ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 20

 New Total Rewrite Revision Page Change

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.

Document Title:

Rocky Flats Plant – Occupational Medical Dose

Document Number: ORAUT-TKBS-0011-3

Revision: 01

Effective Date: 04/23/2007

Type of Document: TBD

Supersedes: Revision 00

Subject Expert(s): Theresa Lopez

Site Expert(s): N/A

Approval: Signature on File Approval Date: 03/30/2007

Robert Meyer, Document Owner

Concurrence: Signature on File Concurrence Date: 04/04/2007

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 03/30/2007

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 03/30/2007

James P. Griffin, Deputy Project Director

Approval: Brant A. Ulsh Signature on File for Approval Date: 04/23/2007

James W. Neton, Associate Director for Science
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 2 of 20

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION

NUMBER DESCRIPTION

02/09/2004 00 New Technical Basis Document for the Rocky Flats Plant –

Occupational Medical Dose. First approved issue. Initiated by 

Robert Meyer.

04/23/2007 01 Approved Revision 01 initiated to revise Table 3.4.2-2 (now Table 3-

6), text, and dose estimate tables to be consistent with ORAUTOTIB-0006 Rev 03 PC-1. Revised Table 3.2-1 (now Table 3-1) and

text to specify the inclusion of termination X-rays for the period of 

1952-1986. Revised Table 3.4.1-2 (now Table 3-5) per commitment 

tracking form dated 02/06/2006. Revised to include attribution 

information per ORAU direction. The Worker Outreach comment 

from CT-0203 was addressed. Worker outreach comment from the 

June 23, 2004, meeting of the United Steelworkers of America Local 

8031 and Rocky Flats Security Officers Local Union 1 was addressed 

in Section 3.1. Incorporates formal internal and NIOSH review 

comments. Constitutes a total rewrite of document. This revision 

results in an increase in assigned dose and a PER is required. 

Training required: As determined by the Task Manager. Initiated by 

Robert Meyer.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 3 of 20

TABLE OF CONTENTS

SECTION TITLE

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

PAGE

4

3.1 Introduction ..............................................................................................................................6

3.1.1 Purpose........................................................................................................................6

3.1.2 Scope...........................................................................................................................7

3.2 Background..............................................................................................................................7

3.3 Examination Frequency ...........................................................................................................8

3.4 Equipment and Techniques......................................................................................................8

3.5 Organ Dose Estimates ........................................................................................................... 10

3.5.1 Parameters and Estimation Method............................................................................10

3.5.2 Organ Dose Estimates for RFP Workers ....................................................................12

3.6 Uncertainties..........................................................................................................................12

3.7 Attributions and Annotations .................................................................................................. 16

References ........................................................................................................................................18

Glossary ............................................................................................................................................19

LIST OF TABLES

TABLE TITLE

3-1 X-ray examination frequencies.................................................................................................

PAGE

8

3-2 Description of X-ray equipment used at RFP and proxy information......................................... 9

3-3 Equipment settings and ratings ................................................................................................9

3-4 ICRP dose conversion factors; absorbed dose for organs at various AL HVL ........................ 11

3-5 Analogs for IREP organs not specified in ICRP (1982)........................................................... 12

3-6 Organ dose estimates for PA chest........................................................................................ 13

3-7 Organ dose estimates for AP and LAT lumbar spine (1952–1974)......................................... 14

3-8 Organ dose estimates for photofluorography, 1952 through 1968.......................................... 14

LIST OF FIGURES

FIGURE TITLE PAGE

3-1 Kerma in air at 1 m from X-ray source as a function of total filtration for 

various values of tube potential.............................................................................................. 10
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 4 of 20

ACRONYMS AND ABBREVIATIONS

AP anterior-posterior

CFR Code of Federal Regulations

cGy centigray

cm centimeter

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act

ESE entrance skin exposure

Gy gray

HVL half-value layer

ICRP International Commission on Radiological Protection

in. inch

IREP Interactive RadioEpidemiological Program

kerma kinetic energy released per unit mass

keV kiloelectron-volt, 1,000 electron-volts

kg kilogram

kV kilovolt

kVp kilovolts-peak, applied kilovoltage

LAT lateral

m meter

mA milliampere

mAs milliampere-second

mGy milligray

mm millimeter

NIOSH National Institute for Occupational Safety and Health

ORISE Oak Ridge Institute for Science and Education

PA posterior-anterior

PFG photofluorography

POC probability of causation

R roentgen

RFP Rocky Flats Plant

s second

SI International System of Units

SID source-to-image distance

SSD source-to-skin distance

Sv sievert

TBD technical basis document

TIB technical information bulletin
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 5 of 20

U.S.C. United States Code

yr year

§ section or sections
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 6 of 20

3.1 INTRODUCTION

3.1.1 

Technical basis documents and site profile documents are not official determinations made by the 

National Institute for Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historic background information and guidance to assist in the preparation of 

dose reconstructions at particular sites or categories of sites. They will be revised in the event 

additional relevant information is obtained about the affected site(s). These documents may be used 

to assist NIOSH staff in the completion of the individual work required for each dose reconstruction.

