1. NAME AND TITLE

INREM II: Computer Implementation of Recent Models for Estimating the Dose Equivalent to Organs of Man from an Inhaled or Ingested Radionuclide.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 370/3033.

4. NATURE OF PROBLEM SOLVED

INREM II reads dosimetric and metabolic information about the radionuclides in a chain and calculates the resultant dose equivalent to various organs of a reference adult human following inhalation or ingestion of the first (or parent) nuclide of the chain. The ICRP Task Group Lung Model is used to estimate the deposition and retention of inhaled particulates and their absorption into the blood and clearance into the GI tract. A four-segment model of the GI tract with first-order mass transport and absorption of activity permits calculation of residence times of radionuclides in the tract and the dynamics of their assimilation from that site. Residence times of activity in other organs are computed from retention functions that are linear combinations of decaying exponential functions.

5. METHOD OF SOLUTION

The dose equivalent to a target organ is computed as the sum of contributions from each source organ in which radioactivity is assumed to be situated. This calculation utilizes a matrix of S-factors supplied by the user for the particular choice of source and target organs. Output permits the evaluation of crossfire components of dose when penetrating radiations are present.

The residence times of the radioactive daughters are calculated with consideration of their differential transfer among the body's compartments. This approach permits each nuclide in the chain to be cleared from the lungs, absorbed from the GI tract, and taken up and retained by other organs in accordance with its own properties.

Solution of the system and subsequent integration of the activity levels are accomplished using an approach based on solving parts of the system in closed form and approximating certain continuous transfers of activity by discrete counterparts.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

The sample problem executed in 2.19 minutes on the IBM 370/ 3033.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on the IBM 370/3033 computer. It requires 236 K of storage.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran H Extended compiler is required. The code uses standard I/O plus punch and log 16.

10. REFERENCE

G. G. Killough, D. E. Dunning, Jr., J. C. Pleasant, "INREM II: A Computer Implementation of Recent Models for Estimating the Dose Equivalent to Organs of Man from an Inhaled or Ingested Radionuclide," NUREG/CR-0114, ORNL/NUREG/TM-84 (June 1978).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source codes and sample problem input and output.

12. DATE OF ABSTRACT

February 1982.