Dosimetry of 177Lu-PSMA

New metabolic internal radiotherapy treatments, such as Lu-177-PSMA, as well as compliance with regulatory requirements will ultimately lead to the systematic implementation of personalized dosimetry to estimate the absorbed dose to the organs at risk and to the tumors targeted by the treatment. However, several steps are essential before getting started. In this article, we propose to detail them based on our personal experience and data from the literature, highlighting the difficulties relating to their realization. The first of these steps, often minimized, concerns the implementation of all the elements (settings, determination of correction and conversion factors) required to obtain images suitable for quantification on a conventional SPECT-CT camera. We will then detail the difficulties involved in delineating the volumes of the organs and tumors studied, obtaining their pharmacokinetic curves, to finally finish with the determination of the absorbed dose and discuss its limits. (C) 2023 Elsevier Masson SAS. All rights reserved.