OCAS-IG-001

External Dose Reconstruction

Implementation Guideline

Report from the Procedures Review 

Subcommittee

Presented to the

ABRWH Full Board Meeting

Augusta, Georgia 

March 12, 2013
OCAS-IG-001 Summary

• Provides general (not specific) guidance on 

the components, standards, and methods to 

be used to reconstruct external radiation dose 

for probability of causation (POC) calculations

• Detailed implementation guidance and related 

information is provided in other site-specific 

or issue-specific technical documents, 

procedures, and workbooks.

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OCAS-IG-001 Timeline

• May 2002 – Revision 0 – Not Reviewed by SC&A

• August 2002 – Revision 1

• January 17, 2005 – SC&A Review of Revision 1

• July 27, 2006 – Discussed with Subcommittee

• August 25, 2006 – Revision 2

• October 29, 2007 – SC&A Review of Revision 2

• March 5, 2012 – Revision 3

• April 11, 2012 – SC&A to Review Revision 3 Only to 

Determine which Findings were Closed

• February 5, 2013 – Discussed with Subcommittee – All 

findings Closed

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Findings Summary: OTIB-0070

• 24 Findings in total– complete histories captured in the Board Review System (BRS)

– http://app-cinc-dcas.cdc.gov:8106/documents/default.aspx?mode=ASSIGNED

• Revision 1 – 17 Findings

• Revision 2 – 7 Findings

• All 24 Findings are Closed

• Resolution spanned 11 Years; May 2002 – February 2013

• The following slides provide summary information on 

resolution of each Finding – Details in BRS and handout

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IG-001, Rev 1 Review Findings

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# Finding Resolution

1 Deficiencies with procedure layout 

include: (1) fragmented structure, 

(2) excessive amount of useless 

data and/or historical background 

in main body, and (3) critical data 

for dose reconstruction found in 

Appendices rather that main body. 

Closed on July 31, 2012 

The Subcommittee determined that this 

finding is Closed. Concerns raised by this 

issue are covered in Finding 19 (below).

2 Guidance for deriving (1) film and 

TLD dosimeter uncertainty, (2) 

neutron dose from source term, 

and (3) occupational medical dose 

using x-ray machine operating 

parameters requires data and 

resources that are not available to 

the dose reconstructor.

Closed on November 1, 2012 

IG-001 provides general principles, not 

specific guidance. Detailed 

implementation guidance and related 

information are found in other documents 

and procedures.
IG-001, Rev 1 Review Findings

6

# Finding Resolution

3 IG-001 provides inadequate 

guidance for classifying a case 

as potentially < 50% POC or > 

50% POC and should identify 

the role of Task 2 personnel. 

Closed on July 27, 2006

IG-001 is intended to provide general DR 

guidance. The level of detail suggested in this 

comment is not needed in this implementation 

guide. This guidance is found in PROC-006.

4 IG-001 recommends 

inappropriate methods for 

estimating TLD uncertainty.

Closed on August 25, 2006 / October 29, 2007 

Revision 2 of IG-001 eliminated recommending 

inappropriate methods for TLD uncertainty and 

includes guidance that directs the dose 

reconstructor to site specific documentation, 

when available.
IG-001, Rev 1 Review Findings

7

# Finding Resolution

5 IG-001 recommends a range 

of LOD values for 1956-1960 

that the reviewer considers 

too low for the period. 

Closed on August 25, 2006 / October 29, 2007 

In Revision 2, Table 2.1 that referenced LOD 

values for the 1956–1960 period has been 

modified to remove any date-specific LOD 

values. 

6 Guidance implies that LOD for 

deep dose from gamma may 

also be applied to electron 

dose, which is inconsistent 

with historical data that show 

uncertainty for shallow dose is 

considerably higher than deep 

dose. 

Closed on August 25, 2006 / October 29, 2007 

Revision 2 of IG-001 removes the example that 

implies LOD for deep dose from gamma is also 

appropriate for electron dose.
IG-001, Rev 1 Review Findings

8

# Finding Resolution

7 IG-001 assumes NTA film 

dosimeters were insensitive to 

neutron below 500 keV, 

however, reviewer contends 

that the dosimeter is 

insensitive to neutron <1 MeV.

Closed on August 25, 2006 / October 29, 2007

Revision 2 indicates that a variety of energy 

thresholds for NTA film dosimeters are cited in 

the literature and recommends reviewing sitespecific information for determining actual 

threshold values.

8 Methods for reconstruction of 

neutron doses from survey 

data or source term data do 

not appear practical, 

achievable, and defensible.

Closed on July 31, 2012

Revision 3 has included the use of more 

practical methods such as employing neutronto-photon ratios. 
IG-001, Rev 1 Review Findings

9

# Finding Resolution

9 IG-001 does not acknowledge 

the likely use of neutron/ 

photon ratio methods in 

neutron dose reconstruction 

and erroneous states that “... at 

most facilities, neutron 

exposure were generally less 

than 20% of the photon 

exposures.” 

Closed on August 25, 2006 / October 29, 2007

Revision 2 modified Section 2.2.2 to eliminate 

the offending statement, and introduced a 

statement acknowledging the use of sitespecific neutron-to-photon ratios.

10 IG-001, Appendix B, DCFs for 

bone surface and red marrow 

are underestimated. 

