Positron imaging system with improved count rate and tomographic capability
AssigneeG. D. Searle & Co.
InventorsGerd Muehllehner, Michael P. Buchin
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Abstract
A positron imaging system and method in which two opposed Anger cameras are employed on opposite sides of an organ to be imaged. The cameras include a planar unitary scintillation crystal approximately one inch in thickness, and the electronics which process the signals from the cameras include pulse shaping circuitry to reduce both the duration and the integration time of pulses resulting from radioactive events. Both cameras exclude collimators to enable radiation incident upon them at many angles to be accepted, and means are included to rotate the opposed cameras about the organ of interest to enable transverse tomographic imaging.
Claims11
In a positron imaging system with improved count rate capability for detecting the radioactive distribution of positron events within an organ of interest of a living subject, and including scintillation detectors producing electrical signals in response to said events, electronic means for processing said electrical signals and for supplying image reconstruction signals to a display means to produce an image of said radioactive distribution, the improvement comprising:
- a pair of Anger-type scintillation cameras as said scintillation detectors, each camera having a unitary planar scintillation crystal, said crystal being greater than one-half inch in thickness, said cameras being respectively positioned on opposite sides of said organ;
- and pulse shaping means for reducing the pulse duration below approxmatley 900 nanoseconds, and for reducing the integration time of said pulse below approximately 500 nanoseconds, whereby the count rate capability and counting statistics of the system is improved for greater image quality and processing speed.
In a positron imaging scintillation system for detecting the radioactive distribution of positron events within an organ of interest of a living subject, and including scintillation detectors producing electrical signals in response to radiation, electronic display means, electronic means for processing said electrical signals and for supplying reconstruction signals to said display means to produce an image of said radiation distribution of positron events, the improvement which comprises a pair of Anger-type scintillation cameras as said scintillation detectors, each having a unitary planar scintillation crystal, said cameras being respectively positioned on opposite sides of said organ, both of said cameras excluding collimators to accept radiation not traveling within planes perpendicular to said scintillation crystals;
- coincidence circuitry means monitoring the output of both of said cameras and providing validation signals to said signal processing means to identify those pulses associated with positron events;
- and means for rotating said opposed heads about an axis which passes through said organ of interest.
A method of positron imaging for detecting the radioactive distribution of positron events within an organ of interest within an living subject, for use with a pair of opposed Anger-type scintillation cameras and electrical means for processing the signals from said camera and for supplying image reconstruction signals to a display means, said method comprising:
- viewing the organ of interest with said two cameras with said organ positioned between said opposed detectors;
- rotating said opposed scintillation cameras about the organ of interest;
- evaluating the electrical pulses produced by said cameras by means of coincidence circuitry to identify signal pulses from one camera which are coincident with signal pulses from the other camera;
- providing said signal processing means with a validation signal to idenitfy said coincident signal pulses, whereby said coincident signals are selectively processed by said processing means;
- and reducing the duration and integration time of said signal pulse to improve the count rate capability and thereby the quality of the resultant image.
Dependencies are inferred from the claim text.