An integrating X-ray dosemeter, reading directly in skin dose

Abstract

This instrument includes an ionization chamber covering the whole X-ray beam in the master cone of the set, a cathode follower circuit mounted on the cone, and a trigger unit (near the control panel) based on a cold cathode relay valve. The use of special high insulation relays and electrometer valves is avoided. The indicator steps are made to represent 5 r skin dose for any treatment condition by the use of variable bias (calibrated directly in terms of, for example, applicator field size) on the trigger circuit. The calibration remains constant within ± 2% over a period of months and is sensibly independent of mains voltage variations.