on the total number of examinations and the age distribution of those having various hospital examinations, the adult examination rates for medical diagnostic x-ray procedures can be derived. Since data on age distributions of dental examinations wem not available for 1980, it was assumed that the distribution has not changed h m 1970,,ie., 75 percent of dental radiographic examinations were performed in adults. The active bone mar- doses per d&pstic radiology examination derived for the 1970 study were computed by Shlebn et aL (1978).using expaimmtal data derived fmm radiotherapy with x-ray beams having similar n u m a i d beam qualities (HVL),but h m x-ray spectra af higher kVp and lesser total filtration than diagnostic x-ray spectm. A second doaimetry technique,using a Monte Carlo transportcode and mathematical anthmpomorphic phantom applied by Rose ' ' (1976).cau also be used to generate activemarrnw doses far diagnostic x-ray exposme conditions. This method utilizes diagnostic x-rayspectra T h e d t s o f thetwomethodshavebeencompdcrullefullyf o r a e of exposme amditicms typical of the 1970 Xl3S study, and d'" am observed that am dependent on the x-ray projections and views. These difkmces, detailed by Rosenstein (1976). can be traced to diffening assumptims mgadbg beam quality,mllimation, method ofmmputation ofthedosestothe~utedmassesofactivebtmemarrrmv,~of other tissue regim in the phantom such as the lungs, and accounting in thephantomfardosestotheactivehe~fmmphotans~ outside the primary beam. Inthis~twoestimatesarecomputedofthemeanactivebone mamw dose to adults for 1980. One is derived fmm the data given in Shle.k et a! (1978)for 1970. The smnd uses comparison ratios tabuked by Roeenstein (1976)for a number of cornman projections and applies the comparison ratios to the 1980 x-ray examination distrhution.The cornparison ratio8 for the two methis for each of the examh&im in the m t c a l a a a s am given in W l e 3.23. Computed tomography was not available in 1970, but it was a significant examid5011 by 1980 and is includd in the 1980 c a l c u l a h . The active bone manaw d m from computed tomography is djf6cult to evaluate due to the limited measurement data and the marked variation in equipmmt, expoeuw mode, and tedmique. Most CX scanners ploduce a

8.9 MEAN ACTIVE BONE MARROW DOSE

I

a

~ d a w o20to f 100 mGy(2to 10rad)forasinglealiceand l.2to1.7 times bigher for multiple dices (Mand Wyne, 1978). Fm head CT,tbetbeh~hqappearstobeaboPlt22mGy(220~ pe~exam~f~bodycZ:itisabaut3.5mGy(3M)mred)~earam ( H u h 1984;E m et aL, 1983; McCrdzan et d,1987). TABLE 3.25--&-

mtas fir lmscomfnatiorufiactkm bone m a m u cbw

E

'

"

Comparieonratid

Skull

0.93 Not applicable Not appkabk 0.63 A ~ ~ ~ ~ . u r e t e r S , ~ 0.58) Biliar~r 0.75 0.49 Thoracicspine Lumbar0.60 mspine 0.55 Upper tm3 0.68 Bariumenama 0.65 Inhavenoua pyebgmm 0.66 WVhhip 0.47 CervicalSpirre 0.62 E Not applicablec Dental 0.88

IieadCT MY CI' Chest

~Ra~ddoseshmRoeeaul~(1976)tod~hmShleieaetd (1978). bcamparison mtioti for spedic views (AP.PA,LAT,OBL)given in reference(as a p p k ~ ble)f~~ofviewsdtbeeo~skinerpoerneslrssumedfor1980. =Not assume value ob 1.0.

'Igble 3.24 pwents estimates for the adult mean active bone mamw d o s e t o e d u l ~ f o r 1 9 8 0 , u s i n g t h e ~ e t( d 1978)~andalsothe conespanding d t s when tbe data of Ramst& (19'76) are used The authors have used dif&mntmodels and beam m. ~Rosemstein's model ismarerealisticwhentechnicalfadorsfordiagwsticradiology~cansidered.Ontheotherhand,Shleimin&desanestimatefarthe~ portion af examinations w h a s Rose&& does not. The mean active bone marrow dose is 1.15mGy (115mrad) using Shleien's data and 0.75 mGy (75 mrad) using RimemMds oomparism ratiaa Barium enema, . an? upper gaslmint.estjnal, and hmbarhmbmacml spine the largest contributc~~ to adult mean active bcme mamm dosa The dative contributions of varim pFocedures for the two studies are iradicated in %ble 3.25. for computing examinah dose is If RmmskSs (1976) extended to the data for 1964 and 1970, the results are 0.54 mGy (54 mad)for 1964 and 0.65 mGy (65mrad) fm 1970.

.

I

44

3. DIAGNOSIIC X-RAY EXAMINATIONS

Numerical o a m w have been made behem mean active born marmwdoseandwholeboctydose.~caUy,k~~ sewed as the basis for the oftm quoted s b w t that the contribution of diagnostic medical radiation is -ely equal to the ~ o n t r h t i ~ a ofnatural~dradjation~thepop~mdose.Thishasleadto the cxmneous pmamptim that the health consequences of the average whole body dcme fmm natural badcgmmddiatim and the mean active bone manwu dose h m diagnostic radiology are a p p i m h d y equal McNeil et d (1985) have painted out that clrrer 80 percent af the total b~theactiwbanemarrowoccursinpatientsclrrerthsageof40and nearly 60 percent after age 55. This suggests that the potential number afinducedleukemiasfram~radiologymaybelawerthanp viausly estimatEd

ActivemanaradoeeG1Gy)l.

Examination skull Head CT

MY cr Cheat

Mean active mamw dm (pGyY p e r m o i l Shim Fkemtein Annual Shleien Ramstab eta1 (1978) (1976) exam rate et ol(1978) (1976) 780

2,XW

730 !2,2Oob

3,100

3.m

1.470 1,680 2,470 4,000 640 5.360 8,750 4,m

850 1,!260 1.210

60

--wwmb1-

0.022 0.015 0.003 0.335

17 33 11 34

16 33 11 20

63 32 25 288

37

225 236 W 22

24 12 173 3 153 164 54 10

23 40

12 34

Rehiship

830

390

0.043 0.019 0.010 0.072 0.008 0.042 0.027 0.023 0.026

CervacaltTpineBother head and neck Dental

620

~0 80

0.044 0.430

B* Thorecic* Lumbar-spine mspiae U p p a ~ t e a t i ~ l Barium enema Intra--

90

2,400 3M)d

3,640 5.690 2.360

6

TABLE 3 . 2 6 - ~ o o n t r i b u t i o n I f n ~ o f U m i w -8iailpmcedww 9~

lo

ad& mem ochochue tammantno doss in the United !htes 15190

Sh4

1.5 2.9 ~ 1.O chest 3.0 ~ w W % ~ M a d d a ) 6.6 BiliarY 2.8 Thdspine 2.2 L l u u b ~ ~ m m 26.3 Full* 0.4 Upperge&dhdd 19.8 Barium epleana 20.8 8.6 ~vis,hip 1.9 Cenieal~&&headandd 2.0 Dental 3.5

Head CT W Y

2.1 4.4 1.5 2.7 5.0 3.2 1.6 23.2

0.4

20.6 20.6 7.2 1.3 1.6 4.6

Quantih that have been used by various authors to assess somatic detrhmt indudec (1) the mal@mq signihnt dose (MSD) and (2) the leulrsmia significant dose (LSD). A somatic dose index which uses individualargerndosesweightedaccordingtosex~~t~furthe dativeradhtionriskforcanoersandleukemiahasalsobeenpposed (Lawsand Roseastein, 1978). Inadditiontotheseamcepta.ICRPintauducdthe~ofeffective dose equivalent (HE) in 1977. This latter amqt has been described in Sectian 2. The sum of all effective dam equivalents fmm each type of ~oncanbe~toasthe~veef6ectivedoseequivalent from diagnostic medical imdatim ~ a r e e o m s ~ ~ n c e p t u a l p m b l e m s m u ~ H , f m t h "mof e~" detriment from diagmdc radiology One difficulty is that the Heancept aswunes an equal populatimof males and females. This dearly is not the case for some examinations such as mammogqhy. ?b deal with this and otberproblems,~appma&es~beendeveloped.Modelsthathave ' Jdthe~ceafrisksonfactarssuchas~ageateorpoenne, and time from exposme have been utilized both by the National Academy of Sciences (BELR 111) (NASNRC, 1980)and the National Institutes of Health m development of -ologiad tables (NIH, 1985).Beninson and Sawby (1985)have mtmdued a proposal for a quantity that could logically qresent tbe impact of medical radidogy better than the effec tivedoseequivalent.Theproposedc~nQptutilized"~factors"

46

1

3. DIAGNOSMC X-RAY EXAMINATIONS

(P,) andsexspecifkfactors.Thederiivedvaluewastermedthe"~ted dose." The reason for $eaivatcm of a "weighted dose" was that the ICRP risk coefficients and effective dew equivalent apply to the ocmpatiexposed popdatiian, without diffemtiating for age or sex. when the effective dose equivalent is applied to medical radiaticm situations, there may be an owmtimation of detriment since the effective dose equivalent does not re£lect the diffenmtial risks for an exposed popWcm with a substantially difkzent sex distriitim and a substantially d u c e d life expmtmcy,due to age and health factors. In 1980. the report of the RED 1 data (FDA, 1986)from United States hospitals indicated that 25 percent of all diagnoetic medical radiographs were performed on patients over the age of 64, even though this group v t e d only 11 pe.mnt of the popuhtim Thus, the age distribution o f t h e ~ m ~ v i n g m e d i c a l ~ m i s s u b s t a n ~ ~ dative to the @popdatimat large. Inordertodeb ' themagnitudeofthediffesencebthe "collective weighted dose" as described by Beninsm and *by (1985)

and the "collective e M v e dose equivht"of the ICRP (19'771, these two appmach have been applied to medical x-rayexaminationsperformed in U.S.hospitals (Mettleret aL, 1986). The average beam quality,entrance a p s m + and number offilms per tion view for most exmhations performed were obtained from the U.S.Fbpdatim X-ray Exposum Survey as qorted by Laws and Rosenstein (1978).Using this material the average entrance e~tpownrefor ~viewofeshch~mwascal~Theabsarbedd~~each organ of inhest was obtained by usjng the argan dose tables published by Garsan et a1 (1984). Spedc pediatric organ close tables were used for the calmdatim of organ dosss in the 14and-ude.r age p u p . The weighted dose for a spedfk tissue for each sex and age group was the31 obtained by multiplying the p a d e d h factor (Bmimmand Sowby, 1985) by the absorbed dose in that tissue,The " h d e r " tissues indicated by the ICRP wen? calculated as being 30 percent of the total weighted dose or effectivedoseequivalent. ~~answerethenmade.ThetirstwastheICRP~ effectivedose equivalent for each of the major catqpies of examinathm (seeAppendix A for example of method). The second calculatim derived a serIesof~teddosesforeachradiologicalexaminationbasedcmage groupdsa~Thelatts~~multi~bythenumberofdnations done for each speci£ic sac and age gmup and wlene then added to yield the oollective weighted dose for each -OIL Data published pdously by Evans and Mettles (1Wi)wen?. used for computed tome w h y -. The rwults of using the two methods UCRP (1977); & ' and

3.10 SOMATIC DOSES AND EFFECTIVE DOSE EQUIVALENT

1

47

Sowby (1985)lare shown in Wle 3.26. Using the ICRP txhMcm, the callective~doseequivalenthdiagnd~inU.S.hospitals is a,ppmha&ely 72,000 pemnSv (7.2 x lo4 pemonmd. wbemw whenageandsex~ted~~~tedaccordingtothemethod of Beninsoa and k b y (1985).the value is 46,000 permn-Sv (4.6 x lo4 ~ ~Use of the ~age and s e ) i & e t . weighting fact~ra d t s inan~36percestreductionofpossibledetrimsntc~mpared to the ICRP (1977) method-.

