Office of Compensation Analysis and 

Support 

Technical Information Bulletin 

Document Number: 

OCAS-TIB-0013 

Effective Date: 10/26/2005 

Revision No. 0 

Special External Dose Reconstruction Considerations for 

Mallinckrodt Workers 

Page 1 of 10 

Approval: Signature on File Date: 10/26/2005

 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 

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 Mallinckrodt workers in 

particular job classifications. The factors are to be used for the periods of time where the individual’s 

work history places him/her in that job. Job classifications will be discussed in section 3.0. 

2.0 Special Exposure Considerations 

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

Mallinckrodt workers in particular. Jobs at the facility ranged 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 

(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. 
 

 

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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 distance between the 

external radiation source, the organ of interest, and the dosimeter. Organs in the lower torso are 

affected most. The dose to lung is considered to have been reasonably approximated by the 

dosimeter at least to within the dosimeter uncertainty and the dose to the face and head would have 

been lower than the dose measured by the dosimeter worn on the lapel. 

2.2 ATTILA Radiation Transport Software 

Attila is a deterministic radiation transport environment that can directly use CAD data and 

model complex geometry efficiently and accurately to solve large 3-D problems. 

Attila can solve for neutron, gamma, charged particle and infra-red transport and accounts for 

the same transport effects as Monte Carlo but is faster and 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 

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. 
 

 

 

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Louis Downtown Site and the St Louis Airport Site, St. Louis, Missouri, Period of 

Operation: 1942–1958 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 line A in figure 1. 

A 

Figure 1 Diagram of Human Torso (4) 

Three uranium 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. 

Only the photon contribution was analyzed. This is not a misrepresentation as we are 

interested in relative values between body locations and the photon components will reflect 

the beta problem. The human figure was divided into head, upper torso, badge, lower torso 

and hands. Dose factors were developed based on flux/dose at the badge relative to the 

other body locations. 

The pictorial results for pitchblende/cleanup activities, ingot/machining activities and denitration pot activities are seen for in figures 2, 3 and 4 respectively. Each factor is relative 

to the dosimeter/badge worn on the upper chest. The factors, as calculated, are in table 1. 

Table1 

INGOT PITCHBLENDE DENITRATION POT 

HEAD 0.4 0.409448819 0.571428571 

BADGE 1 1 1 

LOWER TORSO 2.125 2.11023622 0.033333333 

HANDS 3.65 1.204724409 1.666666667
 
 

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

and the lower torso of the de-nitration pot. In assigning the badge dose to these body 

locations we are being claimant favorable. 

Figure 2 Pitchblende/Cleanup 
 

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Figure 3 Ingot/Machining 
 

 

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Figure 4 De-nitration Pot 

3.2 Application of Geometry Correction Factor 

At Mallinckrodt there are numerous different work stations 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. A review of the claimant work history information 

in conjunction with the job descriptions in Table 18 of the Mallinckrodt site profile 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 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 
 

 

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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 rates changed such that it is not 

practical to partition the dose measured on the lapel dosimeter accordingly. 

As a result, the 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 2. 

Table 2 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... 

4.0 Comparison of Model Estimate to Dosimetry Data 

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

1949, for a 5 week period, selected workers were issued ring dosimeters in addition to their 

whole body dosimeter. At the current time, a full comparison of this 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 3 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. 
 

 

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Table 3 

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 

Attila Estimated Hand Ratio 3.65 

(a) Estimated Midpoint – the data indicate whole body dosimeter was between 251 mR and 300 mR. 

Geometric Correction Ratio for the Hands 

4.0 

Geometry Ratio (Ring/Whole Body) 3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

Ring Dosimetry Derived Ratios 

Attila Modeled Estimates 

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

Probability 

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

comparison data. 
 

 

 

 

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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. 

3.3 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 

• Assignment of badge results where actual reduction due to geometry occurs 

• Assignment of correction factor all jobs within the 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 known that the information cannot 

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

4.0 Summary 

This Technical Information Bulletin provides guidance for dose reconstruction to organs located in the 

lower torso. The dose reconstruction to organs in the lower torso should multiply the 

measured and the missed dose by the factor 2.1 for all members of the general job 

categories of table 2. 

7.0 References 
 

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1. 42 CFR 82, Methods for Radiation Dose Reconstruction Under the Energy Employee 

Occupational Illness Compensation Program Act of 2000; Final Rule, Federal 

Register/Vol.67, No. 85/Thursday, May 2, 2002, p 22314. 

2. NIOSH, (2002) External Dose Reconstruction Implementation Guideline, Rev 1, 

OCAS-IG-001, National Institute for Occupational Safety and Health, Office of 

Compensation Analysis and Support, Cincinnati, Ohio.