ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 46

Document Title:

Dose Reconstruction from Occupationally 

Related Diagnostic X-Ray Procedures

Document Number: ORAUT-OTIB-0006

Revision: 03 PC-1 

Effective Date: 12/21/2005

Type of Document: OTIB

Supersedes: Revision 02

Subject Experts: Ronald L. Kathren and Vernon E. Shockley

Document Owner

Approval: Signature on File Approval Date: 06/29/2005

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 06/29/2005

Richard E. Toohey, Project Director

Approval: Signature on File Approval Date: 08/02/2005

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE REPLACE THE PRIOR REVISION. 

PLEASE DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0006 Revision No. 03 PC-1 Effective Date: 12/21/2005 Page 2 of 46

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

11/14/2003 00 New document to establish the technical basis for the development 

of a generic document to use to perform dose reconstruction from 

occupationally related diagnostic X-ray procedures. First approved 

issue. Initiated by Judson L. Kenoyer.

12/08/2003 01 Revision that limits the use of this document to post 1970. Approved 

issue of Revision 01. Initiated by Judson L. Kenoyer

12/29/2003 02 Revision that includes information to re-instate the ability for the 

document to cover exposures pre-1970. Approved issue of Revision 

02. Initiated by Judson L. Kenoyer

08/02/2005 03 Revision to add photofluorography use table and lumbar spine xrays. Deleted footnote b and adjusted footnote references in Table 

7-6. Approved issue of Revision 03. No retraining required. Initiated 

by Vernon E. Shockley and Ronald L. Kathren.

12/21/2005 03 PC-1 Approved page change revision. Page change initiated to 

incorporate recent direction from NIOSH to include DOL review 

comments on page 8. Deletes two obsolete paragraphs on page 8 in 

Section 1.0. Corrects table number reference on page 20 in Section 

4.0. No sections were deleted. No retraining is required. Initiated by 

Vernon E. Shockley and Ronald L. Kathren.

Approval:

Document Owner:

Judson L. Kenoyer, Task 3 Manager

Signature on File____________________________12/14/2005

Kate Kimpan, Projector Director

Signature on File____________________________12/14/2005

James W. Neton, Associate Director for Science

Signature on File____________________________12/21/2005
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 3 of 46

TABLE OF CONTENTS

Section

Publication Record ..............................................................................................................................

Page

2

Acronyms and Abbreviations ...............................................................................................................6

1.0 Introduction................................................................................................................................. 8

2.0 Technical Factors Affecting Diagnostic X-Ray Dosage................................................................ 8

2.1 Applied Kilovoltage and Filtration ..........................................................................................8

2.2 Current and Exposure Time ................................................................................................ 10

2.3 Distance..............................................................................................................................11

2.4 Collimation and Waveform Characteristics .......................................................................... 11

2.5 Screens, Grids, and Other Factors Potentially Affecting Patient Dose................................. 13

2.6 Summary and Application of Technical Factors................................................................... 14

3.0 Reconstruction of Diagnostic Medical X-Ray Doses.................................................................. 14

3.1 Reconstruction When Measurements Are Available............................................................ 15

3.2 Reconstruction Using Technique Factors............................................................................ 17

3.3 Reconstruction Using Default Values .................................................................................. 20

4.0 Application and Reporting of Occupational Medical CHEST X-Ray Dose 

Reconstruction..........................................................................................................................20

5.0 Photofluorography.....................................................................................................................20

6.0 Lumbar Spine ...........................................................................................................................21

7.0 Fluoroscopy ..............................................................................................................................23

8.0 Reconstruction of Organ Dose From Radiography Equipment Using 

Minimal Collimation...................................................................................................................27

9.0 Uncertainty Analysis For Diagnostic Medical X-Ray Doses....................................................... 28

References ........................................................................................................................................30

Appendix A Organ Doses from Pelvis AP X-Rays in the 1940s .........................................................34

A1.0 Data..........................................................................................................................................35

A2.0 Dose Calculation.......................................................................................................................35

A2.1 ICRP Publication 34 (1982) Methodology............................................................................ 35

A2.2 Determination of Entrance Kerma ....................................................................................... 36

A2.3 Selection of ESD and HVL for ORGAN Dose Determination ............................................... 36

A2.4 Dose Conversion Factors.................................................................................................... 37

A2.4.1 For ICRP 34 (1982) Beam .......................................................................................... 37

A2.4.2 For Modified Beam ..................................................................................................... 37
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A2.4.2.1 Organs Above the ICRP 34 Field Center.......................................................... 39

A2.4.2.2 Organs Below the ICRP 34 (1982) Field Center ............................................... 40

A2.4.2.3 Active Bone Marrow ......................................................................................... 40

A2.5 Doses..................................................................................................................................40

A2.5.1 Organs Other than Skin in the Beam .......................................................................... 40

A2.5.2 Skin in the Beam ........................................................................................................ 40

A2.5.3 Skin Outside but Near the Primary Beam ................................................................... 41

A2.5.4 Organs Outside but Near the Beam............................................................................ 41

A2.5.5 Body Parts Well Outside the Beam............................................................................. 41

A2.5.6 Organ Dose Tables .................................................................................................... 42

References ........................................................................................................................................46
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LIST OF TABLES

Table

2-1 Relationship of beam intensity and various technical factors..................................................

Page

14

3-2 Analogues for IREP organs not included in ICRP 34..............................................................18

3-3 Example of summary data based on actual beam measurements for the 

Hanford site............................................................................................................................19

3-4 Default dose values by procedure..........................................................................................20

6-5 Organ doses for default entrance kerma values .....................................................................22

7-6 Use of photofluorography at DOE sites ..................................................................................24

7-7 Example of lumbar spine X-ray operating parameters, dates of use, and 

frequency of examinations .....................................................................................................24

7-8 Values used to calculate organ dose, AP and lumbar spine...................................................25

7-9 Example of average absorbed dose per unit entrance air kerma for AP and 

lateral lumbar spine X-ray views, organs DCFs, and beam quality .........................................25

7-10 An example of organ dose estimates for ORNL AP and lateral lumbar spine 

radiographs to be used as IREP inputs ..................................................................................26

9-11 Substitute dose conversion factors.........................................................................................28

A-1 Pelvis AP x-ray doses reported by Lincoln and Gupton..........................................................35

A-2 Beam/patient geometry parameters assumptions ..................................................................37

A-3 DCFs for a pelvic AP x-ray (HVL 2.0 mm Al) for organs listed in ICRP 34..............................42

A-4 DCFs for pelvic AP x-ray (HVL 2.0 mm Al) for analogue organs not listed in 

ICRP 34 ................................................................................................................................. 42

A-5 Impact of modified beam on organs outside ICRP 34 beam...................................................43

A-6 Assigned DCFs for organs above field center of ICRP 34 beam ............................................43

A-7 Parameters related to dose to testes......................................................................................44

A-8 Organ doses from a pelvis AP x-ray.......................................................................................45

LIST OF FIGURES

3-1 Anatomy of a human torso .....................................................................................................

Figure 

18

A-1 Beam profiles and body anatomy...........................................................................................38
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ACRONYMS AND ABBREVIATIONS

Al aluminum

AP anterior-posterior

cGy centigray

cm centimeter

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

ESE entrance skin exposure

Gy gray

HVL half value layer

ICRP International Commission on Radiological Protection

ICRU International Commission on Radiological Units and Measurements

in. inch

IREP Interactive RadioEpidemiological Program

Kev kilo electron volts

kVp Peak Kilovoltage, applied kilovoltage

LAT lateral

mA milliampere

mAs milliampere-second

mGy milligray 

mm millimeter

mR milliroentgen

mrad millirad

NCRP National Council on Radiation Protection and Measurements

NEXT Nationwide Evaluation of X-Ray Trends

NIOSH National Institute for Occupational Safety and Health

OCAS Office of Compensation Analysis and Support

PA posterior-anterior

PFG photofluorography

R roentgen

RMS root mean square

sec second(s)

SID source to image distance

SSD source to skin distance

TLD thermoluminescent dosimeter
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TSD target to skin distance

U.S.C. United States Code

WDH Washington State Department of Health (Radiation Section)
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1.0

Technical Information Bulletins (TIBs) are general working documents that provide guidance 

concerning the preparation of dose reconstructions at particular sites or categories of sites. They will 

be revised in the event additional relevant information is obtained. TIBs may be used to assist the 

National Institute for Occupational Safety and Health in the completion of individual dose 

reconstructions.

INTRODUCTION

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act of 2000 (42 U.S.C. § 7384l(5) and (12)).

The purpose of this Technical Information Bulletin (TIB) is to provide information to allow ORAU Team 

dose reconstructors to assign doses to workers who have no or limited monitoring data, based on site 

coworker data.

2.0

A number of factors determine the dose to the patient from a diagnostic x-ray procedure. For a more 

or less standard medical radiographic (i.e. diagnostic) unit with a tungsten target (anode) and focal 

spot size of 1 to 2 millimeters (mm), these factors include the basic machine settings used for the 

exposure, viz. the applied kilovoltage of the beam (kVp, also known as peak kilovoltage or kilovolt 

peak), beam current (milliampere [mA]), and time of exposure (sec), distance, waveform, amount and 

kind of filtration used, collimation or use of diaphragms, tube housing characteristics, the type and 

speed of the film, development procedure, screens, grids and the size of the patient. While the list of 

factors enumerated looks formidable, in the absence of direct measurements of the beam itself, which 

are rarely available, the dose to the patient can be estimated with a reasonable degree of accuracy 

with knowledge of only the three basic machine parameters: applied kilovoltage, current, and time, 

along with filtration, collimation and waveform characteristics. The implications of these factors 

insofar as patient dose is concerned are briefly discussed below.

TECHNICAL FACTORS AFFECTING DIAGNOSTIC X-RAY DOSAGE

2.1 APPLIED KILOVOLTAGE AND FILTRATION

The energy of the x-ray beam is determined by the applied kilovoltage and the filtration, and is 

sometimes referred to as beam quality. X-rays, as produced in a typical medical x-ray tube, are 

bremsstrahlung produced when electrons from the cathode are accelerated into the anode as a result 

of the potential difference or applied kilovoltage between the two electrodes. As such, x-rays from a 

medical x-ray tube are a distribution or spectrum of energies ranging from zero to the applied 

kilovoltage, which refers to the potential between the anode and cathode of the tube. For a typical 

unfiltered x-ray spectrum, the average energy is about one third of the peak or maximum x-ray 

energy, which is equal to the applied kilovoltage. Therefore, most of the x-rays produced are very 

much lower in energy than the applied kilovoltage of the beam, and thus are attenuated by the torso 

or other portion of the body being radiographed and never reach the film. These low energy x-rays 

are of little value in radiography but contribute significantly to patient dose.

To reduce the dose to the patient, filtration in the form of a specified thickness of absorbing material is 

added to the beam port. This has the net effect of absorbing a large fraction of the lower energy xrays that are of little or no value in making the radiograph while allowing a greater fraction of the more 

energetic and radiographically useful x-ray photons to pass. In this manner, the dose to the patient is 

significantly reduced while at the same time radiographic quality may be enhanced. A filtered x-ray 
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spectrum has a correspondingly higher average energy than before it was filtered, although the 

photon fluence rate and corresponding dose rate is much reduced. Such a beam is said to have been 

hardened. A corollary to this filtration technique is to use a higher applied kilovoltage, and filter the 

beam relatively heavily to eliminate most of the low energy radiographically useless photons from 

reaching the patient. 

Beam energy is specified in terms of quality, or hardness, which in turn may be specified in terms of 

the half value layer (HVL) in millimeters of aluminum. Unfortunately, this parameter is seldom 

available, and even if known is of limited value, in part because it does not specify the maximum 

energy of the beam or its true quality, since as the HVL measurement is made, the absorbers act as 

filters and the beam is further hardened. Thus the first HVL is always smaller than the second HVL 

beam, which in turn is smaller than the third, and so forth. A useful although rarely available measure 

is the homogeneity factor, which is simply the ratio of the second and first HVLs. Since the first HVL 

is always the smallest, the homogeneity factor will always be less than 1, and the closer it approaches 

unity, the more closely the beam approximates a monoenergetic photon beam whose energy can be 

determined from the HVL. What is most commonly used, although not always available, is the kVp of 

the machine and the external or added filtration. All x-ray tubes have so-called inherent filtration, 

which is the window, aperture or port in the tube enclosure through which the x-ray beam passes or 

emerges from the x-ray tube. In medical diagnostic units, the window or beam port through which the 

useful beam emerges is purposely made very thin, typically equivalent to 0.5 mm Al in attenuation, 

and hence provides little beam hardening. Other than the beam port itself, the tube housing is 

shielded to eliminate leakage radiation from the tube. Thus the beam port effectively characterizes 

what might be considered the inherent collimation of the tube.

