During the past four decades knowledge about biological effects of ionizing radiations on mammalian cells, normal tissues and tumours has increased enormously and has enabled radiotherapists to obtain a better insight into the advantages and disadvantages of cancer treatments with modified regimens of irradiations and combinations with chemotherapeutic agents. Even for the older scientists and clinicians who have wit- nessed all these developments and have contributed to the vast amount of information, it is difficult to integrate this knowledge and to apply it in their daily work. For younger workers it is often difficult to select the important main concepts and results from the overwhelming number of publications. It is evident that a book which provides an integrated view of basic and applied radiation oncology can be of great value to students, scientists and, most importantly, to clinicians who can devote only part of their time to the task of understanding the radiobiological background of their application of radiation in cancer treatment. This book "Radiation Oncology" is written by a radiotherapist who has for a long time participated in the integration of basic knowledge and clinical experience. He has selected radiobiological information which is considered important to radiotherapy and in the description and interpretation of normal tissue tolerance and tumour eradication probability, he illustrates how basic knowledge can be applied clinically.