Division of Compensation Analysis and 

Support

Technical Information Bulletin

Document Number: 

 DCAS-TIB-0013

Effective Date: 11/23/2010

Revision No. 1

Selected Geometric Exposure Scenario Considerations for 

External Dose Reconstruction at Uranium Facilities

Page 1 of 16

Approval: Signature on file Date: _11/23/2010_

 J.W. Neton, Associate Director for Science

Supersedes:

 Revision 0

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE

DATE

REV. 

NO.

DESCRIPTION

10/26/2005 10/26/2005 0 Document initiated to provide guidance on the 

application of geometry-based dose correction 

factors to external dosimetry badge data for 

Mallinckrodt workers in particular job 

classifications. 

10/14/2010 11/23/2010 1 Incorporated SC&A comments; reorganized 

procedure format; included dose reconstruction 

instructions for the application of geometric 

correction factors to the upper and lower torso; 

added information to clarify the bounding 

parameters associated with the Attila 

computation; NIOSH internal comments 

including procedure title change and applicability 

to other uranium facilities.

1.0 Purpose

The purpose of this technical information bulletin (TIB) is to provide guidance on the 

application of geometry-based dose correction factors to external dosimetry badge data for 

uranium process facility workers. A specific example for Mallinckrodt worker job 

classifications has been used to show how to apply a correction but the process is 

completely general. Mallinckrodt data has also been used for comparison to ATTILA 

software computational results. The correction factor is completely determined by geometry. 

Photon fluence was determined at the surface of the dosimeter on the upper torso and at the 

surface of the person on the lower torso and head in each scenario. No dose computation 
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was performed, only the relative relation between fluence. Before the geometry correction 

factor can be used the dose reconstructor must determine energy, rotational corrections, and 

absorption/ penetration through badge filters. After those corrections are made, the 

geometry correction factor is applied. Bremsstrahlung is not taken into account in this TIB. 

The dose reconstructor handles that before the correction is applied. A photon from the 

source, regardless of energy, will reach the surface of the upper torso and lower torso in the 

same proportion. The factors are to be used for the periods of time where the individual’s 

work history places him/her in a job for which a correction may be necessary. Specific job 

classifications for which these factors apply are discussed in section 4.0. If abdomen 

dosimetry data is available, it should be used in place of this TIB. Likewise if wrist/ring 

dosimetry is available then it should be used instead of extrapolating from this TIB.

2.0 Geometric Exposure Considerations

Consideration must be given to the role that geometry plays in dose reconstruction for 

uranium facility workers. Jobs at a facility range from those that required continuous hand or 

near-hand contact during a work day to those jobs where contact was only at a distance and 

of short duration. The distance and time factors could result in an underestimation of the 

reconstructed dosimeter and missed dose to organs located in the lower torso region of the 

body (e.g., stomach, liver, bladder, prostate, ovaries, testes, etc...) for high contact jobs. The 

degree of underestimation, or in some cases overestimation, is also dependent upon the 

shielding between the worker and source of radiation. 

2.1 Exposure Geometries

Exposure geometry is a special consideration in dose reconstruction of energy employees 

who worked with uranium metal, powders and residues. An underestimation of the dose 

could occur if the energy employee wore his/her dosimeter on the lapel and not the center 

area of the chest or on the waist. This underestimation could result due to the difference in 

relative distances among the external radiation source, the organ of interest, and the 

dosimeter. Organs in the lower torso are affected most. The dose to the lung is considered 

to be reasonably approximated by the lapel dosimeter, at least to within the dosimeter 

uncertainty, while the dose to the face and head could be lower than the dose measured by 

the dosimeter worn on the lapel. 

2.2 ATTILA Radiation Transport Software

The Attilla Radiation Transport Software(1) was used to evaluate several near hand exposure 

scenarios. Attila is a multi-group deterministic radiation transport program that is capable of 

modeling complex geometries efficiently and accurately to solve large 3-D problems.
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Attila can solve for neutron and photon transport equations and accounts for the same 

transport effects as Monte Carlo but is faster as no variance reduction is required. Attila 

directly solves the differential form of the Boltzmann transport equation. For charged 

particles, the Boltzmann-Fokker-Planck transport equation is solved. It discretizes in space, 

angle and energy to solve for flux as a function of angle, energy and particle type, at every 

location in the computational domain.

3.0 Methodology

3.1 ATTILA Model Development, Mallinckrodt Example

A review of table 18, Job titles and classifications with geometry factor, from the “Basis for 

Development of an Exposure Matrix for the Mallinckrodt Chemical Company St. Louis 

Downtown Site and the St Louis Airport Site, St. Louis, Missouri, Period of Operation: 1942–

1958”

(2) was made to determine the type of scenario/s for which ATTILA could be used to 

develop general correction factors for the lower torso of an energy worker. The lower torso is 

defined as those organs below the lungs in figure 1. These organs include but are not limited 

to the stomach, liver, kidney, gall bladder, ureter, pancreas, small intestine, large intestine, 

rectum, ovaries, uterus, urinary bladder, and prostate.

