“How Do You Feel About Dosimetry?” The Gretchenfrage of Radionuclide Therapy

Abstract

Dosimetry is Radionuclide Therapy which is a topic often and sometimes even passionately debated among scientists. It revolves around the question whether dosimetry calculations are useful or even necessary and if the calculated values have any clinical significance or advantage for the patient.This article aims to give answers to these questions by systematically reviewing the different aspects of Radionuclide Therapy. First, the most important radionuclides, carrier molecules, and corresponding imaging techniques used in diagnosis and therapy are discussed in the ways they can be combined for theragnostic approaches. Furthermore, the different forms of dosimetry and their levels of detail are outlined including a precis on the physical and radiobiological dose quantities found in literature.Moving forward the evidence for dose-effect relationships is presented, i.e., quantifiable tissue responses as a function of the calculated radiation dose. This includes radiotoxicities of normal, healthy organs which cause an upper limit of the administered activity and are controlled very well. In the case of the kidney the toxicity by Radionuclide Therapy was successfully described via radiobiologic models.Regarding the dose-response of malignant tissue the data is not as comprehensive as in external beam radiotherapy; however, the few studies clearly indicate the existence of a mathematical relation for the mean absorbed dose as well as for more complex dose quantities.Finally, the results are discussed in the context of personalized medicine where the benefits and limits of dosimetry in Radionuclide Therapy are presented.