ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 12

Document Title:

Argonne National Laboratory – West –

Occupational Medical Dose

Document Number: ORAUT-TKBS-0026-3

Revision: 01

Effective Date: 07/30/2007

Type of Document TBD

Supersedes: Revision 00

Subject Expert(s): JoAnn M. Jenkins

Site Expert(s): Norman D. Rohrig

Approval: Signature on File Approval Date: 07/20/2007

Jo Ann M. Jenkins, Document Owner

Concurrence: Signature on File Concurrence Date: 07/10/2007

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 07/12/2007

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 07/27/2007

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 07/30/2007

Brant A. Ulsh, PhD CHP

 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 No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 2 of 12

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

09/09/2004 00 New Technical Basis Document for the Argonne National Laboratory 

– West – Occupational Medical Dose. First approved issue. Initiated 

by Norman D. Rohrig.

05/16/2005 00 PC-1 Approved page change revision. Replaces first paragraph of section 

3.2 on page 4 and the associated table specifying x-ray /age 

requirements. Revises Table 3A-1 on page 11 to reflect these 

changes No changes were needed as a result of NIOSH formal 

review. No training required. Initiated by Norman D. Rohrig.

Approval:

Norman D. Rohrig, Document Owner

Signature on File 05/10/2005

Judson L. Kenoyer, Task 3 Manager

Signature on File 05/09/2005

Richard E. Toohey, Project Director

Signature on File 05/10/2005

James W. Neton, Associate Director for Science

Signature on File 05/16/2005

07/30/2007 01 Approved Revision 01 initiated to add Attributions and Annotations 

section. Moved Appendix into document. Constitutes a total rewrite 

of the document. Incorporates formal internal and NIOSH review 

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

Initiated by Jo Ann M. Jenkins. 
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 3 of 12

TABLE OF CONTENTS

SECTION TITLE

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

PAGE

4

3.1 Introduction.................................................................................................................................5

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

 3.1.2 Scope................................................................................................................................6

3.2 Examination Frequencies............................................................................................................6

3.3 Equipment and Techniques ........................................................................................................7

3.4 Organ Doses...............................................................................................................................8

3.5 Uncertainty..................................................................................................................................9

3.6 Attributions and Annotations ..................................................................................................... 10

References ........................................................................................................................................11

Glossary ............................................................................................................................................12

LIST OF TABLES

TABLE TITLE

3-1 Skin entrance air kerma values ................................................................................................

PAGE

8

3-2 Organ doses from occupational medical exposures at ANL-W................................................. 8

3-3 IREP organs not included in ICRP Publication 34 .................................................................... 9
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 4 of 12

ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

ANL-W Argonne National Laboratory–West

AP anterior-posterior

cm centimeter

DOE U.S. Department of Energy

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

Hz hertz

ICRP International Commission on Radiological Protection

INEEL Idaho National Engineering and Environmental Laboratory

IREP Interactive RadioEpidemiological Program

kerma Kinetic Energy Released to Matter

kg kilogram 

kVp kilovolts-peak, applied voltage

LAT lateral

lb pound

mA milliampere

mAs milliampere-second

mm millimeter

mrad millirad

ms millisecond

NCRP National Committee for Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

OCAS Office of Compensation Analysis and Support

ORAU Oak Ridge Associated Universities

PA posterior-anterior 

POC probability of causation

s second

SRDB Ref ID Site Research Database Reference Identification (number)

TBD technical basis document

U.S.C. United States Code

§ section or sections
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 5 of 12

3.1 INTRODUCTION

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.

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.

• Radiation from naturally occurring radon present in conventional structures

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

 1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the POC.
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 6 of 12

3.1.1

This TBD discusses the occupational medical dose workers received during employment at the 

Argonne National Laboratory–West (ANL-W), which has operated from February, 1951 to the present. 

