ORAU Team

Dose Reconstruction Project for NIOSH

Validation of Thorium Annual Dose Conversion Factors

Document Number:

ORAUT-OTIB-0028

Effective Date: 03/07/2005 

Revision No.: 01 

Controlled Copy No.: ______

Page 1 of 7 

Subject Expert: Elizabeth M. Brackett

Document Owner

Approval: Signature on File Date: 03/02/2005

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Date: 03/05/2005

Richard E. Toohey, Project Director

Approval: Signature on File Date: 03/07/2005

James W. Neton, Associate Director for Science

Supersedes:

Revision No.: 00
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 2 of 7

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 01/12/2005 00-A New technical information bulletin for the 

validation of thorium dose conversion factors to 

be used for internal dose assessment. Initiated 

by Elizabeth M. Brackett.

02/14/2005 02/14/2005 00 First approved issue. Initiated by Elizabeth M. 

Brackett.

Draft 02/18/2005 01-A Revised to add Th-228 values. Initiated by 

Elizabeth M. Brackett.

03/07/2005 03/07/2005 01 Approved issue of Revision 01. Initiated by 

Elizabeth M. Brackett.
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 3 of 7

1.0

This document verifies the annual dose conversion factors used for the assessment of 232Th and 228Th 

doses. 

PURPOSE

2.0

The IMBA Expert OCAS-Edition computer program is used for intake and dose assessments by the 

dose reconstructors on the Oak Ridge Associated Universities Dose Reconstruction Project for the 

National Institute for Occupational Safety and Health. The program was not designed to emulate 

independent kinetics for radionuclides with progeny chains, but the International Commission for 

Radiological Protection (ICRP) assumes independent kinetics for the progeny of several 

radionuclides. While this does not affect intake calculations, it results in inaccuracies for some of the 

doses. Dr. Keith Eckerman of the Oak Ridge National Laboratory (ORNL) generated annual dose 

conversion factor tables to be used in place of the IMBA values when a best estimate is needed. 

Verification of these values was provided by Dr. Eckerman; details are incorporated into this 

document.

BACKGROUND

3.0

3.1 Discussion

VERIFICATION

Annual organ equivalent dose coefficients for inhalation of Th-228 and Th-232 in the workplace were 

derived for an acute intake of 1 becquerel (Bq) at time zero and for a chronic intake of 1 Bq over a 

year. The latter set of coefficients was derived by convolution of the organ dose rate following a unit 

acute intake. The calculations were performed using ORNL’s DCAL code system. This code system 

was used in the calculations for ICRP Publication 68 (ICRP 1994) and provided in electronic form 

(CD) in the ICRP database of dose coefficients (ICRP 2001). Verification of the annual organ dose 

coefficients derived in this work can be achieved by comparing the values of the committed dose 

coefficients computed during the course of this work with the values tabulated by the ICRP since 

these numerical values (annual and committed) are derived from a common set of data; namely the 

organ dose rate at selected times following a unit intake. All input data into these calculations are 

those recommended by the ICRP.

The following data files were provided by Dr. Eckerman and are used: 

Th228AM5.INT, Th228AS5.ANN

Th232AM5.INT, Th232AS5.ANN

The files with extension INT contain the annual dose coefficient (Sv Bq-1) for each year (65 values) 

following an acute intake at time zero. The files with extension ANN contain the annual dose 

coefficient (Sv Bq-1) for each year (65 values) following chronic uniform intake of 1 Bq during year 1. 

The first 5 characters in the root name of the file identify the radionuclide; that is, Th228AM5.INT 

contains information on Th-228. The “A” denotes that these data are for the adult. The seventh

character (M or S) denoted assumed absorption type of the aerosol and the eighth character (5) 

indicates that the data are for an assumed aerosol characterized by a AMAD of 5 μm.
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 4 of 7

3.2 Results

Tables 3-1 and 3-2 compare the values of the committed equivalent dose coefficient (and effective 

dose) derived during the course of the calculations (under the column headed DCAL) with values 

tabulated by the ICRP. When a numerical difference occurs they appear to arise from round of the 