Although the benefits of filtration with respect to improved radiographic images were known and 

understood as early as March 1896, within months of the discovery of x-rays (Magie, 1896), initially 

diagnostic radiographs were made with no added filtration. Recommendations, albeit not specific as 

to thickness, were put forth in 1937 by the International Committee for Radiological Units and 

Measurements (ICRU, 1937), which specified aluminum filters for x-rays of 20 to 120 kVp, which 

incorporated the diagnostic x-ray energy range. This was consistent with, although not as specific as, 

the 1936 recommendation of the U.S. Advisory Committee on X-Ray and Radium Protection, the 

forerunner of the National Council on Radiation Protection and Measurements (NCRP), which called 

for total filtration 0.5 mm of Al equivalent for radiographic installations, and 1 mm Al for fluoroscopy 

(NBS, 1936). In general, manufacturers of radiographic x-ray tubes complied with this standard, and 

medical radiographic tubes in use in the 1940’s typically had inherent filtration of 0.5 mm Al (Morgan 

and Corrigan, 1955, pp. 308-310). 

Typical external or added filtration in the 1940’s ranged from none to 1 mm Al. In 1949, the NCRP 

recommended 1 mm of added Al filtration for radiographing thick parts of the body such as the chest 

(NBS 1949) and was in use during World War II in 100 mA units in larger military hospitals, and hence 

presumably at the various Manhattan District sites which were under the aegis of the U.S. Army 

(Olson, Trask and Dessent, 1966). Subsequently, recommended thicknesses were increased not 

only for patient protection but for improved radiographic image quality; in 1955, the NCRP 

recommendation for diagnostic x-ray units called for 2 mm total Al filtration for new machines (NBS, 

1955), the recommended filtration increased again to 2.5 mm by the 1960’s for medical diagnostic 

units operating above 70 kVp (NCRP, 1968). For machines already in operation, these recommended 

filter thicknesses might not have been utilized for some time after the date of the recommendation.
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The relationship of beam intensity1 to applied kVp and to filtration is complex and to some extent is 

machine specific and hence is best determined empirically. However, in the absence of empirical 

data for a specific machine, adequate contemporary empirical and theoretical data exist upon which to 

determine within a reasonable degree of uncertainty, the machine output. Additional filtration reduces 

the entrance skin exposure2

I = I(o) e-0.5t

(ESE), generally in an exponential manner. For a typical single phase 

half, full or self rectified machine operating in the diagnostic range of 80 –100 kVp, each additional 

mm of Al filtration will effect a reduction of about 40 per cent in the ESE (Trout et al., 1952; Taylor, 

1957). The approximate intensity reduction afforded by any thickness of Al filtration can thus be 

determined by the following exponential equation:

or

ln (I/Io) = - 0.5 t

in which t is the thickness of Al, in mm, and I and Io are the beam intensities with and without the filter, 

respectively. In the absence of specific measurements or empirical data, this correction can be 

applied to determine the effect of filtration on beam intensity, and is consistent with the guidance put 

forth in OCAS-IG-001 Revision 1 (2002).

Similarly, increasing the kilovoltage (kVp) will increase the beam intensity or exposure rate. This can 

be calculated using Kramer’s rule, but such calculations are difficult, complex and time consuming, 

even with high speed computers, and are at best approximations. However numerous empirical 

studies of beam intensity as a function of the range of (kVp) used in medical diagnosis have been 

carried out over the years and provide ample credible evidence to show that for a given amount of 

filtration, increasing the applied kVp will increase the beam intensity according to the 1.7 power of the 

applied kilovoltage (Handloser, 1951; Trout et al., 1952; Kathren, 1965; Cameron, 1970). In the 

absence of specific measurements or empirical data, this function can be applied to determine the 

effect of applied kilovoltage on beam intensity, and is fully consistent with the OCAS guidance 

document (NIOSH 2002). 

It should be noted that the effects of filtration and kVp tend to offset one another; addition of filtration 

reduces the exposure or dose per milliampere-seconds (mAs), while increasing the kVp increases the 

exposure and dose per mAs. Higher kVp radiographic techniques typically require shorter exposures 

in terms of milliampere-seconds, and the dose reduction from additional filtration at the recommended 

level more than offsets the additional dose from using increased kVp. However, there is not a direct 

correspondence or proportionality between the effects of filtration and kVp. 

2.2 CURRENT AND EXPOSURE TIME

Diagnostic x-ray exposures are typically specified in terms of mAs, the product of x-ray tube current 

and the exposure time. Other factors being equal (e.g. kVp, filtration, film, development and screen 

combination) radiation exposure and hence dose delivered to the patient is proportional to the number 

 

1

 As used herein, beam intensity refers to the output of the machine in terms of exposure in the special sense per mAs. 

Exposure in the special sense is referenced to ionization in air and as such is not a dose quantity. 2 Throughout this document, italics will be used to differentiate exposure in the special sense from exposure in the general 

sense. Thus exposure refers to exposure in the special sense. A brief discussion of exposure in both the general and 

special sense can be found in numerous publications, including NCRP Report 82 (1985) and International Commission on 

Radiological Units (ICRU) Report 60 (1998). It is important to note that the definition and application of the quantity 

exposure and its concomitant unit the roentgen have undergone several important modifications over the years, which 

have been documented throughout the literature.
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 11 of 46

of mAs. The current in an x-ray tube refers to the number of electrons accelerated across the 

evacuated volume of the x-ray tube, flowing from the cathode to the anode. For a given applied 

kilovoltage, the number of x-ray photons produced, and therefore the exposure will at least in theory 

be directly proportional to the x-ray tube current, and indeed this is and has been historically true for 

most medical radiography units over their designed tube current range. Thus, in the absence of 

measurements or other data or information to the contrary, it is reasonable and consistent with long 

standing radiographic practice (Sante, 1946, p. 61) to assume linearity of beam intensity and hence 

patient dose with tube current.

Exposure time refers to the time that the beam was on or the machine was producing x-rays and is, 

for all practical purposes, linear with exposure. To avoid or minimize image blurring from the beating 

heart, exposure time was minimized, and the current concomitantly and proportionately increased to 

obtain the desired exposure in terms of mAs. However, from a dose reconstruction standpoint, it 

should be noted that earlier medical radiographic units were equipped with mechanical timers whose 

accuracy was not as good as the electronic timers used on later model machines. Gross bias errors 

in timer accuracy are unlikely in that these would result in over- or underexposure of the radiograph 

and so would be quickly detected and corrected. Subtler are small random errors, which might 

produce uncertainties of perhaps ± 20 per cent in the exposure. 

Chest photofluorography (PFG), which resulted in a much greater patient dose from a diagnostic 

procedure, was used sporadically until as late as the early 1960’s. PFG used a smaller film (4 x 5 

inches), a smaller SSD (42 inches), and a higher kVp and typically resulted in a several fold greater 

exposure in terms of mAs. Exposure was regulated by photometers, which utilized the exposure to 

the film to determine the time of exposure. 

2.3 DISTANCE

X-ray beam intensity is a function of distance from the target, approximating inverse square at large 

distances (i.e. more than a few tens of centimeters) from the tube. Radiographic chest films were 

taken at a standard source to image distance (SID) of 72 inches; the source refers to the focal spot of 

the tube and the image to the plane of the film. The distance to the patient, sometimes expressed in 

terms of the source to skin distance (SSD), is somewhat smaller since the patient is positioned 

between the source and the film cassette. Therefore, the ESE to the patient is somewhat greater than 

the exposure at the plane of the film. In addition, patient attenuation would further reduce or attenuate 

the number of photons reaching the film. To compensate for the increased attenuation provided by a 

larger patient, x-ray technicians would sometimes increase the beam settings for a large patient, or, if 

the machine was so equipped, might use a high speed Bucky diaphragm, likely with a somewhat 

higher kVp. It thus may be appropriate for an individual dose reconstruction to increase the ESE or 

skin entrance kerma for a large or stout patient. Based on standard contemporary techniques (Picker, 

1941, p 67; Fuchs 1958, p184; Cahoon, 1961, p 183) for patients with a chest thickness of 25-27 

centimeters (cm), an increase of +50% from the ESE to the average patient should be sufficiently 

conservative; for still larger patients, a factor of 2 would be appropriate. The average worker chest 

size is taken to be 22-24 centimeters. 

2.4 COLLIMATION AND WAVEFORM CHARACTERISTICS

Among the other factors that potentially affect patient organ dose are collimation (i.e. beam size) and 

waveform. X-ray waveforms are of three types: half wave rectified, which is almost never seen; full 

wave rectified, which is typical of virtually all medical radiographic units, and constant potential. A half 

wave rectified machine produces 60 half sinusoidal shape pulses of x-rays per second, each with a 

duration of 1/120 of a second. A full wave rectified machine produces 120 half sinusoidal pulses of x-
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 12 of 46

rays per second, each with a duration of 1/120 second. Thus, for a given setting of kVp and mA, the 

intensity of the beam from a half wave rectified machine will be half that of the beam from the full 

wave rectified type. A constant potential machine produces a more or less steady (i.e. unpulsed) 

output of x-rays and has a somewhat greater beam intensity (approximately 10%) as compared with a 

full wave rectified machine operating at the same kVp and mA. 

Collimation refers to the size of the beam. In the early years following the discovery of x-rays, the 

philosophy was to use a fairly large aperture (i.e. limited collimation) to ensure that the entire area of 

interest was included in the radiograph. Subsequently, because of patient protection concerns, 

beams were collimated such that the smallest beam consistent with the area of interest was used, 

thereby limiting the area of the patient exposed, and, in the case of chest radiography, minimizing 

dose to organs such as gonads, thyroid, and gastrointestinal tract. A practical check of collimation 

can be made by reference to the radiograph; a well collimated beam will leave a small unexposed 

area or penumbra effect at the edges of the radiograph, while a poorly collimated beam will produce a 

radiograph that is exposed all over its area. Beam diameter limiting cones were widely used in 

radiography during the 1940’s and beyond to improve radiographic image quality by reducing scatter 

(Glasser et al., 1944, p. 136) and were sometimes equipped with an Al filter of 1 mm in early years 

and thicker ones later on. A standard albeit largely undocumented practice was to collimate the beam 

to a size at the receptor (i.e. film) that was about one inch larger in all directions than the beam itself. 

This would provide a satisfactory picture quality as well as ensuring that the area desired was 

included in the radiograph. Thus for a 14 x 17 inch chest radiography, a beam diameter of 16 x 19 

inch might be used, providing a ratio of (16x19/14x17 = 1.28). Wochos, Detorie, and Cameron (1979) 

analyzed the 1972-1975 Nationwide Evaluation of X-Ray Trends (NEXT) data and found that at some 

facilities, primarily internal medicine and general practitioners, the beam area to film area ratio could 

be as high as 2.0, but more significantly also noted that the beam area to film area was significantly 

lower at hospitals and radiology facilities where more routine diagnostic x-rays were conducted. To 

ensure claimant favorability, the beam area to film ratio of 2.0 should be used in the absence of 

information to the contrary with respect to collimation (Webster 1992). This ratio would be achieved 

by exposure from an additional 3 inches of exposure and extension of the beam in all directions 

around a 14”x17” standard radiographic film. 

In the absence of measurement data, the beam size at any distance from the tube can be 

approximated, assuming no external collimation or coning, by the application of geometry, if the size 

of the beam port and the effective depth of the focal spot are known or can be assumed. If these are 

known, the diameter of a beam without a cone or other external collimation would, at the location of 

the patient, be approximately equal to the SSD times the ratio of effective depth to the beam port 

diameter. Typically, beam apertures or port diameters did not exceed two inches. The effective depth 

of the focal spot from the aperture, however, was more variable and typically six inches or so, giving a 

ratio of about one-third. Thus, for a patient undergoing a standard posterior–anterior (PA) chest 

procedure, the SSD is about 153 cm and the diameter of a beam with no external collimation or cones 

would correspondingly be 51 cm or about 20 inches. The ratio of beam size to film area in this case is 

1.32, which is consistent with what was observed by Wochos, Detorie, and Cameron (1979). For 

early years (before 1970), x-ray beam or scatter measurement data, techniques, and beam port 

information may not be available to estimate the collimation of the x-ray beam. Feldman et al. (1957) 

noted wide variation in their review of x-ray dose literature in 1957. Through measurements, Feldman 

et al. (1957) noted a factor of 10 increase in the gonadal dose when no external collimation was used. 

Lincoln and Gupton (1958) also noted that the gonadal dose varied by a factor of 5 among the eight xray facilities at Oak Ridge. Webster and Merrill (1957) discussed the effects of cone size and 

centering on the gonadal dose, and concluded that filtration, kVp, and the smallest possible cone size 

were most important to reduce the gonadal dose. 
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If actual dose measurements or inspection of the radiographs that indicate that collimation was used 

prior to 1970, this information should be used for organ dose determination. However, due to the 

reported variation in the literature and measurement data on the effects of collimation, the claimant 

favorable assumption of minimal external collimation of the primary beam should be used when 

measurement data, technique, or other information to describe the collimation are not available for xrays taken prior to 1970. This is based on the following claimant favorable assumptions and 

professional judgment: 

1. In the late 1950s, there was significant research into the gonadal dose and the reasons for the 

observed variation in dose. This research described the effects of filtration, collimation, and 

centering. By the early 1960s, techniques were being modified incorporating additional 

collimation. While these techniques were likely fully incorporated at most DOE facilities by 

1965, to allow for the possibility that some smaller facilities might not have had the resources 

to update their equipment and to be claimant favorable, the year 1970 was selected as the 

cutoff year. 

