Protection Requirements of One-Million-Volt (1-Mv.) and Two-Million-Volt (2-Mv.) Roentgen-Ray Installations

Abstract

The protection against radiation produced at one million volts and higher has been determined in the past mainly from attenuation data obtained under conditions differing considerably from those found in practice. Most absorption curves have been based on measurements made with narrow beams, while protective barriers generally are exposed to broad cones of radiation. It has been shown previously (1) that the attenuation is less with broad beams because part of the scattered radiation is retained within the confines of the primary beam. It is important, therefore, that the protection requirements be based upon measurements made under conditions actually met in practice. In many instances the lack of dependable data has resulted in inadequate protection against the primary beam and in an excessively high factor of safety for the barriers exposed to scattered rays only. The purpose of this paper is to report the results of our radiation surveys of nine one-million-volt (1-Mv.) and one two-million-volt (2-Mv....