Bone marrow radiation dosimetry of high dose 131I treatment in differentiated thyroid carcinoma patients

Background: Radia on absorbed dose to the red bone marrow, a cri cal organ in the therapy of thyroid carcinoma, is generally kept below 2 Gy for non-myeloabla ve therapies. The aim of this study was to calculate bone marrow radia on dose by using MIRDOSE3 package program and to op mize the safe limit of ac vity to be administered to the thyroid cancer pa ents. Materials and Methods: In this study, 83 thyroid cancer pa ents were divided into 3 groups based on the amount of ac vity administered into the body. In the groups, 3700 MBq, 5550 MBq and 7400 MBq ac vi es were used respec vely. The curves of me-ac vity were drawn from blood samples counts and effec ve half-life and residence me were calculated. Correla ons of bone marrow radia on dose and radioiodine effec ve half-life were determined as a func on of administered ac vity via ANOVA test. Tg levels and tumour diameters were compared using Spearman’s correla on. Results: The effec ve half-lives of 131 I for three groups of whole-body, receiving 3700 MBq, 5550 MBq and 7400 MBq were calculated as 20.57±5.4, 17.8±5.8 and 18.7±3.9 hours, respec vely. The average bone marrow doses for 3 groups of pa ents were 0.32±0.08 Gy, 0.42±0.14 Gy and 0.60±0.24 Gy, respec vely. Conclusion: It was concluded that, the bone marrow dose to the pa ents s ll remains within the recommended level even a9er administering an ac vity of 7400 MBq of 131 I to the pa ents.