2. In 1968, the NCRP, in Report 33, updated their guidance on medical x-ray protection. While 

many DOE facilities had probably already incorporated the guidance in this report, some 

smaller facilities might not have incorporated the guidance by 1968. To ensure that these 

facilities were in fact in conformance with the 1968 recommendations, an additional two-year 

period was added, again making 1970 the cutoff year. 

3. By the late 1950s, reports in the literature of most of the surveys of medical x-ray facilities 

revealed low gonadal doses, indicating adequate collimation. A few surveys clearly indicated 

the use of collimation was limited. Of the eight surveyed facilities at Oak Ridge, only one 

(13%) had a moderately high male gonadal dose (5 mrad). At all of the other facilities, the 

male gonadal dose was less than 2 mrad. Variation among the other facilities appeared to be 

the result of differences in the use of filtration and cone size. Thus most facilities were using 

some form of collimation by the late 1950s, and by the mid 1960s most, if not all, facilities were 

probably using some form of collimation. Since references as to when all facilities were using 

adequate collimation were not found, professional judgment was used to estimate this time 

period to be the mid 1960s. To fully assure claimant favorability, this assumption has been 

further expanded by 5 years to 1970 to allow for the uncertainty in professional judgment. 

2.5 SCREENS, GRIDS, AND OTHER FACTORS POTENTIALLY AFFECTING PATIENT 

DOSE

A number of other factors also affect the x-ray exposure required to obtain a proper radiograph and 

hence the dose to the patient. However, knowledge of these factors is unnecessary for dose 

reconstruction purposes if beam measurements are available or if the primary machine characteristics 

of applied kilovoltage (kVp), time (sec) and current (mA) are known along with the amount of primary 

beam filtration. Although the other factors can be used as additional confirmation of the applicability 

of the reconstructed dose. Hence, for completeness, only brief mention will be made of these factors, 

which are: tube housing, type and speed of the film, development procedure, screens, and grids.

X-ray tubes used for diagnostic radiography are typically enclosed in a protective lead tube housings 

with the primary beam brought out through a port or window in the side of the housing. Although 

some reduction of the dose to the patient is achieved, largely through elimination of scattered 

radiation and improved collimation, this so-called diagnostic tube protective housing is primarily for the 

purpose of protection of the operator and unexposed x-ray film and nearby individuals other than the 

patient. The issue is moot, however, because virtually all x-ray tubes used to x-ray the DOE weapons 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 14 of 46

worker cohort have been equipped with protective tube housings, which limited leakage to less than 

0.1 R/hr at one meter from the tube. 

The exposure needed for a suitable diagnostic radiograph is in some measure a function of film speed 

and development. Fine-grain emulsions produce a superior radiographic image but require additional 

exposure as compared with fast films, which typically have a larger grain size. Underdevelopment of 

films will also require additional exposure to achieve satisfactory radiographic quality. Intensifying 

screens are used within the cassette to intensify the radiographic effect and thereby effectively 

increase film speed and reduce patient dose. Film speeds have typically increased since the 1940’s 

and reduced patient doses appreciably, perhaps by half. Grids, specifically the Potter Bucky 

diaphragm (colloquially known as a Bucky) are sometimes utilized for thick section radiography, but 

rarely used for chest radiography except with very large patients. In any case, the above are all 

factored into the technique (i.e. kVp, mA) that is used and except in rare instances and a virtually 

complete absence of other data, are not of importance in dose reconstruction.

2.6 SUMMARY AND APPLICATION OF TECHNICAL FACTORS

For convenience and possible application to cases in which other and more suitable data are not 

available, or for generic use, the effect of various technical factors has been tabulated below in 

Table 2-1.

Table 2-1. Relationship of beam intensity and various technical factors. 

Parameter Units Relationship with intensity

Applied voltage kVp Intensity proportional to 1.7 power of kVp

Tube current mA Linear

Exposure time sec Linear

Filtration mm Al Intensity decreases by ~40% for each additional mm Al

Patient size (chest thickness) 25-27 mm 

> 27 mm

Dose increased by factor of 1.5 

Dose increased by factor of 2

Distance d Approximately inverse square relationship (1/d2) holds for 

distances > about 30 cm from target

Uncertainty ± 30% Assumes all errors are positive, + 30% should be used 

3.0

Not all workers were required to undergo medical diagnostic x-ray examinations as a condition of 

employment. Among those who were, the procedure was usually limited to a single PA chest film, 

although a lateral chest film might also have been taken. Stereo chest films also may have been 

taken on some individuals; this procedure required two separate films with the views slightly displaced 

and thus required two exposures. Some workers were examined with chest PFG units, which 

produced a much greater dose than the standard PA radiograph. A very small fraction might have 

undergone lumbar spine or other specific procedures if there was a medical indication. Pelvic x-rays 

may have been routinely carried out at some DOE sites for workers that had a potential for exposure 

to fluoride. A protocol for calculating doses from pelvic x-rays is provided in Appendix A to this 

document.

RECONSTRUCTION OF DIAGNOSTIC MEDICAL X-RAY DOSES

The incidence of defective films necessitating retakes is not known, but it is likely to have been very 

small and certainly no more than a few per cent and probably much less. Trout et al (1973) in their 

analysis of the rejection rate of chest radiographs obtained during the Coal Mine “Black Lung” 

program reported an average rejection rate of 3% among 67,000 radiographs. Retakes should serve 

as a signal to give special consideration to the evaluation of technique factors, and hence the 

resultant dose calculations. A retake in a very large individual might serve as a signal that the initial 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 15 of 46

radiograph was taken with technique factor settings suitable for a smaller person, and that the second 

radiograph reflected an additional and larger dose. Retakes in African-Americans may signal that the 

initial exposure was too great, and indicative of an overriding of the standard or automatic technique 

factors because of a perception held by some x-ray technicians that African-Americans had greater 

bone density or other characteristics that required additional exposure. Similarly, retakes in females 

may be indicative of manually altered settings to increase beam intensity under the misimpression 

that additional exposure was required for women because of the larger amount of breast tissue. 

Unless machine settings have been recorded, it is impossible to determine whether the retake was 

necessitated by an arbitrary manual increase in machine settings to obtain a greater exposure. If 

machine settings are available, then an adjustment for the increased doses can be made using the 

data provided in Table 2-1. If machine settings are not available, then to ensure claimant favorability 

for African-Americans and women whose records indicate retakes, an upward adjustment of the organ 

doses from the first radiograph is indicated. Increasing doses by a factor of two in these cases should 

more than compensate for the supposed additional exposure. 

Diagnostic medical x-ray dose reconstruction is best accomplished when actual measurements of 

beam intensity are available. Use of actual measurement data is the simplest and most direct means 

of assessing diagnostic medical x-ray doses, typically requires few, if any assumptions, and has the 

least amount of uncertainty. Hence, use of actual measurement data, where available, is preferred for 

diagnostic medical x-ray dose reconstruction and should be used if available. Actual beam 

measurements are most likely to provide the most accurate estimates of organ doses.

X-ray output measurements are likely to be unavailable, particularly prior to about 1980. In the 

absence of suitable measurement data, medical diagnostic x-ray dose reconstruction can be 

accomplished using technique factors along with published output data that provide beam intensity 

per mAs as a function of kVp, filtration, and distance. The use of technique factors will typically 

require a number of assumptions, and these of course, should be claimant favorable. If both 

measurement data and technique factors are unavailable or unknown, then dose estimates can be 

made using the default values shown in Table 3-4. Use of default values is a last resort. To reiterate, 

the first choice should be to use actual beam measurement data when available. 

3.1 RECONSTRUCTION WHEN MEASUREMENTS ARE AVAILABLE

Although beam output measurements may typically be unavailable, diagnostic medical x-ray dose 

reconstruction using actual measurement data is the preferred method for determining the dose to the 

worker from this source, so much so that special effort to determine if such measurements have been 

made is justifiable. Beam output measurements are typically made in terms of exposure and are 

quantified in units of R, and depending on the measurement device and technique may have a wide 

range of uncertainty. The best measurements are those made with integrating ionization chambers 

designed for medical x-ray applications. Until about 1970 or so, there were two such instruments in 

common usage and availability in the United States, the Victoreen R-meter, or Landsverk L series ion 

chambers. Subsequently, a wide variety of such instruments have become available. Measurements 

with R-meters and similar chambers, if properly done, have a high degree of reliability and a low 

degree of uncertainty. In general, the uncertainty of properly done measurements in the energy 

region of interest should not exceed +2% of the measured value (Kathren and Larson, 1969). 

Other integrating devices such as film, thermoluminescent dosimeters (TLD) and pocket ionization 

chambers have also been used for beam output measurements. Measurements made with these 

types of dosimeters should be used with great caution. All are, to varying degrees, energy 

dependent, and correction for beam energy is a necessity. This requires knowledge of the x-ray 

beam energy and the response of the dosimeter as a function of energy. Typically, pocket ionization 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 16 of 46

chambers provide the least reliable measurements with the greatest uncertainty. Therefore, results 

obtained with these devices are highly suspect and should be used with great caution. Film and TLD, 

if appropriately calibrated to the beam energy, can provide satisfactory measurements, albeit with a 

considerable degree of uncertainty. The widely used LiF TLDs, compared with higher Z phosphors 

and film, show relatively good energy and other response characteristics, and, if properly used can 

provide uncertainties similar to those of R-meters. Considerably greater uncertainty – perhaps on the 

order of several tenths of a percent – may apply to film dosimeters. No specific uncertainty values 

can be provided here, as each film dosimeter and TLD system is different, and reference to the 

literature is necessary to determine the appropriate values for specific dosimeter systems. 

Beam output measurements usually define or directly determine the ESE, or can be corrected to 

obtain a reasonable estimate of the ESE for a given procedure by using the generic intensity 

relationships shown in Table 2-1. The ESE will, of course, be in units of R, which must be converted 

to kerma and then to organ dose. As discussed above, an exposure of 1 roentgen (R) is typically 

taken to be equal to a kerma of 1 rad (10 mGy); actually, 1R is slightly less than 1 rad (10 mGy) of 

kerma, but the difference is small and making the numerical equivalence greatly simplifies the dose 

reconstruction as well as providing a small additional measure of claimant favorability.

Once the ESE has been converted to entrance kerma, doses to a number of different organs from 

various radiographic procedures can be obtained from tables A2 through A8 of International 

Commission on Radiological protection (ICRP) Publication 34 (ICRP 1982). ICRP 34 (1982) Tables 

A2 through A8 do not provide dose conversion factors for un-collimated x-ray machines. Use of these 

tables requires knowledge of the x-ray beam quality expressed in terms of the HVL in millimeters of 

Aluminum (Al). If the kVp and filtration are known, HVLs can be estimated from the data given in 

Table A16 of ICRP Publication 34 (ICRP 1982, p. 77) or Table B.2 in NCRP Report No. 102 (1989 p. 

98). In general, the greater the kVp and filtration, the greater the HVL. If the actual beam quality is 

unknown, as is likely the case, to ensure claimant favorability a higher rather than a lower HVL should 

be assumed. In the absence of actual data, recommended default values for beam quality are 2.5 

mm Al HVL for radiographs taken prior to 1980, and 4.0 mm for subsequent radiographs. These 

values are likely overestimates of HVL and hence are claimant favorable.

However, Tables A2 to A8 in ICRP Publication 34 (1982) do not include all the organs that have been 

identified in the Interactive RadioEpidemiological Program (IREP) code. For those organs included in 

the IREP but not specifically identified in ICRP Publication 34 (1982), use of the dose conversion 

factors for the organ specified in ICRP Publication 34 (1982) that is anatomically the closest would 

seem to be a reasonable and simple first order approach that generally would be claimant favorable 

or neutral. Refer to Figure1 below. Thus, the factor for lung would be applied to all other organs 

within the thoracic or abdominal cavity that may be intercepted by the primary beam – i.e. thymus, 

esophagus, stomach, and liver/gall bladder/spleen. Since an appreciable fraction of the skeleton, and 

in particular the trabecular bone which has a large surface-to-volume ratio and the sternum which is a 

primary location of the red marrow in the adult, lies within the trunk, the factor for lung would also be 

applied to the bone surfaces. For organs in the lower abdomen – i.e., urinary bladder, and 

colon/rectum, – the dose conversion factor for ovary would be used. For the eye/brain, the analogous 

organ is the thyroid. These relationships are shown in tabular form in Table 3-2. Skin dose can be 

obtained by reference to Table B.8 in NCRP Report No. 102 (NCRP, 1989, p. 103), which provides 

backscatter factors for different beam qualities and field sizes. For chest radiography, a backscatter 

factor of 1.35 is recommended to ensure claimant favorability. (The backscatter factor of 1.35 is for 

2.5 mm Al HVL; NCRP Report No.102, 1989, Table B.8, P.103 provides a range of backscatter 

factors for various HVLs.) 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 17 of 46

It is useful to prepare a summary table of beam parameters as shown in Table 3-3. This table is 

taken from actual data and measurements available for the Hanford Site and is shown here as an 

example of what a summary table should include where measurements are available. The table 

includes not only the measured values for given time periods, but a reference to those values as well 

as other salient data pertaining to beam and exposure. It is of interest albeit not unexpected to note 

that there is a generally decreasing trend of ESE with time, which is wholly consistent with what has 

been the general experience nationally (Gray 1996). For conservatism in determining or 

reconstructing doses and in accordance with the guidance put forth in OCAS-IG-001, the ESE should 

be assumed to have been constant from the time of the measurement until the time of the next 

measurement. 

