Performance evaluation of Compton based camera for high energy gamma ray imaging

The imaging performance of Compton scattering based gamma-ray camera and Anger camera with high energy general purpose (HEGP) collimator, in terms of spatial resolution, variance of reconstructed image and detection sensitivity for high-energy 364.4 Kev photons of 1-131, are evaluated by modified uniform Cramer-Rao bound and Monte Carlo Simulation. Compared to the conventional collimated gamma-ray camera, the electronically collimated camera has the potential for superior imaging quality due to its improved counting efficiency and spatial resolution for I-131 radiotracers. The simulation platform for the Compton imaging system and conventional SPECT are realized on GEANT4 and GATE (Geant4 application for topographic emission), respectively. In the Compton imaging system, the first scattering detector - electronic collimator has 32times16 silicon pads with dimension of 1.4 mm times 1.4 mm times 1.0 mm (widthtimeslengthtimesthickness); the second absorption detector is modeled as a NaI scintillation detector with thickness of 9.5 mm. A conventional sodium iodide SPECT camera is also simulated using GATE with crystal thickness of 9.5 mm and 381 mm times 508 mm field of view. The preliminary study demonstrates that the modeled Compton camera is more efficient than the conventional collimated camera for 364.4 KeV photons with higher sensitivity about 30times. Meanwhile, for the same desired PSF, the Compton camera has lower variance than the conventional Anger camera with HEGP collimator