Purpose

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 [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the POC [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 

(42 U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally derived radiation 

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external dosimetry monitoring results are considered valid for use in dose reconstruction. No efforts 

are made to determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationally 

derived:

] guidelines established under 

subsection (c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation

guidelines (nor the dose reconstruction regulation) define “performance of duty” for DOE employees 

with a covered cancer or restrict the “duty” to nuclear weapons work.

 1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 7 of 20

• Radiation from naturally occurring radon present in conventional structures

• Radiation from diagnostic X-rays received in the treatment of work-related injuries

3.1.2 

The following sections describe the methodology used to estimate absorbed dose from X-ray 

exposure for Rocky Flats Plant (RFP) workers. Where data are unavailable, the assumptions made 

are favorable to claimants [1]. Section 3.1 provides introductory text. Section 3.2 describes X-ray 

examination frequency at RFP. Section 3.3 provides information on equipment and techniques used 

at RFP, including assumptions necessitated by lack of protocol, measurement, or records data. 

Section 3.4 provides organ dose estimates by calendar year and type of X-ray. Section 3.5 

documents uncertainties.

Scope

3.2 BACKGROUND

As part of the requirements for employment at RFP, entrance, exit, and periodic physical 

examinations were performed on all employees. These physical examinations included radiographic 

examinations of the lungs and, for some employees, the lumbar spine [2]. NIOSH, in its role to 

reconstruct occupational dose under EEOICPA, has classified diagnostic medical X-rays administered 

in conjunction with routine or special physical examinations required for employment as occupational 

exposures (NIOSH 2002). Only medical exposures that were required as a condition of employment 

are included; diagnostic and therapeutic procedures not required for employment are excluded (e.g., 

exposures received in the treatment of work-related injuries).

As described in International Commission on Radiological Protection (ICRP) Publication 34, 

Protection of the Patient in Diagnostic Radiology, the amount of energy absorbed in the body and its 

distribution in specific organs can be determined by measurement or calculation (ICRP 1982). 

Absorbed dose in tissue, measured in units of gray, is equal to the energy absorbed per unit mass at 

a point in the human body. The quantity of radiation in terms of exposure from ionization of a specific 

mass of air by X-rays was in previous years measured in roentgens. The current International System 

of Units (SI) expresses this quantity in air kerma (kerma derives from kinetic energy released per unit 

ma

The radiation dose received in a given examination varies widely throughout the body. Doses are 

highly dependent on the technical factors employed, characteristics of the equipment, collimation of 

the beam, and number of films taken. The general equation for total annual occupational medical 

dose provided by NIOSH guidelines (NIOSH 2002) is:

ss). An exposure of 1 R corresponds to an air kerma of 8.7 mGy.

Dom = ΣnDi (3–1)

where 

Dom = occupational medical dose

n = number of examinations in a calendar year

Di = dose from the X-ray procedure

The NIOSH guidelines state that medical records should contain the dates, types, and number of 

X-ray examinations, and that if no information is known about the energy spectra, values should 

conservatively be assumed to be in the 30- to- 250-kV photon range (which is favorable to claimants). 

The guidelines also state that the uncertainty distribution about each X-ray procedure is assumed to 

follow a normal distribution, with Dom being the mean dose. 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 8 of 20

3.3 EXAMINATION FREQUENCY

The frequency of X-ray examinations varied significantly for RFP workers (Table 3-1). A protocol for 

frequency of a single posterior-anterior (PA) view chest X-ray as a function of job category was not 

established until approximately 1986. After that date, the frequency of routine chest X-rays varied 

widely: None for office personnel, every 5 yr for respirator wearers, and annually for beryllium and

asbestos workers over age 45 and with a 10-yr history of asbestos exposure (RFP 1991). Before 

approximately 1986, many production workers would receive single-view chest X-rays on a nearly 

annual basis. (In a sample of medical records of production workers, no one was found to have 

consistently received annual chest X-rays due to occasional missed examinations and periods when 

examinations were apparently not provided on an annual basis [3].) Inspection of medical records 

has not revealed any more specific designation of X-ray protocol by worker classification or job 

description [4]. Based on the records reviewed during preparation of this document, no worker 

received such examinations more often than annually [5]. Termination chest X-rays are also 

recommended for the period 1952 to 1985 because they were common at other DOE sites and the 

RFP protocol for this period has not been found [6]. Termination X-rays are believed by former 

medical workers to have been uncommon at RFP [7].

Table 3-1. X-ray examination frequencies.

Period Frequency View Comment

1986–

present

Annually Chest (PA) Beryllium workers; asbestos workers over age 45 with 

10-yr work history exposure to asbestos (RFP 1991)

Every 5th yr Chest (PA) Respirator wearers (RFP 1991)

None Chest (PA) Office personnel (RFP 1991)

1952–1985 Annual and 

termination

Chest (PA) All workersa

1952–1968 Annual Chest (PFG) All workersa 

1952–1974 Once Lumbar (AP and LAT) All workers

a. Assumed all workers received X-rays because protocol has not been found [8]. Production workers were known to 

receive annual chest X-ray examinations; this protocol is assumed to have occurred for all years [9].

Between 1952 and 1974, all workers received spinal X-rays during their initial employment (prehire) 

medical examination. This X-ray series consisted of a 14- by 17-in. anterior-posterior (AP) view and a 

10- by 12-in. lateral (LAT) view of the lumbosacral spine [9].

