A novel method improving the imaging resolution of a table-top Compton camera

For a table-top Compton camera, which is currently under development in our group, the interaction position resolution of the absorber detector is a critical or limiting detector parameter that most seriously affects the imaging resolution of the Compton camera. Currently, it is assumed that all the interactions occur at the centers of the detector segments of the absorber detector, which is simple, but obviously not the best choice considering that the interaction depths of the photons in the absorber detector is not distributed uniformly, especially for the low-energy photons. To this end, the present study develops a novel method, called "average interaction depth (AID) method" to improve the imaging resolution of Compton camera by additionally considering the interaction depth of the incident photon in the absorber detector. Our simulation studies with Geant4 show that the imaging resolution of Compton camera can be significantly improved by using the AID method. The imaging resolution of the table-top Compton camera was improved from 9.9 mm to 7.6 mm in full width at half maximum (FWHM) for a 511 keV gamma point source. For a 364 keV gamma point source, the imaging resolution was improved more significantly, i.e., from 11.4 mm to 7.2 mm.