ICRP values to 2 digits while the DCAL values are listed to 3 places. As noted above all the data in 

the files provided in this work stem from a common data set. Thus the agreement evident in Tables 3-

1 and 3-2 provides verification of the calculations. 
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 5 of 7

Table 1. Comparison of the committed equivalent dose coefficients (Sv/Bq) for Th-228 computed 

using DCAL with the values tabulated by the ICRP: AMAD = 5.0μm 

 --- Type M --- --- Type S ---

 f_1=5.0E-04 f_1=2.0E-04

 DCAL ICRP DCAL ICRP

Adrenals 7.74E-07 7.7E-07 3.79E-08 3.7E-08

Bladder Wall 7.78E-07 7.8E-07 3.47E-08 3.4E-08

Bone Surfaces 2.80E-04 2.8E-04 1.23E-05 1.2E-05

Brain 7.71E-07 7.7E-07 3.45E-08 3.4E-08

Breast 7.71E-07 7.7E-07 3.80E-08 3.7E-08

GI-Tract 

 St Wall 7.72E-07 7.7E-07 3.70E-08 3.6E-08

 SI Wall 7.75E-07 7.7E-07 3.70E-08 3.7E-08

 ULI Wall 1.09E-06 1.1E-06 6.53E-08 6.5E-08

 LLI Wall 1.73E-06 1.7E-06 1.42E-07 1.4E-07

Kidneys 7.33E-06 7.3E-06 3.24E-07 3.2E-07

Liver 1.17E-05 1.2E-06 5.15E-07 5.1E-07

Resp. Tract 

 ET1-bas 7.57E-04 7.6E-04 7.56E-04 7.6E-04

 ET2-bas 5.73E-05 5.7E-05 2.14E-04 2.1E-04

 LN-ET 3.22E-06 3.2E-06 4.98E-05 5.0E-05

 BBi-bas 1.17E-04 1.2E-04 1.60E-04 1.6E-04

 BBi-sec 3.64E-04 3.6E-04 4.81E-04 4.8E-04

 bbe-sec 9.83E-05 9.8E-05 1.46E-04 1.5E-04

 AI 4.16E-05 4.2E-05 1.57E-04 1.6E-04

 LN-Th 1.31E-05 1.3E-05 1.41E-04 1.4E-04

 ET Region 5.79E-05 5.8E-05 2.14E-04 2.1E-04

 Lung 1.27E-04 1.3E-04 2.08E-04 2.1E-04

Muscle 7.71E-07 7.7E-07 3.58E-08 3.5E-08

Ovaries 2.34E-06 2.3E-06 1.03E-07 1.0E-07

Pancreas 7.72E-07 7.7E-07 3.69E-08 3.6E-08

Red Marrow 2.16E-05 2.2E-05 9.53E-07 9.4E-07

Skin 7.70E-07 7.7E-07 3.50E-08 3.4E-08

Spleen 7.73E-07 7.7E-07 3.69E-08 3.6E-08

Testes 2.37E-06 2.4E-06 1.04E-07 1.0E-07

Thymus 7.71E-07 7.7E-07 3.87E-08 3.8E-08

Thyroid 7.71E-07 7.7E-07 3.58E-08 3.5E-08

G Bladder 7.73E-07 N/A 3.56E-08 N/A

Heart 7.73E-07 N/A 4.07E-08 N/A

Uterus 7.72E-07 7.7E-07 3.45E-08 3.4E-08

Remainder 8.66E-07 8.7E-07 1.46E-07 1.5E-07

Effective Dose 2.21E-05 2.2E-05 2.53E-05 2.5E-05

------------------------- 

Output files: Th228AM5.hef, Th228AS5.hef

<< HTAB32 Ver 6.0 (July 30, 2004) --- Run Jan 18, 2005, at 14:48 >>

HTAB32 exe file was: HTAB32.EXE 49kb 07-30-04 15:02

Dose rate file was: TH228AM5.HRT 63kb 01-18-05 14:48 

Dose rate file was: TH228AS5.HRT 63kb 01-18-05 14:49 
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 6 of 7

