[Individual collimators as an aid in improving the accuracy of positioning, the reproducibility of irradiation and the sparing of critical organs].

Despite the technical progress regarding radiotherapeutic facilities, the positioning and fixation of the patient and the reproduction of the daily irradiation geometry is still the critical point in planning and performance of radiotherapy treatments. Besides the use of irradiation masks, an improved adjustment precision and reproducibility as well as an individualization of the target volume is achieved above all by individual collimators. The use of individual absorbers offers a precise and fast adjustment of irradiation fields at the therapy unit, an optimum adaptation of the irradiation volumes to the anatomical features of the patient and the loco-regional tumor extent as well as a selective protection of radiosensitive structures. The historical method of field-shaping by standard absorbers should be abandoned.