Without a review of the specific energy employee’s X-ray file (stored at the Denver Federal Center), 

an exact count of the X-rays is impossible. The medical files (also stored at the Denver Federal 

Center) did not always document each X-ray taken, at least not in the years before the mid-1970s 

[10]. An approach to the estimation of the X-rays taken that is favorable to claimants would therefore 

assume lumbosacral spine X-rays were taken if the energy employee started work between 1952 and 

1974. If an annual single-view chest X-ray is also assumed, this potential overestimation of X-ray use 

would compensate for the few repeat radiographs taken because of poor quality of the initial X-ray 

[11].

3.4 EQUIPMENT AND TECHNIQUES

Although RFP radiological practices are assumed to have followed standards of medical practice to 

minimize dose to the workers, the type of equipment, technique factors, and machine calibrations are 

not fully known for years before 2001. Members of the RFP TBD team interviewed Medical and 

Records group personnel and Colorado Department of Public Health and Environment personnel and 

determined that X-ray machine records for equipment in use before 2001 are not readily available

[12]. However, some information has been found related to equipment type and ratings; these data 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 9 of 20

have been used in conjunction with default data where needed to provide estimates of potential 

exposure that are favorable to claimants. Individual medical records should contain notations about 

dates and purposes of X-ray examinations, but reviews of medical records showed that this was not 

always the case before the mid-1970s [13]. 

X-ray organ dose estimates for occupational X-rays administered at RFP are provided here for known 

equipment (Type I – June 11, 2001, to present) and default estimates are provided for earlier periods 

(ORAUT 2005). The use of proxy data is based on the belief that RFP, like other DOE sites, used the 

standard radiological procedures of the time. All assumptions made were conservative (favorable to 

claimants). The default dose estimates are from the Technical Information Bulletin (TIB) Dose 

Reconstruction from Occupationally Related Diagnostic X-ray Procedures (ORAUT 2005) for chest 

and lumbar spine X-rays.

Photofluorography (PFG) could have been performed at RFP. While no specific records or protocols

have been found in relation to PFG at RFP, a note indicating that a fluoroscope was removed from the 

Plant in 1968 indicates that fluoroscopy could have been performed (Dean 2003), and workers recall 

that a “portable x-ray machine” was used. Therefore, it has been assumed that PFG could have been 

performed. Fluoroscopic equipment is different from photofluorographic equipment and was not 

generally of much use for occupational medical examinations that would have been performed 

(ORAUT 2005). However, because no further site-specific information has been found, and 

considering the uncertainty related to PFG use and input from former workers, default estimates of 

PFG exposure from ORAUT (2005) have been recommended in this TBD if any evidence of PFG use 

is found in individual claim files.

Efforts will continue to find all related information for RFP. However, until more accurate records are 

found, these assumptions provide estimates for medical X-ray exposure that are favorable to 

claimants.

Tables 3-2 and 3-3 summarize known information regarding equipment and techniques.

Table 3-2. Description of X-ray equipment used at RFP and proxy information.

Classification Period Equipment Source

Type I June 11, 2001–present Hologic/BXT202W Dean 2003 [13]

Type II May 29, 1987–March 6, 2001 Eureka XMA tube; Generator unknown Dean 2003 [13]

Type III September 1, 1976–May 28, 

1987

Generator unknown; Victoreen R Meter; 

BRH test stand; X-ray Timer; Aluminum 

Filter set; light meter

Dean 2003

Type IV July 1953–August 30,1976 Keleket Dean 2003

Table 3-3. Equipment settings and ratings (Dean 2003).

Machine Period View Current (mA) Voltage (kVp) Exposure time(s)

Type I

a 6/11/2001–present Chest PA 300 110 0.003

Type IIb 5/29/1987–3/6/2001 Chest PA 360 130 Unknown

Type IIIb 9/01/1976–5/28/1987 Chest PA Unknown 80 Unknown

Type IVb 7/1953–8/30/1976 Chest PA 200 140 Unknown

1952–1974 Lumbar APc 200 140 Unknown

1952–1974 Lumbar LATc 200 140 Unknown

a. Typical setting varied from 0.8 mAs for an average-sized person to 2.3 mAs for a very large person; 2.3 mA was used to 

be conservative.

b. Maximum machine ratings (Dean 2003); data not used to calculate doses, but are presented for informational purposes.

c. Performed only from 1952 to 1974 [14]; settings are maximum machine ratings (Dean 2003).
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 10 of 20

3.5 ORGAN DOSE ESTIMATES

Organ dose estimates are provided in this section. Section 3.5.1 describes the methodology used to 

estimate these doses; Section 3.5.2 discusses the results. 

3.5.1 

The ICRP (1982) guidance uses the following parameters to estimate air kerma and absorbed dose:

Parameters and Estimation Method

1. Source-to-image distance (SID) in centimeters

2. Total filtration (millimeters of aluminum) 

3. Estimate of person thickness (AP and LAT)

4. Machine settings (mAs, kVp, film size, and single-phase or three-phase)

If measured air kerma data are available, these should be used. If not, air kerma rates can be 

estimated from Figure 3-1 (ICRP 1982) if average technique factors and total filtration are known.

Figure 3-1. Kerma in air at 1 m from X-ray 

source as a function of total filtration for various 

values of tube potential (from ICRP 1982). 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 11 of 20

Figure 3-1 is for single-phase machines; results should be multiplied by 1.8 for three-phase machines. 

