Patent GB-1156262-A (GB)
Title: Radiation Scanning Device
IPC: G01T1/29
Filed: 1967-05-18
Abstract: 1,156,262. Radiation scanning device. INTERTECH Inc. May 18, 1967 [June 1, 1966], No.23222/67. Heading G1A. [Also in Division H4] A device for scanning the radiation emitted by an object such as a patient to whom an isotope has been administered comprises a number of photoelectric devices individually responsive to the gamma emanations from respective points defined by a pre-selected collimating arrangement, the array including a corresponding number of scintillation detectors and being movable over a preselected scanning pattern to produce a composite output indicative of scanned intensity and array position, which can be used to establish the radiation distribution within the object. The head, Fig. 5, comprises ten lead collimators 54 each having a number of rows of rectangular passages directed at a point, and opening out on to respective scintillation crystals 56 which may be of sodium iodide, the scintillations being conducted to photomultipliers 60, adjacent ones of which are staggered, by light guides 58 which may be of lucite. The scanning head is mounted on a wheeled carriage which can be driven by an electric motor along a pair of rails, and the rails may be adjusted in height by another motor, and stopped laterally according to the scanning pattern by a further motor. An interlacing scanning pattern in which a number of successive scans backwards and forwards are followed by a retraced scan between the original lines and finally by a further scan backwards and forwards in the original direction at a closer spacing between all the previously scanned lines is described with reference to Fig. 12 (not shown). The scanning line and the position of the head along the lines are indicated by binary code, and the positional information is stored in X and Y registers 98, 101, Fig. 13. Photo-multiplier pulses within a predetermined amplitude range selected by analyzers 68 are stored in accumulators 72, from which they are tapped at times correlated with the scanning by a channel commutator 74, and fed to a Z register 86. The register outputs are gated to a tape recorder 14, and applied via digital-to-analogue converters 92, 100, 102 to a cathode ray display of parallel tubes 106-108. The cathode ray display may be viewed directly, photographed, or televised, and a counter 18 may be adapted to display the number of counts in a selected scan line, in a selected channel, or in all ten channels. The counter may also integrate to count from a selected channel over ten cycles to give a better statistical average. The system is timed by an adjustable master oscillator, and provision is also made for the manual injection into the cathode ray display of marks corresponding to anatomical features. An analyzer comprising a pair of transistor level discriminators feeding an anti-coincidence circuit is described with reference to Fig. 19 (not shown), and the acceptable limits are made adjustable equally in respect of a central line by a pair of oppositely fed potentiometers, the wipers of which are coupled, and which are connected to add and subtract respectively to and from a bias fed in common to the two discriminators. A magnetic tape layout is exemplified.