[Spiral comb filter]. / Spiralnyi grebenchatyi fil'tr.

The paper is concerned with some considerations on ridge filters used for proton beam therapy. Such filters are able to transform the beam energy spectrum and the corresponding Bragg curve defining proton beam depth dose distribution. Some difficulties in the manufacture of ridge filters are discussed. The authors describe a ridge filter design which is simple and fit for continuous production. An account of a calculation method and production process is given.

Permeability of the blood-brain barrier in the rat after local proton irradiation.

Rats were irradiated laterally through the brain with 200 MeV protons. The beam was of circular cross-section with a diameter of 5 or 7 mm. The doses were 50, 70, 100 and 150 Gy. After irradiation the rats were examined several times by use of injected 99Tcm-pertechnetate. The uptake of the substance increased to a maximum after 20 to 30 days and then decreased to a normal level. Differences in maximum uptake with respect to dose were significant only for the smaller beam diameter.