Some effects of whole-body 32-Mev proton irradiations on primates.

Abstract

From a biological standpoint, the protons of space may arbitrarily be considered to be either hard or soft, the protons being those having insufficient energy to penetrate to the more sensitive deep structures such as the gastrointestinal tract or the bone marrow. The hard protons represent the conversethey are able to reach these deeper structures. In studying the effects of these protons, it is desirable that the experimental subject not be exposed to a spectrum of proton energies, since the hard component could cause destruction of the sensitive deep structures and thereby not allow full development of radiation changes in the more superficial tissues. To simulate the effects of irradiating man, the primate Macaca mulatta, with a body configuration similar to that of man, was chosen as the experimental subject. The 32-Mev proton energy was selected because these protons have a range of approximately 1 cm in unit-density soft tissue (1), which will allow heavy irradiation of the skin, skin appendages, and muscle of the primate without significant irradiation of the bone marrow or the gastrointestinal tract.