Table 2. Comparison of the committed equivalent dose coefficients (Sv/Bq) for Th-232 computed 

using DCAL with the values tabulated by the ICRP: AMAD = 5.0μm 

 --- Type M --- --- Type S --- 

 f_1=5.0E-04 f_1=2.0E-04

 DCAL ICRP DCAL ICRP

Adrenals 4.37E-06 4.4E-06 4.12E-07 4.1E-07

Bladder Wall 4.36E-06 4.4E-06 4.05E-07 4.0E-07

Bone Surfaces 1.45E-03 1.5E-03 1.42E-04 1.4E-04

Brain 4.37E-06 4.4E-06 4.06E-07 4.0E-07

Breast 4.35E-06 4.4E-06 4.11E-07 4.1E-07

GI-Tract

 St Wall 4.36E-06 4.4E-06 4.08E-07 4.1E-07

 SI Wall 4.36E-06 4.4E-06 4.07E-07 4.1E-07

 ULI Wall 4.45E-06 4.5E-06 4.31E-07 4.3E-07

 LLI Wall 4.64E-06 4.6E-06 4.80E-07 4.8E-07

Kidneys 2.26E-05 2.3E-05 2.36E-06 2.4E-06

Liver 2.28E-05 2.3E-05 2.51E-06 2.5E-06

Resp. Tract

 ET1-bas 4.37E-06 4.4E-06 4.75E-07 4.7E-04 

 ET2-bas 1.48E-05 1.5E-05 1.05E-04 1.1E-04

 LN-ET 4.89E-06 4.9E-06 7.09E-04 7.1E-04

 BBi-bas 5.84E-06 5.8E-06 3.28E-06 3.3E-06

 BBi-sec 2.43E-05 2.4E-05 2.75E-05 2.8E-05

 bbe-sec 2.12E-05 2.1E-05 4.06E-05 4.1E-05

 AI 1.12E-05 1.1E-05 1.68E-04 1.7E-04

 LN-Th 6.71E-06 6.7E-06 2.61E-03 2.6E-03

 ET Region 1.48E-05 1.5E-05 1.06E-04 1.1E-04

 Lung 1.58E-05 1.6E-05 7.73E-05 7.7E-05

Muscle 4.36E-06 4.4E-06 4.08E-07 4.1E-07

Ovaries 1.32E-05 1.3E-05 1.28E-06 1.3E-06

Pancreas 4.36E-06 4.4E-06 4.09E-07 4.1E-07

Red Marrow 5.74E-05 5.7E-05 6.16E-06 6.1E-06

Skin 4.36E-06 4.4E-06 4.06E-07 4.0E-07

Spleen 4.36E-06 4.4E-06 4.10E-07 4.1E-07

Testes 1.34E-05 1.3E-05 1.30E-06 1.3E-06

Thymus 4.36E-06 4.4E-06 4.13E-07 4.1E-07

Thyroid 4.36E-06 4.4E-06 4.08E-07 4.1E-07

G Bladder 4.36E-06 N/A 4.07E-07 N/A

Heart 4.36E-06 N/A 4.16E-07 N/A

Uterus 4.36E-06 4.4E-06 4.05E-07 4.0E-07

Remainder 4.55E-06 4.6E-06 4.80E-07 4.8E-07

Effective Dose 2.93E-05 2.9E-05 1.20E-05 1.2E-05

-------------------------

Output files: Th232AM5.hef, Th232AS5.hef

<< HTAB32 Ver 6.0 (July 30, 2004) --- Run Jan 18, 2005, at 14:50 >>

HTAB32 exe file was: HTAB32.EXE 49kb 07-30-04 15:02

Dose rate file was: TH232AM5.HRT 67kb 01-18-05 14:50

Dose rate file was: TH232AS5.HRT 67kb 01-18-05 14:51 
Effective Date: 03/07/2005 Revision No. 01 Document No. ORAUT-OTIB-0028 Page 7 of 7

REFERENCES

ICRP (International Commission on Radiological Protection), 1994, Dose Coefficients for Intakes of 

Radionuclides by Workers, Publication 68, Pergamon Press, Oxford, England.

ICRP (International Commission on Radiological Protection), 2001, ICRP Database of Dose 

Coefficients: Workers and Members of the Public, Ver. 2, Pergamon Press, Oxford, England.