[The question of the possibility to reproduce field positions in high-voltage therapy (author's transl)].

In order to obtain informations about the possibility to reproduce field positions in high-voltage therapy, controls were made by therapy films on several patients during the irradiation with a linear accelerator and a telecobalt unit. An incorrect position of the fields and/or lead satellites was found in 51% of the controls. The authors discuss possible reasons and their consequences for the radiotherapeutic practice. It must be taken into consideration especially when therapy plans are elaborated, that their realization may cause difficulties in the daily practice.