[Dose distribution of photons and neutrons outside of the irradiation field of a 8-mev linear accelerator (author's transl)].

During the irradiation with a continuous radiation of 8 MeV by the linear accelerator LINAC SL 75/10, the dose distribution of photons and neutrons was measured outside of the irradiation field. The dose distribution of photons was mostly determined by thermoluminescence dose meters. There was a significant maximum of leak radiation on the back of the emitter head which showed a dose rate amounting to 7,5% of the dose rate of the central ray. Whereas the leak radiation on the patients' table was less than 0,1% of the dose of the central ray, the dose of scattered radiation emitted by the patient still amounts to 2% of the central ray dose in a distance of 15 cm from the field edge. The isodoses measured in the room demonstrate above all the importance of the lock for a sufficient radioprotection.--The dose rate of the neutrons formed in the shielding material by photonuclear reactions were measured mostly with uranium fission-track dosimeters. The highest equivalent dose rate was found on the back of the emitter head; it is about 17 rem/h. The maximum value of the equivalent dose rate of neutrons on the patient's table amounts to 1,4 rem/h and is almost independent of the size of the diaphragm. The isodoses in the room depend largely on the shape of the irradiation room; they confirm the existence of a sufficient radioprotection.