The site required preemployment and periodic physical examinations as part of its occupational health 

and safety program. At first, the U.S. Atomic Energy Commission (AEC) provided these medical 

examinations for all onsite Federal and contractor personnel. Later, the examinations became the 

responsibility of the site prime contractor. 

Purpose

3.1.2

The examinations typically included diagnostic chest X-rays. The dose from these procedures 

depended not only on the characteristics of the X-ray machine and the procedure used, but also on 

the frequency of examinations. This document discusses various X-ray techniques and equipment 

used over the years at the Idaho National Laboratory (INL). ANL-W employees were a part of the 

Idaho National Laboratory medical program (Creighton 2003). The primary source of information on 

medical X-rays is a report that Collings and Creighton (2002) prepared at NIOSH request. 

Scope

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 3.6.

3.2 EXAMINATION FREQUENCIES

A review of the NIOSH-Office of Compensation Analysis and Support (OCAS) Claims Tracking 

System (NOCTS) showed that the database contains ANL-W worker X-ray records. From this it can 

be concluded that chest X-rays were given annually from 1959 to about 1975. It can be assumed that

they were given annually before that time. This contradicts the practice at INL even though these 

X-rays were given through the INL medical organization.

The Appendix to Chapter 0528 of the AEC Manual (AEC 1969) specified the following:

• A chest X-ray would be part of a medical examination.

• Workers under 40 would receive an examination at a frequency influenced by several factors.

• Workers over 40 would receive an examination at least every 2 years (approximately annually 

when indicated).

The 1971 Annual Report of the Health Services Laboratory (AEC 1972) stated that the schedule for 

examinations is “at time of hire, at ages 25, 30, 34, 37, and 40, every two years until age 62 and then 

annually.” This is identical to the frequency reported by Collings and Creighton (2002) and is 

assumed to apply from 1975 to 1976.

Beginning in 1976, physicals occurred every 2 years for workers under 45 and every year for those 45 

and over (Collings and Creighton 2002). On February 1, 1978, INL eliminated routine chest X-rays 

during periodic physicals with the exception of high-risk individuals (as determined by the physician), 

in which case the examinations were performed every 4 years. Records from the exposures are 

reported in each worker’s medical file. 
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 7 of 12

3.3 EQUIPMENT AND TECHNIQUES

The standard distance from source to image was 72 inches (183 cm).

The available information indicates that none of the INL examinations used fluoroscopic techniques 

(Creighton 2003). AEC (1972) identifies the use of a medical van for 22% of the 4,426 X-ray 

examinations. In addition, that report mentions that the Idaho Falls Navy dispensary performed X-ray 

examinations. Both of these facilities performed standard chest X-rays and did not do 

photofluoroscopy. A keyword search of the INL records system using the terms collimation, 

fluoroscopic, Health and Safety, Health and Safety Services, Medical X-ray, photofluorography, and xray resulted in nothing that indicated the use of photofluorographic techniques (Vivian and Rockhold 

2003).

From 1954 to February 1990, X-ray examinations were performed with a single-phase General 

Electric Model DXD350 machine. The voltage was 90 kVp, the current was 300 mA, and the duration 

of the exposure was 0.0667 s (67 ms). Added filtration of 2 mm Al was used, and a 10:1 grid was 

used to reduce scatter radiation (Collings and Creighton 2002). Tube window thickness is assumed 

to be about 0.5 mm. Based on Table A16 of International Commission on Radiological Protection 

(ICRP) Publication 34, Protection of the Patient in Diagnostic Radiology (ICRP 1982), the half-value 

layer at 90 kVp and 2.5-mm total aluminum filtration is 2.58 mm Al.

From February 1990 to the present, X-rays have been performed with a three-phase Gendex Model 

110-0030G2. The voltage is 100 kVp, the current is 300 mA, and the duration is 32 ms. Added 

filtration of 2 mm Al was used, and a 10:1 grid was used to reduce scatter radiation (Collings and 

Creighton 2002). Tube window thickness is assumed to be about 0.5 mm. Based on Table A17 of 

ICRP (1982), the half-value layer at 100 kVp and 2.5-mm total aluminum filtration is 3.3 mm Al.

