Measurement of 153Sm-EDTMP bone uptake by whole-body scintigraphy and its application to individualized treatment dosimetry of bone metastasis

To calculate a safe and effective 153Sm-EDTMP therapy dose, a whole-body scintigraphy technique for prospective individual dosimetry was developed and the results were compared with 5 h urine collection method in 20 patients with bone metastases. Anterior and posterior whole-body images were obtained 10 min and 5 h after intravenous injection of 740 MBq 153Sm-EDTMP and the bone uptake value was determined. There is a close correlation between the bone uptake value obtained from the whole-body scintigraphy and 5 h urine collection method (r = 0.93). The radiation absorption dose to red marrow was limited to 1.4 Gy and the administered activity calculated from bone uptake value by whole-body scintigraphy was 1.40-2.27 GBq (mean 1.90 GBq). If the activity was calculated according to the standard body weight of 37 MBq·kg-1, the administered activity would be 1.75-2.41 GBq (mean 2.18), the radiation absorption dose to red marrow would be 1.37-2.27 Gy (mean 1.63 Gy), but at these doses significant myelotoxicity would be anticipated, thus emphasizing the need for individual prospective dosimetry