Clinical dosimetry in the treatment of bone tumors: old and new agents

Treatment of multisite, sclerotic bone metastases is successfully performed by radionuclide therapy. Pain palliation is the most common aim for the treatment. Two radiopharmaceuticals are currently approved by the European Medicines Agency ((153)Sm-EDTMP and (89)Sr-Cl₂) whilst other radiopharmaceuticals are at different stages of development, or are approved in some European countries ((186)Re-HEDP, (117)Snm-DTPA and (223)Ra-Cl₂). The tissues at risk for the treatment are bone marrow and normal bone. A review of the methods applied for dosimetry for these tissues and for tumours is performed, including the calculation of S values (the absorbed dose per decay) and optimal procedures on how to obtain biodistribution data for each radiopharmaceutical. The dosimetry data can be used to individualise and further improve the treatment for each patient. Dosimetry for radionuclide therapy of bone metastases is feasible and can be performed in a routine clinical practice.