Effect of source encapsulation on the energy spectra of 192Ir and 137Cs seed sources

The effect of source encapsulation on the energy spectra of 192Ir and 137Cs seed sources, both with stainless steel and with platinum encapsulation, was determined from results of Monte Carlo simulation. The fractional scatter dose around these sources has also been determined from Monte Carlo simulation. The platinum-encapsulated 192Ir source exhibited greater attenuation of the primary spectrum, as expected, and, consistent with this greater attenuation, exhibited more scattered radiation. Significantly less scatter was seen with the 137Cs source than with either 192Ir source, as is consistent with the higher-energy photons from 137Cs.