Design studies of collimated gamma ray sources

The authors are studying the design of collimated gamma ray sources of energies below 1 MeV for a variety of applications. In medical imaging such sources are very important in the laboratory for the study and characterization of scintillator detectors and also collimators. For the purpose of this study the authors have developed a Monte Carlo based simulation model, to follow up the interactions of a photon from the source. Initial results on the spatial, angular, and energy distribution characteristics of the surviving gamma rays that arrive at a 'detector' plane at a given distance from the source have been studied and presented here. Such information will be very useful in the design of an optimum gamma ray source which has to meet certain specifications regarding spot size, angular spread, and Compton tail.