Idac-alpha: An alpha dosimetry software for normal organs and tissues

Radiopharmaceuticals have been used for the treatment of various forms of cancer since the 1940s. In recent years, the advantages of alpha emitting radionuclides have emerged as a favourable treatment option. However, most alpha emitting radionuclides have long decay chains with long-lived daughter radionuclides. This leads to uncertainties in the dosimetry for normal organs and tissues, when established dosimetry models are employed. The aim of this project is to assign each progeny its own biokinetic behaviour. The novel dosimetry model was applied to 223Ra-dichloride, frequently used for the treatment of patients with metastatic bone disease from castration-resistant prostate cancer. In this dosimetry model, individual biokinetics for each daughter radionuclide was included. This resulted in a decrease in absorbed dose to bone surfaces and red marrow and increased absorbed dose to liver and kidney, when compared with dosimetry models assuming that the daughter nuclides follow the biokinetics of the parent radionuclide.