Radiation therapy refers to a technique used for treating cancer with the help of high energy charged particles. It is one of the three major modalities utilized for the treatment of malignant diseases, the other two modalities being chemotherapy and surgery. Radiotherapy utilizes ionizing radiation to treat cancer and is significantly reliant on modern technology. It is also dependent on the joint efforts of a number of medical specialties, such as radiation oncology and medical physics, whose coordinated team approach has a significant impact on the outcome of the treatment. Radiation therapy for cancer requires an understanding of radiation physics along with the interaction of ionizing radiation with human tissue. It is utilised as a primary treatment for cancer, and can be given individually or in combination with other treatments like medications or chemotherapy. This book explores all the important aspects of radiation therapy in the present day scenario. It is a valuable compilation of topics, ranging from the basic to the most complex advancements in this form of cancer therapy. This book is appropriate for students seeking detailed information in this area as well as for experts.