Development of a Position-Sensitive 4π Compton Camera Based on a Single Segmented Scintillator

Abstract

Scintillator-based Compton cameras, which comprise of a separated scatter and absorption detectors, neglect the Compton scattering that is followed by a photoelectric effect in a single set of scintillators, wherein the detection efficiency is severely limited. In this study, we propose a 3-D position-sensitive Compton camera that uses a single set of scintillators, wherein radiation interactions inside the scintillator can be discriminated. The proposed Compton camera comprises a segmented lutetium–yttrium oxyorthosilicate scintillator coupled with two position-sensitive silicon photomultipliers on both sides. Compton image reconstruction algorithms, such as simple back-projection, list-mode maximum likelihood expectation maximization (MLEM), and filtered back-projection, were applied and compared. The single position-sensitive Compton camera identified the positions of multiple radiation sources with various energies in a $4\pi $ field of view. The signal-to-noise ratio (SNR) and full-width at half-maximum (FWHM) of a reconstructed 511-keV point source were approximately 12° and 22°, respectively, after MLEM was applied, and the two 511-keV sources with an angle difference of 40° were separately reconstructed. The intrinsic efficiency of the proposed Compton camera was $2.23\times 10^{-2}$ for 511 keV.