Estimation of radiation absorbed dose in man from 166Ho-EDTMP based on biodistribution data in Wistar rats

Abstract Bone marrow malignancies including multiple myeloma are treated by the myeloablative radiotherapy and subsequent stem cell transplantation. Radiopharmaceuticals are used for the selective delivery of radiation absorbed dose to bone marrow. In this work, the radiation absorbed dose of various organs of the adult man from 166Ho-EDTMP radiopharmaceutical was estimated based on biodistribution data in Wistar rats. The MIRD dose calculation method and the Sparks and Aydogan methodology for extrapolation of %IA of organs from animal to human were applied. The results shows that, more than 61% of injected activity is cumulated on the surface of the trabecular and cortical bones. Red marrow and osteogenic cells radiation absorbed doses were estimated to about 1.4 and 3.1 mGy/MBq, respectively. Compared to other aminophosphonate radiopharmaceuticals, 166Ho-EDTMP requires a minimum activity to deliver a therapeutic dose of 25 Gy to the red bone marrow. The result were compared with available data from literature.