THE CALCULATION OF NEUTRON-INDUCED PHYSICAL DOSES IN HUMAN TISSUES.

The purpose of the investigation was to calculate improved multicollision neutron fluence-to-dose conversion factors by solving the combined neutron and gamma-ray transport problems in phantom models designed to represent human beings. Also, new neutron fluence-to-kerma factors and improved secondary gamma-ray yields were to be determined for the elements composing the slabs. The computer code ANISN was employed in solution of the transport equation. Multicollision neutron fluence-to-dose conversion factors were calculated for neutron sources, either beams or isotropic fluxes of energies from 15 MeV to thermal incident on a 30 cm slab with infinite or finite transverse dimensions. The curves representing the total of the neutron and gamma-ray energy deposition were found to range from approximately 6 to a factor of two lower than those previously reported. This effect is attributed primarily to the treatment of secondary gamma rays and becomes more pronounced with increasing depth. Results are presented for 38 different combinations of source and geometry and for the maximums as a function of the source energy for each set of calculations. Author