[Localization and field control in deep therapy]

The localisation is an important part of irradiation planning. The development of special therapy simulators takes this significance into account. Focussing under observation is difficult because of the limited size of the monitors. If focussing is complicated, control radiograph of the field, taken on the therapy unit with the therapeutic rays, grants optimal safety. In routine clinical procedure, simpler focussing is preferable, as it need not intricate control. High-voltage films show characteristic peculiarities with regard to their production and evaluation.