Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 2 3 2015 09 30 172 183 EN Hamidreza Hemmati Department of Radiation Medicine Engineering, Shahid Beheshti University, Tehran, Iran Alireza Kamali-Asl Department of Radiation Medicine Engineering, Shahid Beheshti University, Tehran, Iran Reza Haghshenas Department of Radiation Medicine Engineering, Shahid Beheshti University, Tehran, Iran 2016 04 12 2016 04 12 Purpose- Some practical and theoretical efforts have been made to investigate the effects of designing parameters on the performance of anger camera. In this study, the effects of light guide thickness on the accuracy of position estimation, linearity, and uniformity response of a typical gamma camera has assessed using Geant4 Monte Carlo (MC) simulation toolkit. Methods- Three MC simulations are done using T/R values of 0, 0.5, and 1, where T is the thickness of light guide and R is the effective radius of a hexagonal photomultiplier tube. For each T/R value, the accuracy of position estimation was investigated by the analysis of the relations between the true and estimated positions of scintillation events. Also, the differential non-uniformity and average non-linearity maps have been used to assess the effect of light guide thickness on the linearity and uniformity responses, respectively. Results- The results showed that the accuracy of position estimation depends on the depth of scintillation causing erroneous estimated positions for T/R values of 0 and 0.5. For the case T=R, that dependency was eliminated due to the enough broadening of optical photon cones and the position estimation errors were in the range of intrinsic spatial resolution of camera. Conclusions- Lack of a proper thickness of the light guide on the gamma camera can ruin the accuracy of position estimation on the gamma camera. In addition, both linearity and uniformity responses have a strong dependency on the thickness of light guide. https://fbt.tums.ac.ir/index.php/fbt/article/view/70 https://fbt.tums.ac.ir/index.php/fbt/article/download/70/58