Hybrid collimation for industrial gamma ray imaging: combining spatially coded and Compton aperture data

The combination of a mechanically-collimated gamma-ray camera with an electronically-collimated gamma camera offers both the high efficiency and good angular resolution typical in a mechanically-collimated camera for lower photon energies and the uncoupling of spatial resolution and efficiency provided by an electronically-collimated camera at higher energies. The hybrid portable gamma camera (HPGC) combines a MURA coded aperture camera with a Compton scatter camera to provide a broad range of energy response suitable for industrial imaging situations (50 keV to 2 MeV). This paper compares the relative information content per photon for the three imaging modalities possible with the HPGC: mechanical collimation, electronic collimation and hybrid collimation, which combines information from the spatially-coded aperture with Compton aperture information (on an event-by event basis).