X=ray equipment radiation level control circuit - converts brightness image into digital signals for correction circuit controlling tube emission level

摘要

X-ray treatment appts. has an image amplifier (3) on the opposite side of the patient (2) to the tube (1) with an optical system (4) for a TV camera (5). This is connected to an A/D converter (6) followed by an equaliser circuit (7) whose output signals are fed to an image storage device (8) which is also connected to a D/A converter (9) and a monitoring screen (10). The A/D converter changes the camera image into sections having a digital value, and the digital signals are passed to a corrector (11) and detector (12) forming part of a brightness monitoring system which is used to control the level of radiation from the X-ray tube. The detector includes an average value forming circuit which passes the corresponding brightness signal obtained to a subtracting stage connecting it to the correction circuit.