Office of Compensation Analysis and 

Support

Program Evaluation Report 

Document Number: 

 OCAS-PER-005 

Effective Date: 

 06/09/2006 

Revision No. 0 

Misinterpreted Application of the External Dose Factor for Hanford 

Dose Reconstructions

Page 1 of 5

Subject Expert: Gregory V. Macievic. PhD 

 

Approval: Signature on File Date: 6/09/2006 J.W. Neton, Associate Director for Science 

Supersedes: 

 None 

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO.

DESCRIPTION

06/09/2006 06/09/2006 0 

New document to evaluate the programmatic 

effect of the misinterpreted application of the bias 

factor for Hanford Dose Reconstructions 

1.0 Description

On June 29, 2005, an error in the interpretation of the Hanford External Dose Reconstruction 

Technical Basis Document (TBD)(1) was identified by OCAS during the course of dose reconstruction 

review. Prior to this date, the Hanford External Dose TBD was interpreted by ORAU to indicate that 

the energy employee’s recorded dose was overestimated (bias) from 1944-1994 with bias values 

varying from 1.01 to 1.27 (Table 1). 

Table 1: Hanford Bias Factors 

Dosimeter Period of Use Bias Estimated Range 

Two-element film 1944 – 1957 1.27 1.13 - 1.60 

Multi-element film 1958 – 1971 1.02 0.86 – 1.12 

Hanford TLD 1972 - 1983 1.12 1.04 – 1.16 

Hanford TLD 1984 – 1994 1.01 0.95 – 1.05 

Commercial TLD 1995 - 2003 1.00 0.95 – 1.05 
Effective Date: 6/09/2006 Revision No. 0 Procedure No.OCAS-PER-005 Page 2 of 6 

Other portions of the Hanford External TBD however, indicate that the response of the dosimeter 

changed significantly depending upon the photon energy spectra and could either underestimate or 

over estimate the true dose. Since the specifics of the exposure scenario would dictate either an 

over-response or an under-response, and since this information in generally not available, the OCAS 

TBD reviewers interpreted the Hanford External Dose TBD to conclude a claimant neutral position 

that no bias factor that reduced the recorded dose would be applied. The ORAU Dose 

Reconstruction Team came to a different conclusion from the same information and implemented the 

bias correction factor methodology into the Hanford Best Estimate Dose Reconstruction Tool / 

Template. This bias factor effectively reduced the recorded dose by the factors listed in Table 1. 

It is important to note that not all Hanford cases completed to date have been affected by this 

misinterpretation. Only cases using the Hanford Best Estimate Dose Reconstruction Tool were 

affected. As of August 3, 2005, 1184 Hanford cases had been completed, and of these, only 115 

(10%) used the best estimate tool which contained the error. The reason for the low number of cases 

was that the best estimate tool was not implemented until 5/3/2005. Of these 115 cases, 51 were 

still undergoing internal review and were subsequently returned to the initial dose reconstructor for 

rework (i.e. removal of the bias factor and recalculation of the external dose). Three cases were 

modified internally by the OCAS reviewers in the early stages of identifying this problem, thus the bias 

factor had been removed and the cases did not require further evaluation. An addition 18 cases only 

had employment in years for which the bias factor was 1.0 and therefore did not require further 

evaluation. Fourteen cases were compensable claims and, since the bias factor reduced the external 

dose, correcting the error would only increase the dose and further increase the probability of 

causation which was already greater than 50%. Thus, these cases also did not require further 

evaluation. Of the 115 cases, 31 required evaluation for potential impact on the probability of 

causation calculation. A graphical breakdown of the 115 cases is provided in Figure 1. 

42.6% In Review - Returned to Dose 

Reconstructor for Rework

(n=49)

27% Submitted to DOL

Evaluation Required

(n =31)

15.7% Employment outside

of Bias Factor application

(n=18)

12.2% Compensable Claims 

Submitted to DOL

(n=14)

2.6% Internally Modifed by OCAS Before 

Submission to Claimant for Review

(n=3)

Figure 1: Distribution of Hanford Best Estimate Cases 
Effective Date: 6/09/2006 Revision No. 0 Procedure No.OCAS-PER-005 Page 3 of 6 

2.0 Evaluation

2.1 Dose Evaluation 

The application of this bias factor effectively reduced the recorded external dose by the values listed 

in Table 1. Thus, for the period 1944 to 1957, the recorded external doses were inadvertently 

reduced by 27%. During other time periods the magnitude of the reduction was significantly less, 

however, in this report all of the reductions have been evaluated. This evaluation, the external dose 

for each of the 31 cases was recalculated after the bias factor was removed. During the review, one 

case was found to contain a significant external dose reconstruction error (external dose uncertainty 

had not been incorporated into the dose reconstruction). Fortunately this case had not gone through 

the Department of Labor’s final adjudication process and had been sent back to OCAS by DOL for 

rework due to an unrelated error in the initial employment information provided to OCAS. Since this 

case is currently being reworked, it was excluded from this evaluation. Of the 30 cases evaluated, 

the maximum increase in external dose was 4698 mrem and the minimum increase in external dose 

was 78 mrem. 
Effective Date: 6/09/2006 Revision No. 0 Procedure No.OCAS-PER-005 Page 4 of 6 

2.2 Probability of Causation Evaluation 

Since this magnitude of the dose reduction could have a significant effect on the probability of 

causation calculations, the probability of causation was recalculated for each cancer. The average 

increase in the 99th percentile of the probability of causation was 0.83% with a maximum of 2.65%. 

