Study of a new design of P-N semiconductor detector array for nuclear medicine imaging by MCNPX simulation

Abstract

Gamma camera is an important apparatus in nuclear medicine imaging. Its detection part is consists of a scintillation detector with aheavy collimator. Substitution of semiconductor detectors instead of scintillator in these cameras has been effectively studied. In this study, it is aimed to introduce a new design of P-N semiconductor detector array for nuclear medicine imaging. A P-N semiconductor detector composed of N-SnO:F, and P‑NiO:Li, has been introduced through simulating with MCNPX monte carlo codes. Its sensitivitywith different factors such as thickness, dimension, and direction of emission photons were investigated. It is then used to configure anew design of an array in one‑dimension and study its spatial resolution for nuclear medicine imaging. One‑dimension array with 39detectors was simulated to measure a predefined linear distribution of Tc2 activity and its spatial resolution. The activity distributionwas calculated from detector responses through mathematical linear optimization using LINPROG code on MATLAB software. Threedifferent configurations of one‑dimension detector array, horizontal, vertical one sided, and vertical double‑sided were simulated. Inall of these configurations, the energy windows of the photopeak were ± 1%. The results show that the detector response increaseswith an increase of dimension and thickness of the detector with the highest sensitivity for emission photons 15-30° above the surface.Horizontal configuration array of detectors is not suitable for imaging of line activity sources. The measured activity distribution withvertical configuration array, double‑side detectors, has no similarity with emission sources and hence is not suitable for imagingpurposes. Measured activity distribution using vertical configuration array, single side detectors has a good similarity with sources.Therefore, it could be introduced as a suitable configuration for nuclear medicine imaging. It has been shown that using semiconductorP‑N detectors such as P‑NiO:Li, N‑SnO299_m:F for gamma detection could be possibly applicable for design of a one dimension arrayconfiguration with suitable spatial resolution of 2.7 mm for nuclear medicine imaging.