Practices before 1954 are unclear. Offsite facilities might have been contracted to perform the 

examinations. The default value for entrance kerma of 200 mrad (ORAUT 2005a) is assumed for that 

period. 

From 1954 to 1970, the chest X-ray consisted of a single posterior-anterior (PA; back to front) image. 

From 1970 to 1978, the procedure consisted of both PA and lateral (LAT) projections. From 1978 to 

1990, the LAT projection was dropped and only a PA projection was made. From 1990 to the 

present, there were both PA and LAT projections. The exposure time for LAT projections was about 

1.25 times that of the PA projection. In Collings and Creighton (2002), the terms PA and AP 

(anterior-posterior, front to back) appear somewhat interchangeably. Creighton attributed this 

presumed interchangeable usage to a typographical error. The August 21, 1975, Energy Research 

and Development Administration (ERDA) requirement for occupational medical programs (replaced in 

1982) specified the minimum requirements for chest X-rays and a PA projection at least once every 5 

years, as well as when a worker with cardiorespiratory system stress transferred to a different job 

(ERDA 1975).

Collimation and control of scatter for INL facilities generally followed the state of the medical art as it 

improved. However, in the absence of particular information about collimation, this TBD uses the 

dose conversion factors in Table 6-5 of ORAUT (2005a) for the pre-1970 period.
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 8 of 12

3.4 ORGAN DOSES 

The entrance air kerma for 100 mAs can be determined from Table B3 of National Council on 

Radiation Protection and Measurements (NCRP) Report 102 (NCRP 1989) and the beam voltage, 

distance, and total filtration. Table 3-1 lists air kerma values.

Table 3-1. Skin entrance air kerma 

values (mrad).

Air kerma PA LAT

Pre-1954 200 500

1954 to Jan 1990 52 74

Feb 1990 to present 53 76

Tables A2 to A9 of ICRP (1982) list Monte Carlo calculation results of the ratio of organ doses to air 

kerma for a 70-kg (154-lb) male or female for the thyroid, ovaries, testes, lungs, female breast, uterus 

(embryo), active bone marrow, and total body under different exposure conditions. For organs where 

there is a difference for males and females, the larger value is used. A linear interpolation, applicable 

to all years, was used between the dose ratios for half-value layers of 2.5, 3.0, and 3.5 mm Al to the 

values of 2.58 and 3.3 mm Al (ICRP 1982). The skin entrance surface was assumed to be 30 cm 

from the film for the PA projection and 40 cm from the film for the LAT projection (ORAUT 2005a). 

These distances account for body thickness and any space between the person and the film. The 

dose to the skin is the product of the entrance skin exposure and a backscatter factor from NCRP 

Report 102 (NCRP 1989, Table B-8).

The organ dose from a PA image is the product of the two table values, an inverse square correction, 

and the product of exposure current and time. Table 3-2 lists these values. For LAT images, a similar 

calculation was performed and added to the PA result. The first heading row in this table lists the 

organs identified in ICRP Publication 34 (ICRP 1982) and the second heading row lists the organs in 

IREP that are not listed in Publication 34. 

Table 3-2. Organ doses from occupational medical exposures at ANL-W.

Period Frequency

ICRP 34 organs

Organ doses (mrad) from ANL-W chest X-ray

Thyroid Testes Lungs Breast

Ovary 

Embryo

Bone 

marrow

Other organs

Eye

Brain

Thymus

Esophagus

Stomach

Bone surface

Liver/spleen

Gall bladder

Uterus

Bladder

Colon Skin

Geometry

Before 1954 No information PA 69 1.8 93 10 34 19 272

Assume annual

1954–1974 New hires PA 18 0.5 24 2.7 8 5 70

Annual

1975–1976 New hires PA, 

LAT

10 0.008 41 22 0.1 8 171

25, 30, 34, 37, 40

Biennial 40 to 62

Annual >62

1977–1978 New hires PA, 

Biennial <45 LAT

Annual >45

1979–Jan 1990 New hires PA 1.8 0.001 24 2.7 0.1 5.0 70

4 years High risk

Feb 1990–present only PA, 

LAT

14 0.008 53 27 0.3 11 180
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 9 of 12

