Dosimetry for Radioembolization of Liver Metastases: essential knowledge for Interventional Radiologists

In transarterial radioembolization (TARE) for liver metastases, dosimetry is essential to optimize therapeutic response while minimizing toxicity. Dose planning or pre-treatment dosimetry have evolved from empirical and single-compartment models to multi-compartment approaches, leading to improved tumour response and overall survival. More recently, voxel-based dosimetry has emerged as an advanced technique that provides high-resolution spatial dose mapping. Dose verification or post-treatment dosimetry using post-treatment imaging is essential for establishing dose-response relationships and defining clinically relevant dose thresholds. Even when such thresholds are proposed, their translation into clinical practice is challenging due to the numerous uncertainties introduced throughout the radioembolization workflow. Several physical and biological factors, including the effects of microsphere density remain insufficiently understood, making it difficult to determine their true impact on treatment outcomes. Collectively, these challenges underscore the need for standardized dosimetric methodologies and more robust evidence to enable reliable, personalized dose planning and verification, ultimately improving outcomes and expand the indications of radioembolization for liver metastasis.