Abstract: A gamma camera having a Compton scattered radiation deemphasizer. A summing device produces pulses proportional to the total energy of each scintillation caused by absorption of gamma photons in a scintillation crystal. Scintillation events are displayed at the x,y coordinates of the event on a cathode ray tube screen by unblanking the tube with z pulses applied to its control electrode. The deemphasizer determines where the peaks of total energy pulses fall in a part of the energy spectrum or window and between lower and upper limits. The deemphasizer causes small z pulses to be produced in the part of the spectrum where Compton scatter is most prevalent and causes increasingly larger z pulses as total energy increases to the midpoint of the spectrum where Compton scatter is insignificant. Constant amplitude z pulses are produced at and after the midpoint.

Abstract: In a scintillation camera system, the output pulse signals from an array of photomultiplier tubes are coupled to the inputs of individual preamplifiers. The preamplifier output signals are coupled to circuitry for computing the x and y coordinates of the scintillations. A cathode ray oscilloscope is used to form an image corresponding with the pattern in which radiation is emitted by a body. Means for improving the uniformity and resolution of the scintillations are provided. The means comprise biasing means coupled to the outputs of selected preamplifiers so that output signals below a predetermined amplitude are not suppressed and signals falling within increasing ranges of amplitudes are increasingly suppressed. In effect, the biasing means make the preamplifiers non-linear for selected signal levels.