Trans-arterial Radioembolization Dosimetry in 2022.

Trans-arterial radioembolization is currently performed using Y-loaded glass or resin microspheres and also using Ho-loaded microspheres. The goal of this review is to present dosimetry and radiobiology concepts, the different dosimetry approaches available (simulation-based dosimetry and post-treatment dosimetry), main confounding factors as main clinical dosimetry results provided during the last decade for both hepatocellular carcinoma (HCC) and metastases of colorectal carcinoma (mCRC). Based on the different number of microspheres or different isotope used, radiobiology of the three devices is different, meaning that tumouricidal doses and maximal tolerated doses are different. Tumouricidal doses described for HCCs were 100-120 grays (Gy) with Y resin microspheres and 205 Gy with Y glass microspheres. For mCRC, it is 39-60 with Y resin microspheres, 139 Gy with Y glass microspheres and 90 Gy with Ho microspheres. An impact of tumoural doses with overall survival has also been reported. Personalised dosimetry has been developed and is now recommended by several international expert groups. Level-one evidence of the major impact of personalised dosimetry on response and overall survival in HCC is now available, bringing a new standard approach for TARE in clinical practice as well as for trial design.