[Role of radiotherapy in the XXI century]

In the last twenty years the extraordinary rise of information technology has made possible key technological developments at the service of precision in radiotherapy treatments: in obtaining three-dimensional images, in systems planning and in radiation units. Thus in less than two decades there progress has been made from radiotherapy in two dimensions (RT 2D) to 3D conformal radiotherapy (3DCRT) and to modulation of intensity modulated radiotherapy for maximum conformation (IMRT). High precision in radiation delivery adjusts the prescribed dosage to the white volume, better preserving the adjacent healthy tissue. It is thus possible to aspire to improving the therapeutic index in two respects, either reducing late toxicity when this is a problem of sufficient scale, or scaling the dosage in the white volume in order to increase tumour control without provoking further toxicity. A final component in reaching the present state of radiotherapy is of capital importance: the guided image which makes it possible to direct the beams of radiation, adapting them to the possible changes of position of the white volume before or during treatment.