This book provides an in-depth account of all aspects of radioembolization, a relatively novel technique based on the efficacy of radiotherapy for the treatment of liver tumors. Radioembolization combines embolization (intravascular deployment of particles microspheres loaded with yttrium-90) and brachytherapy (local administration of radiotherapy), thereby allowing delivery of high doses of beta-radiation specifically to the tumoral area in an attempt to overcome the problem of permanent radiation-induced damage to nontumoral liver parenchyma. Performance of the procedure demands close familiarity with the hepatic vascular anatomy in order to ensure avoidance of vessels going to other territories. Furthermore, a detailed knowledge of liver function, tumor volume, and liver vascular shunting is needed in order to calculate the appropriate therapeutic dose in each particular case. All of these topics are addressed in depth in this book, and initial promising clinical results are presented.