TABLE3.26--Cbllectiuew v edoss e q u i d rmd mClective weighted dose ftwn diagnostic md&gy muing 1 W i n United Sinbrr hospPtoLP CoILecCive~vedose equivaleut

-trpe

W

Chest

4,339 (5.9) 1,560 (2.1) 630 (0.8) 6 . W (9.1) 5,340 (7.3) 15,770 (21.5) 3.730 (5.11 15,400 (21.0) 7,910 (10.8) 5.460 (7.4) 2.730 (3.7) 200 (0.3) 3,660 (5.0) 73,000(100)

Skull&h (3rvkalspine

B w Lumbarspine Upper g c s t m i n e Abdomen kidneys, ureters, bladder) Bariumenedlw ~ V = W P -

hlvis Hip E '

'"

~ted'Ibunograph~

P

RoundedW .lpersonSv = 100peaeon-rem. bNumbasinpw&xwaretbepenentoftotaL

(xktive-)Lb

5650 (5.7) 1.280 (2.8) 430 10.9) 3.820 (8.3) 3.580 (7.81 9,030 (19.6) 3,470 (7.6) 7.470 (16.3) 6.630 (14.5) 4,280 (9.3) 1.560 (3.4) 110 (0.2) 1,700 (3.7) 46.000 (1001

c ~ ~ i c ~ t a a w e l l a B r a d i ~ h i c .

The use of age and sex-weighted risk factore is mom appropriate far medical~mthanisuseoftheeffectivedose~t~the d c u k i a n of detrimmt by accounting adequately for the age and sex iti ion of the popuhtian win become mrne important in the next several decades because them will be a substantial aging of popuki0118in ckwdoped countries, * in North Amerh, Eutrope, and the SovietUllim A s t h i s ~ ~ t h e m a g o i t u d e d t h e d B e m n c e i n ~ t c a l c u l a t e d b y t h e I C R P d ~ t e d d o s e ~ w i n ~ t i n u e t o ~ Additional estimates w e n made of the coktive e & d h dose lent fmm all medical dhgmetk x-rays for the U.S.popdath m 1980

I

48

3. DIAGNOSITC X-RAY EXAMINATIONS

these caldationa, the p j d m half-value layea and en~~andtheaveqpnuxnberoffilms~ob~fFoanthe data of Laws and Rmembh (1978).Organ doeea wem then appbd to thesedata (Gorsanet 4 1984). dose equblents wen? calculated . ..Effectbe TbeU~'orgaas,asindicated fort be most^ (Bible 3.27). Far

by theICRP(1977).wem takentobe90pera3ntofthetotaleffectiwdose equivalentsinceavailableorgandosetableadonotincludecalculationsfar these " d * ' The " . - "mratewasobtabled£twndata p1wented~yin~on3.3.Theprcaputeffective~~alent£twndiagnosticmedicalimdiathiscal~tobeabout0.40mSv (40 mmml for 1980. If age and sar weighted risk factors rn used, the CcHTeaPondingweightedvahmwouldbeabout 40 pertxmt l m , that is, about 0.23 mSv (23 mrem). These estimates do not include the amtnitionfmmCI'scans,andthedatausedforthediagnosticradi~ "om pmqpoae "good technique". However, m balance. the c a l u F caput effecthdose equivalent of 0.40 mSv (40 rmem)far the year 1980 may be somewhat low.

TABLE 3.27-ColIectiw fl& dose eqldualent from mhgnostk meclicolavuys unitedslates198D

Examination

Cbeet Slrull Cervicalepirre

Blliarv

Lumbar spine UpperfzastKhM AMomen&idneye, UmtemMedder) Barium enemn Intra-Whrie Hip.

...

0th'

. H E - E W dose equivalent. bl mSv = 100 mrem. ClpemuSv=1 0 0 ~ r e L u dE&mated from the average of an

Exnminntinnn

CollectiveHa.

Itis~ctivetopostulatethefutul8activityd~of~ medical~dtoexamine~iareasaf~~islittle d c m b t t h a t t h e ~ e n c y a n d t o t a l n u m b e r o fimrdving ~ medical i r d i a t h willsu~tiaUyincreasebytheyear2000.The severalmasonsfarthisprojectedinmaseincludeagingofthsU.S.popula t h (O'Nejll, 1982),which, as hdicated abave, now m t s for a dkpw portianatenumberofmedicaldiagnosticexaminatiions,d h m a a e m t h e totalpopulatian There are some offsetting factors in theae calculations. As the popula timages,thed~tdhavelesstimetobe~and useofanageweighteddoseequivakntwauldassumemone~ ' ' 'am V i d altematie, although the number and fnqumcy of might matme, the older segment of the population would haw a shorter p e r i o d b i n g w h i c h t k y w e r e a t r i s k o f ~ ~ ~ cancer. In addition to age, e&imatim of the genetically drmifirsnt dose dependsupontherepruductionrate.Thisdprwidean~offsetting factorin the txlmhtion ofgenetically significantdosa

4 Nuclear Medicine Nuclear medicine is that speciaIty in which radiare u s e d f o r ~ r e s e a t c h andtkmpy , Nuclearmedi~imageshave h w r spatial resaluticm than those produced via radiagqhc jmaging procedureaN-, ~tracersarewidelyusedtoasseasand quantitate regianalblood flow, organ function, and o k in vim biological pmmmea This has pmided nuclear medicb a unique place in medical diagmih and practk Nuclear medicine has gmvn mpidly since the end of World War I1 with the advent of readily available radionuclides and r a d i o p W t i c a 4 as ~astheamtinuousimpmmmntofimagingand~instrumda Along with the advent a n d m expansion of both amputed tomogmphy and gray scale u l m d , them has been a marked inmase in the frequency of nuclear medicine pmadures (Mettler et d , 1982). The pwpoeesofthisSectimamtoassessthetrendsmthevarious~ure~~ to compare the frequency af specific pmcedum with competing modalities, and, M y , to establish a base of information that can be used for suchas as estimating the absorbed dose to the population frcan the practice of nuclear medicine This Section will not consider the tkapeutic use of radionudkles far masons similar to those g i m above in the d.imwion of radiological studies. AU in vim tests are also exchdd ~ t h i s a n a l y s i s ~ ~ c a t e g o r y i n ~ m p a t h t ~

42Data Saaroes Data on the fmpency and total number of nuclear medicine pmcedma have been &ved fmm sevepal difhmt sources. The 1972 data weze cdkted by J. Lloyd Johnson Associates m coopemtion with the American College of Radiology and were pmsmted m a survgr on regionahtion in nuclear medicine (ACR, 1975). Data for the years 1973 and 1975 were obtained m a similar fashion and published m the Ame3ican College of hddagy Manpower Survyy (ACR, 1982). Tbe U.S.Food and Drug A ' ' ' ' Itioninitiated a pilot pnoject in 1975 to survey nuclear medicine in six hospitals.These data wezs reparted thmugh the Medically Orkmted Data System (MODS). The

4.3 NUMBER OF EXAMINATIONS

1

51

project was later expaded to indude a stratified sample of 26 hoepitals, a n d d a t a f r o m t b e s e h o s p i ~ ~ ~ ~ A u g u s t 1 9 7 7 ~ July 1978. Cornpdmmiw data on 1980 diagnostic imaging pmedum valume,inchxhgnuclearmedicine,.c~erecollectedbyJ.~dJohnson &so&&a (Johmmand Abemathyt 1983). In 1980 end 1981, the B m m of Radialogid Health, m m the Center for Devkea and I h W u g k d Health (CDRH), conducted a hospital--basedsurvqr, which was called tbe Radiation Expsience Data (RED 1) Study (FDA, 1986). Data for 1981 and 1982 are available £mm the CDRH study (RED 2) cited earlier. A

~ptimofmostof~surveysis~031~inW0a3.1ofthie q o x t Although much of the CDRH data (MODS,RED 2) w m a h unpublished,thisMomxition is a v W l e to thepublic Another study was done in 1981-1982by hrker et d (1984).The latter study included a randomized sample of 10 percent of the U.S.hoepitab perf~nuclearmedicinep~ures.Tbesurveywasdirected~cdy at thymid examhtinnn but also prwided data cammhg the total numberofinvivonuclearmedkhe "om. Allof thestudieslistedabcmwexebasedonhospitaldataonly,a n d m believed to be adequate, since less than 1 parcent of all nuclear medkhe pmedum ate paformed outside of hospitals. Johnson and Abernathy (1983) i n d k h that only 30,000 of 5,830,000 in v i m nuclear lnedicine examinatimsmperformedinprivatesttingsm1980.

The number and type of diagnostic radimuclide plocedure performed during several years between 1972 and 1982 are shown m Isble 41. The38 mae fewer donuclide brain imaging exambtinnn in 1982 than m 1972, pnsumably due to mphmmnt by oomputed.Liwr imaging

increased by 300 percent in this decade. and bone imaging i n d by over1,000pera3nt.Thegtowthincardi~~ureswaseven more im& (fmm 25,000 procedures in 1972 to ahmost 1,000,000 in 1982). Other p m c e d w such as mml, lung, and tumor imaging, haw

experh4modemtegIuwth.Dataonthe~encyofthyroid~

timate<)~npliUbythefadthatuptakesand~maften &m-though*nnavbeperfd-*.In Isble 41,thymid imaging and uptakes performed tqgethes are usually listed as one examination On the other hand, a hmg perfusion and ventilation imaging study is listed as two miratmy exmidkm. Tbe probable reason for this is that di£femtradiophammcmticals typicany areusedforeachpartof~studyThe~ofalldiagnosticnudear ~~uresincreasedcnerthedecade~16perthousand popuhtiion in 1972 to 32 per h a n d population in 1982

52

1

4. NUCLEARMEDICINE

Brain

-H Liver

Bane Reraw ThynA* uinary Hlmcr Cardiw&

aber

~ d i & e n t ~ ~ a v a i k b l e f a r t . h e s a m e y e a r1~9 8~ 9~4 a ~ d ~ ~ RED 1 (FDA. 1986h mpadidyl difbeaeat eaurzsem a v a i U e for tlm same year (RED2 d Park at 4 1984. tivelY).

dScllm anduptakea.

~~iadicatenumberd

*Numberein

'

"d1.000 pphh.

