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Purpose: Technical progress in the development of radiation therapy simulators provided valuable addition of electronically stored images and monitor indicators for individual radiation parameters. One can store as well as print these data as a treatment plan. The possibility of supplementing older simulators with these technical options will be reported in the following paper., Methods: The modification of our simulator installation was done simply. The new equipment needed to expand our simulator facility was almost exclusively derived from the fields of entertainment and home electronics (Visualizer/video camera, video tape recorder, video mixer, additional monitor; personal computer and printer)., Results: With these modifications we reached the technical standards of the latest simulator generation. In addition, we succeeded in implementing additional technical options: e.g. image inversion with contrast alignment to diagnostic displays, complete magnetic tape recording of the entire x-ray process with possible repetition, electronic overlapping of the simulator image and the diagnostic image (e.g. NMR; angiograms) to determine the treatment volume, automation in x-ray documentation., Conclusion: Increased precision and rational work steps employing readily available equipment will lead to further improvement in the quality of radiotherapy.

A report is given about the linear electron accelerator operating at the Alfried Krupp Krankenhaus in Essen. This is the first accelerator of the type Therac Saturne supplied for 15 MeV. Besides a description of the most important technical data and the service instructions, dosimetric data for 12 MV photon radiation are presented. The authors communicate the clinical experiences gained hitherto with the accelerator and the patient-orientated verification and recording system which has still to be improved, especially as far as the recording part is concerned. The accelerator meets the requirements of radiologic oncology.

Irregular body-surface contours in the treatment part of high-energetic photon fields are producing an inhomogeneous dose distribution within the target volume. Homogenization of the dose is necessary in order to avoid over- or underdosage. A technique of making compensators is described. These are individual compensation filters substituting tissue layers which are lacking, they are correctly scaled down and optimally corrected in view of absorption and scattering according to the actual irradiation conditions. A simple mechanical device makes possible the production of a mould for heavy-metal compensators immediately in the course of scanning of the body-surface. A universal semi-automatic version of this method is appropriate to clinical practice; it records optically, and therefore without contact and quickly, all body-contours desired. By means of the image of moiré contour-lines thus obtained can be made the mould for the compensator in a second operation using an electronically controlled copy-milling machine.

A holding system is presented which allows a good, easy, and reproducible positioning of the patient in percutaneous head and neck radiotherapy. The patients are lying comfortably on a neck support and are fixed in such a way that they are not able to turn in a lateral or longitudinal direction. The distance chin-jugulum can be easily determined by an integrated measuring tape. Due to the use of UV ink and UV lamps, the field marking of the patient's skin cannot be seen in the spectrum of visible light.

Therac 15-Saturne is a linear accelerator for photon and electron radiation with a double scattering screen system. It has proved its worth during more than three years of clinical use. The dosimetric data of both kinds of radiation correspond to the international requirements for modern therapy units. The trimmer system for electron radiation is equipped with a continuous field size adjustment device for the whole range of field sizes. Thus a fast and precise adjustment is possible without any changing of tubes.