This concise but comprehensive textbook sets out the essentials of the science and clinical application of radibiology for those seeking accreditation in radiation oncology, clinical radiation physics and radiation technology. Fully revised and updated to keep abreast of current developments in radiation biology and radiation oncology, the fourth edition continues to present in an interesting way the biological basis of radiation therapy, discussing the basic principles and significant developments that underlie the latest attempts to improve the radiotherapeutic management of cancer. New topics for the fourth edition include chapters on the mechanisms of cell death, biological response modifiers, and biological image guided radiotherapy, with major revisions to sections on the molecular basis of the radiation response, tumour hypoxia and the dose-rate effect. A variety of new authors have contributed to this revision, who, together with the new Editorial team, have used their significant international teaching experience to ensure the content remains clear and comprehensive, and as valuable to the trainee as it is to the established radiation oncologist.