Measurements with a Cerium 144 Beta-ray Applicator

Abstract

A clinical β-ray applicator using cerium 144 is described. When the source is 14·5 mc, the dose-rate on the skin is 59 r/min. Measurements show that depth doses obtained with this applicator are an improvement over those obtained with phosphorus 32, strontium 90 and radium β-ray applicators. The effect of source-skin distance, collimator design, filtration and backscatterers upon dose-rate and percentage depth dose have been investigated. As a result, a form of “β-ray teletherapy” unit is proposed using a 100 mc source of cerium 144 at a source-skin distance of 3·4 cm. Such a unit would give a surface dose-rate of 94 r/min and an intensity of half this value at a depth of 3·2 mm.