Theoretical performance comparison of a Compton-scatter aperture and parallel-hole collimator

Using the Uniform Cramer-Rao bound on variance, the performance of a conventional parallel-hole collimator has been compared with that of a ring-geometry Compton-scatter aperture. Objects used for the evaluation were uniformly emitting disk sources with diameters ranging from about 4-30 cm. Results for a 7.5 cm diameter disk and 141 keV incident energy show that a Compton-scatter aperture, constructed with Si detectors having 230 eV FWHM energy resolution, can be 15 times more efficient than a standard parallel-hole collimator at the same operating point.