Results of Scattering in Radioisotope Imaging

It has long been recognized that in-patient scattering can lead to significant ima, ge degradation in nearly all radioisotope imaging. Using biased Monte Carlo codes and experimental determinations, we have undertaken a study of three aspects of this problem: 1. Scattering and attenuation within the patient, 2. Selective rejection of scattered radiation by angular selection of the collimation system, 3. Selective rejection of scattered radiation by energy selection. The model we have assumed consists of point gamma ray sources of energy between 140 and 511 keV, located at depths between zero and 10 cm below the surface of a semi-infinite water medium. Ellett has shown that at the energies of interest here, water is a good representation of a tissue medium. A wide variety of general data on the energy and spatial distributions of the escaping scattered radiation have been catalogued.