Book excerpt: The publication of this fourth edition, more than ten years on from the publication of Radiation Therapy Physics third edition, provides a comprehensive and valuable update to the educational offerings in this field. Led by a new team of highly esteemed authors, building on Dr Hendee’s tradition, Hendee’s Radiation Therapy Physics offers a succinctly written, fully modernised update. Radiation physics has undergone many changes in the past ten years: intensity-modulated radiation therapy (IMRT) has become a routine method of radiation treatment delivery, digital imaging has replaced film-screen imaging for localization and verification, image-guided radiation therapy (IGRT) is frequently used, in many centers proton therapy has become a viable mode of radiation therapy, new approaches have been introduced to radiation therapy quality assurance and safety that focus more on process analysis rather than specific performance testing, and the explosion in patient-and machine-related data has necessitated an increased awareness of the role of informatics in radiation therapy. As such, this edition reflects the huge advances made over the last ten years. This book: Provides state of the art content throughout Contains four brand new chapters; image-guided therapy, proton radiation therapy, radiation therapy informatics, and quality and safety improvement Fully revised and expanded imaging chapter discusses the increased role of digital imaging and computed tomography (CT) simulation The chapter on quality and safety contains content in support of new residency training requirements Includes problem and answer sets for self-test This edition is essential reading for radiation oncologists in training, students of medical physics, medical dosimetry, and anyone interested in radiation therapy physics, quality, and safety.