Measurement of Tissue Dose of Ionizing Radiation. I. Beta Ray Isotopes Uniformly Distributed in a Homogeneous Tissue.

摘要

In general it may be said that 'irradiation equilibrium' exists at a point in as absorbing medium when in a small volume surrounding the point, the rate at which energy leaves the boundary is balanced exactly by the rate at which energy enters the small volume and is absorbed therein. In the case of a beta ray emitting isotope uniformly distributed in a homogeneous tissue, irradiation equilibrium exists everywhere except in a peripheral layer of thickness equal to the maximum range of the beta rays. Everywhere else in the tissue mass the energy absorbed per graph of tissue in unit time is equal to the energy liberated by the isotope in one gram of tissue in the same time. Therefore, knowing the number of disintegrations per second occurring in one gram of tissue and the average energy per disintegration, it is a simple matter to calculate the energy absorbed per gram of tissue.