A Monte Carlo Simulation Study of Optimization for Pinhole Collimator Designs with CdTe Semiconductor Gamma Camera System

Abstract

Background: In the gamma camera system, the appropriate utilization of detector and collimator design is very important. Among used detectors, the semiconductor detector based on cadmium zinc telluride (CZT) and cadmium telluride (CdTe) are considered the most promising material due to high density and better spatial resolution. Especially, the use of CZT and CdTe semiconductor detector with pinhole collimator can acquire the excellnt spatial resolution because of high intrinsic resolution. However, the pinhole collimator system has low sensitivity due to small diameter of the hole. Thus, the optimization between the sensitivity and spatial resoution is an essential part for the determination of image performance in the gamma camera system. The purpose of this study was to design an optimized pinhole collimator to achieve appropriate the sensitivity and spatial resolution in gamma camera system using CdTe semiconductor detector. Methods: For that purpose, we used Geant4 Application for Tomographic Emission (GATE) simulation toolkit. To evaluate image performances of proposed system, the sensitivity and spatial resolution were estimated by changing magnification factor and pinhole diameter. The optimal pinhole diameter was determined from trade-off curves with the compromise of the sensitivity and spatial resolution. Furthermore, we designed a hot-rod phantom to assess overall image performance. Results: According to the results, we confirmed difference of tendency in sensitivity and spatial resolution variations with respect to the magnification factor and pinhole diameter. Finally, the optimal pinhole diameter is approximately evaluated 1.4 mm in trade-off curves using our proposed system. Conclusion: In conclusion, we demonstrated optimum conditions of pinhole collimator with CdTe semiconductor detector.