[Progress in radiotherapy and current status].

Within the first decade of the 20th century, years after the discovery of X-rays, radiotherapy was established as an independent medical discipline. Since then, the knowledge of and the applications in radiotherapy have grown enormously. In the year of 1994 the clinical disciplines radiology and radiooncology finally became separate clinical specialities in Austria. Radiotherapy plays an important role in the curative and palliative setting of oncologic therapy. Tridimensional volumetric definition of the tumor and the proximity to organs at risk are based on high precision technique like ultrasound sonography, computerised tomography, magnetic resonance imaging and positron emission tomography. The main goal of radiation therapy is the successful sterilization of tumor cells in a carefully defined target volume considering adequate safety margins. The volume of the irradiation is often irregular and therefore shaped fields were used, which minimise the amount of radiosensitive normal tissue within the radiation fields. In this way, it is possible to decrease acute and late radiation induced complications. Dose-volume histograms ascertain irradiated volumes and dose distributions of the target and critical organs. The key breakthrough development of computer-controlled multi-leaf-collimators enables time-saving and precise irradiation of a target (macroscopic tumor and an adequate safety margin), permitting a dose distribution that confirms exactly to the intended target volume. The procedures of 3D conformal radiotherapy are more complex and expensive than conventional radiotherapy, but are essential for assuring high quality of modern cancer treatment.