Figure 2 depicts the probability distribution of the change in PC values for the 30 cases. Table 2 

provides a summary of the 30 remaining cases that were revaluated and the individual impact on the 

PC calculation. Note that all of the PC calculations both original and revised presented in Table 2 

used NIOSH-IREP version 5.4. 

 

Hanford Bias Factor Effects

Probability

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

Change in PC Value

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Coefficients:

Mean = 0.83

Sigma = 0.66

r 2 = 0.89

n =30

Figure 2: Normal Probability plot of change in the 99th percentile PC value
Effective Date: 6/09/2006 Revision No. 0 Procedure No.OCAS-PER-005 Page 5 of 6 

Table 2: Evaluation Summary of 30 cases submitted to the DOL 

# Cancer Type Original PC (%) Revised PC (%) Change in PC (%) Dose DR Report (rem) External % of Total Dose Original External Dose (rem) Revised External Dose (rem1 Bladder 40.69 41.56 0.87 54.360 95.0 51.631 54.067 2 Bladder 37.79 38.46 0.67 40.754 99.3 40.460 41.843 3 Bladder & Prostate 37.76 37.93 0.17 21.878 72.7 15.900 16.081 4 Esophageal 41.00 42.07 1.07 37.748 80.4 30.342 32.631 5 Esophageal 36.00 36.86 0.86 31.738 95.8 30.398 31.597 6 Hodgkin's Disease 27.37 28.00 0.63 35.293 89.5 31.593 33.322 7 Kidney 43.33 43.49 0.16 43.952 95.6 42.009 42.583 8 Leukemia 36.01 36.13 0.12 14.138 66.5 9.399 9.477 9 Lung 43.14 43.30 0.16 89.884 19.1 17.158 17.919 

10 Lung 41.09 41.15 0.06 82.534 24.4 20.154 20.907 11 Lung 42.61 42.82 0.21 49.620 37.8 18.732 19.713 12 Lung 43.47 43.78 0.31 63.877 38.5 24.580 25.601 13 Lymphosarcoma 34.89 36.43 1.54 71.245 97.7 69.623 74.321 14 Malign. Fib. Histiocytoma 29.68 29.84 0.16 15.600 86.5 13.487 13.628 15 Multiple Cancers 41.80 44.45 2.65 8.551 98.7 8.442 8.717 16 Multiple Myeloma 28.87 30.14 1.27 53.213 65.7 34.942 38.340 17 Multiple Myeloma 17.68 18.45 0.77 43.947 60.1 26.420 28.141 18 Pancreatic 40.89 42.20 1.31 84.992 88.8 75.514 79.817 19 Prostate 29.65 30.66 1.01 44.701 99.2 44.341 46.242 20 Prostate 43.34 43.48 0.14 59.429 63.7 37.833 38.252 21 Prostate 41.66 43.18 1.52 71.822 79.2 56.864 60.473 22 Prostate 37.64 38.53 0.89 58.088 97.8 56.802 59.002 23 Prostate & Lymphoma 40.41 41.70 1.29 36.320 97.7 35.479 37.623 24 Prostate & Renal 39.83 40.38 0.55 22.696 92.5 20.993 21.647 25 Prostate & Skin Cancers 40.82 40.96 0.14 11.542 98.6 11.382 11.647 26 Rectum 21.50 22.11 0.61 57.663 81.2 46.838 48.721 27 Renal 29.40 31.16 1.76 25.169 97.5 24.542 26.826 28 Stomach 27.35 28.40 1.05 29.904 97.4 29.136 30.826 29 Thyroid 41.86 44.45 2.59 10.865 78.2 8.494 9.431 30 Thyroid 42.67 43.01 0.34 5.514 66.1 3.644 3.756 

 Average 0.83 
Effective Date: 6/09/2006 Revision No. 0 Procedure No.OCAS-PER-005 Page 6 of 6 

Although all of the PC values increased as expected, all of the affected cases PC values were still 

less than 45%. Thus, no special consideration for 10,000 iterations was necessary. The range of the 

increase in PC was greatly affected by the magnitude of the energy employees original dose and the 

subsequent change in dose, the type of cancer, and the relative percentage that the external dose 

contributed to the total organ dose. 

3.0 Resolution / Corrective Action

The immediate resolution to this problem was to implement the provisions of the TBD correctly. Thus, 

the ORAU removed the bias factor from the Hanford Best Estimate Dose Reconstruction Tool and all 

active claims in review were returned to the ORAU team for rework. 

Concurrently, all claims submitted to DOL were reevaluated as described above. Although the 

external dose increased in each case, the increase in PC value was insufficient to change the 

compensability decision (i.e. all modified PC values remained less than 45%). 

4.0 Summary

An error in interpretation and application of the bias factor information in the Hanford External Dose 

Reconstruction Technical Basis Document(1) resulted in an underestimate of the external dose for 

certain Hanford claims. Claims that were potentially affected by this error were identified and those 

that had not already been submitted to the Department of Labor were returned to the ORAU team for 

rework. The cases that had been submitted to DOL were reevaluated by removing the bias factor, 

thus developing a revised external dose. The probability of causation (PC) for each of the affected 

claims was recalculated. This evaluation found that although this error appeared upon discovery to 

be rather significant, there was no impact on compensation decisions made by the Department of 

Labor. 

5.0 References

 

1. ORAU Team, Technical Basis Document for the Hanford Site – Occupational External Dosimetry, 

ORAUT-TKBS-0006-6 Rev 01 (2004).