' I ' h e f q u e n c y o f n u c l e a r m e d i c b ~ i n t b U . Sat. 32per1.000 popukicm is g e n e d y higher than that of other dedoped anmtries. The cb ti an^ (ger 1,000 ~ O W O ~ ) i sreported asn~ws: Sweden, 8.4 in 1971 and 13.6 in 1976; Denmark, 3.8 in 1973 and 14 in 1985; Great Britain,7.0 in 1982 (Wall et 4 1985); and Austria, 17.5 in 1977 (UNSCEAR, 1982). In the last decade, not only has the mix of nuclear medicine pIocedures changed markedlx but the o w d l frequency

0fexaminationshasdoubLedasWea

4.4 Population DemTbe age dbtrhtion of the! U.S. population that undemmt nuclear medicine in 1980 is s h a m in Wle 4.2. The £requmcyof and sex are given spec& nuclear medicine prwdums as a function of in 'Igbles 4.3 to 4;lO. These data indicate that appmxhately onethird of a ~ i n ~ i v o ~ ~ ~ ~ ~ p a s o ~ 0 r r e r t h e e g e o f 6 4 y e a r s

and mom d m 75 percent cm persans u m the age of 45 years. Howevw only llpercmtof thetotalU.S.populatonin 1980wen?overtheageof64 andonly 20percentwmbetweentheagesof 45and65.

Manyofthe~tialtremlsendcompdmswith r d b ~ ~ ~ ~ ~ i n t + e t i m 3 . E Z 2 Z 2 t b a e area?rtab othertreplds that shddbehchdal In thedecade 1972 to 1982,the fquency of in viw diagm&ic nuclear mediche d a u b l e d . I I l ~ o a g r m a o r s y s t e a n s , t h e ~ ~ o f ~ havem-tedeachatbeawhile,mothers,them~~ pcedum h e been qhaA The war leg,laament, of course, has occlaedintheareadhrainbagkgThsinfL wrppliedbya a m ~ C I ' s c a n a n d ~ ~ c e i m a g i n g i s ~ m thatitisnot&~butaleotosams~tph~qejc "

Bothsexea Male

Female Unkwwn

Bothsexes Mele Female

1.176 524 627 25

26 14 13

122 63 69

139

335

606

48

64

1'63 172

225

b

b

b

b

b

16 9 23

65&clver

unkncnm

2.1 23

0.1

Procedurerate pm 100 pemma 16-29 30-44 46-64 0.1 0.2 0.3 0.8

Allages

Under15

0.5 0.6

0.1

0.6

86


0.2 0.2

0.3 0.4

0.8 0.8

280

1.9

54

1

4. NUCLEARMEDICINE

Number of w a d m s (inthoumxh) Bathaexes Male Female Unkmmm

506 91 398 17

8 3 6 I,

77 12 65

128 21 106

164 32 132

88 17 71

b

b

b

b

41 6 19 16

Prodmrateper 100pereaas A U a g e ~ Under15

Bothsexes 0.2 Male 0.1 Female 0.4 .FDA (1986).

c0.05 c0.05 <0.05

16-29

30-44

45-64

0.1 c0.06 02

0.3 0.1 0.5

0.4 0.2 0.6

6S&m U-

0.4 0.2 05

0.1

b u d a b l e data. maximum contributh tn any are pnredure rate fmm unkncAlm age'-

Nnmher of pmcedum (intbcmsambb Botheexea

Male Female unkwwn

Both sem Male

Feanale

129 52 76

320 158 163

345 151 193

32

b

70 24 46

b

b

b

b

b

b

<0.06 <0.05

0.1 0.1 0.1

03 0.3 0.4

0.7 0.8 0.7

1.4 1.5

0.1

898 401 486 10

3 2

0.4 0.4 0.4

PFDA(1985). bunreliable data

b

1.3

b b

4.5 DIFFERENTIALTRENDS

55

1

TABIE4.6-E9timOtBdd nwnber and mte of heart n u d e a r d p d inlSIEIDiyageMdSQ0

Botbeexes

Male F d

All ages

Under16

16-29

30-44

46-64

65 &over

Unknown

658 330

2

12 8

224

b

4

66 43 23

285 177 108

168 86 82

24

b

4

b

b

b

b

b

16-29

30-44

45-64

0.2 0.2 0.1

0.7 0.9 0.6

Lhklmm

A n m

Bothsexes Male

U&

0.2 0.3 0.2

15


<0.05 ~0.06 <0.06

65&-

Female b aFDA (1986). bUrueliabledata CMaxirmunamtnition ta any one pmcedure rats fnnnunknown &sex.

TABLE 4.7-Esbina&dannual

b b b

UnklWlWnC

0.7 0.9 0.5

0.1

numbsrand mdp oftiuerand spleen nrcclemnwdidnepmcahrres

fnl98Dbyageandsee

Number of &urea

Bothsexea

Male Female Unknown

1,399 661 706 32

16 10 6 b

89 43

","

(inthousands)

146 70 76

623 246 276

294

b

b

b

80 36 14 30

660 266

PrPcedruerateper100perecma All-

Bothscores

Male Female

0.6 0.6 0.6

Undea15

16-29

30-44

46-64

<0.05 <0.05 c0.06

0.1 0.1 0.1

0.4 0.4 0.4

1.2 1.3 1.2

'FDA (1986). bUrueliabledata maximum contnitionto my om pmdure rats h

m

65 &2.3 2.7 2.0

hagelaex.

U* 0.2

56

1

4. NUCLEARMEDICINE

~4.8-Enthddannuoltnan&rond~of~nudora~plrrcsdLaes inl851Dbyaged#r

Number ofpmcedma tin tboueaode) All-

Bdho~am ale

FePnale 'FDA (lWE

0.1 0.1 0.1

Undm16

16-29

Screa

46-64

&&om

Unknown


<0.05 c0.m c0.05

0.1 0.1 0.1

0.1 0.2 0.1

0.2 0.8 0.1

0.1

.
bUmeliable data. ~MarimnmcantrlbutSontoanyaae~ratetmmunknownaedmL

All-

Bothmxea

1,907

Male

668

FBmale

710 28

Unknown

Bothsexea Male

F

d

0.6 0.5

0.6

Number of mdum(fntJmmd8) 16-29 30-44 46-64 470 26 63 121

Under16

8S&m

638 248

unknown 98

14 11

36 20

b

b

b

b

b

28

0.1 0.1 0.1

0.3 0.2 0.4

1.1 0.9 1.3

23

0.3

0.1 0.1 <0.06 .

44 77

180

289

47 21

2.7

20

'PDA (1985). bumliabledate.

~M~~~ll~tosnyoneproeedrwlate~unkmnnegelee~

4.5 DIFFERENTIALTRENDS

Bothsexea

Male Feaaale

67

1

86 &m Unknown

Allages

Under 16

16-29

30-44

46-64

368 155 146

16 9

34 19 14

42 20 22

102 64 48

94 44

b

50

b

b

b

b

b b

UIlknOWn

i7

7 b

b

Ihcdum rate pea 100persona Allages

~ o t h s e x e ~ 0.2 Male 0.2 Femah3 0.2

Under16

16-29

30-44

46-64

86 &omr

Unknowne

~0.05 ~0.05 0.1

0.1 0.1 <0.06

0.1 0.1 0.1

o.a 0.3 0.3

0.6 0.6 0.4

0.2

.FDA (1986). bUmdiabledata maximum contriition to any one pcedumrate fmm unknown age/-

The number d radiocolloid liver imaging studies appears to have peaked crevendwreased(mle4.11).Themason for this isdi£Ecult todeteomine. Cedainy, both u l and Cl' have had an effect. It is virtuaIly im~itoassesstheMumcedbodyCr,~idmWanufh organofin~forwhichaWominalCTscausareperformedisnot usuallyavailableinsurveydata Thpse are lessonsto be l e a d fmm the evaluation of these bind data. Thefkstisthatthe~cticmofthefukuP:ofnuclearmedicineis eXtrenaey difficult. The t m d s fhm 1972 to 1975 Wle 4.1)could have been used to estimate the total number and typea of in 1980. If this were done, the to& number uf paedicted and actual mambdions ddhave~H~thenumbeasf~thevariaustypesofe;gaminations used to derive the total would have bean largely wmng. For examph, in the absence of (3T scanning, o w would have predicted that radionu* brain imaging would have amtimed to grow, and,in additian, there was little reason in 1975 to expect the rapid growth of cardiac

-

58

1

4. NUCLEARMEDICINE

TABLE 4.1 1-Hepric tnqeingpmdww in lbspidds in the united sd~oes(En thmmd+ Year

hih&livereo~n HepaticulHepaticCP

466

-

636

1.302

1.368

-

-

-

-

-

-

1,446 314 13

1,424 676 14

'h M e W e et d (1986). bThianumberdoesnot~ala~~afaWominal~~hwhich the argan of intereet is u q m d f i d

Themlessonistbatthe~afnuclearmedicinetoevahrate regional physiology and metabolism has been and will continua to be its stmgth ItremainstobesemwhethermAgnetic~jmagingand spectroscopy will be able to supply such infcumaha Because of the time mpthd to annpile data, this Rspd includes data only through 1982. Since that time, t h e have been &pihut changes that undoubtedly a£fectthemunbersandtypesofnuclearmedicimprocedures~per

foamed.

For~tjcaleused~entlyinn~mediciae,absorbed rdation dosea per unit of a&hi&sd activity for certain organs of intmwt, including gonads, rue given m 'Igble 4.12.The average amount of

..

adrrrrmstered~tyusedintheUnitedStabformoststudiesis '' m 1966 and 1981 not k n m Data am.available for thymid d are shown m Wle 4.13. The range of administeredradioactivity used at tbe various institutions in both 1966 and 1981 is wide Penker et ul (1984) have e&matd that in 1981 there were 106,400 scans withut uptakes, 413,000scans with uptakes, and 33,000uptakes akme Data far 1966 in the U.S. indicate (UNSCEAR, 1977)that 300,000uptakes and 150,000scans wem performed with average administered activity of 2.1 MBq (57pCi) for an 'B'Uscanand 1.3 MBQ (36pci) for an '"'Iluptaka Assumingthat all l8'Iscans heduptakea andthatthemminderwem lB'1 uptakes alone yields a collective thymid absorbed dose of 18.1 x lCrGy (18.1 x 106 wd) -( et aL, 1985).The annual c o l k t k thymid does in 1966 and 1981 am. c o e in Wle 4.14. 'Ibtal rrrlministnrerl activity is shown in Wle 4.15, and colledive doses to organs other than theth~dandtothewholebodyareshin'Igble4.16. In terms of diopharmacmticd usage in 1981, T c pe&&&ak ~tedfor53~tdallthymidscans,1S'Ifor10~tof~ d 54 pemmt of uptakes,and IlPI for 37 percent of scans and 46 perceolt

4.6 ABSORBED DOSE IN NUCLEAR MEDICINE

1

69

obuptakss.Tbe10~tofth~ecans~e~e~hwith~~'IiB s u q x b g in light d the widespread avahbility of seTc, md the d edly higher diation d m andporn imagingcharactePieticsof '"L

RadiophamMmutical H~dw3'-3(InulIn aH

Ovary

'Ibtm

Whole body

-,

-

-

-

-

-

Otba

0.016 0.00011 O m 1 1 0.00013 -0.00088 "Cmonox&(hbdatkm) 0.0024 0.0024 0.0030 Heart0.023 Sp)eem 0.011 0.0029 "camimwrine(aral) 1% Inulin 0.0010 0.0010 0.0011 Kidney0.0077 Blsdder 0.16 Mhianwatrate 8.0 4-32 a0 sgeea7-41 Lim 7 4 1 Hldneg 18 6'Co bleomycin 0.028 0.02 0.027 BladderO.3 h0.1 1.0 0.1 4.0 Liver 26 b 7 C ~ v i h n h B(oral) ,, Kidney 4.0 %vitamin Bl, (aral) 3.6 0.66 6.0 Liver 100 Kidrwy 10 Waeitrate 0.17 0.16 0.18 Cdm0.96 Splesn0.41 WGa citrate 0.076 0.065 0.07 -0.19 W e atsate 0.013 0.011 0.014 Smalli n t . O . 0 6 7 Cobn 0.048 h6.8 1.4 3.0 22 Kidney 6.9 =Srilm 1.o 1.0 1.5 skabtaI4.w Memrw 4.0 gg"Tc perkcbetate 0.008 0.0024 0.004 StoMO.07 Thyroid 0.04 with perchlorate blocking 0.009 0.009 0.009 Stomach0.02 Thymid0.003 DMSA 0.005 0.002 0.004 RPmal~0.3 Kidney 0.2 ODmTcDTPA 0.006 0.004 0.002 ~ 0 . 0 1

. .