Using Attila, three near hand job exposure scenarios were evaluated that exemplified the 

range of body/source orientations for which badge correction factors could be determined.

These were pitchblende/cleanup activities, ingot/machining activities and de-nitration pot

activities. For development of the geometry correction factor, only the photon contribution 

was analyzed, since only the relative values between body locations and the photon 

components were of interest. For the model development, the human figure was divided into 

head, upper torso, badge, lower torso and hands. Dose correction factors were developed 

based on fluence at the badge relative to the other body locations. 

It should be reiterated that the purpose of this ATTILA model was to demonstrate that, due to 

geometry, a relative flux factor exists between the badge and different points of the body for 

each of 3 source term scenarios. Because of this it was necessary to create a realistic model 

of a human body or provide photon fluence at those points. 
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Figure 1: Diagram of Human Torso (3)

The results for pitchblende/cleanup activities, ingot/machining activities and de-nitration pot 

activities are provided for in figures 2, 3 and 4 respectively. Each geometric correction factor 

is relative to the dosimeter/badge worn on the upper mid-chest. The human figure is six feet 

tall. The factors, as calculated, are provided in Table 1. Based on the ingot and pitchblende 

exposure scenario results, a factor of 2.1 should be applied to the lower torso. The detail of 

each scenario follows in the next three sections. Relational distances are provided after

each figure. 

Table 1 Geometry Correction Factors for Specific Jobs

Body Location Attila Exposure Scenario

Ingot / Machining Pitchblende Clean-up De-nitration Pot

Head 0.4 0.41 0.57

Badge (Upper Chest) 1.00 1.00 1.00

Lower Torso 2.13 2.11 0.03

Hands 3.65 1.20 1.67
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3.1.1 Pitchblende/Cleanup scenario

Cleanup activities at Mallinckrodt occurred on a frequent basis in several areas. The 

purpose of this scenario was to simulate the positional relationship between the worker and a 

pitchblende/cleanup spill. The material was spread in a circular pattern on the floor. This 

was seldom a hands-on activity.

Figure 2: Pitchblende/Cleanup
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Figure 2a: Dimensions for Pitchblende/Cleanup
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3.1.2 Uranium Ingot Scenario

In some situations workers would come in close contact with uranium metal during machining 

or sawing. This scenario demonstrated the positional relationship of an ingot at waist level in 

close association to the worker’s body. 

Figure 3: Ingot/Machining
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Figure 3a: Dimensions for Ingot/Machining
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3.1.3 De-Nitration Pot Scenario

Some activities would place a worker near a uranium de-nitration pot or drum. The individual 

would have the lower torso shielded by metal or some other material with the majority of 

photon flux being delivered to the hands, upper torso and head.

Figure 4: Cut away exposure view of De-nitration Pot
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Figure 4a: Dimensions for cut away exposure view of De-nitration Pot
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3.2 Comparison of Attila Model Estimate to Mallinckrodt Dosimetry Data

Limited ring badge dosimetry data was used to validate the Attila modeled geometry ratio. In 

1949, for a 5 week period, selected Mallinckrodt workers were issued ring dosimeters in 

addition to their whole body dosimeter.(4) At the current time, a full comparison of site 

dosimeter data is not possible since the detailed dosimetry for most of the study participants 

has not yet been obtained from DOE. However, for three individuals with a non-zero dose, a 

comparison of the ring dosimeter to whole dosimeter was possible. Table 2 provides the 

data comparison and the calculated geometric correction ratio. Figure 5 provides this limited 

data on a probability plot to indicate the range of values with the three Attila point estimates. 

Table 2 Comparison of Ring Dosimeter to Whole Body Dosimeter

Study 

Subject

Radiation 

Type

Ring Dose Whole Body Dose Geometric Correction 

Ratio

1 Beta 195 85 2.29

2 Beta 95 30 3.17

1 Gamma 440 150 2.93

3 Gamma 560 275(a) 2.04

4 Gamma 460 275(a) 1.67

Maximum Attila Estimated Hand Ratio 3.65

(a) Estimated Midpoint – the data indicate whole body dosimeter was between 251 mR and 300 mR. 
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Geometric Correction Ratio for the Hands

Probability

0.5 1 2 5 10 20 30 50 70 80 90 95 98 99

Geometry Ratio (Ring/Whole Body)

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Ring Dosimetry Derived Ratios

Attila Exposure Estimates

Figure 5: Probability Plot of Attila modeled point estimates and limited 

ring dosimetry comparison data.

The limited dosimetry data clearly indicate that the model reasonably predicts the geometric 

correction factor. As a result, the dose reconstruction to organs in the lower torso should 

multiply the measured and the missed dose by the factor 2.1 as indicated by the Attila model. 

 Also for comparison, the geometry factors generated from ATTILA and used in the 

Glove Box Worker Technical Information Bulletin 00010 provide a reasonable idea of the 

spread of ratio values between upper and lower torso. The geometric mean and standard 

deviation of the glove box are as follows: 2.19 and 1.34 respectively. This spread is based 

on a Crystal Ball Monte Carlo analysis of 30 different upper and lower torso points. Since 

this is only geometry dependent, it would hold for this TIB as well.

