Book excerpt: This volume discusses the background and various clinical applications of radiation therapy in the treatment of non-malignant diseases. It documents the radiobiological and physical principles of treatment and the rationale underlying the use of radiotherapy for various disorders of the CNS, head and neck, eye, skin and soft tissues, bone and joints, and vascular system. In so doing, it draws attention to and elucidates the scope for application of radiotherapy beyond the treatment of malignancies. Both the risks and the benefits of such treatment are fully considered, the former ranging from minor clinical problems to life-threatening diseases.