-

'Ibtalb

kidney 0.42

-gythrocytes

-

-

Marrm~0.002

0.01

Spleen0.04

Luuga 0.03 Heart 0.02

Marmw 0.01

60

1

4.

NUCLEAR MEDICINE

Whole -tical

other

body

Overy

- T c ~ u ~ ~ h e p t o n a t e 0.003

0.009

0.009

vcph-b

0.01

0.006

0.003

Kidneyo.06 M a m 0.003 Bladder 0.03 KidneyO.01 Skeleton0.016 Bladder 0.06 Mamm 0.008

W c hindacetate d d v ativas, HIDA, DISIDA, PIPLDA, e t c 0.01

0.006

0.004

Liver 0.0%

Gallbladck 0.04

Colon 0.09 DomTcsulhPcollaid

0.0016

DomTc microsphews or mecrp aggI8gatedalbumin 0.001

0.0003

0.006

0.001

0.003

Mamm 0.005 Liver0.09 spleen 0.05 Marrow 0.007 LungaO.08

Thyroid 0.02

MarmW 0.004

ll1In autdogma leukocytaa

-

-

0.14

SpleenS.6 Liver 1.0

lllInbhmycin

0.046

0.03

0.05

1llIn platelets

-

-

0.10

LiverO.5 !3plem 0.2 Marmw0.1 Spleen6.7 L i w 0.17

'"I ianic(aal0r intra-)

0.0076

0.003

0.009

l P B I o r t h o i 0.006

0.003

0.001

'4 ianic(d ar h-)

0.04

0.27

0.07

Thyroid6.9 Marrow 0.06 Nmbarn thyloid 32-76 1pm 22-51 5 yenra 10-26 10 6-15 15 4-11 Kkhqy0.016 mtallyobat..ructed kidney 1.6 Malmw 0.002 Thyroid340.

4.6 ABSORBED DOSE IN NUCLEAR MEDICINE

1

61

Tm4.12-

lhle

.

'

RdK@mmmticel 'mI ionk (olala intra-m)

Whale

Ovary

'Me43

otk

body

0.02

0.008

0.19

0.063

0.044

0.08

0.04

0.m

0.26

Manmv0.041 Newbw tbymid 4300-6,100 1 y8aT 1,m-2,100 6 years 700-960 10 geare 420-670 15 yeere 270-400 Adult 330 SphnO.26 Lunge 0.17 MammO.11

a '"1 ionic (d )-ni 'SDI i o n k ( d a r intra-) 1811ionic (arala n i-1

Nenbornthymid3~800 1 yeaa ~.200-3,900 6 WE 1.000-1.900 10 yeers 600-1,100 15 pears 420-780 Adult 530 KidaqO.23 ?btally*dedkidneys4 u w 0.036 B0.26 Marmw0.005

1811 &ehb&puab

0.008

0.008

0.006

In% gaa 0

0.oOOa

0.OOOS

I a X e g a e o

0.0004

0.0003

='IT1 h

0.10

0.20

0.oooSS LuugaO.007 BKRlchue 0.01 0.0004 Lump0.009 Bmrscbus0.03 0.0415 Kiclnqr0.3 Heart 0.15 Thymid0.20

hM & and Mom& (1986). ~VahK8qUotedaremfdrange~~theli' ZIbobtainradehnCi,m&iplyvhin?Bbleby3.7.Rauted VemmSnnleaaatbPawieespedfied. a

'

' '

'

tiaaisfnbe

* A b s o r b e d d o e a e b t h e ~ m ~ ~ e p s e t e r w h ~ t o ~ greatarthanl2yeereofeea 'I'hymidebearbeddosevariee~tlywithaga

1

62

4. NUCLEARMEDICINE

Year

R&

A uptalpe:

Iodine123 Iodine131 scam

Averaae

-

-

999 kBq

743,700 kBq

Range

6.4 MBq 3.7-11.1 MBq 1.1 MBq 74-3.700 kBq

-

' k h m ~ 9 9 r n ~ t s 236.8 MBq 37-656 MBq Iodine123 7.6 MBQ 3-16.9 MBq Iodine131 2.1 MBq 370-5.660 kBq 2.9 MBq 370-3.700 kBq

-

'1 MBq = 27 fiCi bIodk-123 and 'lMmtbr99m pertechnetatswm not used for thesepurposes (UNSCEAR, 1977). ~Parkeret d (1984).

T~8~~4.14-~~ondEollactit;s~~&~fnmrth~eomr~ anduptakesin the USn

Number or percent

I'mcdure 'Il~yroidsams (totalnumber)

"-% 1291 1311 Thydduptakeawithscan Thymid uptakes without scan

1291 1311

1966

1981

160,000 0 0 100% 160.000 150.000 0 100%

519.400 53% 37% 10% 413,000 34.000 46% 64%

4.6 ABSORBED DOSE IN NUCLEAR MEDICINE

oVw @eaeoPG~). ' h 3 h

WY)~

216 66 263 720

7 2

9 4 96 6.910

I

232 71 362 6.910

63

14 whalebody @=~-C+Y] Effectivedcee equivalent @#m-Sv) 280 'Adapted fmm Roeenberget d (1986). bl Gy = 100r8d; 1 Sv = 1 0 0 m ~Assumeethat60~tofstudiesare~~~andr10~tonmalee.

1

64

F

'

4. NUCLEARMEDICINE

"on

'm

Brain Hepatobiliary

Boae Reephatay tlerfusim! VentWb ThFJid

Raral Abas&mm WwascuIar

Estimatedadmhi&& -per ' h b s 740 MBq W c DTPA (60) 740@8Wrco4(60) 185 MBqW c imino diacetic ecid (IDA)(10) 1ssMBqoomTcmllfW d o i d (90) 740 MBq W c phosphate 185MBqgBmTcmamggm gated albnmin 0(66) 370 MBq Ia3Xegae (34) 185 M B q q 0, (80) 3.7 MBq 1811 (10) 11.1 MBq leal (10) 740 MBq W c DTPA (601 9.26 MRq 1811 hippnsn (40) lllMBq~lGndtrats 740 MBqW c labelled red blood L-dla (40) 111 MBq mlTl chloride(40) 740 MBq eDmTe phoephabe (20)

Gonedaldoee(c43 far each ~oaadal l d i o p ~ t i c a i ~ t ~IGYP (mWP

(4'~ e

Male

Female

Male

FIerrmle

2.2 1.6

4.4 4.4

1.9

4.4

0.2

1.7

0.2

0.6

0.2 3.7

0.4 4.4

3.7 0.3

4,4 0.3

0.4 0.1 0.4 < 0.1 < 0.1 2.2 < 0.1 7.2

0.4 0.1 1.1 0.1 0.1 4.4 < 0.1 8.4

0.3

0.9

1.3

27

7.2

8.4

0.2 465 3.2

0.8 11.1 4.4

18.9

6.7

.SeeSedm3.8fardefinition. bNumber in pmwntbwa is tbe eahmted pecent of examh&m type with a particular -tical. '1 MBq = 27 &i *lmOy = lOOmrad

d

~

4.6 ABSORBED DOSE IN NUCLEAR MEDICINE

TAB=4.18--

1

65

s i g n i m t doae@iW) to the U S p p u h h i n lQXl/5umdiagnostic nudem medicimp-

Relative Sex

'Qpeofetion

Male

Biain Hqahbiky

Bane Lung

m m Rend CardiwasCdar

AWtumor

Femele Brain He~ah e Lung T h m

Red Cardio~asculfu Abcesaltumar

Gonadal

£mqumcyof

doee

examination

(mGy). 1.85 0.19 3.70 0.28 0.31 1.34 18.92 7.22

4.44 0.50 4.44 O M 0.91 2.68 5.65 8.44

10-3 4.63 5.68 4.74 3.60 0.77 0.70 2.86 1.33

(X

5.32 6.94 5.92 4.11 3.26 0.54 1.87 1.21

Relative

child

GSD . far.

agarmnatron

t?me

(I~&)F

-cyb 0.166 0.124 0.123 0.116 0.259 0.197 0.064 0.235 SubW

1.41 0.13 2.16 0.11 0.06 0.19 4.65 226 10.87

0.136 0.077 0.071 0.111 0.207 0.192 0.042 0.158 SubW ?btal

821 0.23 1.87 0.14 0.62 0.28 0.44 1.61 8.40 19.27 rGy

.I mGy = 100mred. ~

b~childearpectancydetstothemunberofchiMrernexpectedfortha~ ~ ~ t b i s ~ t i o a '1 rGy = 100pad.

In~of~mradiatimeaqwx~lreduetothymidnuclearmedicine diagnostic prwedures in 1981, lS1I8~~..1(1~lllted far over 85 peacent d the thyroid dose, although it was used far cmly 10 percent of scans and &gMy over 50 prcent of uptakes. Theat? is a marked variatian in the

thymiddiatiandosewitheachofthe~~mmonapproarhesandthe mdhtb doee variea by a factor of over 30, fmm 27 mGy (2.7 rad)to 1,030 mGy (103 rad) far scans with uptakes. If lS1I used only for uptakee, the range is 27.400 mGy (2.7-40 rad), and if not used at ail, 2736 mGy (2.73.6 red) fon scanning and thymid uptake examiuaw If lSIIwem eliminatedhmuseinthymidstudies,thetutalthyroid~beddosefrom ~ s h a u M ~ t o a p ~ t a l y ~ ~ t hx o10'peasanr 1 . 4 Sv (1.4 x 1V person-~II) per year. Eliminaticm of lS1Ifrom use has been h a m p d by pmblems in availability and purity af lZSI.In most instances,

~ , t h ~ a c a n s ~ b e ~ d w i t h D O " T c ~ T h e u s e ofiodinsfarup~studieacannmbelargeysupplantedbyotherclinical

66

1

4.