The machine present at RFP from June 11, 2001, until Plant closure is assumed to have been threephase. Once the kerma rate is estimated, the air kerma at 100 cm is calculated by multiplying the 

estimated air kerma rate by the number of mAs used for each radiograph (ICRP 1982).

Next, the source-to-skin distance (SSD) is calculated by subtracting the AP or LAT thickness of the 

standard (reference) worker or person and distance between the worker and the film (default distance 

of 5 cm) from the SID. Air kerma at the SSD is then estimated using the following equation:

air kerma at SSD (mGy) = (100/SSD)2 × air kerma at 1 m (mGy) (3-2)

Tables A.2 through A.9 of ICRP (1982) are then used to estimate organ dose directly. Dose to the 

skin was estimated by multiplying the air kerma at SSD by the appropriate factor from Table B-8 of 

National Council of Radiation Protection and Measurements Report 102 (NCRP 1989). The tables list 

organ doses in milligray normalized to an air kerma of 1 Gy in air at the skin, as a function of 

half-value layers (HVLs) in millimeters of aluminum. In addition, ICRP (1982, Appendix A) provides 

tables for estimating the HVL if it is not known. Table 3-4 lists all such values used in this TBD.

Table 3-4. ICRP dose conversion factors; absorbed dose (1 mGy) for organs at various Al HVL (1-Gy 

entrance air kerma in air without backscatter). Image size 35.6 by 43.2 cm (ORAUT 2005).

Organ

Chest PA

(pre-1970)a,b

at 2.5 mm Al HVL

SID = 183 cm

Entrance kerma 

= 0.2 cGy

Chest PAa

(1970 to 1985)

at 2.5 mm Al HVL

SID=183 cm

Entrance kerma 

= 0.1 cGy

Chest PAa

(1985 to present) 

at 4 mm Al HVL

SID = 183 cm

Entrance kerma = 

0.05 cGy (prior to 2001)

Lumbar 

spinec at 

2 mm 

Al HVL

AP

Lumbar 

spinec at 

2 mm 

AL HVL 

LAT

Thyroid 174d 32 78 0.2 0.01

Eye/brain 32 32 78 0.2 0.01

Ovaries N/A 1 5.2 N/A N/A

Liver/gall bladder/spleen 451 451 674 62 10

Urinary bladder N/A 1 5.2 N/A N/A

Colon/rectum N/A 1 5.2 N/A N/A

Testes N/A 0.01 0.01 N/Ae N/A

Lungs (male) 419 419 628 62 10

Lungs (female) 451 451 674 62 10

Thymus 451 451 674 62 10

Esophagus 451 451 674 62 10

Stomach 451 451 674 62 10

Bone surfaces 451 451 674 62 10

Remainder 451 451 674 62 10

Breast 49 49 116 18f 9.5f

Uterus (embryo) N/A 1.3 5.2 N/A N/A

Bone marrow (male) 92 92 178 24 15

Bone marrow (female) 86 86 172 24 15

Skin N/A N/A N/A 1.32 1.32

N/A = as reported in ORAUT (2005).

a. Dose conversion factors from ICRP (1982, Tables A.2 through A.9), ORAUT (2005).

b. Assumes minimal collimation.

c. From ORAUT (2005).

d. Dose conversion factor for AP cervical spine, corrected for depth by 0.2.

e. Organ dose values for the testes, ovaries, and lumbar spine reflect actual measurement per Lincoln and Gupton (1958).

f. Dose conversion factors for lumbar spine examination not given in ICRP (1982). Values for the respective upper gastrointestinal 

examinations (i.e., AP and LAT) were used instead. 

The ICRP tables used to estimate absorbed dose do not include all organs that have been identified 

in the Interactive RadioEpidemiological Program (IREP) computer program. For those organs 

included in the IREP but not specifically identified in the ICRP tables, the dose conversion coefficient 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 12 of 20

that is anatomically closest to the IREP-specified organs can be used to estimate dose. For example, 

the factor for lung can be applied to all other organs in the thoracic cavity, such as the esophagus and 

bone surface (ORAUT 2005). For abdominal organs (e.g., bladder, colon), the dose coefficient for 

ovaries should be used (ORAUT 2005). This approach should be either favorable to claimants or 

neutral. Table 3-5 provides analogs for IREP organs.

Table 3-5. Analogs for IREP organs not specified in ICRP (1982).

a

Anatomical 

location

ICRP (1982) 

reference organ IREP organ analogs

Thoracic cavity Lung Thymus

Esophagus

Stomach

Bone surface

Liver/gall bladder/spleen

Remainder organs

Abdominal cavity Ovaries Urinary bladder Colon/rectum

Head and neck Thyroid Eye/brain

a. As presented in ORAUT (2005).

Dose estimates for PA chest X-rays and prehire AP and LAT lumbar spine X-rays are presented in 

Tables 3-6 and 3-7 for each organ listed in ICRP (1982). All dose estimates are default values as 

presented in ORAUT (2005) except those for June 11, 2001, to present, which are based on known 

machine settings (Dean 2003) and information such as HVL supplied by former medical workers 

(Lopez 2003).