3.2 RECONSTRUCTION USING TECHNIQUE FACTORS

When beam measurement data are unavailable, as is likely to be the case, technique factors can be 

used to obtain reasonable estimates of exposure. The basic data required are kVp, filtration, 

exposure in mAs, and distance. Beam output data are available from a number of publications, 

including NCRP Report No. 102 (NCRP 1989). Table B.3 in this report (p. 99) provides average air 

kerma rates for medical diagnostic x-ray equipment operating at various kVp with 2.5 mm Al filtration 

at distances from 30 to 182 cm from the source. Correction for different thickness of Al filtration can 

be made by reference to Table 3.1, p. 13 in NCRP Report No. 102 1989. As an alternative, Figure 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 18 of 46

Figure 3-1. Anatomy of a human torso (Merck 2003, Section 1, 

Chapter 1).3

Table 3-2. Analogues for IREP organs not included in ICRP 

34. 

Anatomical

location

ICRP 34

reference organ IREP organ analogues

Thorax Lung Thymus

Esophagus

Stomach

Bone surface

Liver/gall bladder/spleen

Remainder organs

Abdomen Ovaries Urinary/bladder

Colon/rectum

Head and neck Thyroid Eye/brain

B.1 (p. 109) in NCRP Report No. 102 provides a graphical representation of air kerma at 100 cm for 

various values of kVp and filter thickness greater than 2.5 mm Al (NCRP 1989, p109). Using these 

tables, a reasonable estimate of beam output and hence entrance kerma can be obtained. Once the 

entrance kerma has been determined, organ doses are determined in the manner described above for 

reconstruction using measurement data.

 

3 Source: http://www.merck.com/mrkshared/mmanuel_home/illus/1i1.jsp. 
Document No. ORAUT-OTIB 0006 Revision No. 03 Effective Date: 08/02/2005 Page 19 of 46

Table 3-3. Example of summary data based on actual beam measurements for the Hanford site. Date measured 10/18/1999 2/04/98 4/22/1997 11/11/1993 3/30/1990 1/21/1988 1/20/1988 1/28/1983 4/12/1959 2/1/1946 Before 2/46

Procedure Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Chest PA 

14"×17"

Machine type XMA - 360 XMA - 360 CONXI Type 

12

CONX Type 

12

CONX Type 

12

CONX Type 

12

CONX Type 

12

G.E. DXR 750 Unknown Unknown Unknown

Machine settings 

kVp:

110 110 110 110 110 110 110 100 80 80 Unknown

mA 300 300 300 200 200 200 100 200 300 500 Unknown

Exposure time 1/60 sec 1/60 sec 1/30 sec 1/30 sec 1/30 sec 1/20 sec 1/10 sec 1/20 sec 1/30 sec 1/20 sec Unknown

mAs 5 5 10 6.7 6.7 10 10 10 10 25 Unknown

Added filter 2.7 mm 2.7 mm 2.5 mm 2.5 mm 2.5 mm 2.5 mm 2.5 mm 2.5 mm 1.5 mm 1.5 mm 1.5 mm

Assumed HVL, Al 4.0 mm 4.0 mm 4.0 mm 4.0 mm 4.0 mm 4.0 mm 4.0 mm 2.5 mm 2.5 mm 2.5 mm 2.5 mm

Source to skin 

distance

72" 72" 72 " 72 " 72 " 72 " 72 " 72 " 72 " 72 " 72 "

Entrance skin 

exposure

11 mR 11 mR 17 mR 21mR 21 mR 

(Assumed)

35 mR 35 mR 35 mR 40 mR 79 mR 120 mR

mR/mAs 2.2 2.2 1.7 3.3 3.3 3.5 3.5 3.5 4 3.2 Unknown

Date range 2/98 to date 4/97 to 2/98 3/90 to 4/97 1/83 to 3/90 4/59 to 1/83 2/46 to 4/59

Reference Washington 

State Dept. 

of Health 

Measurement

Washington 

State Dept. 

of Health 

Measurement

Washington 

State Dept. 

of Health 

Measurement

Washington 

State Dept. 

of Health 

Measurement

Measured at 

11.7 mR by 

State. The 

1993 value 

was used, as 

it was higher 

for same 

settings & 

machine. 

Washington 

State Dept. 

of Health 

Measurement

Washington 

State Dept. 

of Health 

Measurement

Kathren to 

Heid 

memorandum 

Dated 1/28/83

Rising & 

Soldat letter 

to Norwood 

dated 

4/30/59

Mancuso et 

al. Dated 

1966

Based on 

experience & 

references of 

early 1940s 

x-ray dose. 

Assumed for 

Hanford.
Document No. ORAUT-OTIB-0006 Revision No. 03 PC-1 Effective Date: 12/21/2005 Page 20 of 46

3.3 RECONSTRUCTION USING DEFAULT VALUES

Default values of entrance kerma have been developed for the three most commonly used 

occupational medical diagnostic x-ray procedures: PA chest radiography; lateral (LAT) chest 

radiography; photofluorographic (PFG) chest films when actual measurement data or knowledge of 

technique factors are absent. The default values are considered to be maxima or upper limit values 

developed from review of patient doses as reported in the literature, machine characteristics, and 

knowledge of x-ray procedures used during the time periods indicated and hence are claimant 

favorable. Sufficient conservatism was included in the determination of the default values to ensure 

with near certainty (99+ per cent confidence) that the actual exposures from the specified procedures 

would not exceed the default values, thus ensuring claimant favorability. In determining these factors, 

it was assumed that a minimum of filtration was used along with low kilovoltage techniques, slow film 

speeds with standard development, and no additional collimation or use of cones. The default 

entrance kerma values for the three procedures are given in Table3-4.

Table 3-4. Default dose values by procedure. 

Period

Entrance 

kerma, cGy

PA chest

Entrance 

kerma, cGy

lateral chest

Entrance kerma, cGy

photofluorographic 

chest

Pre-1970 0.20 0.50 3.0

1970-1985 0.10 0.25

Post 1985 0.05 0.13

These default values can then be used as described above in lieu of actual measurement data or 

entrance kerma derived from technique factors, but need to be applied with care. As a rule of thumb, 

the ESE and entrance kerma for a lateral chest x-ray is assumed to be 2.5 times that from a 

corresponding PA chest radiograph, a conservative and hence claimant favorable value based on 

measurements from Hanford (Kirklin et al. 1969) where a factor of 1.94 was observed, and other 

measured data which suggest that the ratio of ESE from lateral and PA chest radiographs could have 

been somewhat greater (Cardarelli et al. 2002; Stanford and Vance 1955). To ensure that dose from 

this source was not underestimated, the moderately conservative factor of 2.5 was assumed for the 

ratio of ESE from lateral to PA chest radiography for the purpose of organ dose calculations.

This value should be used with the appropriate tables (A.2 through A.8) from ICRP Publication 34 

(ICRP 1982) to determine organ doses. It needs to be stressed that it is the entrance kerma or ESE 

of a lateral view that is 2.5 times the kerma or ESE of a PA view, and not the organ doses. 

4.0

Because 

of geometry and other considerations, the organ doses for a lateral view do not scale linearly with the 

ESE for a PA view, and need to be determined accordingly from the ICRP 34 (1982) tables A.2 

through A.8.

Table 6-5 provides organ dose conversion factors and organ dose calculations for chest radiography 

dose reconstruction for the default case provided in Table 3-4 above.

APPLICATION AND REPORTING OF OCCUPATIONAL MEDICAL CHEST X-RAY 

DOSE RECONSTRUCTION

5.0

Photofluorography (PFG), also known as photoroentgenography, was utilized for routine chest 

radiography and, as has been well documented in the literature, typically produces higher patient 

doses than conventional radiography (Braestrup 1958, p. 140; Laughlin et al., 1957; Moeller, Terrill 

PHOTOFLUOROGRAPHY 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 21 of 46

and Ingraham, 1953). It is reasonable to presume that at least some of the occupational medical 

diagnostic chest x-rays with the DOE and its predecessor organizations were accomplished by PFG 

and in the absence of data to the contrary, the use of PFG should be assumed to ensure claimant 

favorable dose reconstructions. PFG differed from conventional radiography with film in that while 

kVp and mA settings could be manipulated by the technician, the exposure time was regulated by the 

amount of light generated in the PFG unit, with a cutoff or maximum exposure time. An exposure of 

15 mAs (150 mA for 0.1 second) was sufficient to produce a satisfactory image on 35 mm film; larger 

film required greater exposures (Sante, 1954, p. 129). 

Typical operating parameters reported for 1950’s PFG were 24 mAs at 83 kVp at a target to film 

distance of 36 inches (Braestrup, 1958, p. 143), and 30 mAs at 90 kVp with a target to film distance of 

40 inches and 2.4 mm added filtration. In the absence of data, added filtration of 2.5 mm should be 

assumed for dose determinations and is claimant favorable (Feldman et al., 1958). The reported 

gonadal doses equated to 0.15 and 0.36 mrad, respectively, for females and males in the United 

Kingdom (Stafford and Vance 1957), and 1 and 2 mrad, respectively for females and males, in an 

American study (Laughlin et al.1957). In another study in the United States, (Feldman et al. 1958), it 

was reported gonadal exposures equivalent to doses of 0.73 for males and 15 mrad for females, the 

large difference being attributable to assumed collimation. Data in the literature indicate an ESE in 

the region of about 0.5 to 1 R (Laughlin et al. 1957; Feldman et al. 1958; Moeller, Terrill and 

Ingraham, 1953). Measurements at the Hanford site indicated that for a 60 mAs PFG exposure at 

100 kVp, the ESE was 1.53 R (Rising and Soldat, 1959), which is likely an upper limit value based on 

a large patient and is consistent with an ESE of about 600-700 mR for a 24-30 mAs exposure at 

somewhat lower kVp. Thus, although the Hanford measured value is likely an upper limit and hence 

an overstatement of the actual exposure from photofluorography to the average patient, this 1.53R 

ESE value should be used in the absence of data to ensure claimant favorability. 

Organ doses for chest photofluorography are calculated in a different manner from organ doses 

calculated for conventional radiography using the entrance kerma values. Table 6-5 provides dose 

conversion factors for the ICRP organs based on a distance of 102 cm and beam quality of 2.5 mm Al 

HVL. Where entrance kerma values are unavailable, default values for organ doses should be used; 

these are given in Table 3-4. 

Dose estimates for PFG represent absolute upper limits and must be used to ensure claimant 

favorability in the absence of more specific information. At sites where measurements or technique 

factors are available, the organ doses could very possibly be lower.

The use of PFG has been documented for different DOE sites and specific dates. The specific dates 

for the last documented use of the photofluorography equipment and techniques are listed in Table 7-

6. In addition, the table lists the references used for the documentation.

6.0

At some sites, lumbar spine radiographs were routinely required for certain classes of male workers to 

determine the presence of back problems. The frequency of lumbar spine views, if required, was 

variable. Typically if lumbar spine radiography was required, it was performed as part of the 

preemployment physical examination, and for many workers this may have been the only occasion on 

which lumbar spine radiographs were taken. However, the possibility of periodic lumbar spine 

examinations, including an exit employment physical examination should not be precluded. Lumbar 

spine examinations for evaluating back problems might have included both an AP and lateral view, 

and in the absence of data to the contrary, it should be assumed that both views—a total of 4 views (2 

AP and 2 lateral) as indicated in Table 7-7—were taken. Recommended practice was to use a 5” 

LUMBAR SPINE
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 22 of 46

Table 6-5. Organ doses for default entrance kerma values. 

Organ View

Dose conversion factor 

(mGy per Gy air kerma)(a)

HVL 2.5 mm Al for photofluorography (PFG)(b)

Beam for PFG includes 

thyroid, and thoracic 

organs. It does not 

include gonads, bladder, 

or colon/rectum.

Organ dose 

PFG (rem)

March 1945 to 

January 31, 1962

Dose conversion 

factor (mGy per Gy air 

kerma)(a)

HVL 2.5 mm Al

minimal collimation

Organ dose 

pre-1970 (rem)

(c,d)

minimal collimation

Thyroid PA 174(h) 5.22E-01 174 (h) 3.48E-02

Lat 137 6.85E-02

Eye/brain PA 32 9.60E-02 32 6.40E-03

Lat 137 6.85E-02

Ovaries PA N/A 2.5 E-02 (g) N/A 2.5 E-02 (g)

Lat N/A 1.3 E-02 (g)

Liver/gall 

bladder/spleen

PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Urinary bladder PA N/A 2.5 E-02 (g) N/A 2.5 E-02 (g)

Lat N/A 1.3 E-02 (g)

Colon rectum PA N/A 2.5 E-02 (g) N/A 2.5 E-02 (g)

Lat N/A 1.3 E-02 (g)

Testes PA N/A 5.0 E-03 (g) N/A 5.0 E-03 (g)

Lat N/A 2.5 E-03 (g)

Lungs (male) PA 419 1.26E+00 419 8.38E-02

Lat 193 9.65E-02

Lungs (female) PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Thymus PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Esophagus PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Stomach PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Bone surfaces PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Remainder PA 451 1.35E+00 451 9.02E-02

Lat 220 1.10E-01

Breast PA 49 1.47E-01 49 9.80E-03

Lat 255 1.28E-01

Uterus 

(embryo)

PA N/A 2.5 E-02 (g) N/A 2.5 E-02 (g)

Lat N/A 1.3 E-02 (g)

Bone marrow 

(male)

PA 92 2.76E-01 92 1.84E-02

Lat 37 1.85E-02

Bone marrow 

(female)

PA 86 2.58E-01 86 1.72E-02

Lat 29 1.45E-02

Skin (e) PA 4.05E+00 2.70E-01

Lat 6.75E-01
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 23 of 46

Table 6-5 (Continued). Organ doses for default entrance kerma values.

