A system for stereotactic radiation therapy using narrow bremsstrahlung beams for pathological and normal intracranial structures is examined. The system is based on an LUÉR-20M medical linear accelerator.

The Central Research Institute of Roentgenology and Radiology and the Research and Production Complex, Radiation Training Center, D. V. Efremov Research Institute of Experimental Physics have been the first in Russia to design a narrow photon-beam unit for stereotactic radiation therapy of intracranial small formation. Fifty one patients were treated. Thirty six presented arteriovenous malformations, 4 had hypophyseal adenomas. The hypophysis was exposed to radiation in 11 patients with prostatic cancer. The unit has been found to have great operational and clinical capacities.

The design, construction, and testing of prototype accelerators for applications in nondestructive testing, medicine, radiation technology, activation analysis, and isotope production have been carried out. Beam stability and safety are increased, beam characteristics reproducibility is improved, accelerator components are unified, automatic control is realized, and mass and overall dimensions are reduced. A klystron for 2450 MHz with an output power 5 MW has been developed for operation at an anode voltage of not more than 55 kV; the use of a periodic system of permanent magnets for beam focusing in this klystron makes it possible to exclude the electromagnet with the stable supply source. For klystron excitation, a compact pilot generator with an output power of 100 W and a frequency stability of 10-5 has been developed

Secondary-emission meters are simple in structural practicability: they have small dimensions and are reliable. They permit measurements to be made of the current strengths of constant and pulsed beams over a wide range of current densities with an accuracy of ±0.5%, and they permit observation of the pulse shape of a beam with a duration of up to 10−9 sec.

The design and sensitivity of a secondary emission monitor of accelerated electron beam position are considered in this paper. The emitting electrode-foils are cut into two equal halves, in two mutually perpendicular directions. The monitor sensitivity, measured at two values of beam pulsed current, 50 an d 100 mA appeared to be equal to 8.8 and 7.6 μA/mA mm respectively. At the given values of beam pulsed current the calculated sensitivity is respectively equal to 10.6 and 9.6 μA/mA mm.