Cancers in several other organs, as listed in the Interactive RadioEpidemiological Program (IREP), 

are compensable. The ratio of doses for two organs is affected by the relative atomic numbers of the 

tissue (bone dose is higher than dose in nearby muscle), the relative positions of the organ and the 

X-ray beam, and the depth in the body. Table 3-3 lists these other organs and the organs from ICRP 

Publication 34 (ICRP 1982), which were used to estimate the dose, in the third column.

3.5 UNCERTAINTY

Uncertainties in the occupational medical dose result from uncertainties in the current, voltage, and 

exposure time. In addition, organ doses are influenced by the size of the person. If an analog organ 

is used from the ICRP (1982) organs, the IREP organs are generally deeper in the body so the dose 

will be lower than that for the analog organ. No estimate is made of this one-sided uncertainty 

because it cannot lead to a larger dose.

Table 3-3. IREP organs not included in ICRP 

Publication 34 (ICRP 1982).

Anatomical 

location

ICRP (1982) 

reference organ

IREP organ 

analogs

Head Thyroid Eye

Brain

Thorax Lung Thymus

Esophagus

Bone surface 

Stomach/spleen

Liver/gall bladder

Abdomen Ovaries Urinary bladder

Colon

Uterus

The uncertainties assigned in the Savannah River Site (SRS) site profile (ORAUT 2005b) are 

generically valid for X-ray programs. The uncertainty at one sigma due to voltage was 9%, that due to 

current was 5%, and that due to time was 25%. The uncertainty for voltage assumes a 5% voltage 

uncertainty and, because the output has a V1.7 dependence, results in a 9% uncertainty. Output is 

directly proportional to current, which is assumed to have a 5% uncertainty. The usually unfiltered 

voltage output from the voltage rectifier causes a pulsed character to the X-ray output at 120 Hz 

(twice the supply frequency). For a short exposure time, this results in only a few pulses and thus a 

fairly large uncertainty due to time.

All Monte Carlo calculations have an uncertainty determined by the length of the run and the number 

of events scored for each calculation. For the organ dose calculations from ICRP Publication 34 

(ICRP 1982), this uncertainty was not stated. Based on judgment, it is assumed to be 5% at 1 sigma, 

which would require at least 400 counts in each scoring unit [1]. 

The error due to worker thickness has two components: (1) an increase for a larger person being 

closer to the source and (2) a decrease due to additional attenuation in the body. The Monte Carlo 

calculations in ICRP Publication 34 (ICRP 1982) assumed 70-kg (154-lb) male and female 

geometries. The 10% uncertainty assigned in the SRS TBD (ORAUT 2005b) was due to the first 

cause, but, because the effects counteract, that value is appropriate for the combined effect. This 

should be taken as 1 sigma on a normal distribution. These sources of uncertainty added in 

quadrature result in a combined uncertainty of ±30% at 1 sigma or 84% confidence [2]. 
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 10 of 12

3.6 ATTRIBUTIONS AND ANNOTATIONS 

Where appropriate in this document, 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 in the Attributions and Annotations section, with 

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

which are provided in the next section of this document, link data, quotations, and other information to 

documents available for review on the Project’s Site Research Database.

