GB1174558A - A Detector for Determining the Distributon of Radioactive Materials - Google Patents

Abstract

1,174,558. Television. SIEMENS A.G. 1 March, 1968 [3 March, 1967], No. 10212/68. Heading H4F. To determine the distribution of rays (gamma rays) from a radio-active subject, a scintillation layer (crystal) is disposed at an aperture in a radio-active shield, e.g. a lead shield, and an image intensifier for the scintillations is disposed between the scintillation layer and a plurality of photo-electric transducers, the signals from the transducers being converted by means of a matrix circuit into a representation of the position and brightness of the scintillations which may be displayed on a storage oscilloscope and photographed. A collimator is preferably disposed in the aperture in the shield, and light conductors may couple the scintillation layer to the image intensifier which may comprise a vacuum or solid-body type intensifier. Alternatively, the image intensifier may comprise a television camera directed towards the scintillation layer, the video signals from which are applied via an amplifier to a reproducing device, the image screen of which is associated with the photo-electric transducers. Light conductors may also couple the output of the intensifier to the inputs of the transducers, a glass plate being positioned between the intensifier and the light conductors. The outputs from the transducers are preferably differentiated before they are applied to the matrix circuit to provide signals corresponding only to the rise in intensity of each scintillation. In the embodiment described, four photoelectric transducers 16-19 are connected to a matrix as shown in Fig. 3. The X and Y axis position signals for the oscilloscope 27 are obtained by means of difference circuits 34 and 42, the resulting signals being amplified and shaped in circuits 37 and 43. The Z-signal is obtained from the matrix as shown, amplified 48 and applied to the input of a pulse height selector 49 whereafter it is shaped 50 and applied to open a gate 53 which allows a second path from amplifier 48 via a discriminator 51 and a pulse shaper 52 to pass to the intensity input 54 of the oscilloscope. Selector 49 is set for signals which are characteristic of the isotope employed and which are set up in the scintillation layer.