[Effect of satellite supports of different materials on the surface dose in telecobalt therapy]

The surface doses were measured behind shield supports of different materials with a focus-skin distance of 140 cm. The shield supports were at a distance of 40 cm from the skin. The plates were made of lead glass with a thickness of 11.3 mm, window glass with a thickness of 2.6 mm, plexiglas with a thickness of 5 and 10 mm, and perforated plexiglas with a thickness of 6 mm. The greatest contamination of the useful ray with secondary electrons was measured behind the plexiglas plates, the least contamination was measured behind the plate of lead glass. The relative surface dose is increased by at most 18.5% by plates of plexiglas, while the lead glass plate causes an increase of 3.3%.