ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 9

Document Title:

Guidance on Wound Modeling for Internal 

Dose Reconstruction

Document Number: ORAUT-OTIB-0022

Revision: 00

Effective Date: 11/18/2005

Type of Document: OTIB

Supersedes: None 

Subject Expert: Thomas R. LaBone

Document Owner

Approval: Signature on File Approval Date: 11/10/2005

Edw ard F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 11/15/2005

Patricia C. Kimpan, Project Director

Approval: Signature on File Approval Date: 11/18/2005

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

FOR DOCUM ENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION ANDDISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 2 of 9

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

11/18/2005 00 New technical information bulletin to provide information and 

guidance to Oak Ridge Associated Universities (ORAU) Team Dose 

Reconstructors regarding the best estimate of internal dose from a 

contaminated wound. First approved issue. Training required: As 

determined by the Task Manager. Initiated by Elizabeth M. Brackett.
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 3 of 9

TABLE OF CONTENTS

SECTION TITLE

1.0 Purpose.................................................................................................................................

PAGE

4

2.0 Background...........................................................................................................................4

3.0 Wound Modeling....................................................................................................................4

 3.1 Behavior of Plutonium in a Wound..............................................................................4

 3.2 Suggested Wound Model............................................................................................5

 3.3 Medical Intervention ...................................................................................................6

 3.4 Example.....................................................................................................................6

 3.5 Other Radionuclides...................................................................................................8

References.......................................................................................................................................9

LIST OF FIGURES

FIGURE TITLE PAGE

3-1 IMBA input for wound model..................................................................................................5

3-2 IMBA plot for initial fit to example wound case........................................................................7

3-3 IMBA plot for modified fit to example wound case...................................................................8
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 4 of 9

1.0

The purpose of this technical information bulletin (TIB) is to provide information and guidance to dose 

reconstructors regarding the best estimate of internal dose from a contaminated wound.

PURPOSE

Technical information bulletins (TIBs) are general working documents that provide guidance 

concerning the preparation of dose reconstructions at particular sites or categories of sites. They will 

be revised in the event additional relevant information is obtained. TIBs may be used to assist the 

National Institute for Occupational Safety and Health in the completion of individual dose 

reconstructions.

2.0

This discussion focuses on how to use the Integrated Modules for Bioassay Analysis (IMBA) 

computer program to evaluate intakes of plutonium by wound. The National Council on Radiation 

Protection and Measurements (NCRP) is currently working on a generic wound model (Guilmette and 

Durbin 2003; Durbin 2003), but that model is not yet available for general use. The approach 

suggested herein is based on experience with plutonium and is consistent with the information 

currently available on the NCRP wound model.

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 FACILITY” AS 

DEFINED IN THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION 

PROGRAM ACT OF 2000 [42 U.S.C. SECTIONS 7384L(5) AND (12)].BACKGROUND

3.0

3.1 BEHAVIOR OF PLUTONIUM IN A WOUND

WOUND MODELING

When plutonium is introduced into the body via a wound, four things can happen to the plutonium, 

assuming there is no medical intervention:

• The plutonium can be absorbed from the wound into the bloodstream.

• The plutonium can be transported from the wound to the lymphatic system. The classic 

example of this is the transport of plutonium from a wound on the hand to the axillary lymph 

nodes (in the armpit). This plutonium (and associated 241Am) can be detected in a chest count 

and be improperly read as a lung deposition (Sharma et al. 1997). 

• The plutonium can be retained in the tissue in the vicinity of the wound.

• The plutonium can be removed from the wound to the environment by natural processes (e.g., 

when a scab falls off the wound).

Ideally, assuming that the isotopic composition of the plutonium is known and that we can 

compensate for attenuation of photons in the tissue and in the plutonium, a wound count performed 

immediately after the accident would show the total plutonium deposited in the wound. Repeated 

measurements over time would show that the quantity of plutonium in the wound is decreasing in a 

multiple exponential fashion as material is absorbed, transported, and removed. However, the wound 

count cannot tell what fraction of the deposition is going where.
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 5 of 9

From a dosimetric perspective, the plutonium retained in the wound and removed from it are of 

negligible significance unless a cancer develops at the wound site, which is rare. The plutonium 

transported to the lymphatic system is of dosimetric significance if the plutonium dissolves in the

lymph nodes and is absorbed into the bloodstream or if a cancer develops at the site of the lymph 

nodes. To compound the problem, there are no standard models for calculating the dose to the 

wound site or the lymph nodes; IMBA therefore does not calculate the dose to the wound site or 

lymph nodes such as the axillary lymph nodes. For this reason, the dose to the wound site and 

lymph nodes associated with the wound will be ignored unless a cancer develops at one of those 

sites. In such a case, a custom dose calculation will be necessary.

3.2 SUGGESTED WOUND MODEL

In most cases, the fraction of the deposition absorbed from the wound site into the bloodstream is the 

most important dosimetrically because it will be metabolized as if it had been absorbed from the lung 

or gastrointestinal tract. This means that standard models (and IMBA) can be used to evaluate 

urinary excretion and calculate the dose to the systemic organs following an uptake via a wound. The 

urinary excretion resulting from a wound often exhibits a pattern consistent with two single exponential 

feed compartments; one with a relatively short half-life, on the order of 1 day, and one with a relatively 

longer half-life, on the order of hundreds of days. As a starting point, the following absorption model 

is suggested:

( )

t days t day Rwou t e e150

ln(2)

1

ln(2)

0.9 0.1

− −

= + (1)

where Rwou(t) is the fraction retention of the plutonium in the wound assuming no radioactive decay 

and t is the time since the wound occurred. These parameters are entered into the user-defined 

wound model of IMBA as shown in Figure 3-1.

