Statistical performance evaluation and system modeling for a Compton medical imaging system for higher energy photon imaging

The objective of this research is to study the performance of a dual-planar silicon/Anger camera based Compton imaging system for imaging higher energy photons emitted from 131-I using, and compare it with a conventional collimated Anger camera. The Compton imaging system is a potentially effective medical imaging device for monitoring radionuclide cancer treatments that can obtain greatly improved performance in both detection efficiency and spatial resolution for higher energy photons (e.g., 364keV) over conventionally collimated Anger cameras. The Compton imaging system decouples the tradeoff between spatial resolution and detection efficiency inherent to absorbing collimation. System performance is primarily determined by Doppler broadening, energy resolution and spatial resolution of the scattering and absorbed detectors (in addition to the Compton image formation process). In the study, the effective system model of the Compton imaging system was developed considering all factors involved in the Compton process including above three primary uncertainties. Based on the system model, the system performance and comparison were analyzed using the modified uniform Cramer-Rao bound we developed and verified along with the Monte Carlo calculation. From the illustrated bound curves that compare the effect of silicon detector energy resolution and system spatial resolution by simulating a 2D disk having uniform activity, the limiting factor is Doppler broadening for Compton camera performance at 364 keV. Our predictions show that performance of the proposed Compton imaging system is superior to the collimated Anger camera especially as the desired image resolution is better than the “natural” resolution of the conventional collimator.