PFG could have been used at RFP, but no information about protocol has been found. Lacking any 

further information on PFG at RFP (notes indicate only that a fluoroscope was removed in 1968 and 

workers recall a “portable x-ray machine” being used), default dose estimates have been used

(ORAUT 2005). It is assumed, until further information is found, that the frequency of PFG was once 

per year from 1952 to 1968, and that it was used for the chest only [15]. As noted, a fluoroscope is 

not the same as photofluorography equipment (ORAUT 2005) but, considering the uncertainty of PFG 

use at RFP and input from former workers, PFG cannot be ruled out. The dose estimates should be 

used if a worker’s file indicates a PFG examination.

3.5.2 

Table 3-6 lists default organ dose estimates from PA chest X-rays for each period. Table 3-7 lists the 

default organ dose estimates for AP and LAT lumbar spine X-rays (note that the values have been 

halved to account for two views; ORAUT 2005). Table 3-8 lists default PFG exposure from chest 

examinations (ORAUT 2005).

Organ Dose Estimates for RFP Workers

At this time, there is insufficient information to calculate site-specific organ doses for RFP from chest 

X-rays before 2001, all lumbar spine X-rays, and all PFG examinations. The organ doses presented 

here will be revised if additional site-specific information is found that allows the calculation of organ 

doses.

3.6 UNCERTAINTIES

As stated in ORAUT (2005), error is defined as deviation from the correct, true, or conventionally 

accepted value of a quantity, and uncertainty is defined in terms of the potential range of a stated, 

measured, or assumed or otherwise determined value of a quantity. Error and uncertainty provide an 

indication of confidence in the dose estimates. Uncertainty, expressed in terms of a confidence level, 

is a more appropriate term than error, which implies that the actual value is known. Uncertainty, 

stated as a probability of falling within a stated range, includes precision and reproducibility of the 

measurement as well as accuracy (that is, how close the estimate comes to the actual value).
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 13 of 20

Table 3-6. Organ dose estimates for PA chest (mGy)

Period: June 11, 2001, to present [16]

Organ

Estimated dosea

HVL = 4.0 mm AL

Air kerma at skin = 0.134 mGy

mGy rem

Thyroid 1.05E-02 1.05E-03

Eye/brain 1.05E-02 1.05E-03

Ovaries 6.99E-04 6.99E-05

Liver/gall bladder/

spleen

9.06E-02 9.06E-03

Urinary bladder 6.99E-04 6.99E-05

Colon/rectum 6.99E-04 6.99E-05

Testes 1.34E-06 1.34E-07

Lungs (male) 8.44E-02 8.44E-03 

Lungs (female) 9.06E-02 9.06E-03

Thymus 9.06E-02 9.06E-03

Esophagus 9.06E-02 9.06E-03

Stomach 9.06E-02 9.06E-03

Bone surfaces 9.06E-02 9.06E-03

Remainder 9.06E-02 9.06E-03

Female breast 1.56E-02 1.56E-03

Uterus 6.99E-04 6.99E-05

Bone marrow (male) 2.39E-02 2.39E-03 

Bone marrow (female) 2.31E-02 2.31E-03

Skin 1.91E-01 1.91E-02

Period: 1985 to June 4, 2001

Organ

Estimated doseb

HVL = 4.0 mm Al;

Entrance kerma = 0.05 cGy

mGy rem

Thyroid 3.90E-02 3.90E-03

Eye/brain 3.90E-02 3.90E-03

Ovaries 2.60E-03 2.60E-04

Liver/gall bladder/

spleen

3.37E-01 3.37E-02

Urinary bladder 2.60E-03 2.60E-04 

Colon/rectum 2.60E-03 2.60E-04

Testes 5.00E-06 5.00E-07

Lungs (male) 3.14E-01 3.14E-02 

Lungs (female) 3.37E-01 3.37E-02

Thymus 3.37E-01 3.37E-02

Esophagus 3.37E-01 3.37E-02

Stomach 3.37E-01 3.37E-02

Bone surfaces 3.37E-01 3.37E-02

Remainder 3.37E-01 3.37E-02

Female breast 5.80E-02 5.80E-03

Uterus 2.60E-03 2.60E-04

Bone marrow (male) 8.90E-02 8.90E-03

Bone marrow (female) 8.60E-02 8.60E-03

Skin 7.00E-01 7.00E-02 

Table 3-6 (Continued). Organ dose estimates for PA chest.

Period: post 1970 to 1985

Organ

Estimated doseb

HVL = 2.5 mmAl;

Entrance kerma = 0.10 cGy

mGy rem

Thyroid 3.20E-02 3.20E-03

Eye/brain 3.20E-02 3.20E-03

Ovaries 1.00E-03 1.0E-04

Liver/gall bladder/

spleen

4.51E-01 4.51E-02

Urinary bladder 1.00E-03 1.00E-04 

Colon/rectum 1.00E-03 1.00E-04

Testes 1.00E-05 1.00E-06

Lungs (male) 4.19E-01 4.19E-02 

Lungs (female) 4.51E-01 4.51E-02

Thymus 4.51E-01 4.51E-02

Esophagus 4.51E-01 4.51E-02

Stomach 4.51E-01 4.51E-02

Bone surfaces 4.51E-01 4.51E-02

Remainder 4.51E-01 4.51E-02

Female breast 4.90E-02 4.90E-03

Uterus 1.30E-03 1.30E-04

Bone marrow (male) 9.20E-02 9.20E-03

Bone marrow (female) 8.60E-02 8.60E-03

Skin 1.35E+00 1.35E-01 

Period: pre-1970

Organ

Estimated doseb

HVL = 2.5 mmAl;