Figure 3-1. IMBA input for wound model.

The coefficients and rate constants can be modified to produce a better fit to the observed urinary 

excretion. Additional terms can be added, but this is seldom necessary. If an individual has had more 

than one intake via a wound, individual models can be entered by clicking “Advanced” on the tool bar 

on the main page and deselecting “Apply Model Params to All IRs.” 

This approach provides only the fraction of the total wound deposition that is absorbed into the 

bloodstream. As a result the initial wound deposition measured by in-vivo methods is likely to be 

greater than the wound deposition calculated with the urine data because of insoluble material 
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 6 of 9

present in the wound. Because the soluble fraction of the initial deposition is usually the most 

important dosimetrically, greater weight should be given to the initial wound deposition calculated from 

urinary excretion. Any plutonium absorbed from material transported to the lymph nodes will likely be 

accounted for in the long-term component of the wound model. 

3.3 MEDICAL INTERVENTION

Medical intervention frequently occurs after wound depositions because of the high doses to systemic 

organs that can result and because physicians can typically take action to reduce the dose. That 

“action” is chelation therapy and/or the excision of contaminated tissue from the wound. Chelation 

therapy consists of the injection or inhalation of a chelating agent or the introduction of the chelating 

agent directly into the wound site. A chelation agent is a chemical compound that binds to the 

plutonium atom and alters its chemical properties so that it is rapidly excreted rather than deposited in 

systemic organs, which results in a reduction of dose to systemic organs and tissues.

The usual approach to evaluating urinary excretion after chelation therapy is to model only the urinary 

excretion observed more than 100 days after the last administration of the chelation agent (Jech et al. 

1972). Other, more complex approaches (LaBone 2002) can be used if necessary, but they are not 

discussed herein.

The excision of contaminated tissue from the wound site creates a discontinuity in the source term. 

For example, assume that 1 nCi of plutonium is deposited in a wound and the processes described 

above promptly begin to translocate it from the wound. If the physician excises 0.5 nCi of plutonium 

from the wound a day later, there is a sudden reduction in the quantity of plutonium in the wound. 

This reduction is equivalent to a negative intake and can be difficult to model. One approach is to 

simply ignore the urinary excretion data prior to the excision and model the data observed afterwards. 

This often works well because excisions are usually performed within days of the wound event.

3.4 EXAMPLE

An individual had two major incidents that resulted in contaminated wounds. The first is at t=0 day 

and the second at t=367 days. Both wounds were evaluated with the default model, using a 

maximum likelihood fit with square root errors in IMBA. This results in intakes of 715 dpm for the first 

wound and 13,000 dpm for the second. The IMBA plot is shown in Figure 3-2.
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 7 of 9

Figure 3-2. IMBA plot for initial fit to example wound case.

Tissue was excised from the wound after the second incident. The fit to the first intake is improved by 

reducing the errors associated with the first five data points. A value of 0.5 was assigned to k for the 

first five data points versus a k of 1.0 for the rest of the results. The fit in Figure 3-3 was produced.

The intakes are now estimated at 4,300 dpm for the first intake and 10,890 dpm for the second. Note 

that the total intake (the sum of the two) does not change significantly when we force the first intake to 

be higher, but this fit will result in the person receiving the dose sooner than determined from the first 

fit. Finally, it is interesting to note that this individual had measurable quantities of 241Am in the area of 

the wounds and in his chest (is the activity in the lymph nodes or lungs?) 20 years after these 

incidents. This raises the question of whether an inhalation intake should be assigned to this 

individual sometime during his work history? Because he has a cancer of a systemic organ, an 

additional inhalation intake of an insoluble material would add little additional dose. If he had cancer 

of the respiratory tract, the possibility of an inhalation intake would become more important. In this 

case the claimant-favorable approach would be to assign an inhalation intake that was consistent with 

the other available data.
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 8 of 9

Figure 3-3. IMBA plot for modified fit to example wound case.

3.5 OTHER RADIONUCLIDES

The general approach illustrated here with plutonium may be applied to other radionuclides. First, 

model the urinary excretion using a single feed compartment with a short half-life to simulate a wound 

with instantaneous uptake to the blood. If the shape of the curve does not adequately fit the observed 

urinary excretion, the half-life of the short-lived compartment can be increased and a second longlived feed compartment added. 
Document No. ORAUT-OTIB-0022 Revision No. 00 Effective Date: 11/18/2005 Page 9 of 9

REFERENCES

Durbin, P.W. and Guilmette, R. A., 2003, “Scientific Basis for an NCRP-ICRP Biokinetic Model for 

Contaminated Wounds,” presented at the 48th Annual Meeting of the Health Physics Society, 

San Diego, CA.

Guilmette, R. A., and Durbin, P. W., 2003, “Scientific Basis for the Development of Biokinetic Models 

for Radionuclide-Contaminated Wounds,” Radiation Protection Dosimetry (105) Nos 1-4, pp. 

213-218.

Jech, J. J., Anderson. B. V., and Heid, K. R., 1972, “Interpretation of Human Urinary Excretion of 

Plutonium for Cases Treated with DTPA,” Health Physics (22) pp. 787-792.

LaBone, T. R., 2002, “A Comparison of Methods Used to Evaluate Intakes of Transuranics Influenced 

by Chelation Therapy,” presented at the 2002 Health Physics Society Summer School on 

Internal Dosimetry, Gainesville, FL.

Sharma, R. C., Haridasan, T. K., and Surendram, T., 1997, ”False Indications of an Actinide Lung 

Burden Arising from a Contaminated Finger Wound,” Health Physics (73) pp. 820-825.