NUCLEARMEDICINE

hborahy tests of thyraid M a n CT,, T,,and TSH assays). With the exception of changjng diqbmmmticals, bis little posshiliity for doseIeductioninn~~~oninadmb&edactivity aften causes markedly i n d imagiug time and subrsequent motion dqpdatimofimages.

Withthein~useofnuclear&e,bhasbeeaanin~ ing interwt in assessment of the radiation doae hm breast milk fobwing tion of mdiophannaceuticals to nursing mothers. Many authors haw published cm the subject (Cmody and Higham, 1975; 0 ' and S u m 1976; Ogunleye, 1983; "Ikibukait and Swedjemark, 1978).The nahrre of the radiophamacmtical significautly afSects breast secretion with tmAmhn-99m ethaving the highest rate of breast s m m t h In almost all instances,the concentratian in milk 24 hours after radiq-=tical injection is in&nScant.

47 Gonadal and Genekkally Significant Dose The genetidly dgdkant dose (GSD)from diagmdc nuclear medicine examinations has been i3stimated. using population param&m and fcw mulae Section 3.8. Thegonadaldosefmmvariousmcbphar maceuticals is taken from the data of LinM (1981)and the UNS(=EAR (1982).Since diffwnt radiopharmacmticals may be used for scanning the same organ (ag.,T d ) , or -Tc DTPA for brain imaging), the percentage of each examhticm using a partiah radi-tical and a sdghted avemge gonadal dose were c a h l a b d far each -an type

mle 4.17). The gonadal doses, dative examination fmpency, dative child expecb ancy, and the resulting GSD for each sex and type of Pmaminntirrn m given in 'IBble 4.18. The pea caput estimated GSD due to the practice of diagnostic nuclear medicine in the U.S.in 1980 is 19 pGy (1.94). For the years 1956 through 1958, the GSD fmm the w e ofradiophamm -ticals in medical diagnosis varied from 0.1 to 0.3 pGy (0.01 to 0.03 mrad)pex year in developed cuuntaies (UNSCEAR, 1972).With the clinical intmdmtion of BBmTc (which has better imaging pnptks) and a wider variety of mdbphatmwmticals, the use of nuclear medicine has became lIxm3-

In the United S t . , newer OBmTc COmpOllndg have, to a large degme, repiaced betm?mittingd q h m m m t i c a l s such as kalI,which amtxib uted higher absohbed dosea to the patient. Many T c radi-ticalsaxeregidy~£mmthebodyviatheurinaytrace.Asan example,almostall of the injected activity used for dthsr T c diethylene triambpentsmtk acid (DTPA) or gtucoheptonate scans is cleared by thekidneyswithinseveaalhours.Whilethisisusefulinreducingthe

4.8 EFFECTIVE DOSE EQUIVALENT

1

67

--

backgnund~tysothatleaionacanbe~~italso~~ activity in the bladder and leads to a & t i d y high gonadal doea The othePradianuclidethatbasbeccime~availableism'TIchloride,which alsoma-highgonadalh'IBble4.17mhtesWpe~ unit d m b h b d activity, m 1 ' I l C h 1 0 3 i d ethe ~ highestgonadaldoeeob any

Its E f f h Dose Equivaht

Tbe adhdive e f k t h e dose equivalent (ICFLF 1977)may be qmmed as caput e f k t h e dose equivalent for the popuhhn of the United Stafes. L i m i t a h of this method, when applied to populations with skewed age distribuths, were discwsd in Section 3.10.For the plnposes of this Sectkm, the callective effective dose equivalent, as well as a new concept, the agespecific weighted dose equivalent, are ptwented. The use of an age and sexwdghkd dose equivalent allows c o m c t b for the skewed n a b of an exposed population so that detthental effects can be oompad with those from other mdia!ion sources (Beninson and Sowby, 1985).For puqmses of calculation, absorbed dose and Bffective . dose equivalent VI,)pea unit of txbmtad adivity war! obtained from Lindell(1981). For oomparison, the collective effective dose equivalent (as dehed by . .. type and the the ICRP) is ahawn in 'Wle 4.19 foa each waighted dose equivalents are compared The k p m c y ofnnaminRtjnnn, by age for most cmmhiiang, is available from the RED 1 Survey (FDA, 1985). Regardless of the quantity calculated ( w i v e effectiive dose equivalent or ageweightedcollective Qse equivalent),the major mdhtim saurces in nuclear medicine am from bane, brain, thymid,and c a r d i m lar examhatiom. The annual per mput dose equivalent derived by the standardICRP~mis140&(14~,mditisredudbymara than half to 59 pSv (5.9mem) when patient agea am taken into aaxnmt (ageweighteddoee equivalent). The per caput annual e f f d v edose equivalent in the United States is higher than that reported for meet o h dedopedanm~prhnarilyduetothe~frequencyafexaminatiansdativetootharmtrk Reportedannualvaluesfmm~anmtries are as f o h ~ s 20 : pSv (2mmm) in Austaalia in 1980 (UNSCEAR, 1982),M) pSv (5 rmem)in Denmark m 1986 (Ennow, 1986).60 pSv (6 m r d m Swedenin 1983(Johanssonet aL, 1984).and 17 pSv (1.7 mrem) in the United Kingdom in 1982(Hughesand Roberts. 1984).

.

68

1

4. . NUCLEAR MEDICINE

-

Brain

Liw Boae

Thyloid Renal 'Rmoa lbtal

5. summary Although there are no recent comprehensive national surveys of diagnostic radiologic and nuclear medicine examinations, there have been a variety of limited surveys for special groups and somewhat larger surveys involving hospital use. In this Report, all of the sources are combined, and they yield relatively tmmistmt data There is little question that the fniquency of diagnostic x ray examinatio~ls(both medical and dmtal) has significantly increased in the decade 19701980 (Mettler, 1987). This inuease involved not only the new imaging W q u e s , such as computed tomography, but also standard examins tioas such as chest and exhmity x rays. The increase in rate per unit population for medical radiographic examinations from 1970 to 1980 was 18 percent while dental radiographic examinations increased by SO percent. The population d v i n g diagnostic x rays is substantially skewed with ward to age distribution. Over half of the persons are over the age of 45 and onefourth are over the age of 64. The genetically significant dose due to diagnostic x-ray examinations is estimated to be about 0.3 mGy (30 mrad) per caput for 1980. A precise number is difficult to ascmtah due to factors discussed in the text, which include uncertainties in the actual gonadal doses in 1980, the actual use of gonadal shielding, the contribution from fluoroscopy, and the general improvement of field size limitation. The estimate for per caput mean active bone marrow dose to adults in the U.S. in 1980 from diagnostic radiology is 1.15 mGy (115 mad) if the 1970 examination doses of Shleien are used, and 0.76 mGy (76 mrad) if the modified 1970 examination doses of Rosenstein are utilized. Either estimate represents about a 13 per cent increase from corresponding estimates for 1970 and about a 38 percent increase from corresponding estimates for 1964. There is uncertainty in these numbers due to the lack of actual doses to active bone marrow for 1980. These increases reflect only the influence of changes in the examination rates estimated for 1980 as compared to ratea estimated for 1964 and 1970. There has been an attempt to evaluate the age and sex distribution of the medid population and its effect on ultimate estimation of possible detriment. When the method of Beninson and Sowby (1986) is corn-

70

1

5. SUMMARY

pared to the ICRP (1977) effective dose equivalent, the former d t s in a detriment estimate appmximately 40 percent leas than the latter. The annual per caput effective dose equivalent to the U.S.population is estimated to be about 0.40 mSv (40 m m ) . Thkiq into m u n t the age and sex distribution of the exposed population and using the &sex weighting factors of Beninson and Sowby, yields an estimate of about 0.23 mSv (23 mrem). Comparison with the effective dose equivalent mported in other countries is difficult, since many authors do not use the same organs for evaluation. The average per caput effective dose equivalent for diagnostic x-ray examinations in other cou$ries has been mported as shown in W l e 5.1. A similar comparison can be made for the genetically significmt dose as shown in 'Mle 5.2. TABLE 6.1-Annualperaput effective dose equivalent fordiagnostic z-my eromincritions in select& oountAes b e y

Year

Effective dose eouivalent

Fraum

1982 1979 1983 1980 1980-1981

0.4 mSv (40 mrem) 1.3 d v (130 mrern) 0.3 mSv (30 rmem) 0.4mSv (40mrern) 1.4 mSv (140 rnrem)

Japan United Kingdom United S t a h U.S.S.R.

RefBanedittini et d,1983 UNSCEAR. 1982 Shrimptonet d,1986 This Report

Vorobyev e t d , 1984

TABLE5 . 2 - A ~ g e n e ~signi-t y

Country

Yeer

Canada

1980 1982 1976 1979 1980 1977 1980 198&1981

Fnlnca Italy Japan Nether-

UnitedKingdom united states U.S.S.R.

dose for mbgnostic x-my exadndon.9 in selected oowtlies Genetically &pificant dose Referena,

0.3 mSv (30 mrem) 0.3 mSv (30 mrem) 0.3 mSv (30 mmm) 0.2 mSv (20 mrem) 0.3 mSv(30 m m ) 0.1 mSv (10 mrem) 0.3 mSv (30 mmm) 0.2 rnSv (20 mrem)

MacEwan et d,1982 Benedittini et d,1983 B e n a d et d,1977 UNSCEAR, 1982 UNSCEAR, 1982 Hughas and R o b , 1984 This Report Vorobyev et d,1985

Diagnostic nuclear medicine procedures also increased substantially in the decade 1972-1982. During this time. they essentially doubled in number and frequency per unit population. At the present time, an estimated seven million examinations are per formed annually. Marked changes occumd in the percentages of the total for particular types of examinations. Rsdionuclide brain scanning markedly decreased as a percent of the total while cardiovascular studies dramatically increased.

SUMMARY

1

71

The population undergoing diwostic nuclear medicine examine tions is, in general, much older than the average patient having diagnostic x-rays. At the present time, threefourths of all nuclear medicine examinations am performed on persons over the age of 45 and more than onethird on persons over the age of 64. There appear to be few possibiities for dose Auction in nuclear medicine with the exception of replacement of iodinel31- by iodh3123- or technetium-99mlabeied radiophannaceuticals in thyroid studies. Thegenetkdy~cantdosefromdiagnosticnudearmedibeexam inations in the U.S. in 1980 was estimated to be 19 pSv (1.9 mmm). A major new and important contribution to the GSD has orne fmmthe uae of lhahm201 chloride for studies of myocardial perfusbn The genetir tally sigdkant dase due to nuclear medicine in the United States, while low,ishigherthanthat~forotherdevelapedcountaies.Forexample, in the United Kingdom in 1982, the mporkd GSD was lower than 3 pSv (0.3mrem)(Hughesand Roberts 1984). The annual per caput effective dose equivalent from diagnostic nuclear medicine procedures in the U.S. in 1982 is estimated to be 0.14 mSv (14 mrem). This is also markedly higher than reported for most other developed countries. The effective dose equivalent reported for the United Kingdom in 1982 was 17 pSv (1.7 rnrem) (Hughes and Roberts, 1984)and was 25 to 40 pSv (2.5 to 4.0 mrem) in the U.S.S.R. for 1980-1981 (Vombyev e t al, 1985).The most pmbable mason that the U.S. per caput absorbed dose and GSD values for nuclear medicine are substantially higher than those of other developed countries is that the fmquency of examinations per 1,000 population is almost double that of other developed countries. For example, the annual number of examinaticms per 1,000 population in the U.S. is 32 cornpad to 15 in Sweden, 14 in Denmark, 18 in Austria, and 4 in the U.S.S.R. A second reason is the high gonadal dose from use of thallium-201chloride. The age of the population undergoing nuclear medicine procedures has a marked influence on the estimated detriment when ICRP effective dose equivalent is compared with age and sex-weighted dose equivalent. The computed values are 0.14 mSv (14 m m ) for effective dose equivalent and 0.059 mSv (5.9 mrem) for the "weighted'' dose equivalent. Use of the ICRP effective dose equivalent yields a potential calculated detriment due to nuclear medicine approximately 2.4 times larger than the "weighted"dose equivalent approach. The combined average annual per caput effective dose equivalent to the U.S. population h m diagnoetic radiology (1980 data) and nuclear medicine (1982data) is estimated to be about 0.54 mSv (54mrem). Recommendations of the Committee for futum areas of emphasis include the fol-.

