Design and simulation of a semiconductor detector-based Compton imaging system with efficiency analysis

Abstract

In recent years, Compton cameras that use electronic collimators have become common. One or more scatterer detectors and an absorber detector make up the Compton camera, which is sensitive to the energy and location of scattered gamma rays. It predicts the distribution of gamma-ray sources by reflecting all valid events in the image space using conical surfaces. Compton cameras are designed for specific applications and image reconstruction using various methods. Based on studies on the efficiency of the Compton camera, the current work provides a novel detector design that includes scatterer and absorber detectors. This design includes eight scatterer detectors spaced 1 mm apart and an absorber detector 30 mm from the last scatterer detector. The distance between the source and the first scatterer detector was 5 mm. The scatterer and absorber detector plates were 70*70*2.125mm3 and 70*70*10mm3, respectively. The Compton imaging system is simulated using the GEANT4 toolkit. In addition, this study uses an analytical method to reconstruct Compton camera images. The method used for analytical reconstruction in the Compton imaging system differs slightly from simple restoration methods used in other imaging systems. In the analytical method, the equation related to the data reflected by the image must be solved to reconstruct the image directly. This method, the C++ code was developed to reconstruct Compton camera images. According to the results, using the analytical method to identify the best circumstances and the parameters impacting efficiency, the value of FWHM achieved was 3.7 mm with an angular uncertainty of about 2.7 at an energy of 0.662 MeV. Furthermore, the FWHM value decreased by 0.7 mm, compared to another (experimental) design that employed the analytical image reconstruction approach.