Norman Rohrig served as the initial Document Owner for this document. Mr. Rohrig was previously 

employed at INL which shared boundaries with ANL-W and used the same dosimetry systems and his 

work involved management, direction or implementation of radiation protection and/or health physics 

program policies, procedures or practices related to atomic weapons activities at the site. This 

revision has been overseen by a new Document Owner, who is fully responsible for the content of this 

document, including all findings and conclusions. Mr. Rohrig continues to serve as a Site Expert for 

this document because he possesses or is aware of information relevant for reconstructing radiation

doses experienced by energy employees who worked at the site. In all cases where such information 

or prior studies or writings are included or relied upon by the Document Owner, those materials are 

fully attributed to the source. 

[1] Rohrig, Norman. ORAU Team. Health Physicist. June-September 2003.

ICRP (1982) did not state an uncertainty, but scientific expertise implies there is one. A 5% 

value would be consistent with stating the results to two significant digits. A significantly 

smaller uncertainty would increase the effort significantly. This uncertainty does not drive the 

total uncertainty.

[2] Rohrig, Norman. ORAU Team. Health Physicist. June-September 2003.

“Added in quadrature” refers to taking the square root of the sum of the squares of the 

individual error contributions, which are 9%, 5%, 25%, and 5%.
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 11 of 12

REFERENCES

AEC (U.S. Atomic Energy Commission), 1969, "Chapter 0528, Occupational Health Program," AEC 

Manual, Washington, D.C., December 5. [SRDB Ref ID: 4644]

AEC (U.S. Atomic Energy Commission), 1972, 1971 Annual Report of the Health Services Laboratory, 

IDO-12076, Idaho Operations Office, Idaho Falls, Idaho. [SRDB Ref ID: 1431]

Collings, L. H., and P. Creighton, 2002, Idaho National Engineering and Environmental Laboratory 

(INEEL) History of the Occupational Medical Program (OMP) X-Ray Process, Bechtel BWXT 

Idaho, Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho, April 8. 

[SRDB Ref ID: 1774, p. 9]

Creighton, P. N., 2003, “Transmittal of Medical X-ray Information for the INEEL,” letter to L. Johnson 

(National Institute for Occupational Safety and Health), Idaho National Engineering and 

Environmental Laboratory, Idaho Falls, Idaho, June 24. [SRDB Ref ID: 4646]

ERDA (U.S. Energy Research and Development Administration), 1975, "Chapter 0528, ERDA 

Contractor Occupational Medical Program Handbook," ERDA Manual, Washington, D.C., 

August 21. [SRDB Ref ID: 4643]

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

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

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.

ORAUT (Oak Ridge Associated Universities Team), 2005a, Dose Reconstruction from Occupationally 

Related Diagnostic X-Ray Procedures, ORAUT-OTIB-0006, Rev. 03 PC-1, Oak Ridge, 

Tennessee, December 21.

ORAUT (Oak Ridge Associated Universities Team), 2005b, Savannah River Site, ORAUT-TKBS0003, Rev. 03, Oak Ridge, Tennessee, April 5.

Vivian, K. A., and L. E. Rockhold, 2003, "Transmittal of Medical Documents from the INEEL," letter to 

N. Rohrig (Intrepid Technology and Resources), CCN 46313, Bechtel BWXT Idaho, Idaho 

National Engineering and Environmental Laboratory, Idaho Falls, Idaho, November 18. 

[SRDB Ref ID: 7975]
Document No. ORAUT-TKBS-0026-3 Revision No. 01 Effective Date: 07/30/2007 Page 12 of 12

GLOSSARY

U.S. Atomic Energy Commission

Original agency established for nuclear weapons and power production; a predecessor to the 

U.S. Department of Energy.

anterior-posterior (AP)

Irradiation geometry in which the radiation passes from the front of a person to the back.

lateral (LAT)

Irradiation geometry in which the radiation passes from one side of a person to the other.

posterior-anterior (PA)

Irradiation geometry in which the radiation passes from the back of a person to the front.

rad

The unit for absorbed dose, 1 rad = 100 erg per gram.

X-ray 

Ionizing electromagnetic radiation of external nuclear origin or an image generated by 

exposing a detector (e.g., film) to X-rays.