Abstract: In order to supply a dose rate which is as constant as possible over the cross section of the x-ray cone for radiation therapy, especially at lesser tissue depths (e.g. 3 cm), the surfaces of the collimator which define the margin of the x-ray cone are roughened for example by means of grooves transverse to the radiation direction, the grooves having semicircular or step-shaped cross sectional configuration, and advantageously being formed in a thin walled sleeve of low atomic number.

Abstract: A beam defining system for an electron accelerator has an adjustable collimator with an accessory holder attached thereto for retaining an electron applicator. The electron applicator has an applicator wall which encloses an electron beam cone from the collimator. A frame-shaped spacer which can be brought into contact with the patient is attached to the applicator wall. A frame-shaped limiting aperture additional to limiting members in the collimator are provided on the applicator wall in order to limit the electron-beam cone at marginal regions facing away from the beam defining system.

Abstract: An ionization chamber for analyzing inhomogeneities in a radiated beam from a particle accelerator system has two measuring chambers formed by three mutually parallel walls spaced apart by spacer rings. Two of the three walls have single electrodes arranged thereon whereas a third wall has several mutually insulated electrodes applied on a measuring chamber side of the wall. The mutually insulated electrodes include a central circular electrode and a group of electrode segments arranged in circular fashion around the central electrode. Inhomogeneities in the radiation intensity of a beam being analyzed are detected by unequal currents in the central electrode relative to surrounding electrode segments or in the electrode segments themselves relative to each other.

Abstract: In an electron accelerator having a target which is subjected to an electron beam for the production of deceleration radiation, a collimator is provided behind the target which has a passageway adapted to receive a beam cone of maximum dimensions. Adjustable x-ray aperture plates are provided behind the collimator and an electron absorber is provided behind the target. An additional electron absorber is positioned in a widened portion at one end of the passageway in the collimator. Both electron absorbers are made of a material having a relatively low atomic number as compared with electron absorbers of the prior art.

Abstract: A monitoring system for the high-voltage supply of an ionization chamber of a particle accelerator has a measuring system which is free of hysteresis and which is electrically isolated from the high-voltage to be measured by opto-electronic couplers. The measuring system controls a switching member for supervising operation of the particle accelerator.