Organ

Chest

view

Dose conversion 

factor (mGy per 

Gy air kerma) (a)

HVL 2.5 mm Al

collimated

Organ dose 1970-

1985

(rem) (c,d)

collimated

Dose conversion 

factor (mGy per Gy air 

kerma)

HVL 4.0 mm Al (a)

collimated

Organ dose

post 1985

(rem) (c,d)

collimated

Thyroid PA 32 3.20E-3 78 3.90E-3

Lat 115 2.88E-2 164 2.13E-2

Eye/brain PA 32 3.20E-3 78 3.90E-3

Lat 115 2.88E-2 164 2.13E-2

Ovaries PA 1 1.00E-4 5.2 2.60E-4

Lat 0. 6 1.50E-4 2.5 3.25E-4

Liver/gall 

bladder/spleen

PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Urinary bladder PA 1 1.00E-4 5.2 2.60E-4

Lat 0. 6 1.50E-4 2.5 3.25E-4

Colon/rectum PA 1 1.00E-4 5.2 2.60E-4

Lat 0. 6 1.50E-4 2.5 3.25E-4

Testes PA 0.01 1.00E-6 0.01 5.00E-7

Lat 0.1 2.50E-5 0.1 1.30E-5

Lungs PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Thymus PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Esophagus PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Stomach PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Bone surfaces PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Remainder PA 451 4.51E-2 674 3.37E-2

Lat 220 5.50E-2 351 4.56E-2

Breast PA 49 4.90E-3 116 5.80E-3

Lat 255 6.38E-2 343 4.46E-2

Uterus

(embryo)

PA 1.3 1.30E-4 5.2 2.60E-4

Lat 0.6 1.50E-4 2.1 2.73E-4

Bone marrow PA 92 9.20E-3 178 8.90E-3

Lat 37 9.25E-3 76 9.88E-3

Skin (f) PA 1.35E-1 7.00E-2

Lat 3.38E-1 1.82E-1

a. Dose conversion Factors from Tables A.2 through A.8, ICRP Publication 34 (1982).

b. Image Receptor Size (cm) 10.2 x 12.7 or 12.7 x 25.4 for stereo films. 

c. Source to Imaged-Distance 183 cm.

d. Image Receptor Size (cm) 35.6 x 43.2 

e. Calculated using backscatter factor of 1.35 for HVL of 2.5 mm Al from NCRP Report No.102, Table B-3 

f. Calculated using backscatter factor of 1.40 for HVL of 4.0 mm Al from NCRP Report No.102, Table B-3 

g. Modified from Webster, if measurement data is available it should be used.

h. Dose Conversion Factor for AP c-spine, corrected for depth by 0.2.

cone (Sante 1954, p. 207) for improved radiographic quality, thus limiting the beam diameter to 5” at 

the skin entrance point. 

Examples of lumbar spine radiograph technique factors used at Oak Ridge National Laboratory are 

shown in Table 7-7; Tables 7-8 through 7-10 give values for organ dose calculations and examples of 

calculated doses based on the ORNL experience. Note that the image receptor size—i.e. the beam 

size at the film—implies a larger beam diameter than 5” at the skin entrance point and hence is 

claimant favorable. In the absence of actual site-specific data, the ORNL technique factors and the 

resultant doses derived from these can be used to provide claimant favorable dose estimates from 

lumbar spine radiography. 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 24 of 46

7.0

Fluoroscopy, not to be confused with photofluoroscopy previously discussed above in which a 

photograph is taken of an activated fluorescent screen, involves real time viewing of a fluorescent 

screen continuously activated by x-rays. Because of the time and limitations of fluoroscopy, this 

procedure was not generally amenable to mass examinations or to preemployment screening of 

workers, although it did find occasional application in the occupational setting for examination of the 

chest. The eminent American radiologist Leo Rigler devoted but a single paragraph, reproduced in its 

entirety below, under the heading “Chest Fluoroscopy” in his book Outline of Roentgen Diagnosis, 

which was a standard text published in1938 and has but a single paragraph on the topic: 

FLUOROSCOPY

Table 7-6. Use of photofluorography at DOE sites. 

DOE site

Last documented

use of PFG Comments Reference

Hanford January 31, 

1962(a) ----- Rising, F. L. and J. K. Soldat, 1959, “Radiation Exposures During Diagnostic Radiographic 

Examinations at Kadlec Methodist Hospital,” letter to 

Dr. W. D. Norwood, April 30, 1959

K-25 1956 ----- J. J. Cardarelli, "A Potential Consequence of Excluding 

Work-related X-Ray Exposures when Computing 

Cumulative Occupational Radiation Dose at a Uranium 

Enrichment Plant," Dissertation, Univ. Cincinnati, 

Cincinnati, Ohio, 2000.

LANL 1964 Pre-1964 

medical records 

being reviewed

Shipman, T.L., “Annual Report of the Health Division” 

1954, LA-1888, Los Alamos, New Mexico, January 

1955.

ORNL October, 1947 ----- ORNL, 2002, “ORNL Historical X-ray Practices and 

Protocols,” no date 

Portsmouth October 1957 ----- Claimant’s medical file

Rocky Flats Potentially used 

from 1953 to 1968

----- Memo: Excel file labeled “X-ray Machine Info from 

Rocky Flats, 2003” (printed from Rocky Flats medical 

records database)

Savannah River Early 1967 ----- Cooley, R. C. Memorandum to E. C. Morris “Progress 

Report Calibration of Medical X-Ray Machine at the 

Savannah River Plant” dated November 4, 1966 

(Revised November 10, 1966).

Fernald ----- PFG Not used Memo from FEMP to DOE dated May 7, 2000 

INEEL ----- PFG Not used Based on review of records.

Iowa Ordnance Plant ----- PFG not used Based on review of records.

Mound ----- PFG not used Based on review of records.

NTS ----- PFG not used Based on review of records and discussions with 

Martha DeMarre at the NTS.

Paducah ----- PFG not used Interview with site personnel knowledgeable of the 

history of the medical x-ray program

a. The Hanford x-ray record form listed PFG until 1/31/1962, thus PFG may have been used until that date.

Table 7-7. Example of lumbar spine x-ray operating parameters, dates of use, and frequency of 

examinations (taken from ORNL ORAUT-TKBS-0012-3 Rev0, P 17).

Dates X-ray equipment Location Techniques X-ray conditions People involved

April 6, 

1950, to 

September 

23, 1953

Picker 200-mA Control & 

Generator- Model R-2 

ORNL Lumbar spine series, 

4 films: AP, AP spot, 

Lateral, and Lateral 

spot

AP & AP spot

Filter=0.04 mm Al, 80 kVp, 

40 mA, 4 sec @ 99 cm. 

distance, w/ 20-cm cone

Craft workers

Lat & Lat spot

Filter=0.04 mm Al, 86 kVp, 

40 mA, 8 sec @ 99 cm 

distance, w/ 20-cm cone
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 25 of 46

Table 7-8. Values used to calculate organ dose, AP and lateral lumbar spine.

Years included Examination Workers affected ESE (rem) HVL (mm Al)

1950-1953 LS APa Preplacement for craft workers 4.0E+00 c 2.0

1950-1953 LS Latb Preplacement for craft workers 1.0E+01 2.0

a. The ESE for the LS AP represents both the AP and spot AP exposures (i.e., 2 exposures). Values in Table 7-9 also 

indicate organ doses from both exposures.

b. The ESE for the LS Lat represents both the Lat and spot Lat exposures (i.e., 2 exposures). Values in Table 7-9 also 

indicate organ doses from both exposures.

c. This value rounded up to 4.0E+00 rem from 3.8 E+00 rem (2X1900) listed in Table VII Lincoln & Gupton (1958b).

Table 7-9. Example of average absorbed dose per unit entrance air kerma 

for AP and lateral lumbar spine x-ray views, organ DCFs, and beam 

quality,

a April 6, 1950 to September 23, 1953.

Organ View b Source-image distance (cm)

Image 

receptor 

size (cm)

Dose conversion factor 

(mGy per Gy air kerma) 

for HVL = 2.0 mm Al 

Thyroid LS AP 99 35.6 × 43.2 0.2

LS Lat. 99 35.6 × 43.2 0.01

Eye/Brain LS AP 99 35.6 × 43.2 0.2

LS Lat. 99 35.6 × 43.2 0.01

Ovaries LS AP 99 35.6 × 43.2 N/A (d)

LS Lat. 99 35.6 × 43.2 N/A (d)

Testes LS AP 99 35.6 × 43.2 N/A (d)

LS Lat. 99 35.6 × 43.2 N/A (d)

Lungs LS AP 99 35.6 × 43.2 62

LS Lat. 99 35.6 × 43.2 10

Breast LS AP 99 35.6 × 43.2 18 (c)

LS Lat. 99 35.6 × 43.2 9.5 (c)

Uterus (embryo) LS AP 99 35.6 × 43.2 217

LS Lat. 99 35.6 × 43.2 20

Bone marrow LS AP 99 35.6 × 43.2 24

LS Lat. 99 35.6 × 43.2 15

LS Lat. 99 35.6 × 43.2 --

Skin (e) LS AP 99 35.6 × 43.2 1.32 (e)

LS Lat. 99 35.6 × 43.2 1.32 (e)

a. Dose conversion factors (DCFs) for an HVL of 2.0 mm Al are from Tables A.2 through A8 of ICRP 

34 (1982), assuming good collimation of the beam, unless otherwise noted. 

b. LS = lumbar spine.

c. Dose conversion factors for lumbar spine examination not given in ICRP 34. Values for the 

respective Upper G.I. exams (i.e., AP and Lat) were used instead.

d. Organ dose values for the testes and ovaries for lumbar spine for 1950 – 1953 reflect actual 

measurement reported in (Lincoln and Gupton 1958b).

e. Skin dose values include backscatter factors of 1.32 from Table B.8 of NCRP Report No.102 

(1989).

“This is of value in determining the movements of the diaphragms, the position and 

motion of the mediastinum, the aeration of various parts of the lung, in detecting and 

localizing gross changes especially pleural encapsulation, abscess, extensive 

tuberculosis. It is of little value in the detection of early lung changes and in the 

diagnosis of early tuberculosis.” (Rigler 1938) 

In his book A Handbook of Roentgen Diagnosis—The Chest”, second edition published in 1954, 

Rigler had this to say (p. 18): “In consideration of the value of fluoroscopy it should be borne in mind 

that its usefulness is largely related to the grosser lesions of the thorax.” (Rigler 1954). Contemporary 

diagnostic radiology texts of the time are more or less consistent with the views succinctly expressed 

by Rigler [de Lorimer et al. (1953); Rabin (1968)]. One widely used standard textbook of radiology,

while noting that “Fluoroscopic methods of examination have a definite place in the x-ray analysis of 

chest conditions”, qualified this statement by further noting that the value of chest fluorography was 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 26 of 46

Table 7-10. An example of organ dose estimates for ORNL AP 

and lateral lumbar spine radiographs to be used as IREP inputs.

a

Organ View Organ dose (rem) 1950–1953

Thyroid LS AP 8.00E-04 (b)

LS Lat. 1.00E-04 (b)

Eye/brain LS AP 8.00E-04 (b)

LS Lat. 1.00E-04 (b)

Ovaries LS AP 1.12E+00 (b) (d)

LS Lat. 1.52E+00 (b) (d)

Liver/gall bladder/spleen LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Urinary bladder LS AP 1.12E+00 (b) (d)

LS Lat. 1.52E+00 (b) (d)

Colon/rectum LS AP 1.12E+00 (b) (d)

LS Lat. 1.52E+00 (b) (d)

Testes LS AP 5.40E-02 (b) (d)

LS Lat. 1.12E-01 (b) (d)

Lungs LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Thymus LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Esophagus LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Stomach LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Bone surfaces LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Remainder LS AP 2.48E-01 (b)

LS Lat. 1.00E-01 (b)

Breast LS AP 7.20E-02 (b)

LS Lat. 9.50E-02 (b)

Uterus (embryo) LS AP 8.68E+00 (b)

LS Lat. 2.00E-01 (b)

Bone marrow LS AP 9.60E-02 (b)

LS Lat. 1.50E-01 (b)

Skin (c) LS AP 5.28E+00 (b)

LS Lat. 1.32E+01 (b) 

a. The exposures for various date ranges should be matched to the X-ray 

examinations listed in Table 7-7. 

b. Value is doubled to account for two exposures.

c. Skin dose values include backscatter factors of 1.32 from Table B.8 of 

NCRP Report No.102 (1989).

d. Organ dose values for the testes and ovaries for lumbar spine for 1950 – 

1953 reflect actual measurements reported in (Lincoln and Gupton 

1958b).

only in the detection of the character of movements and also cautioned “The substitution of 

fluoroscopy for radiographic methods is neither wise, safe, nor even defensible now that 

photofluorographic apparatus is available”. (Hodges, Lampe, and Holt 1947).

