Optimization of high resolution collimator with CdTe detector: a simulation study

Abstract

Photon counting detectors using cadmium telluride (CdTe) or cadmium zinc telluride (CZT) have benefits compared to conventional scintillation detectors. Recently, many studies have been conducted using these materials to improve the sensitivity and spatial resolution of photon counting detectors. The purpose of this study was to optimize the design of a collimator to achieve excellent resolution and high sensitivity on the gamma camera system based on the CdTe detector. We performed a simulation study of the PID 350 (Ajat Oy Ltd., Finland) CdTe detector using the Geant4 Application for Tomographic Emission (GATE) simulation. This detector consists of small pixels (0.35 × 0.35 mm 2 ). We designed two parallel-hole collimators with different shapes and verified their usefulness. One was the proposed pixelated parallel-hole collimator in which the hole size and pixel size are the same, and the other was the hexagonal parallel-hole collimator, which has a hole size similar to that of the pixelated parallel-hole collimator. We evaluated the sensitivity, spatial resolution, and contrast resolution to determine which parallel-hole collimator was best on the PID 350 CdTe detector. The sensitivity was 22.65% higher for the pixelated parallel-hole collimator than for the hexagonal parallel-hole collimator. Also, the pixelated parallel-hole collimator provided 10.7% better spatial resolution than the hexagonal parallel-hole collimator and contrast resolution was improved by 8.93%. In conclusion, we successfully established a high resolution gamma camera system with a pixelated parallel-hole collimator.