Radiation Dose Distribution in Water for 22.5-Mev-Peak Roentgen Rays

This paper describes an investigation of the distribution of dose produced in water by 22.5-Mev-peak x-rays, Central-axis depth doses and several representative isodose distributions for a fixed–position betatron have previously been published (1, 2). The Memorial Center betatron, however, which was used in this study, differs from others previously constructed in its shielding, compensation, collimation, and suspension system. It was designed to be flexible in position so as to permit rapid, accurate alignment of an x–ray or electron beam for therapy. Because it is the model for a number of units now being installed for therapeutic purposes, a detailed study of the collimation system and compensating x–ray filter was made to determine their effect upon dose distribution in water. Instrumentation The data were obtained with an isodose recorder (3) which automatically analyzes and plots the relative space distribution of dosage produced by a radiation beam in air or water. This automatic isodose plotter (F...