Radiation therapy has been officially recognised as an efficient cancer treatment at the International Oncology Congress in Paris on 1922, 25 years after the discovery of X-rays by W. Roentgen and since then tremendous progresses have been made on the basic knowledge on the biological effects of radiations on tumours and healthy tissues, on the modalities and times for dose delivery, planning and irradiation techniques. It may be used as the primary therapy or combined with surgical or medical

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... herapies or to prevent serious symptoms related to the progression of the disease. In recent years the availability of new technologies and results coming from interdisciplinary research where medical and biological competences are working in strict collaboration with physicists and engineers have contributed to a substantial improvement of this treatment by introducing new concepts and procedures which are presented in this paper. The planning treatment has been revolutionised by the possibility to identify in quantitative way tumours and adjacent normal structures in 3D by image processing of CT and/or MRI and/or PET and using virtual simulation for more accurate placement of radiation beams. An enhancement of this technique is £-Dimensional Con-formal Radiotherapy (3DCRT) in which the profile of radiation beam is shaped to fit the profile of the target using a multileaf collimator. In radiosurgery and stereotactic radiotherapy the needed accuracy requires special new techniques to better control the uncertainty related to internal organ motion (for example due to respiration) with real-time adjustment of the radiation beam. The latest developments of Radioisotope Therapy Intra Operative Radiation Therapy and Hadrontherapy are also illustrated.