Entrance kerma = 0.20 cGy

mGy rem

Thyroid 3.48E-01 3.48E-02

Eye/brain 6.40E-02 6.40E-03

Ovaries 2.50E-01c 2.50E-02c

Liver/gall 

bladder/spleen

9.02E-01 9.02E-02

Urinary bladder 2.50E-01c 2.50E-02c

Colon/rectum 2.50E-01c 2.50E-02c

Testes 5.00E-02c 5.00E-03c

Lungs (male) 8.38E-01 8.38E-02 

Lungs (female) 9.02E-01 9.02E-02

Thymus 9.02E-01 9.02E-02

Esophagus 9.02E-01 9.02E-02

Stomach 9.02E-01 9.02E-02

Bone surfaces 9.02E-01 9.02E-02

Remainder 9.02E-01 9.02E-02

Female breast 9.80E-02 9.80E-03

Uterus 2.50E-01c 2.50E-02c

Bone marrow (male) 1.84E-01 1.84E-02

Bone marrow (female) 1.72E-01 1.72E-02

Skin 2.70E+00 2.70E-01 

a. HVL determined from former medical workers (Lopez 2003); machine settings from a memorandum to file (Dean 2003).

b. As presented in ORAUT (2005)

c. Modified from Webster and Merrill (1957) as presented in ORAUT (2005).
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 14 of 20

Table 3-7. Organ dose estimates for AP and LAT lumbar spine

(1952–1974). 

Organ

AP lumbar spinea

ESE = 2 rem

(rem)

LAT lumbar spine

ESE = 5 rem

(rem)

Thyroid 4.00E-04 5.00E-05

Eye/brain 4.00E-04 5.00E-05

Ovariesb 5.60E-01 7.60E-01

Urinary bladder 5.60E-01 7.60E-01

Colon/rectum 5.60E-01 7.60E-01

Testesb 2.70E-02 5.60E-02

Lung 1.24E-01 5.00E-02

Liver/gall bladder/spleen 1.24E-01 5.00E-02

Thymus 1.24E-01 5.00E-02

Esophagus 1.24E-01 5.00E-02

Stomach 1.24E-01 5.00E-02

Bone surfaces 1.24E-01 5.00E-02

Remainder 1.24E-01 5.00E-02

Female breast 3.60E-02 4.75E-02

Uterus 4.34E-01 1.00E-01

Bone marrow 4.80E-02 7.50E-02

Skinc 2.64E+00 6.60E+00

a. As presented in ORAUT (2005); value is halved from that in ORAUT (2005) 

because file review indicated that only AP and LAT views were taken. 

b. Organ dose values for the testes and ovaries for lumbar spine reflect actual 

measurement reported in Lincoln and Gupton (1958). 

c. Skin dose values include backscatter factor of 1.32 from NCRP (1989, 

Table B.8). 

Table 3-8. Organ dose estimates for photofluorography, 1952 to 1968 (as 

presented in ORAUT 2005). Entrance kerma = 3 cGy; HVL = 2.5 mm Al; all 

estimates are for uncollimated beams.

Organ View

Dose conversion factor 

(mGy per Gy air kerma)a

HVL 2.5 mm Al uncollimated

Organ dose (rem)

uncollimated

Thyroid PA 174b 5.22E-01

Eye/brain PA 32 9.60E-02

Ovaries PA N/A 2.50E-02c

Liver/gall bladder PA 451 1.35E+00

Urinary bladder PA N/A 2.50E-02c

Colon/rectum PA N/A 2.50E-02c

Testes PA N/A 5.00E-03c

Lungs (male) PA 419 1.26E+00

Lungs (female) PA 451 1.35E+00

Thymus PA 451 1.35E+00

Esophagus PA 451 1.35E+00

Stomach PA 451 1.35E+00

Bone surfaces PA 451 1.35E+00

Remainder PA 451 1.35E+00

Breast PA 49 1.47E-01

Uterus PA N/A 2.50E-02c

Bone marrow (male) PA 92 2.76E-01

Bone marrow (female) PA 86 2.58E-01

Skinc PA 4.05E+00

a. Dose conversion factors from, ICRP (1982, Tables A.2 through A.9).

b. Dose conversion factor for AP cervical spine, corrected for depth by 0.2 (ORAUT 2005). 

c. Modified from Webster and Merrill (1957), as reported in ORAUT (2005). 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 15 of 20

Although many factors can introduce uncertainty and error into X-ray exposures, five factors 

contribute the most uncertainty to the dose estimate: measurement error, variation in applied 

kilovoltage, variation in beam current, variation in exposure time, and SSD. Film speed, use of 

screens, or use of grids would not affect the beam output intensity. The lack of records for these 

measurements for most years at RFP introduces a large uncertainty into the dose estimates that 

cannot be readily quantified, although there is no apparent reason to believe that practices at RFP

were different from those at other facilities or from recommended standards of the medical community 

at the time [17]. Therefore, use of default estimates and reliance on information from other DOE sites 

when site-specific information was also unavailable is likely to closely approximate X-ray performance 

at RFP. The following estimates of uncertainty associated with X-ray exposure are from ORAUT

(2005), which was relied upon for default information. Further, these same factors affect dose 

estimates of PFG X-rays; proxy default information for PFG was taken from ORAUT (2005) in the 

absence of useful records at RFP.

