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...