Monte Carlo based dose-rate assessment in 18F-Choline PET examination: a comparison between GATE and GAMOS codes

Monte Carlo simulation of radiation transport is the most accurate and patient-specific technique available for internal dosimetry in nuclear medicine. Taking morpho-logical and functional information from CT and PET 3D scans, it is possible to perform MC dose calculations at voxel level. GATE and GAMOS are among the most used and validated toolkits developed for performing such medical physics calculations. Aim ofthis work was the comparison of dose rates evaluated by means of GATE and GAMOS simulations for a case of PET/CT diagnostic exam conducted with18F-choline radiopharmaceutical. The results obtained with the two toolkits showed a good agreement, with just some minor differences imputable to their different procedure of voxel density assignment. A further investigation on spurious decays generated in air was conducted through simulations employing a PET-filtering technique. In this way it was highlighted the effect of PET background on the evaluation of dose rates imparted to air-rich organs, in particular lungs.