Comparison of estimated human dose of 111 Inrituximab by MCNPX code and MIRD method based on mice data

Introduction: Radiopharmaceuticals are widely used in modern treatment of cancer. The injection of radiopharmaceuticals into the patient’s body and its accumulation in target tissue is expected to have the highest therapeutic effect on target tissue. The purpose of this study is to calculate the effective absorbed dose of labeled 111 In-rituximab in human body based on mice biodistribution data through MCNPX code and MIRD method. Materials and Methods: In this investigation, the accumulated activity was first computed for mice source organs; then, it was converted into accumulated activity for human source organs via Sparks and Aydogan formula. After that, the equivalent and effective dose were calculated using MCNPX code and the Medical Internal Radiation Dose (MIRD) method. Results: The results of the effective absorbed dose in human body showed that the highest absorbed dose concentrated in the lung (3.36E-04 Sv/MBq), and the organs that received the next highest doses are kidney (2.29E-04 Sv/MBq), spleen (1.57E-04 Sv/MBq), pancreas (1.19E-04 Sv/MBq) and heart (6.73E-05 Sv/MBq). Although our results were different, they were in good agreement with the literature on this subject. Conclusions: According to the results of the study, as the effective absorbed dose using MIRD method indicates, the highest received doses were identified to be in lung, kidney, spleen, pancreas, heart, stomach, liver and intestine, in descending order.