This book provides an update of those topics that at present constitute the main controversies in the field of clinical radiobiology. The various chapters were carefully prepared by the most prominent scientists in the corresponding area of work. A critical appraisal is given of the clinical results obtained so far by the application of hyperfractionation and accelerated fractionation. In addition, the possibilities and limitations of the methods for evaluation of nonrandomizedclinical studies to derive time-dose relationships for human tumors, the useof the BUdR technique for determination of tumor proliferation characteristics, the validity of the linear-quadratic model at low doses per fraction, the predictive value of SF2 for the outcome of radiotherapy, and methods for the identification of hypoxic cellsare critically reviewed.