SCINTILLATION CAMERAS

摘要

1363246 Scintillation camera NUCLEARCHICAGO CORP 11 Oct 1971 [12 Oct 1970] 47175/71- Heading H4F An Anger-type scintillation camera having a scintillating crystal and a bank of photomultiplier tubes viewing overlapping areas of the crystal with co-ordinate computing circuitry coupled to the photomultipliers, wherein to improve the overall spatial resolution of the resulting display of the scintillations produced by impingingγ-rays non-linear preamplifiers are disposed between the photomultipliers and the computing circuitry which amplify large signals therefrom a greater amount than small signals. Specifically the input-output characteristic of each preamplifier is such that inputs signals smaller than 5% of the maximum input signal (i.e. the output signal from a photomultiplier positioned directly above a scintillation in the crystal) produce substantially no output signals and larger input signals produce amplified output signals which are proportional to the magnitude of the input signal above the 5% threshold magnitude. Each preamplifier comprises a wide band amplifier stage, a threshold amplifier stage having a preselected threshold magnitude, an integration circuit stage, and an output amplifier stage. The scintillating crystal comprises a disc of at least 15À2 cm. diameter (preferably at least 25À4 cm.) and the bank of photomultiplier tubes includes at least seven tubes (preferably at least nineteen tubes) arranged in a hexagonal array. To further improve the spatial resolution the integration time constant in the preamplifier and the delay magnitude of the delay line in each summing amplifier in the co-ordinate computing circuitry may be increased.