Intensity modulated radiation therapy (IMRT) has become standard of care for most cancer sites that are managed by radiation therapy. This book documents the evolution of this technology over 35 years to the current level of volumetric arc modulated therapy (VMAT). It covers every aspect of this radiation treatment technology, including the fundamentals of IMRT/VMAT, basic principles and advanced processes for implementation. The physics of IMRT is followed by the clinical application in major disease sites such as central nervous system, head and neck, breast, lung, prostate and cervix. It also provides updated references on each component of IMRT/VMAT. This book is written by leading experts in the field with extensive clinical experience in the practice and implementation of this technology.