Energy-subtraction Compton scatter camera design considerations: A Monte Carlo study of timing and energy resolution effects

An energy-subtraction Compton scatter camera (ESCSC) was previously proposed for medical imaging applications. This ESCSC consists of a primary detector system (silicon) and a secondary detector system (cadmium-zinc-telluride) for preferred detection of Compton scatter and photoelectric absorption interactions, respectively. To further evaluate the usefulness of this ESCSC for medical imaging, the following characteristics have been simulated: the random emission of gamma rays in time; detector timing, energy and spatial resolution; list mode data acquisition; and post-acquisition coincidence analysis. The resulting optimization of detector characteristics, data acquisition and analysis techniques, and administered activity is presented and discussed. One significant result of these simulations is that a localized activity of about 1.0 mCi allows for recovery of the majority of preferred events while eliminating the majority of interfering events when 10 and 50 ns FWHM timing resolutions for silicon and cadmium-zinc-telluride, respectively, are assumed. Consequently, the proposed ESCSC should be capable of acquiring data for administered activities similar to those used with current mechanically-collimated imaging cameras.