Even so, although fluoroscopy was little used and certainly not a standard routine preemployment or 

occupational diagnostic procedure for the chest, even in the early 1940’s, there are indications that 

fluoroscopic examinations of the chest were conducted and required at least one site (Linde 

Ceramics) during the 1942-43 time frame, and it is possible that such examinations were also 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 27 of 46

conducted elsewhere. Typical fluoroscopes of the 1940’s and 1950’s operated at 100 kVp and 4 mA 

(Braestrup 1958; Files 1956; Sante 1954). As early as 1936, recommended added filtration was 1 

mm Al (NBS Handbook HB20). Machine output was highly variable, producing an ESE rate to the 

patient ranging from about 2 R/min for a well operated ‘modern’ unit with appropriate filtration to 

several tens of R/min for older, poorly maintained units with short target to panel distances and 

also which may not have had adequate filtration. Typically, exposure rates at the panel (i.e. ESE) did 

not exceed 10 R/min. However, the total exposure to the patient was dependent not only on machine 

output but also on exposure time, which in turn was a function of the radiologist. Some radiologists 

applied the x-rays in short bursts, others just “put their pedal to the metal” and basically kept their foot 

on the switch throughout the entire procedure. Inadequate dark adaptation by the radiologist would 

result in higher exposures largely as a result of longer exposure times. For this reason, many 

machines were equipped with timers to restrict exposure, normally to 25 R at the panel, for any given 

examination. For most examinations, total exposure times probably were less than a minute—

perhaps 15-30 seconds, although exposures of a minute or more were not uncommon with some 

radiologists. 

A claimant favorable estimate of dose can be made by assuming an exposure time of two minutes 

(high) and an ESE rate of 20 R/min. The assumed ESE rate is also high and presumes no image 

amplification and a short target to skin distance (TSD). The result is a highly claimant favorable ESE 

of 40 R, which is probably high by at least a factor of two, and at the upper end of the range of 

exposures encountered in chest fluoroscopy. However, in the absence of additional research or other 

data to the contrary, an ESE of 40 R should be taken as the likely claimant favorable exposure.

As a practical matter, all fluoroscopic beams were equipped with diaphragms and hence collimated; 

cross-section was usually rectangular. However, for claimant favorability, maximum beam size 

without diaphragms can be estimated by geometry. Assuming the aperture and distance from the 

focal spot (target) to the aperture are equal, the beam diameter would be equal to the TSD. 

Assuming a large TSD (50 cm) to maximize the beam size, the beam diameter in this case would be 

50 cm or about 20 inches, which would be about the upper limit on beam size. 

Note that ICRP Publication 34 is relatively recent (1982) and calls for an air kerma rate at the patient 

of 50 mGy/min (about 5 R/min) which is about double the standard or rule of thumb used back in the 

1950’s. However, if the ratio of skin dose from fluoroscopy to skin dose from radiography given in 

ICRP 34 holds for earlier years, then the ESE of 40 R given above is certainly claimant favorable and 

perhaps at the upper end (or even somewhat beyond) of what is realistic.

8.0

Prior to about 1970, x-ray measurement data, techniques, or beam port information may not be 

available to estimate the collimation of the x-ray beam. Several papers in the literature have 

considered the effects of cone size and centering on organ doses, and concluded that filtration, kVp, 

and the smallest possible cone size were most important to reduce these doses. Due to the reported 

variation in the literature and measurement data on the effects of collimation, it is claimant favorable 

to assume minimal or no additional external collimation was used when measurement data, 

technique, or other information to describe the collimation are not available for x-ray procedures 

performed prior to 1970. 

RECONSTRUCTION OF ORGAN DOSE FROM RADIOGRAPHY EQUIPMENT USING 

MINIMAL COLLIMATION

Without collimation, organs normally outside of the primary beam, are exposed to the primary beam. 

This necessitates the use of dose conversion factors from ICRP 34 (ICRP1982) other than those for a 

PA or lateral (lat) chest x-ray, since ICRP 34 (1982) dose conversion factors are based on properly 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 28 of 46

collimated beams. For minimally collimated beams used prior to 1970, the substitute dose conversion 

factors in Table 9-11 were used.

9.0

Error (deviation from the correct, true, or conventionally accepted value of a quantity) and uncertainty 

(defined in terms of the potential range of a stated, measured, assumed, or otherwise determined 

value of a quantity) provide an indication of the confidence or validity of the dose estimates. Error 

implies knowledge of what the correct or actual value is, which is, of course, not known. Therefore, 

the more appropriate factor is uncertainty, which is expressed in terms of a confidence level, which in 

turn is expressed as a percent. Thus, the 99% confidence level indicates that the correct or true 

value, although not actually known, has a 99% probability of falling within the range cited. The 

statement of confidence level typically includes all potential sources of error, both random and 

systematic; the precision or reproducibility of the measurement; and accuracy, or how close the 

measurement or estimate of dose comes to the actual or correct value.

UNCERTAINTY ANALYSIS FOR DIAGNOSTIC MEDICAL X-RAY DOSES

Table 9-11. Substitute dose conversion factors. (For some x-ray exams performed prior to 1970).

Organ of interest

Substitute view and organ for which dose conversion 

to use for minimally collimated beams

Thyroid AP Cervical spine corrected for depth by a factor of 0.2 (NCRP 

102, Table B-8, P. 103)

Lat Cervical spine

Eye/brain PA and lat Skull, or PA chest, whichever is larger.

Ovaries and analogues, testes, and uterus PA and lat Abdomen

In theory, a large number of factors can introduce uncertainties or affect the x-ray machine output 

intensity and dose to the worker. However in practice only five factors can be reasonably considered 

to have a meaningful or significant impact on dose uncertainty. These are: 

1. Measurement error

2. Variation in applied kilovoltage (kVp)

3. Variation in beam current (mA)

4. Variation in exposure time (mAs)

5. Distance from the worker to the source of the X-rays (SSD)

The influence of such other factors as use of screens, grids, reciprocity failure, film speed, and 

development, while potentially variable, do not affect the beam output intensity per se except indirectly 

insofar as these may determine the exposure settings (i.e. kVp, mA, and time) used.

Medical x-ray doses, when measured, were largely derived from actual measurement of x-ray 

machine output with R-meters or similar ionization chamber devices suitably designed for 

measurement of photons in the medical x-ray energy range. If properly calibrated and used, R-meters 

and similar instruments typically and historically have had an uncertainty of + 2% for photon energies 

below 400 keV (Kathren and Larson, 1969). Although more recent versions of these instruments 

might provide a somewhat smaller uncertainty, perhaps on the order of + 1% (NBS, 1985; 1988), for 

conservatism, the uncertainty range of + 2% should be applied to measurements of x-ray intensity.

Theoretically, for a given set of machine settings and parameters, x-ray output should be constant and 

unvarying. However, this is not true in practice. Although output is essentially constant unless focal 

spot loading occurs, as might be the case when the power rating of the machine is exceeded, it is 

unlikely that power ratings were ever exceeded because such an event would be difficult to achieve in 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 29 of 46

practice and could result in damage to the x-ray tube. However, even with the use of constant voltage 

transformers to control line voltages, slight variations might occur in line voltage input or other internal 

voltages, which in turn could alter the kVp of the output beam. In general, for a given kVp setting, 

variation in kVp falls within + 5% of the machine setting (Seibert et al., 1991). Since as noted above, 

beam intensity is approximately proportional to the 1.7 power of the applied kilovoltage; this translates 

to an uncertainty of approximately ± 8.6% with respect to output beam intensity in the 80 to 100 kVp 

range used for diagnostic chest radiographs. For conservatism, this is rounded up to + 9%.

Similarly, slight variations in tube current are normal; as a tube ages, or heats up from use, current 

can change and typically will drop. With all other factors constant, beam intensity will be reduced in 

direct proportion to the change in tube current. Typically, the reduction in beam output from current 

variation is not more than a few percent under normal operating conditions; large decreases are 

readily detectable and manifest themselves as underexposed radiographs and result in maintenance 

on the machine to restore the output or, as a temporary measure, an increase in the current or kVp to 

provide the necessary intensity for proper radiography. For a given kVp setting, the output of the 

beam is a function of the tube current, which in turn is measured by a milliammeter, which measures 

average tube current. The measurement is subject to uncertainties; there might be minor changes in 

output as the tube heats from normal use. These variations are typically small, and the estimated 

uncertainty in beam intensity or output attributable to current variation is + 5%. 

Another parameter that has potential to affect the dose from a diagnostic radiograph, perhaps 

significantly, is the time of exposure. The potential importance of this parameter is underscored by 

noting that virtually all medical diagnostic medical x-ray units used in the DOE complex were of the full 

wave rectified type. A full-wave rectified machine produces 120 pulses of x-rays per second. Thus, in 

a typical radiographic exposure time of 1/20 of a second, only six pulses would result. A small error in 

the timer that resulted in a change of only ± 1 pulse would correspondingly affect the output by ± 17%; 

for an exposure time of 1/30 of a second, the change in output corresponding to a deviation of + 1 

pulse is ± 25%. Early mechanical timers were notoriously inaccurate; accuracy improved significantly 

with the introduction of electronic timers. Measurements of reproducibility made in the late 1980s and 

beyond by the State of Washington for the machines at Hanford suggest that the timers, and indeed 

the entire x-ray output, were fairly constant. However, for conservatism, the assumed uncertainty in 

beam output attributable to timers has been taken to be ± 25%. 

The final factor likely to affect worker dose relates to distance from the source of the X-rays, which is 

an important determinant of the entrance skin exposure (ESE) from which organ doses are 

calculationally derived. For a given individual, the SSD will be determined largely by the body 

thickness of the worker and the accuracy of the positioning. For a typical worker, the estimated 

variation in SSD is no more than a few centimeters, with an upper limit of perhaps 7.5 cm. Using 

inverse square, this indicates an uncertainty of ± 10% from this source.

There are two approaches to determine the combined uncertainty from the five potential sources of 

dose uncertainty listed above. The first, and most conservative in that it gives the greatest range, 

would be to assume that the uncertainties are additive, which would give an uncertainty range of 2 + 9 

+5 + 25 + 10 = ± 51%. However, a more reasonable approach would be to assume that the 

uncertainties are in fact random, and to compute the statistical root mean square (RMS) value. The 

RMS value is simply the square root of the sum of the squares, and computes as ± 28.9%. Rounding 

this up to + 30% would seem to provide an adequate and suitably conservative indication of 

uncertainty. Thus, for an individual ESE or derived organ dose, an uncertainty of ±30% at one sigma 

can be assumed; for further conservatism it might be appropriate to assume that errors are all 

positive, and only + 30% should be used. 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 30 of 46

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APPENDIX A

ORGAN DOSES FROM PELVIS AP X-RAYS IN THE 1940S

TABLE OF CONTENTS

Section

A1.0 Data..........................................................................................................................................

Page

35

A2.0 Dose Calculation.......................................................................................................................35

A2.1 ICRP Publication 34 (1982) Methodology............................................................................ 35

A2.2 Determination of Entrance Kerma ....................................................................................... 36

A2.3 Selection of ESD and HVL for ORGAN Dose Determination ............................................... 36

A2.4 Dose Conversion Factors.................................................................................................... 37

A2.4.1 For ICRP 34 (1982) Beam .......................................................................................... 37

A2.4.2 For Modified Beam ..................................................................................................... 37

A2.4.2.1 Organs Above the ICRP 34 Field Center.......................................................... 39

A2.4.2.2 Organs Below the ICRP 34 (1982) Field Center ............................................... 40

A2.4.2.3 Active Bone Marrow ......................................................................................... 40

A2.5 Doses..................................................................................................................................40

A2.5.1 Organs Other than Skin in the Beam .......................................................................... 40

A2.5.2 Skin in the Beam ........................................................................................................ 40

A2.5.3 Skin Outside but Near the Primary Beam ................................................................... 41

A2.5.4 Organs Outside but Near the Beam............................................................................ 41

A2.5.5 Body Parts Well Outside the Beam............................................................................. 41

A2.5.6 Organ Dose Tables .................................................................................................... 42

References ........................................................................................................................................46

LIST OF TABLES

Table

A-1 Pelvis AP x-ray doses reported by Lincoln and Gupton..........................................................

Page

35

A-2 Beam/patient geometry parameters assumptions ..................................................................37

A-3 DCFs for a pelvic AP x-ray (HVL 2.0 mm Al) for organs listed in ICRP 34..............................42

A-4 DCFs for pelvic AP x-ray (HVL 2.0 mm Al) for analogue organs not listed in 

ICRP 34 ................................................................................................................................. 42

A-5 Impact of modified beam on organs outside ICRP 34 beam...................................................43

A-6 Assigned DCFs for organs above field center of ICRP 34 beam ............................................43

A-7 Parameters related to dose to testes......................................................................................44

A-8 Organ doses from a pelvis AP x-ray.......................................................................................45
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 35 of 46

APPENDIX A

ORGAN DOSES FROM PELVIS AP X-RAYS IN THE 1940S

During the early years of atomic weapons work, the Manhattan Engineering District (MED) and the 

Atomic Energy Commission (AEC) sometimes required that pelvis x-rays be taken of personnel who 

worked with materials containing fluorine, to detect bone changes due to fluorosis (Van Horn 1943; 

Osinski 1947; Key et al 1977, p. 321).