 
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3.2.1 Reasonable Claimant Favorable Assumptions

Listed below are several claimant favorable assumptions used in the development of this 

methodology that could result in an overestimate of the actual dose.

 

Claimant favorable model design. Human figure is 6 ft tall, above the average. The 

correction factor over-estimates dose for shorter persons.

Assignment of badge results where actual reduction due to geometry occurs

Assignment of correction factor for all tasks within the job classification

Obtaining data to precisely evaluate each of these parameters requires extensive time and 

research on an individual basis and in some instances it is not known if the information can 

be obtained (i.e., facility has undergone D&D or other significant modification over time). 

4.0 Application of Geometry Correction Factor

It should be noted however that there is a significant reduction in dose to the head for all 

scenarios. In addition, due to shielding provided by the De-nitration Pot, there was also a 

significant reduction in dose to the lower torso. Assigning the badge dose to these body 

locations is claimant favorable. However, as illustrated in Table 1, there are some organs in 

certain exposure scenarios for which dose could be underestimated. 

In a review of selected work histories and dust study estimates of internal exposure, it is clear 

that most operators conducted various different tasks over their career. As a result the 

application of a single factor over their entire work history is also considered claimant 

favorable as some tasks would involve near-hand exposures while others would not. 

As noted there are numerous different work stations (tasks) for which a geometry correction 

factor should be applied to accurately estimate the dose to organs in the lower torso from a 

film badge worn on the lapel. For example, a review of the claimant work history information 

in conjunction with the job descriptions (Tasks) in Table 18 of the Mallinckrodt technical basis 

document indicates that many Production and Chemical Operators worked at various 

stations, some of which require a geometry correction and some do not. Time estimates 

used in the dust studies could be used to estimate the fraction of time a worker would be in 

one geometry versus another; however, the external dose cannot be reasonably partitioned 

based on time since the external dose rate changes from location to location. In addition, 

trades and crafts workers conducted work in and around radioactive materials throughout the 

facility. As with chemical and production operators, time motion dust study data could be 

used to estimate the general time they were in a specific area; however, the external dose 
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rates changed such that it is not practical to partition the dose measured on the lapel 

dosimeter accordingly. 

As a result, the additional claimant favorable assumption is made that the geometry 

correction factor should be applied to all measured and missed dose for the general 

occupations listed in Table 3. 

Table 3 Job Types for which the geometric correction factor should be applied.

General Category Specific Job Titles

Operators and 

Material Handlers 

Chemical Operator, Production Operator, 

Material Handler

Trades and Crafts Pipefitters, Carpenters, Welders, Sheet Metal 

Workers, Electricians, Foremen, etc...

It should be noted, however, that occupations other than those listed above should be 

evaluated on a case by case basis to determine if a correction factor should be applied. A 

review of the current active Mallinckrodt claims indicates that the application of a geometric 

correction factor would not be appropriate for a significant fraction (≈43%) of the current 

Mallinckrodt claimant population. Figure 6 provides the general occupation distribution of the 

current claims received for Mallinckrodt workers.
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Active Mallinckrodt Claims Occupations

Operators 

(Production, Chemical, Material Handlers, etc...)

Trades and Crafts 

(Electrician, Pipefitter, Welder, Carpenter, Foreman, etc...)

Administrative 

(Accounting, Secretarial, Mail, Cafeteria, etc...)

Chemist and Laboratory Workers

Engineers and Draftsmen

Drivers and Vehicle Operators

Security

Operators 37%

Administrative 17%

Trades and Crafts 20%

Engineers 5%

Drivers 5%

Security 2%

Chemist and Lab 

Workers 14%

Figure 6: Breakdown of Active Mallinckrodt Claims

5.0 Summary

This Technical Information Bulletin provides guidance for dose reconstruction to organs 

located in the lower torso. For dose reconstruction to organs in the lower torso the measured 

and missed dose should be multiplied by the factor 2.1 for all members of the general job 

categories of Table 3. 

This TIB can be used for all uranium process facilities using the methods described for 

Mallinckrodt.
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6.0 References

1. McGhee and Wareing (2004) AttilaTM Version 4: User's Manual, Radion Technologies 

Los Alamos, NM

2. ORAUT (2005), Basis for Development of an Exposure Matrix for the Mallinckrodt 

Chemical Company St. Louis Downtown Site and the St Louis Airport Site, St. Louis, 

Missouri, Period of Operation: 1942–1958. ORAUT-TKBS-0005, Rev 1.

3. Merck (2004), The Merck Manual – Second Home edition, illustration obtained at the 

following website. http://www.merck.com/mrkshared/mmanual_home2/fg/fg001_1.jsp

4. MCW Memorandum (1949), Memo from A Piccot to K. Caplan providing results of the 

analysis of the film rings worn beginning April 25, 1949 through May 30, 1949. 

5. Best Estimate External Dose Reconstruction for Glovebox Workers, DCAS-TIB-0010-

Rev-3.