ORAUT (2005) reports that X-ray doses are largely derived from actual measurements of X-ray 

machine output with R-meters or similar ionization chamber devices. Reportedly, these typically had 

an uncertainty of ±2% for photon energies below 400 keV, if properly calibrated and used. Although 

machinery that is more current might have a smaller uncertainty, ±2% should be used to be 

conservative.

Variation in applied voltage generally falls within ±5% of the machine setting. Beam intensity is 

approximately proportional to the 1.7 power of the kilovoltage, which results in an uncertainty of 

approximately 9% in relation to beam intensity for voltages in the 110- to- 120-kVp range (ORAUT 

2005). 

Variations in tube current are normal and generally small. As tube current drops, beam intensity also 

falls in direct proportion to the tube current. Large decreases in beam output would be readily 

detected and would indicate the need for machine maintenance or, as a temporary measure, an 

increase in the current or voltage to provide the necessary intensity for proper radiography. However, 

there is no evidence that such a procedure was ever needed or applied at RFP. Consistent with 

ORAUT (2005), the variation in tube current is assumed to be approximately ±2%. 

Exposure time can also significantly affect the dose received from radiography (exposure times are a 

fraction of a second). Even a small variation in exposure time due to timer error can significantly 

change beam output. Because early X-ray machine timers are known to have been inaccurate, 

uncertainty in beam output due to timers is assumed to be ±25% (ORAUT 2005). Therefore, it is 

recommended that ±25% be applied for RFP estimates, particularly since site-specific exposure time 

was available only for the present machine.

Last, SSD can contribute to variability because the entrance skin exposure is determined by this 

distance. Variations result from accuracy of positioning as well as worker size (thickness). As 

expressed in ORAUT (2005), this is generally thought to vary by no more than a few centimeters, with 

an upper limit of 7.5 cm (±10%). 

A potentially large source of uncertainty for RFP is the number of X-rays taken. As noted above, 

medical files reviewed for this TBD showed that the files did not always document X-rays taken, at 

least before the mid-1970s. Further, the frequency of PFG is completely unknown. It is 

recommended that, as a conservative approach, an annual chest X-ray should be assumed for all 

energy employees of RFP. It should also be assumed that AP and LAT lumbar spine X-rays were 

taken at the start of employment for all individuals employed from 1952 to 1974. If a record of PFG 
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 16 of 20

use is found in an individual’s claim file, an annual PFG X-ray of the chest should be assumed from 

1952 to 1968 [18]. 

Consistent with ORAUT (2005), the statistical root mean square was calculated to estimate total 

uncertainty (ORAUT 2005). The root mean square is the square root of the sum of the squares of the 

individual uncertainty values, and equals 28.9%. An estimate of 30% uncertainty is larger than the 

default NIOSH guidance standard deviation recommendation of 20% (NIOSH 2002). 

3.7 ATTRIBUTIONS AND ANNOTATIONS

Where appropriate in the preceding text, bracketed callouts have been inserted to indicate 

information, conclusions, and recommendations provided to assist in the process of worker dose 

reconstruction. These callouts are listed here again in the Attributions section of the document, with 

information provided to identify the source and justification for each associated item. Conventional 

references are provided in the next section of this document, linking data, quotations, and other 

information to documents available for review on the ORAU Team servers.

[1] Lopez, Theresa. MFG. Senior Toxicologist. July 2006. 

In the absence of data or protocols, assumptions that needed to be made were favorable to 

claimants.

[2] Furman, J. Oak Ridge Institute for Science and Education (ORISE). Former Medical Director, 

Rocky Flats Plant. July 2003. 

Based on work history at the site and available protocols. Documented July 18, 2003.

[3] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files at RFP. Documented July 18, 2003.

[4] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files at RFP. Documented July 18, 2003.

[5] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files at RFP. Documented July 18, 2003.

[6] Lopez, Theresa. MFG. Senior Toxicologist. July 2006. 

Many other DOE sites are known to have conducted termination X-rays. No protocol or record 

of termination X-rays as a standard practice has been found for RFP. A review of medical files 

did not indicate that the practice was common, if it occurred at all. However, former 

nonmedical employees assert that it did occur. Because this was a common practice at other 

DOE sites, it has been assumed to have occurred at RFP up to the date that a protocol stating 

otherwise was published. This assumption is favorable to claimants.

[7] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files at RFP and interviews with medical personnel. Documented 

July 18, 2003. 

[8] Lopez, Theresa. MFG. Senior Toxicologist. July 2006. 

In the absence of a protocol, it was assumed that all workers received these X-rays, even

though they were more likely to have been related to job classification. This assumption is 

favorable to claimants.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 17 of 20

[9] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on personal history of working at the site and medical file review. Documented July 18, 

2003.

[10] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files. Documented July 18, 2003.

[11] Lopez, Theresa. MFG. Senior Toxicologist. July 2006. 

