Monte Carlo dosimetric evaluation in PET exams for patients with different BMI and heights

In recent years, positron emission tomography (PET), associated with multi-detector computed tomography (MDCT), has become a diagnostic technique widely disseminated to evaluate various malignant tumors and other diseases. However, during PET/CT examinations, the doses of ionizing radiation experienced by the internal organs of the patients due to 18F are unknown, and may be substantial. The aim of this study was to determine a set of S values derived from the 18F-FDG and to use them to determine the absorbed and effective doses of 8 different virtual anthropomorphic phantoms (4 of each gender). These phantoms have different Body Mass Index (BMI), to represent different anatomical characteristics of patients examined in PET. The results of the S values were calculated using the MCNPX (2.7.0) Monte Carlo code. These results were compared to the ICRP 106 reference values, obtained with mathematical anthropomorphic phantoms (MIRD model). Our results of the S values were higher than those obtained and presented at the ICRP 106, mainly due to the differences between the phantoms. The differences between the relative distances of the organs and the chemical and physical characteristics of the phantoms used in this study, in relation to mathematical model, reflected the use of a detailed set of phantoms. Therefore, the results presented in this study provide accurate and reliable data for internal dose calculations for patients undergoing PET examinations.