Résumé : Radioembolization (also called selective internal radiation therapy, SIRT) with yttrium-90 (90Y)-loaded microspheres has been broadly adopted as a locoregional therapy for primary and metastatic liver cancers. Although radioembolization is a well-established therapy, efforts to personalise and refine the planning and administration of therapy are ongoing. The ability to accurately predict, plan and deliver optimal doses to tumour and non-tumour tissues, including final validation of dose distribution, is essential for successful radiotherapy. Determining the true dose absorbed by tissue compartments is the primary way to safely individualise therapy for maximal response while respecting normal tissue tolerances. The overarching objective of this work was to expand our knowledge of dosimetry in 90Y-resin-microsphere radioembolization, with the ultimate goal of improving the clinical outcomes in our patients. Initially we sought to identify the patient- and treatment-related variables that predict radioembolization outcome in patients with intrahepatic cholangiocarcinoma (Chapter 2). Then, as a step toward personalised radioembolization in liver metastases from colorectal cancer patients, we evaluated the relationship between radioembolization real absorbed dose, as determined by 90Y positron emission tomography, and outcome (lesion-based and patient-based) (Chapter 3). In the work described in Chapter 4, we compared predictive (simulated) and post-treatment (real) dosimetry in liver metastases from colorectal cancer patients to pursue radioembolization personalisation. Finally, based on experience accumulated in previous studies and advances reported in the literature, we generated state-of-the-art recommendations to assist practitioners in performing personalised radioembolization with 90Y-resin microspheres in patients with primary and metastatic liver tumours (Chapter 5).