This Appendix provides estimates of organ doses for use in dose reconstruction from AP pelvis 

radiography developed with the aid of dose conversion factors (DCF) in ICRP Publication 34 (ICRP 34 

1982). To account for the possibility that x-ray practices in the 1940s may not have been as effective 

in minimizing doses as those on which ICRP 34 (1982) is based, the beam is assumed to have been 

less well collimated and possibly displaced from the location assumed in ICRP 34 (1982). Scattered 

radiation is considered in estimating doses to portions of the body outside the beam.

Dose reconstructors are cautioned to verify that the assumptions in this Appendix are applicable 

before using the doses estimated here. If conditions are known to have been different from those 

assumed here, then doses based on the actual conditions should be calculated. The methodology of 

this section may be used as a guideline for the calculation.

A1.0

Table A-1 displays data for AP pelvis x-ray exams reported by Lincoln and Gupton (1958). The letters 

B, G, and F in the Table refer to x-ray practices at medical facilities in and near Oak Ridge National 

Laboratory. The reported doses at these facilities were based in part on measurements made using 

Landsverk L-82 thimble ion chambers inserted into cavities in a tissue-equivalent phantom. Data for 

the cases (facilities) denoted by numbers are based on literature reports cited by Lincoln and Gupton 

dated 1955 to 1957.

DATA

Table A-1. Pelvis AP x-ray doses reported by Lincoln and Gupton. 

Data reported by Lincoln and Guptona

Caseb 

Year of

report

Cone

diameter (cm)

Filter

(mm Al) kVp mAs

Dose (mrad)

Skin Testes Ovaries

B 1957 16 None 54 250 4700 160 660

G 1957 None None 54 300 4000 450 560

F 1957 20 1.0 80 160 2400 640 650

1 1955 — c — c 65 100 4700 1100 210

3 1957 — c — c 66 100 500 550 200

4 1956 — c — c — c — c — c 279 690

5 1955 — c — c — c — c — c 1080 400

6 1957 Spec. 3.0 75 80 480 20 80

a. Data from Lincoln and Gupton 1958.

b. Letters refer to medical facilities in or near Oak Ridge National Laboratory. Numbers 

refer to literature references in Lincoln and Gupton 1958 from which the listed values 

were taken. 

c. No data or not applicable.

A2.0

A2.1 ICRP PUBLICATION 34 (1982) METHODOLOGY

DOSE CALCULATION

The methodology of ICRP Publication 34 (1982) is used to estimate many of the organ doses. This is 

judged preferable even for determination of gonadal doses (for which Table A-1 provides values 
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measured on a phantom) because the methodology is based on elaborate Monte Carlo calculations 

for detailed anthropomorphic models that appear to be more representative of the human body than 

the phantom used by Lincoln and Gupton (1958). In ICRP 34 (1982) methodology, organ dose (OD) 

is obtained as the product of entrance kerma (EK) and a dose conversion factor (DCF):

OD = EK *DCF (A-1)

Entrance kerma is defined in ICRP 34 (1982) as “air kerma in air without backscatter.” The DCF 

values depend on the x-ray projection, the organ, and the quality [expressed as the half-value layer 

(HVL)] of the x-ray beam.

A2.2 DETERMINATION OF ENTRANCE KERMA

Lincoln and Gupton provided entrance skin dose (ESD) in units of mrad based on measurement from 

a tissue equivalent phantom. Since the measurement was on a phantom, backscatter was included. 

Therefore, to obtain entrance kerma (EK), the measured dose should be corrected for backscatter, 

which can be done by dividing by the appropriate backscatter factor obtained from NCRP Report 102 

(1989).

A2.3 SELECTION OF ESD AND HVL FOR ORGAN DOSE DETERMINATION

To avoid underestimating doses, and based on direction from NIOSH (Taulbee 2004 a, b), 2400 mrad 

was used from the Oak Ridge facility, case F for calculating organ doses and 4700 mrad from case B 

for skin dose. These cases correspond to the highest organ and skin dose values and are used, on 

this basis, for organ and skin dose determination. To identify the most claimant favorable case, Table 

A-1 provides data for cases from Lincoln and Gupton as shown above. Case 6 was added to show 

the reduction in dose that would occur by increasing the filtration and kV and reducing the mAs. As 

stated above Case F corresponds to the highest organ doses. For Case F, the ESD is 2400 mrad, 

and its calculated HVL is 1.5 mm Al assuming 0.5 mm Al inherent filtration. To allow for variability of 

x-ray technical factors, an upward adjustment of this HVL to 2 mm Al as recommended by NIOSH 

[direction from NIOSH in Davidson email on June 9, 2004 (Davidson 2004)] was made when 

determining organ doses. The entrance kerma (EK) corresponding to this value was calculated by

EK (Gy)(air) = 10-5 f * ESD /BF

EK (Gy)(air) = 10-5 0.93*2400/1.32 = 0.0169

where ESD is the entrance skin dose in mrad = 2,400 per Lincoln and Gupton (1958)

BF is the backscatter factor per Table B.8 of NCRP Report No. 102 (NCRP 1989) = 1.32; 

f is the ratio of energy deposition in air and soft tissue for a given exposure = 0.93, and

10-5 is a constant to convert from mrad to Gy.

The above is applicable only for internal organ dose determination. For skin dose, to ensure claimant 

favorability the maximum value reported by Lincoln and Gupton (1958; see Table A-1) of 4700 mrad 

was used (Davidson 2004). 
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A2.4 DOSE CONVERSION FACTORS

A2.4.1

The DCFs in ICRP 34 (1982) are based on a reference adult patient defined in Kereiakes and 

Rosenstein (1980), Table 94 and Figures 2 and 3. For a pelvis AP x-ray, the DCF values in ICRP 34 

(1982) are based on the assumptions that the image receptor is 102 cm from the x-ray source, that 

the beam is collimated to an image receptor size of 43.2 cm x 35.6 cm (where 35.6 cm represents the 

dimension parallel to the height of the patient), and that the field center of the beam is 80 cm below 

the top of the head of the reference patient (see Table 95 of Kereiakes and Rosenstein 1980). Dose 

conversion factors from a pelvis AP x-ray for organs treated in ICRP 34 (1982) are shown in Table 

A-3. 

For ICRP 34 (1982) Beam

The ICRP 34 (1982) beam would impact some organs of interest that are not explicitly addressed in 

ICRP 34 (1982). These additional organs were identified by overlaying a transparency with an outline 

of the beam cross-section on anatomy drawings to which the beam outline had been scaled. Each of 

the additional organs is in the abdominal region. Based on the guidance on organ analogues in Table 

3-2 of the main text, each is assigned the ICRP 34 (1982) factor for dose to the ovaries for a pelvis AP 

x-ray. Table A-4 lists the organs and the assigned DCFs.

A2.4.2

To account for the possibility that x-ray practice in the 1940s may not have been in conformance with 

the assumptions on which ICRP 34 (1982) is based, and thus ensure claimant favorability, a modified 

beam was postulated. The modified beam assumed minimal collimation (Taulbee 2004b) and thus 

was larger in area than the ICRP 34 (1982) beam and had a circular rather than a rectangular crosssection. Further, the beam was assumed to be possibly displaced vertically by positioning errors and 

was characterized by the following assumptions:

For Modified Beam

• Circular cross-section;

• Beam area at the film equal to twice the film area. (See above)

Additional organs impacted by the enlarged beam were identified by overlaying a transparency with 

an outline of the beam cross-section on anatomical drawings to which the beam outline had been 

scaled. To avoid underestimating the impact on organs near the exit plane of the beam, the beam 

outline represented the size of the beam at the image receptor. The center of the modified beam was 

postulated to be displaced by ± 3 cm vertically from the location assumed in ICRP 34 (1982) — 

upward for identifying additional organs above the ICRP 34 (1982) location and downward for 

identifying organs below the location. 

Beam patient geometry assumptions used for analysis are specified in Table A-2. Figure A-1 shows 

the ICRP 34 (1982) beam and the modified beam superimposed on an anatomical representation of 

the body.

Table A-2. Beam/patient geometry parameters assumptions. 

Parameter Value Basis

Distance, beam focus to image receptor 102 cm ICRP 34 (1982)

Body thickness 23 cm Assumed average worker pelvic thickness

Gap between patient and film 5 cm Kereiakes and Rosenstein (1980), p. 189

From the above, the following parameters were calculated:
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Parameter Value Basis

Distance, beam focus to mid-point of body 85.5 cm = 102 – 5 – 11.5

Distance, beam focus to entrance surface of body 74 cm = 102 – 5 – 23

Any beam dimension (e.g., radius) in a plane parallel to the image receptor can be obtained by 

multiplying the value of that dimension in the image receptor plane by a reduction factor. The value of 

the reduction factor is the distance from the beam focus to the plane of interest divided by the 

distance from the beam focus to the image receptor: Reduction factors for selected planes are as 

follows:

Parameter Value Basis

Reduction factor for plane through mid-point of body 0.838 = 85.5/102

Reduction factor for plane at entrance surface of body 0.725 = 74/102

Figure A-1 shows the ICRP 34 (1982) beam and modified beam superimposed on an anatomical 

representation of the body.

Figure A-1. Beam profiles and body anatomy. 

The rectangle in Figure A-1 represents the area of the ICRP 34 rectangular collimated beam. The 

elongated circle represents the area of the minimally collimated modified beam. The modified beam 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 39 of 46

is circular in cross-section with the elongation from an assumed ± 3 cm vertical displacement or 

variation of the beam center with respect to anatomical location (see Section A.2.4.2). The beam 

sizes are those at the image receptor surface.

A2.4.2.1 Organs Above the ICRP 34 Field Center

Table A-5 lists additional organs above the ICRP 34 (1982) field center that are brought into the beam 

by its assumed enlargement and displacement. The table also indicates the percentage of the 

volume of each organ that was estimated to be inside the boundaries of the modified beam.

For a case in which all of an organ is in the modified beam, the DCF is obtained from an ICRP 34 

(1982) case in which the organ is fully in the beam, if such a case is available. For a case in which a 

substantial part of the organ is outside the beam, a reduced DCF is assigned. This reflects the lower 

deposition of energy in the organ and the fact the DCF in ICRP 34 (1982) was calculated by dividing 

the energy deposited in the organ by the total organ mass, thus if less of the organ is in the beam, 

less energy is deposited and the DCF is lower. (Kereiakes and Rosenstein 1980, p. 160, Taulbee 

2004).

Table A-6 displays DCFs assigned to the additional organs listed in Table A-5 and also to several 

other organs. The DCFs were estimated as follows: 

• Lungs

•

. The overlay of the beam profile on an anatomical drawing indicated that approximately 

10% of the lung volume is in the beam. Therefore, direct interaction with the primary beam 

was estimated to cause 10% of the energy deposition that occurs when the lungs are fully in a 

beam. An additional 10% energy deposition was estimated to be produced by scattering of 

photons to parts of the lung outside the primary beam. This estimate is based on the finding 

that scattered radiation produces a dose to the testes equal to 10% of the central beam dose 

when the testes are just outside a beam (Kereiakes and Rosenstein 1980, p. 205). Therefore, 

it is assumed that the lung DCF for a pelvis AP x-ray is 20% of the lung DCF for a chest AP 

x-ray (i.e., 20% of 381 mGy/Gy for an HVL of 2.0 mm Al per Table A5 of ICRP 34 (1982) 

where the male DCF rather than the lower female DCF is selected).

Esophagus

•

. The overlay of the beam profile on an anatomical drawing indicated that 

approximately 50% of the esophagus volume is exposed to the beam. Based on a 10% 

contribution from scattering, it is assumed that the esophagus DCF for a pelvis AP x-ray is 

60% of the ovaries DCF (i.e., 60% of 174 mGy/Gy).

Bone Surfaces

•

. Based on the discussion in Section 3.1 of the main text, the bone surfaces 

DCF for a pelvis AP x-ray is taken as equal to the lung DCF for a chest AP x-ray as 

determined above (i.e., 20% of 381 mGy/Gy).

Other Organs Identified in Table A-5

•

. The other organs identified in Table A-5 were judged to 

be fully or nearly fully in the modified beam. They were assigned a pelvis AP x-ray DCF equal 

to the ICRP 34 (1982) ovaries DCF.

Remainder Organs. Various listings of "remainder organs" are available. Most of the organs 

in a typical list (Eckerman and Ryman 1993, footnote 2 to Table II.1 on p. 7) would be wholly 

inside the modified beam. Therefore, the pelvis AP x-ray DCF for remainder organs is taken 

as equal to the ICRP 34 (1982) ovaries DCF.
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 40 of 46

• Breasts

A2.4.2.2 Organs Below the ICRP 34 (1982) Field Center

. The percentage of the breast volume in the primary beam is assumed to be the 

same as in the case of the lungs (10%) and the scattering effects are assumed to be the same 

as for the lungs. Therefore, it is assumed that the female breast DCF for a pelvis AP x-ray is 

20% of the female breast DCF for a chest AP x-ray [i.e., 20% of 744 mGy/Gy for an HVL of 2.0 

mm Al per Table A6 of ICRP 34 (1982)]. The same DCF is adopted for a male breast, which is 

claimant favorable.

