Grundlagen der patientenspezifischen Dosimetrie bei Radionuklidtherapien

A prerequisite for the risk assessment in targeted radiotherapy is the knowledge of the patient-specific absorbed dose in critical organs as the biological effect is determined by the absorbed dose. In addition, one needs to take potential inhomogeneous spatial activity distributions, time-dependent dose rates and the energies and emission probabilities of the emitted particles into account. Radiation biology effects should not be neglected for therapy planning. Combining all these factors leads to a reliable dose-effect relationship which is mandatory for the further development of targeted radiotherapy. In the past the absorbed dose was calculated based upon the administered activity, the biokinetics and upon simplified human models. Today, nuclear medicine imaging provides the opportunity to determine, for many organs, the biokinetics of radioactive labelled pharmaceuticals patient-specifically. Recently, many patient-specific methods have been developed for determining the absorbed dose to critical organs. In the present work several methods for the assessment and the critical appraisal of the absorbed dose as well as radio-biological concepts such as the biological effective dose (BED) for therapy planning will be introduced and discussed.