72

1

6. SUMMARY

1. Continuing updates of the fequmcy of radiological and nuclear medicineexaminatiom are necessary, 2. Unifonn expmsaion and methodology for exposum and or absorbed dose is desirable among the studies rerportedin theliteratum 3. Continuing definition of the influence of new technologies (suchas magnetic resonance imaging)upon duction-of the hquency of high dose exRminatinns muld be valuable, 4. Studies on the h p n c y of new high dose interventid p m dutw (mchas coronary angioplasty)will be i m m t , and 5. Attempts to define the benefit derived h m medical radiation so that posslile detriment from these procedures is not discussed out of context ate needed.

APPENDIX A

Appendix A. Sample Calculationof Collective EXfedve Dase Equivalent for a X-ray EnRmination

The sample calculationis shown for radiographic~ t i o n ofsthe chest as found in W l e 3.27. Step 1. Calculation of earposure contriition from egch projectian wed in cheat examinations:

-

Entrsnce Projection

CWb

HVL

AP

0.13 x 0.07 x 0.21 x 0.31 x

2.44 2.51 2.80 2.49

PA= lateral 0 b m

E colltraltiw

Anumber of films

101 101 lo-' lo(

(Clkg)bfrom eachpjection 0.013 X 0.064 X 0.105 x 0.006 x

0.10 0.92 0.60 0.02

rnVahiea forcolumns A-Dare from mble 3.19 (Lnws~and b2.68x lo( Clkg = 1 R. ce anterimposterior;PA, pwterior-antdor.

101 101

lo-' 101

1978).

Step 2 Calculation of absorbed dose contriitins to organs. With information on half-value layer and expomue cantniutim per projee tion, the absorbed dose contn'bution to specific organs can be calmlated from tables found in Gorsan et aL (1984)that give absorbed dose to organs per unit of entrance enrpoaure. Abeorbed doseeontributiom (ray). Active

Wection

AP PA Lateral ObLiqud

bone marrow 2 18 10

1

Lunee M/F

Breast

Thyroid

20115 87194 60186 $17

37 10 91 10

66 67 45

1731202

148

179

Bod

Ovary

lsstie

7 62 67 c

C

C

2 4 c

4 3

126

6

7

- - -2 - - -c

.Ir Gy = 100pad. bVahwafor bone are from DAorler std (1984). c V h lea8 than 1 pGy. Wblique projectiondam mteqolatedbetweea PA and latgal projectionvalues.

Step 3. A

c w t i mOfeffectilm dose equivalent for examinatinn. B ICRP-tine

Ogan

fectm

Marrcrrr Brerset

0.12 0.16 0.12 0.03 0.03 0.26

Lune myroid

Bane Gonads Subtotal

C Absorbed

dose (mGyP 0.031 0.148 0.1W 0.179 0.190 <0.001

JmxC)

EWvedaee equivaht ~m9vIb 0.004(rounded) 0.022 0.023 0.005 0.004 0.058

Step 4 Calculation of d e c t i w eftixtive hequivalent for hot3pital chest examinations. Multiply the examination effective dose equivalent fmm Step 3, 0.083 mSv (8.3 mrem), by the number of hospital chest examinations (52,276,000) to get the value of 4,339 person-% (433,900pamn-rem)found on line 1 in lhble 3.26.

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Health and Humrvl Services Publication FDA 85-8239 (U.S. Government Printing Office,Wmhingtm, DC). R ~ ~ L EK.A., Y , HILL,S.J., WATKINS,R.A. and MOORES,B.M.(1987). "An investigation into the levels of radiation expcmm in diagnostic examinationsinvolving fluomscopY:' Br. J. RadioL 60,167. RUSSELL,J.G. and CARMICHAEI., J.H. (1987)."Developer tmnperature in diagnostic departments:' Br. J. RadioL 60,781. SHLEIEN,B., TUCKER.T.T., and JOHNSON. D.W. (1978). "The mean active bone marrow dose to the adult population of the United Staha h m diagnostic radiolo&' Health Phys. 34,587. S H R I M ~PC., N .WALL.B.F., JONES. D.G., FISHER,E.S., HILLIER. M.C.and KENDALL,G.M. (1986).A National Survey of Doses to Patient's Undergoing a Selection of Routine X-myExaminations in English Hospitals. National Radiological Protection Board Report NRPB-200 (National Radiological Protection Board, Chilton, England). SHRIVASTAVA. PN. (1980). "Model to analyze radiographic factors in mammography," Med. Phys. 7,222. STANTON.R. and TRETIAK.0. (1983). "Dosereduction though variable dose CT scanning: Optometry of the filtered backprojection algorithm,"J. Comput. Asst. 'Ibmgraphy 7,1054. S'l'IEVE, FB.,DRFXLER G. and PORET~I,G. (1985). "Parael dimmsb an quality assurance in x-raydiagnosis,"Br. J. Radial 18(flrppl).168. STIEVE. F.E., SCHMI~. T and P I E ~ HN.. (1977). "Strahlenexposition durch die computerbmographie,"Rontgen-Bericht 69,365. SURAMOI,I., T~RNIAINEN, I?,JOUPPILA. l?, KIRKINEN, F? and LAHDE. S. (1984)."A low dose CI'pelvimew'Br. J. RadioL 57,35. TOLE, N.M. (1985)."Some observations on skin and organ doses during x-rayfluoroscopicexaminations," Br. J. RadioL 58,381. TRIBUKAIT, B. and SWEDJEMARK, G. (1978)."Secretion of technetium99m in b m t milk after intravenous injection of mamaggmgated albumh," Acta RadioL Ther. Phys. BioL 17,379. TYNDALL, D. and WASHBURN, D. (1987). "The effect af rare earth filtration on patient exposum, dose reduction and image quality in oral panoramic radiolo&' Health Phys. 52,17. UNSCEAR (1972). United Nations Scientific Committea on the Effects of Atomic Radiation, Ionizing M t i o n . Larels and Effects, No. E.72.IX.17 and 18(UnitedNations, New York). UNSCEAR (1977). United Nations Scientific Committee on the Effects of Atomic Radiation, S o m e s and Effects of Ionizing Rad&ztion, No. E.77.IX 1(UnitedNations, New York). UNSCEAR (1982). United Nations Scientific Committee on the Effects of Atomic Radiation, Ionizing Radiatiox Sowces and Bie

l o g i d Effects, No. E.82.IX.8., 06300P (United Nations, New York). VOROBYEV, E.I., STAVITSKI, RV., and BARKJUDAROV, R.M. (1984). "Radiation e x p o s u ~of~ the population in the U.S.S.R. in 1981-1982 as a result of using ionizing radiation for medical diagnostic pur poses," At. Energy W, 218. WALL.B.F. and KENDALL. G.M. (1983). "Collective doses and risks from dental radiology in G m t Britain," Br. J. RadioL 66,511. WAU, B.E, HILLIER,M.C and KENDALL, G.M. (1985). "Nuclear medicine activity in the United Kingdom," Br. J. RadioL 66,125. WALL,B.F., HILLIER, M.C.and KENDALL, G.M. (1986).An update on the frequency of medical and dental examinations in Great Britain 1983. National Radiological Protection Board Report NRPB-201 (NationalRadiological Protection Board, Chilton, England). WHO (1983). World Health Organization, A Ranbnal A p p m h to . . l b k n b g m s t i c Investigations, Report TRS-689 (World Health Organization, Geneva). WHO (1986).World Health Organization, Rational Use of Diagnostic Imaging in Pediatrics, !lbcbnical Report Series (WorldHealth Or&zation, Geneva). WIATROWSKI. W.A. (1983). "Factors affecting radiation exposum and radiographicimage contrast in neurolo&' Health Phys. 5,599. WOLFMAN, L. (1986).WolfmanReport on the Photogmphic Industry in the United States,1973-1996(ABCLeisure Publicatio~~s, New York). ZECK,O.F. and YOUNG, RG. (1983)."Radiation level associated with G arm flumscopes,''Health Phys. 4476.

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 mommendations about (a) protection against radiation and (b) radiation measurements, quantitiei, and units, particularly those concamed with radiation protection; 2. M d e a means by which organizations concerned with the scientific and related a s m s 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 quantities, 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 M-ments, and other national and international organizations, gowmmental and private, concerned with radiation quantities, units, and measurements and with radiation protection. The Council is the successor to the unincorporated association 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 over sixty scientific committees of the Council. The scientific committees, composed of experts having detailed knowledge and competence in the particular area of the committee's inter est, draft proposed mcmnmendations. 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 Presidsnt

WARREN K. SINCLAIR

Secretary and l h a m r

W.ROGERNEY

Assistant Secretary

CARLD. HOBELMAN

Assistant !Reasurer

JAMES E BERG

S. JAMESADELSTEIN

Memh

SEYMOURABRAHAII~SON S Jmm A D ~ M PAERR.ALMOND EDWARD L ALPEN JOHN A. AUXJEB WILLIAM J. BAIR MICHAELA. BENDER BRUCEB. B~ECKER JOHN D. BOICE,JR ROEERTL Bmwr ~ N BROOKS E THOMASE BUDMGEB MEWWW.C~RTER RANDALLsCA8WELL JMESE. CLEAVER FRmZCltoss S m u B.~CURTIS GEFLUD D. DODD PATRICIA W.Dumm JOE A. ELDER THOMAS S.EIX JACOB I. FABM R J. MICHAELFRY ETHELS. GILBERT F ~ ~ E RA.TGOEPP Jon. E. G r w ABTHURW. GUY ERICJ. & !L IL NADMl H. fIARLeY WILLIAM EL H E ~ E E DONALD G. JACOBS kEhmurmJ~k1~8J~ BERNDKAHN KENmTHRKASE CHABLEsE. LAND GEORGE R IWPOLD RAYD. Lum,

A m C. L u w CHARLESW. MAYS RooERO. M W JAbm E. M c L 4 u G w B A R B A RMCNEIL A& THOMASF.MEANEY CHARLESB. MEINHOLD MORTWRL MENDEL~OHN FREDA. Ibllmmm WILLIAM A. MILLS DADEW.MOELLER A. ALANMOOH~SSI MARYELLENOXONNOR ANDREWK. FomANsKI

