ESR dosimetry of 89Sr- and 153Sm-in bone

The radiation absorbed dose in the rabbit bone delivered by 153Sm–EDTMP (samarium ethylenediaminetetra methylene diphosphonic acid) and 89SrCl2 (strontium chloride) was measured by means of electron spin resonance (ESR). These radioisotopes are used in systemic radiotherapy for palliation of painful bone metastases. The knowledge of the dose is important in order to avoid side effects to the bone marrow. The ESR radiation dose signal was calibrated by the additive dose method using cobalt-60 gamma rays. For 153Sm–EDTMP, the bone doses in three rabbits were (4 ± 2), (5 ± 1) and (5 ± 2) cGy kg/MBq. For 89SrCl2, a dose of (2 ± 1) cGy kg/MBq was found in one rabbit.