An annual single-view chest X-ray is likely an overestimate of actual practice because a review 

of medical files found that chest X-rays rarely occurred on an annual basis, probably due to

scheduling and machine availability. However, this assumption is favorable to claimants 

because it encompasses more X-rays than were probably taken.

[12] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Documented July 18, 2003. Also documented by Robert Meyer, August 13, 2003.

[13] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on review of medical files and discussions. Documented July 18, 2003.

[14] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on medical personnel interviews and review of medical files. Documented July 18, 

2003.

[15] Lopez, Theresa. MFG. Senior Toxicologist. July 2006. 

No PFG records or protocols have been found. PFG has been assumed to have possibly 

occurred because former workers recall the use of a “portable x-ray machine.” However, 

former medical employees do not recall performing PFG.

[16] Lopez, Theresa. MFG. Senior Toxicologist. July 2006.

Calculated from information given to J. Furman by the Occupational Medicine Group at RFP. 

Documented July 18, 2003.

[17] Furman, J. ORISE. Former Medical Director, Rocky Flats Plant. July 2003.

Based on personal work history at the site.

[18] Lopez, Theresa. MFG. Senior Toxicologist. July 2006.

See Attribution and Annotation [15]. This assumption is favorable to claimants.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 18 of 20

REFERENCES

Dean, A., 2003, “Regarding location of Rocky Flats X-ray documents,” memorandum to file, MFG, 

Fort Collins, Colorado, October 21.

ICRP (International Commission on Radiological Protection), 1982, Protection of the Patient in 

Diagnostic Radiology, Publication 34, Pergamon Press, Oxford, England.

Lincoln, T. A., and E. D. Gupton, 1958, “Radiation Doses in Diagnostic X-ray Procedures.” Radiology. 

volume 71, pp. 208–215.

Lopez, T., 2003, Documented communication of T. Lopez (MFG) with Dr. J. Furman (of ORISE, 

formerly of RFP) regarding information from Dr. J. McInerney (of ORISE, formerly of RFP), 

July 30.

NCRP (National Council on Radiation Protection and Measurements), 1989, Medical X-ray, Electron 

Beam, and Gamma-Ray Protection for Energies Up to 50 MeV (Equipment Design, 

Performance, and Use), Report 102, Bethesda, Maryland.

NIOSH (National Institute for Occupational Safety and Health) 2002, External Dose Reconstruction 

Implementation Guidelines, Rev. 1, OCAS-IG-001, Office of Compensation Analysis and 

Support, Cincinnati, Ohio.

ORAUT (Oak Ridge Associated Universities Team), 2005, Technical Information Bulletin: Dose 

Reconstruction from Occupationally Related Diagnostic X-ray Procedures, ORAUT-OTIB-0006

Rev. 03-D PC-1, Oak Ridge, Tennessee, December 21.

RFP (Rocky Flats Plant), 1991, Occupational Health Examination Criteria, Appendix I, Golden, 

Colorado.

Webster, E. W., and O. E. Merrill, 1957, “Measurements of Gonadal Dose in Radiographic 

Examinations,” New England Journal of Medicine, volume 257, pp. 811-819.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 19 of 20

GLOSSARY

curie (Ci)

A special unit of activity. One curie equals exactly 3.7 × 1010 nuclear transitions per second.

exposure

Expressed in roentgens (R): the ionization produced by photon (gamma and X-ray) radiation 

in air. 

extremities

Elbow through fingers; knee through toes.

gamma rays

Ionizing electromagnetic radiation (photons) originating from atomic nuclei. 

gray (Gy)

The International System unit of absorbed dose.

lumbosacral spine

The five lumbar and five sacral vertebrae of the spine.

neutron

Neutral nuclear particle; mass nearly the same as the proton.

personal dose equivalent Hp(d)

Represents the dose equivalent in soft tissue below a specified point on the body at an 

appropriate depth d. The depths selected for personnel dosimetry are 0.07 mm and 10 mm, 

respectively, for the skin and body. These are noted as Hp(0.07) and Hp(10), respectively. 

photon (ionizing)

X- or gamma radiation. 

photon - X-ray

Electromagnetic radiation of energies between 10 keV and 100 keV whose source can be an 

X-ray machine or radioisotope.

radiation

Alpha, beta, neutron, X-, or gamma radiation. 

radioactivity

The spontaneous emission of radiation from unstable nuclei.

rem

A unit of dose equivalent, equal to the product of the number of rads absorbed and the quality 

factor.

roentgen (R)

A unit of exposure to gamma (or X-) radiation. It is defined as the quantity of gamma (or X) 

rays that will produce a total charge of 2.58 × 10-4 coulomb in 1 kg of dry air. An exposure of 

1 R is approximately equivalent to an absorbed dose of 1 rad in soft tissue for higher (~>100 

keV) energy photons.
Document No. ORAUT-TKBS-0011-3 Revision No. 01 Effective Date: 04/23/2007 Page 20 of 20

shielding

Any material or obstruction that diminishes or attenuates radiation and thus can protect 

personnel or materials from radiation.

sievert (Sv)

The SI unit for dose equivalent. (1 Sv = 100 rem.)

skin dose

Absorbed dose at a tissue depth of 7 mg/cm2

.

X-ray

(1) Radiograph. (2) Ionizing electromagnetic radiation produced outside the nucleus.