NORMAN C. RASMUSSEN

WILIAMC. REINIG C%~ESISR R RICHMOND JAMW S.MBEBTSON MARVIN ROSENmIN LAWRENCE N.ROTHENBERO Leo~Ntll k~ A ~ A N

ROBERTA. QCHLENKEB WILIJAMJ.QCHULL ROYE. SHORE WARREN K.SINCLAIR

PAULSuMc LEWISV. SPENCER WILLIAML T ~ P I E I D N THOMAS S. ~ ~ W O R D E J.W. THIEE~~N JOHN E. TILL ROBERTULWCH ARTRURC. U ~ N GEORGE L Vonz E ~ ~ AW R. WEBSIZR D G w r n ~ MWnxENmG . H. RODNEYWITHERS MARmZlsKIN

Honormy Members

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Cumntly, the following subgroups are actively engaged in formulating mmmendations: SC 1:

Basic Radiation Protection Criteria SC 1-1on Probability of Causation for Genetics SC 1-2 on Risk Eatirnates for Radiation Protection SC 3: Medical X-Ray. Electron Beam and Gamma-Ray Prokction for E n e ~ Up to 50 MeV (EquipmentPerformance and Use) SC 16: X-Ray Protection in Dental Offices SC 18: Standards and Measurement of Radioactivityfor Radiological Urn SC 40: Biological As* of Radiation Protection Criteria SC 40-1 on Atomic Bomb Survivor Dosimetry SC 40-1A on Biological Aspects of Dosimetry of Atomic Bomb Survivor8 SC 45: Radiation Received by Radiation Employees SC 46: Operational Radiation Safety SC 46-2 on Uranium Mining and Milling-Radiation Safety Fkgrams SC 46-3 on A L A R A for Occupationally Exposed Individuals in Clinical Radiology SC 46-4 on Calibration of Survey Instrumentation SC 46-5 on Maintaining Radiation Protection Record8 SC 46-6 on Radiation Protection for Medical and Allied Health Wreonnel SC 46-7 on Emergency Planning SC 46-8 on Radiation Protection Design Guidelinee for Partide A d erator SC 46-9 on ALARA at Nuclear Plants SC 47: Instrumentation for Determination of Dose Equivalent SC 52: Conceptual Basis of Calculationsof Dose Distributione SC 67: Internal Emittar Standard8 SC 57-2 on Respiratory "hct Model SC 57-5 on Gastrointestinal ' h c t Models SC 57-6 on Bone Problems SC 67-8 on Leukemia Risk SC 57-9 on Lung Cancer Risk SC 67-10 on Liver Cancer Risk SC 57-12 on Strontium SC 57-14 on Placental k s f e r SC 67-15 on Uranium SC 69: Human Radiation Exposure Experienca SC 631: Radiation Exposure Control in a Nuclear Emergency SC 6311: Radiation Exposure Control in a Nuclear Emergency SC 6311-1 on Public Knowledge About Radiation SC 6311-2 on Criteriaon Radiation Instruments for the Public SC 6311-3 on Exposure Criteria for Specialized Categariea of the Public SC 64: Environmental Radioactivity and Wasta Management SC 64-6 on Screening Models SC 64-7 on Contaminated Soil as a Source of Radiation Exposure SC 6 4 8 on Ocean Disposal of RadioactiveWaste SC 64-9 on Biological Effects on Aquatic Organisms SC 6410 on Low Level Waste

THE NCRP

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SC 6 4 11 on Xenon Quality Assurance and Accuracy in Radiation Protection Measurements Biological Effects and Exposure Criteria for Ultrasound Biological Effects of Magnetic Fields Microprocessors in Doeimetry Efficacy of Radiographic Procedures Radiation Exposure and Potentially Related Injury Radiation Received in the Decontamination of Nuclear Facilities Effects of Radiation on the EmbrywFetus Guidance on Occupational and Public Exposure Resulting from Diagnostic Nuclear Medicine Procedures Practical Guidance on the Evaluation of Human Exposures to Radio. frequency Radiation Extremely Low-Frequency Electric and Magnetic Fields Radiation Biology of the Skin (Beta Ray Dosimetry) SC 80-1 on Hot Wrticles on the Skin Aseessment of Exposures from Therapy Control of Indoor Radon Study Group on Comparative Risk Ad Hoc Group on Medical Evaluation of Radiation Workers Ad Hoc Group on Video Display 'kmhals lssk Force on Occupational Exposure h l e

In recognition of its responsibility to facilitate and stimulate coop eration among organizations concerned with the scientific and related 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 Medical Phyeics American College of Nuclear Physicians

American College of Radiology American Dental Association American Industrial Hygiene Association American Institute of Ultrasound in Medicine American Insurance Association American Medical Association American Nuclear Society American Occupational M e d i d Association American Pediatric Medical Aeaociation

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American Public Health Association American Radium Society American Roentgen Ray Society American Society of Radiologic ~ o l o g i s t a American Society for Therapeutic Radiology and Oncology Association of University Radiologiets Atomic Industrial Forum Bioelectromagnetics Society College of American Pathologieta Conference of Radiation Control Program Directore Federal Communications Commiseion Federal Emergency Management Agency Genetics Society of America Health Physica Society Institute of Nuclear Poww Operations National Institute of Standards and 'bchnology National Electrical Manufacturers Aseociation Nuclear Management and Resources Council Radiation Research Society Radiological Society of North America Society of Nuclear Medicine United States Air Force United States Army United States Department of Energy United States Department of Housing and Urban Development United S t a t e Department of Labor United States Environmental Proteetion Agency United States Navy United States Nuclear Regulatory Commission United States Public Health Service

The NCRP has found its mlationships with these organizations to be exlmmely valuable to continued progress in its program. Another aspect of the cooperative efforts of the NCRP relates to the special liaison relationships established with various governmental organizations that have an interest in radiation protection and measurements. This liaison relationship provides: (1)an opportunity for participating organizations to designate an individual to provide liaison between the organization and the NCRP; (2)that the individual designated will receive copies of draft NCRP reports (at the time that these are submitted to the members of the Council) with an invitation to comment, but not vote; and (3)that new NCRP e f f d s might be discussed with liaison individuals as appropriate, so that they might have an opportunity to make suggestions on new studies and related matters. The following organizations participate in the specialliaison program: Australian Radiation Laborntory Commission of the European Communities

THE NCRP

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C o d a t i a t a 1'Energie Atomique (France) Defense Nuclear Agency Federal Emergency Management Agency Japan Radiation Council National Institute of Standards and 'LBchnology National Radiological Protection Board (United Kingdom) National Research Council (Canada) Office of Science and 'khnology Policy Office of lbchnology Assessment United States Air Force United States Army United States Coast Guard United States Department of Enargy United States Deoartmentof Health and Human Servica United States ~ e p a r t m e nof t ~abor United States Departmentof Dampatation United States Environmental Protection Agency United States Navy United States Nuclear Regulatory Commission

The NCRP values highly the participation of these organizations in the liaison program. The Council's activities am made possible by the voluntary contribution of time and effort by its members and participants and the generous support of the followingorganizations: Alfred F! Sloan Foundation Alliance of American Insurera American Academy of Dental Radiology -. American ~ c a d e mofi Dermatology American Association of Physicists in Medicine American College of ~ u c l e &Physicians American College of Radiology American College of Radiology Foundation American Dental Association American Hospital Radioloa Administratore American Industrial Hygiene Association American Insurance Association American Medical Aseociation American Nuclear Society American Occupational Medical Association American Podiatric Medical Association American Public Health Association American Radium Society American Roentgen Ray Society American Society of Radiologic Bchuologiats American Society for Therapeutic Radiology and Oncology Association of University Radiologists Atomic Industrial Forum Bioelectromagnetics Society

'

College of American Pathologiets Confe~eneeof Radiation Control F'mpm Dhctore Federal ComrnunicationaCommission Federal Emergency Management Agency Genetic Society of America Health Phyaica Society Institute of Nuclear Power Operations National Bureau of Stan* National Electrical ManufactuemAssociation Radiation Research Society Radiological Society of North America Sodety of Nuclear Medicine United States Air Force United States Army United States Department of Energy United States Department of Houeing and Urban Development United States Department of Labor United States Environmental Protection Agency United States Navy United States Nuclear Regulatory Commiseion

'lb all of these organizations the Council expresses its pmfound appreciation for their support. Initial funds for publication of NCRP reports were provided by a grant £tom the James Picker Foundation and for this the Council wishes to express its deep appreciation. The NCRP eeeks to promulgate information and recommendations based on leading scientific judgment on matters of radiation protee tim and meammment and to foster cooperation among organizations concerned with these matters. T h e efforts are intended to serve the public interest and the Council welcomea cements and suggestions on its reports or activities from those interested in its work.

NCRP Publications NCRP publications are distributed by the NCRP Publications' Office. Information on prices and how to order may be obtained by directing an inquiry to:

NCRP Publications 7910 Woodmont Avenue Suite 800 Bethesda, MD 20814-3095 The currently available publications are listed below.

Proceedings of the Annual Meeting No. 1

3 4

5

6

7 8

Title Perceptions of Risk, Proceedings of the Fifteenth Annual Meeting held on March 14-15,1979 (including Taylor Lecture No. 3) (1980) CriticalIssues in Setting Radiation Dose Limits, Proceedings of the Seventeenth Annual Meeting held on April 8-9, 1981 (including Taylor Lecture No. 5) (1982) Radiation 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, Proceedingsof the Nineteenth Annual Meeting held on April 6-7,1983 (including Taylor Lecture No. 7) (1983) Some Issues Important in Developing Basic Radiution 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 Ekctromagnetic Radiations and Ultrasound, Proceedings of the Twenty-second Annual Meeting held on April 2-3,1986 (including Taylor Lecture No. 10)(1988)

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NCRP PUBLICATIONS

New Dosimetry at Hiroshima and Nagasaki and Its Zmplications 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-fiRh 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 Twenty-sixth 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, 1992 (including Taylor Lecture No. 15) (1992) Symposium Proceedings

The Control of Exposure of the Public to Ionizing Radiation in the Event of Accident or Attack, Proceedings of a Symposium held April 27-29, 1981 (National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1982) Lauriston S.Taylor Lectures

No. 1

2 3 4 5

6

Title The Squares of the Natural Numbers i n Radiation Protection by Herbert M. Parker (1977) Why be Quantitative about Radiation Risk Estimates? by Sir Edward Pochin (1978) Radiation Protection-Concepts and Trade Offs by Hyrner L. Friedell (1979) [Available also in Perceptions of Risk, see abovel From "Quantity of Radiation" and 'Dose" to "Exposure" and "Absorbed Dose"-An Historical Review by Harold 0. Wyckoff (1980) How Well Can W e Assess Genetic Risk? 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

