The Effect of Energy Window on The Sensitivity of Inveon microPET Simulation study using GATE

Abstract: This work is focused on the use of GATE (GEANT4 application for tomographic emission) Monte Carlo package dedicated for small animal PET imaging systems such as mice and rat. In this study, the Inveon microPET system was simulated using GATE to estimate the absolute sensitivity at different energy windows by using ROOT. Two sets of energy windows were used; one with a fixed lower level discriminator (LLD) that was 350 keV and a changing upper level discriminator (ULD) from 600 to 700 keV and the other with a fixed ULD that was 625 keV and a changing LLD from 300 to 450 keV. Also, the Coincidence Timing Window (CTW) was set to 3.432 ns in the all of simulations. An 18F point source (370 kBq) that was positioned at the center of FOV embedded in an acrylic box with a side of 1 cm was used. The sensitivity was calculated by using C++ via Root. The results show that changing of ULD does not have much effect on the sensitivity. On the other hand, when the LLD reaches 450 keV, the sensitivity is dropped to 5.68%, while the sensitivity for 350-625 keV energy window was 8.01%. Limitation of LLD causes that many of coincidence events with low energy to be lost. Therefore, select an appropriate energy window to achieve more sensitivity is very important.

کلیدواژه ها:

GATE ، microPET ، energy window ، sensitivity