**1. NAME AND TITLE**

REPC: Estimation of Nuclear Reaction Effects in Proton-Tissue-Dose Calculations.

**2. CONTRIBUTOR**

NASA Langley Research Center, Hampton, Virginia.

**3. CODING LANGUAGE AND COMPUTER**

Fortran V; CYBER.

**4. NATURE OF PROBLEM SOLVED**

REPC reviews calculational methods for the estimation of dose from external proton exposure of
arbitrary convex bodies and presents the necessary information for the estimation of dose in soft tissue.
The effects of nuclear reactions, especially in relation to the dose equivalent, are retained. REPC
subroutines can be used to convert existing computer programs which neglect nuclear reaction effects
to include them.

**5. METHOD OF SOLUTION**

REPC contains a general method for the estimation of dose in arbitrary convex geometry in terms
of dose conversion factors in slab geometry. These dose conversion factors for protons in tissue are
then represented using buildup factors. A parametric form for the buildup factors is presented. The
values for the parameters are derived from Monte Carlo calculations of various authors. All necessary
information for estimation of dose and dose equivalent for proton irradiation of convex objects of
arbitrary shape is contained in REPC. This method has the advantage that existing proton dose
calculations in which nuclear reactions are neglected can be directly converted by substitution of the
dose conversion factors presented in REPC.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for REPC.

**8. COMPUTER HARDWARE REQUIREMENTS**

REPC was designed for the CYBER computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCES**

J. W. Wilson and G. S. Khandelwal, "Computer Subroutines for the Estimation of Nuclear Reaction Effects in Proton-Tissue-Dose Calculations," NASA TM X-3388 (June 1976).

J. W. Wilson and G. S. Khandelwal, "Proton-Tissue-Dose Buildup Factors," *Health Physics* Vol.
31 (August 1976) 115-118.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source
code.

**12. DATE OF ABSTRACT**

February 1983.

**KEYWORD: ** MONTE CARLO; DETECTOR RESPONSE; KERMA; PROTON DOSE