Radiographic method and apparatus

摘要: 834,815. Automatic X-ray intensity control systems. JOHNSON, R. N. June 6, 1956, No. 17454/56. Class 38 (4). Overall contrast on an film is reduced without loss of small-scale detail by scanning the subject with a spot large compared scan-line spacing and required, maintaining total X-rays transmitted through substantially constant. As shown, electron beam from cathode 10 caused to scan producing target 22 horizontal vertical sweep generators 16 20 hence ray aperture 24 in lead shield 26 forms spot-scanning 28 image sensitive 32; are converted scintillating element 34 into visible light which acts photo-multiplier 36, amplifier 40, electrode 12 keep Instead 20, disc may be used between source subject. The ratio size 3 : 1 1. Specification 790,509, describing somewhat similar photographic method using instead X-rays, referred to.