Closed on August 25, 2006 / October 29, 2007

Revision 2 recommends applying a correction 

factor to the rotational and isotropic DCFs for 

bone surface and red marrow (as well as 

esophagus and lung).
IG-001, Rev 1 Review Findings

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# Finding Resolution

11 IG-001 does not account for 

additional laboratory 

uncertainty for film badge 

readings associated with 

exposure less than 200 mrem. 

Closed on August 25, 2006 / October 29, 2007

Revision 2 added guidance to Section 2.1.1.3 

indicating that site-specific dosimetry data may 

be available in the site profile.

12 IG-001, Appendix B, PA 

geometry DCFs are in error 

and underestimates dose (i.e., 

assumes the dosimeter is 

worn on the posterior). 

Closed on February 5, 2013

Posterior to anterior (PA) DCFs are not

routinely used in DRs. However, since PA DCFs 

could prove useful in some special exposure 

scenarios (if used correctly), the PA DCFs 

should be kept in Appendix B.
IG-001, Rev 1 Review Findings

11

# Finding Resolution

13 IG-001, Appendix B, 

rotational and isotropic 

geometry DCFs are in error 

and underestimates dose.

Closed on August 25, 2006 / October 29, 2007

Revision 2 has introduced a discussion and table 

of correction factors to be applied to rotational 

and isotropic DCFs for bone (surface), bone (red

marrow), esophagus, and lung.

14 Angular sensitivity not 

accounted for in ‘correcting’ 

measured film or TLD 

values. 

Closed on August 25, 2006 / October 29, 2007

Revision 2 added a discussion on the angular 

response of dosimeters to Section 4, and 

guidance that directs the dose reconstructor to 

site specific documentation.
IG-001, Rev 1 Review Findings

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# Finding Resolution

15 No correction recommended 

for backscatter; may be 

significant factor for pre-1984 

when calibrations were done 

‘in air’ as opposed to ‘onphantom.’ 

Closed on July 27, 2006

Non-correction for backscatter only makes the 

reported film dose higher, building some 

conservativeness in early years.

16 Environmental uncertainty 

(i.e. heat, humidity, light, etc.) 

was not addressed IG.

Closed on February 5, 2013

IG-001 contains general guiding information, 

but does not provide specific instructions to 

follow during dose reconstruction. Specific 

instructions are provided in site-specific or 

issue-specific technical documents and 

workbooks.
IG-001, Rev 1 Review Findings

13

# Finding Resolution

17 Guidance for the selection of 

uncertainty distributions for 

total organ dose raises 

question of consistency and 

requires professional 

judgment. 

Closed on February 5, 2013

IG-001 contains general guiding information, 

but does not provide specific instructions to 

follow during dose reconstruction. Specific 

instructions are provided in site-specific or 

issue-specific technical documents and 

workbooks.
IG-001, Rev 2 Review Findings

14

# Finding Resolution

18 SC&A’s review of IG-001, 

Revision 1, identified several 

deficiencies regarding the 

clarity and structure of the 

document.

Closed on July 31, 2012 

Revisions 2 & 3 eliminated much of the 

excessive data and generally improved the 

clarity of the document. 

19 A deficiency (Finding 1) 

identified under the Revision 1 

review was the fragmented 

structure and illogical 

sequencing of information.

Closed on November 1, 2012 

What constitutes the logical, versus illogical, 

sequencing of information is a fairly subjective 

determination. Importantly, the sequence of 

information within the document is not a key 

factor in providing adequate guidance.
IG-001, Rev 2 Review Findings

15

# Finding Resolution

20 Guidance was not provided 

regarding the methodology 

for the assessment of 

neutron doses using source 

term data.

Closed on November 1, 2012 

IG-001 provides general principles, not specific 

guidance. Detailed implementation guidance 

and related information is found in other 

documents and procedures.

21 IG-001 does not consistently 

direct the dose reconstructor

to technical and site-specific 

documents . 

Closed on July 31, 2012

This finding is virtually identical to Finding 22.
IG-001, Rev 2 Review Findings

16

# Finding Resolution

22 OCAS-IG-001 should (but 

does not) direct the dose 

reconstructor to technical 

and site-specific 

documentation, were the DR 

can find more specific 

guidance.

Closed on November 1, 2012 

IG-001 provides general principles, not specific 

guidance. Detailed implementation guidance 

and related information is found in other 

documents and procedures.

23 No discussion added to this 

revision regarding neutronto-photon ratios. 

Closed on July 31, 2012

Revision 3 added a discussion to Section 

2.2.2.2.1 to clarify the evaluation of missed 

neutron data, by recommending the use of sitespecific neutron-to-photon dose ratios.
IG-001, Rev 2 Review Findings

17

# Finding Resolution

24 (1) All DCFs associated with PA 

geometries in Appendix B are 

in error and underestimate 

dose.

(2) Environmental uncertainty 

associated with doimeters are 

not addressed.

(3) Guidance for selection of 

uncertainty distributions 

raises questions of consistency 

and required professional 

judgment.

Closed on February 5, 2013

Posterior to anterior (PA) DCFs are not

routinely used in DRs. However, since PA DCFs 

could prove useful in some special exposure 

scenarios (if used correctly), the PA DCFs 

should be kept in Appendix B.

IG-001 contains general guiding information, 

but does not provide specific instructions to 

follow during dose reconstruction. Specific 

instructions are provided in site-specific or 

issue-specific technical documents and 

workbooks.
Questions?

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