The only additionally impacted organs identified below the ICRP Publication 34 (1982) field center 

were the male testes. The distance between the testes center and the edge of the modified beam at 

the entrance surface was calculated. The testes center was found to be well within the beam (see 

Table A-7). Table 115 on p. 205 of Kereiakes and Rosenstein (1980) indicates that the testes DCF at 

the location found is nearly the same as the DCF of 810 mrad (tissue)/R (i.e., 933 mGy/Gy) that 

occurs when a 2 mm Al HVL beam is centered on the testes. Therefore, for claimant favorability 933 

mGy/Gy is taken as the DCF for the testes. 

A2.4.2.3 Active Bone Marrow

A larger beam would produce a larger dose to the active bone marrow. This was accounted for by 

using data in Table 116 (Active Bone Marrow Dose as a Function of Field Size) on p. 206 of 

Kereiakes and Rosenstein (1980). The ICRP 34 (1982) active bone marrow DCF for a pelvis AP 

x-ray was multiplied by 1.44 based on the upper limit of the correction factor 1.39 ± 0.05 given in 

Table 116 for a 14"x17" abdominal AP x-ray and a field area size ratio of 2.0. This yielded a DCF for 

active bone marrow of 33.1 mGy/Gy. 

A2.5 DOSES

A2.5.1

Except for skin, doses for organs wholly or partially in the beam were calculated using Equation A-1. 

For example, for lung dose the calculation was as follows:

Organs Other than Skin in the Beam

Lung Dose = [0.0169 Gy(air)] [(0.20) (381 mGy(tissue)/Gy(air))]

[0.1 rad(tissue)/mGy(tissue)] [1 rem/rad(tissue)] = 0.129 rem

A2.5.2

Entrance Dose

Skin in the Beam

As stated earlier, skin dose is taken as 4700 mrad (tissue) or 4.70 rem. This dose would affect all 

skin surfaces in the beam on the entrance side of the body (see Figure A-1). To allow for anatomical 

variability and variation in the positioning of the patient, this dose is also assumed to apply to the skin 

of the front of the thighs and to all of the skin of the hands, forearms, and elbows.

Exit Dose

Skin dose in the beam on the exit side of the body was obtained by dividing the entrance dose by an 

absorption factor that accounts for attenuation in the body. Absorption factors are provided in Table 

B.7 of NCRP Report No. 102 (NCRP 1989). For the skin of the lower back and buttocks, an 

absorption factor of 26.6 was obtained by decreasing by 10% (0.9*29.5 = 26.6) the value tabulated for 

an HVL of 2.0 mm Al and a body thickness of 20 cm. The 10% decrease allows for differences 

between the tabulated values and actual values as specified in the footnote to Table B.7 (NCRP 102 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 41 of 46

1989). A body thickness of 20 cm was chosen to allow for a person whose body is thinner than that of 

the average worker (22-24 cm per Section 2.3 of the main text). This yielded an exit skin dose of 

4.70 rem/26.6 = 0.177 rem

For the back of the thighs, an absorption factor of 5.39 was obtained by decreasing by 10% (0.9*5.99 

= 5.39) the value in Table B.7 (NCRP 1989) for an HVL of 2.0 mm Al and a body thickness of 10 cm. 

This yielded an exit skin dose of 

4.70 rem/5.39 = 0.872 rem 

A2.5.3

Entrance and exit doses to portions of the skin outside but near the beam are assumed to be 10% of 

the doses in the neighboring region inside the beam. This is based on the finding that the dose to the 

testes is 10% of the central beam dose when the testes are just outside the beam. Regions "outside 

but near" the beam are considered to be the following:

Skin Outside but Near the Primary Beam

• Upper torso, from the beam edge (Figure A-1) to just below the neck;

• Knees;

• The upper arms, scattered dose (10%)

A2.5.4

The dose to an organ wholly outside but near the beam is taken as 10% of the dose to organs in the 

neighboring region inside the beam. The thymus falls in this category, so the dose to the thymus is 

taken as 10% of the dose to the ovaries.

Organs Outside but Near the Beam

A2.5.5

Doses from scattering to skin and organs in a portion of the body well outside the beam (i.e., beyond 

the "outside but near" region) were estimated using the following parameters and assumptions:

Body Parts Well Outside the Beam

• Entrance skin dose of 4.70 rem (choosing this rather than the alternative ESD of 2.40 rem is 

claimant favorable).

• Average depth dose value of 18.4% [based on Table B.8 of NCRP 102 (NCRP 1989), 2 mm Al 

HVL, 35 cm x 35 cm field size, a 10 cm depth (representing the midpoint of a 20 cm thick 

trunk), and multiplication by a factor 1.1 to allow for the 10% uncertainty of the tabulated 

values].

• 0.0005 ratio of scattered to incident exposure (based on exposure at 1 m due to 90 degree 

scattering of 70 kVp radiation per Table B-2 of NCRP Report No.49 1976).

• Scaling of scattered radiation with distance as 1/r

2

, where r represents the distance from the 

centerline of the modified beam to the closest part of the "well outside" body portion closest to 

the beam. The distance is based on the reference adult patient defined in Kereiakes and 

Rosenstein (1980) (Table 94 and Figures 2 and 3).

The base of the neck was determined to be 0.56 m from the center of the upward-displaced modified 

beam so the scatter dose for the neck and above was calculated as follows:
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 42 of 46

Scatter Dose (to the neck) = (4.70 rem) (0.184) (0.0005) (1 m/0.56 m)2 = 1.38E-3 rem

Similarly, dose from scattered radiation to the knees was calculated by 

Scatter Dose (to region below the knees)= (4.70 rem) (0.184) (0.0005) (1 m/0.48 m)2 = 1.88E-3 rem

The lower edges of the knees were estimated to be 0.48 m from the center of the downwarddisplaced modified beam. This yielded a scattered radiation dose of 1.88E-3 rem below the lower 

edges of the knees. These two doses are assumed to apply to the entrance and exit surfaces of the 

skin and to internal organs in the respective regions. For example, the doses to the thyroid, eyes and 

brain are taken as 1.38E-3 rem.

A2.5.6

Resulting doses and their bases and uncertainties are provided in Tables A-2 through A-7 and 

summarized in Table A-8.

Organ Dose Tables

Table A-3. DCFs for a pelvic AP x-ray (HVL 2.0

mm Al) for organs listed in ICRP 34 (1982).

ICRP 34

table no. Organ

Dose conversion 

factor (mGy/Gy)

A2 Thyroid <0.01

A3 Ovaries 174

A4 Testes 69

A5 Lungs 1.0

A6 Female breast — a b

A7 Uterus (embryo) 244

A8 Active bone marrow 33.1 c

a. Not computed in ICRP 34 (1982).

b. Used 20% of the 744 mGy/Gy DCF for AP chest with 

2.0 mm Al HVL to determine dose in Table A-6.

c. ICRP 34 (1982) DCF was multiplied by 1.44 the upper 

limit of the correction factor 1.39 ± 0.05 from Table 116, 

p. 205 (Kereiakes and Rosenstein). 23* 1.44=33.1

Table A-4. DCFs for pelvic AP x-ray (HVL 2.0 

mm Al) for analogue organs not listed in ICRP 

34 (1982).

Organ

Assigned DCF a

(mGy/Gy)

Bladder 174

Colon 174

Rectum 174

Urinary system (except kidneys) 174

a. Taken as equal to value for ovaries in Table A-3.
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Table A-5. Impact of modified beam on organs outside ICRP 34 beam. 

Organ

Estimated % of organ 

volume in modified beama Scattered dose (%) b

Adrenal gland 100 — c

Female Breast 10 10

Esophagus 50 10

Gall bladder 100 — c

Kidney 100 — c

Liver 100 — c

Lungs 10 10

Pancreas 100 — c

Spleen 100 — c

Stomach 100 — c

a. The field center of the modified beam was assumed to be located 3 cm above the field 

center of the ICRP 34 beam. The beam size was assumed to be that at the image 

receptor. The percentage was estimated as 100% if all or most of the organ was in the 

modified beam.

b. Dose contribution due to parts of the organ outside the beam due to scattered radiation; 

expressed as a percent of the dose that the organ would receive if it were fully in the 

beam.

c. Not applicable.

Table A-6. Assigned DCFs for organs above 

field center of ICRP 34 beam. 

Organ

Reference

dose factor

(mGy/Gy)

Assigned

dose conversion 

factora (mGy/Gy)

Adrenal gland 174 1.74E+02

Bone surfaces — 7.62E+01

Breast 744 1.49E+02

Esophagus 174 1.04E+02

Gall bladder 174 1.74E+02

Kidney 174 1.74E+02

Liver 174 1.74E+02

Lungs 381 7.62E+01

Pancreas 174 1.74E+02

Remainder 174 1.74E+02

Spleen 174 1.74E+02

Stomach 174 1.74E+02

a. Determined per Section A2.4.2.1 of the text.
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Table A-7. Parameters related to dose to testes. 

Location

Distance from 

phantom vertex (cm)a Basis

Testes center 96.3 Kereiakes and Rosenstein (1980), p. 187

Rectangular ICRP 34 beam

Center 80.0 Kereiakes and Rosenstein (1980), p. 188

Distance from center to lower edge, 

at image receptor

17.8 = 35.6/2, where 35.6 cm is height of beam

Distance from center to lower edge, 

at entrance surface

12.9 = 0.725 x 17.8, where 0.725 is the geometric 

reduction factor (from Table A-1)

Lower edge, at entrance surface 92.9 = 80.0 + 12.9

Location of lower edge at entrance 

surface relative to testes center b 

3.4 = 96.3 – 92.9

Circular modified beam

Center 83.0 Assumption

Circle radius at image receptor 31.3

π

2 43 2. xx 35 6. =, per criterion that area of 

circle is twice area of ICRP 34 beam

Circle radius at entrance surface 22.6 0.725 x 31.3, where 0.725 is the geometric 

reduction factor (from Table A-1)

Lower edge, at entrance surface 105.6 = 83.0 + 22.6

Location of lower edge at entrance 

surface relative to testes center b 

-9.3 = 96.3 – 105.6

a. The vertex is assumed to be on the top of the phantom, on the entrance surface, centered [see Kereiakes and 

Rosenstein (1980), Figure 3].

b. A positive value means the lower edge of the beam is above the testes center; a negative value means the lower edge 

of the beam is below the testes center. 
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 45 of 46

Table A-8. Organ doses from a pelvis AP x-ray. 

Organ or region Basis Dose (rem)

Active bone marrow A2.4.2.3, A2.5.1 5.59E-02

Adrenal gland Table A-6, A2.5.1 2.94E-01

Bladder Table A-4, A2.5.1 2.94E-01

Bone surfaces Table A-6, A2.5.1 1.29E-01

Brain A.2.5.5 1.38E-03

Breast Table A-6, A2.5.1 2.50E-01

Colon Table A-4, A2.5.1 2.94E-01

Esophagus Table A-6, A2.5.1 1.78E-01

Eye A.2.5.5 1.38E-03

Gall bladder Table A-6, A2.5.1 2.94E-01

Kidney Table A-6, A2.5.1 2.94E-01

Legs below knees and feet A2.5.5 1.88E-03

Liver Table A-6, A2.5.1 2.94E-01

Lungs Table A-6, A2.5.1 1.29E-01

Neck and above A.2.5.5 1.38E-03

Ovaries Table A-3, A2.5.1 2.94E-01

Pancreas Table A-6, A2.5.1 2.94E-01

Rectum Table A-4, A2.5.1 2.94E-01

Remainder organs Table A-6, A2.5.1 2.94E-01

Skin on entrance side of body:

Front of body in beam (Fig. A-1) A.2.5.2 4.70E+00

Front of thighs A.2.5.2 4.70E+00

Front of torso from just above beam (Fig. A-1) to just below neck A.2.5.3 4.70E-01

Front of knees A.2.5.3 4.70E-01

Skin on exit side of body:

Back of body in beam (Fig. A-1) except thighs A.2.5.2 1.77E-01

Back of torso from just above beam (Fig. A-1) to just below neck A.2.5.3 1.77E-02

Back of thighs A2.5.2 8.72E-01

Back of knees A.2.5.3 8.72E-02

Skin on all parts to the following:

Hands, forearms, and elbows A.2.5.2 4.70E+00

Upper arms A.2.5.3 4.70E-01

Legs below knees and feet A.2.5.5 1.88E-03

Neck and above A.2.5.5 1.38E-03

Spleen Table A-6, A2.5.1 2.94E-01

Stomach Table A-6, A2.5.1 2.94E-01

Testes A2.4.2.2, A2.5.1 1.58E+00

Thymus A.2.5.4 2.94E-02

Thyroid A.2.5.5 1.38E-03

Urinary system (except kidneys) Table A-4, A2.5.1 2.94E-01

Uterus (embryo) Table A-3, A2.5.1 4.12E-01
Document No. ORAUT-OTIB-0006 Revision No. 03 Effective Date: 08/02/2005 Page 46 of 46

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