Study on the Imaging Resolution of a Multiply-stacked Compton Camera

We have investigated the effect of detector parameters, such as the energy and the position resolution, on the imaging resolution and sensitivity of a multiply-stacked Compton camera by using the proof-of-principle system and the GEANT4 simulation toolkit, including Doppler broadening. The multiply-stacked Compton camera consisted of three double-sided silicon strip detectors. The proof-of-principle system shows that the three-Compton method can reconstruct the incident gamma-ray energy distributions and that it helps to illustrate the usefulness of the three-Compton method when gamma rays don't stop completely. Reconstructed images and spectra from a Cs-137 gamma-ray source have been obtained by using an event reconstruction algorithm. The reconstructed gamma-ray energy shows a photopeak of 661.7 keV for Cs-137 at 607.5 keV and has a 149.8-keV FWHM. GEANT4 simulation results show the feasibility of using the proof-of-principle system in the energy range from 661.7 keV to 1400.0 keV. The image resolution was significantly affected by the position resolution of the multiply-stacked Compton camera rather than by the energy resolution of the detector.