NCRP PUBLICATIONS

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The Human Environment-Past, Present and Future by Merril Eisenbud (1983) [Available also in Environmental Radioactivity, see abovel Limitation and Assessment in Radiation Protection by Harald H. Rossi (1984) [Available also in Some Zssws Important in Developing Basic Radiation Protection Recommendations, see above] Truth (and Beauty) in Radiation Measurement by John H. Harley (1985) [Available also in Radioactive Waste, see abovel Biological Effects ofNon-ionizing Radiations: Cellular Properties and Interactions by Herman P. Schwan (1987) [Available also in Nonionizing Electromagnetic Radiations and Ultrasound, see above] How to be Quuntitative 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 abovel Radiobiology and Radiution 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 above] When is a Dose Not a Dose? by Victor P. Bond (1992) [Available also in Genes, Cancer and Radiation Protection, see abovel Dose and Risk i n Diagnostic Radiology: How Big? How Little? b y Edward W. Webster (1992) NCRP Commentaries No. 1

Title Krypton45 in the Atmosphere-With Specific Reference to the Public Health Significance of the Proposed Controlled Release at Three Mile Island (1980) Preliminary Evaluation of Criteria for the Disposal of Tmnsuranic Contaminated Waste (1982) Screening Techniques for Determining Compliance with Environmental Standards-Releases of Radionuclides to the Atmosphere (1986), Rev. (1989)

/

NCRP PUBLICATIONS

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 t h Publitation, Living Without Landfills (1989) Radon Exposure of the U.S. Population-Status of the Problem (1991) Misadministration of Radioactive Material in MedicineScientific Background (1991)

NCRP Statements No. 1

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 Protectionand Measurements (National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1968) Specificationof Units ofNatural Umnium anclNatura1Thorium, Statement of the National Council on Radiation Protection and Measurements, (National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1973) NCRP Statement on Dose Limit for Neutrons (National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1980) Control ofAirEmissions ofRadwnuclides (National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1984)

NCRP Reports No. 8

Title Control and Removal of Radioactive Contamination in Laboratories (1951) Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in

NCRP PUBLICATIONS

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Waterfor 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' in the Management of Patients Who Have Received Thempeutic 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 in a Nuclear Attack (1974) Krypton-85 in the Atmosphere-Accumulation, Biological Signifiance, and Control Technology (1975) 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 Up to 10 MeV (1976) Environmental Radiation Measurements (1976) Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities (1977) Cesium-137fron the Environment to Man: Metabolism and Dose (1977) Review ofNCRP Radiation Dose Limit forEmbryo and Fetus in Occupationally-Exposed Women (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)

NCRP PUBLICATIONS

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-LET Radiations (1980) Management of Persons Accidentally Contaminated with Radionuclides (1980) Radiofrequency Electromagnetic Fields-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) Biological Effects of Ultrasound: Mechanisms and Clinical Implications (1983) Iodine-129: Evaluation ofReleases from Nuclear Power Ceneration (1983) Radiological Assessment: Predicting the Transport,Bioaccumulation, and Uptake by Man of Radionuclides Released to the Environment (1984) Exposures from the Uranium Series with Emphasis on Radon and Its Daughters (1984) Evaluutwn 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 i n 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 ~ad*e*uenc~ Electromagnetic Fields (1986) UseofBioassay ProcedumsforAssessment oflnternal Radionuclide Deposition (1987) Radiation Alarms and Access Control Systems (1986) Genetic Effects from Internally Deposited Radionuclides (1987) Neptunium: Radiation Pmtection Guidelines (1988) Recommendations on Limits for Exposure toIonizing Radiation (1987) Public Radiation Exposure fmm 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 Canada 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 Radon Daughters in Air (1988) Guidance on Radiation Received in Space Activities (1989) Quality Assurance for Diagnostic Imaging (1988) Exposure of the U.S. Population f b m Diagnostic Medical Radiation (1989) Exposure of the U.S. Population from Occupational Radiation (1989) Medical X-Ray, Electron Beam and Gamma-RayProtection for Energies Up to 50 MeV (Equipment Design, Performance and Use) (1989) Control of Radon in Houses (1989) The Relative Biological Effectiveness of Radiations ofDifferent Quulity (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 As Low As Reasonably Achievable (ALARA) for Medical and Dental Personnel (1990) Conceptual Basis for Calculations of Absorbed-Dose Distributions (1991) Effects of Ionizing Radiation on Aquatic Organisms (1991) Some Aspects of Strontium Radiobiology (1991)

98 111 112 113 114

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NCRP PUBLICATIONS

Developing Radiation Emergency Plans for Academic,Medical or Zndustriul Facilities (1991) Calibmtwn of Survey Instruments Used in Radiation Protection for the Assessment of Ionizing Radiation Fields and Radioactive Surface Contamination (1991) Exposure Criteria for Medical Diagnostic Ultrasound: I. Criteria Based on Thermal Mechanisms (1992) Maintaining Radiation Protection Records (1992)

Binders for NCRP Reports are available. Two sizesmake 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. 32-113). Each binder will accommodate from five to seven reports. The binders cany 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 Nos. 8,22 Volume ZI. NCRP Reports Nos. 23,25,27,30 Volume III. NCRP Reports Nos. 32,35,36,37 Volume JV.NCRP Reports Nos. 38,40,41 Volume V. NCRP Reports Nos. 42,44,46 Volume VI. NCRP Reports Nos. 47,49,50,51 Volume VII. NCRP Reports Nos. 52,53,54,55,57 Volume VIII. NCRP Reports No. 58 Volume IX. NCRP Reports Nos. 59,60,61,62,63 Volume X. NCRP Reports Nos. 64,65,66,67 Volume XI. NCRP Reports Nos. 68,69,70,71,72 Volume XII. NCRP Reports Nos. 73,74,75,76 Volume XIII. NCRP Reports Nos. 77,78,79,80 Volume XIV. NCRP Reports Nos. 81,82,83,84,85 Volume XV. NCRP Reports Nos. 86,87,88,89 Volume XVI. NCRP Reports Nos. 90,91,92,93 Volume XVII. NCRP Reports Nos. 94,95,96,97 Volume X W I . NCRP Reports Nos. 98,99,100 Volume XIX. NCRP Reports Nos. 101,102,103,104 Volume XX. NCRP Reports Nos. 105,106,107,108 Volume XXI. NCRP Reports Nos. 109,110,111 (Titles of the individual reports contained in each volume are given above).

NCRP PUBLICATIONS

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The following documents are now superseded andlor out of print:

NCRP Reports No. 1

Title X-Ray Protection (1931) [Superseded by NCRP Report No. 31 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 WasteDisposal of Phosphorus32 and Iodine-131 for Medical Users (1951) [Out of Print] Radiological Monitoring Methods and Instruments (1952) [Superseded by NCRP Report No. 571 Maximum Permissible Amounts of 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 Protection Against Radiations from Radium, Cobalt-60and 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 Externul Sources of Ionizing Radiation (1954) including Maximum Permissible Exposures to Man, Addendum to Nationul Bureau of Standards Handbook 59 (1958) [Superseded by NCRP Report No. 391 X-Ray Protection (1955) [Superseded by NCRP Report No. 261

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100

1

NCRP PUBLICATIONS

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 in 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 Desgn and Use (1968) [Superseded by NCRP Report No. 1021 Medical X-Ray and Gamma-RayProtection 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 i n the United States (1975) [Superseded by NCRP Report No.941 Radiation Protection for Medical and Allied Health Personnel (1976) [Superseded by NCRP Report No. 1051 Radiation Exposure from Consumer Products and Miscellaneous Sources (1977) [Superseded by NCRP Report No. 951 A Handbook ofRadioactivity Measurements Procedures, 1st ed. (1978) [Superseded by NCRP Report No. 58,2nd ed.] Mammography (1980) [Out of Print]

NCRP Proceedings No. 2

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

NCRP PUBLICATIONS

1

101

Other Documents 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 Protedion and Measurements, 6 May 1959,Reprinted from Science, February 19,1960, Vol. 131, No. 3399, pages 482-486 Dose Effect Modifiing 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) Copies of the statements published in journals may be consulted in libraries. A limited number of copies of the remaining documents listed above are available for distribution by NCRP Publications.

INDEX

C2Gmpdkredialogy 16 (k&!cth Dose E q u i v h t 5,73,74 Computed' I h m m y (0 7,8,16,18,20-22,3236,42,43,46,48,50, 61,53,57,69

baneImmwdoee43 diffe~ntiallmnds18 number 20,22 surfac8h43

h t a l X-Ray Ehmk&bm 7,10,11,14,15,17,18,34.40,42,45 data sourcee 7 ~

t

i

a

l

~

1

8

effectivedose-45 eqipxxmt amihbility 10 film usage 10, 15 fiquencyof ' " 14 geneticallyEdgnificantdose40 number and bends 11,15,42 populatian-17 mmatkdose46 Dhgncdc Medical E 6 7,8,11,12,14-18,21,22,25,31,32, 34-36,38,40-45,49,69 absoheddcwre25 banemt~~0~h41-44 cardiac ca-on 21 cardiac imaging 21 chest x-rayexamidions 22

-

~ngiopw 22

rirkhgqhy 21 data sources 7,16 difhmtialtrends 18 dose reduction34-36 ech&ography 21

INDEX

effectiV0dose~ht45 ecpipmmt a v w t y 10 film usage 10.15 ko=3wy7 genetically signific€mtdoee40 21.32 myocardial-21 numbers and k m d s 11.12.14-16,42,49 pediatric examjnatiw 31 plmmaa3UM-22 populatondemogqhics 17

me-34

~ u c l i d ven21 somatic dose 45 whalebodydm44 Digital ' k h d a g y .DefkiDefinition20 Dose Equivalent 4.5.67 Dose F&duction34.71 machinecalibration34 staff and opemtmeducation 34

EffectiveDose Equivalent 5,26,27,33,45-48.67.70.71 age and a e x ~ weighted c 67.70 Entrance Sldn Exposlam (ESE)4,25,31-34.43.48.73 Equipment Availability 10.17 dental nmchkm 17 medicalx-raymachines 17

S g d h n t D m (GSD) 6,3840.49.66.69-71 definition 38 Ganadal Dase 24.38.39.66.67.69.71 a t i o n 38

/

103

Mammogaphy 21,32,33,45 absorbed dose 32,33 bn?astcompmsion 32 computed tomography 33 digital x-ray 33 heavy ion 33 llxgnetic remnameimaging 33 number 21 organ dose 32 skin entrance expome 32 -hy 33 ~ u m i n a ~ 3 3 dtrasonography 33 Monte Carlo 26,27,31,35,42 organ dose 27.35 pediatric examinatim 31

~atural~ticmExpome38 Nuclear Medicine 8.9.16.30.50-53.57-59.65-67.70-72 brain imaging 51.53.57.70 bone imaging 51 cardiacpdUIw57 dov& p d u r w 51.70 data aourcm 50 defiIliti0nM)

d3femtia.l trends 53 dose d u d i o n 71 eI%&wdcxe equivalent 67.71 genetically signi£icantdose 66.71 gonadal dose 66 in vim examhtiona 53 liver imaging 51.57 hmg imaging 5 1 number and fquency 50-52.70 ~ d e m q p p b 5 2 r e d i d v e haam50.58.59 radio-ticals 59,s dimaging 51 t h f l imaging 51.58.59.65 tumor imaging 51 v e n ~ n ~ 5 1

Organ Dase 6.9.25-27.29.32.35.46.73 Monte Carlo 27.35

Quality Asmvance 34,35 dehiticm34 machine cali'bratim 34

!3taffdopexitmedUcati~34