Abstract: A PET scanner is disclosed which includes a gantry, a plurality of sets of detectors supported by the gantry, and a plurality of septa that are supported by the gantry and are constructed of material which blocks photons. The detectors in each set are disposed in a plane and positioned around a central axis that intersects the plane, and the plurality of sets of detectors are spaced along the central axis. The septa are spaced along the central axis to separate groups of two or more detector sets and block external photons from reaching the detectors. The PET scanner further includes a processor means for receiving signals produced by the detectors and indicating annihilation events occurring within a central region around the central axis, and for reconstructing an image from indicated annihilation events.

Abstract: An imaging system for generating SPECT images wherein first and second cameras are mounted to a gantry for rotation about an imaging axis, the cameras are positionible in an L configuration wherein their camera axis intersect at an intersection point, the cameras are mounted such that when in the L position the intersection point is further away from each of the cameras than is the rotation axis allowing the cameras to be moved radially inward with respect to the rotation axis thus reducing the degree of table movement within the imaging area required to position an object to be imaged adjacent the cameras.

Abstract: A PET scanner includes a ring of detector units which receive gamma rays produced by annihilation events. Each detector unit includes a 6.times.6 array of BGO scintillation crystals mounted in front of a 2.times.2 array of photomultiplier tubes. The position of a scintillation event within the crystal array is determined more accurately by selectively painting the side surfaces of the array crystals.

Abstract: A simplified method of determining tissue blood flow such as cerebral blood flow is provided by calculating the partial derivatives with respect to flow rate constant (k) and partition coefficient (.lambda.) of the sum of errors squared for calculated tissue concentration of a diffusible inert gas such as xenon minus measured tissue concentration of xenon based on CT numbers.

Abstract: A method and apparatus for correcting for the spatial distortions of scintillation cameras or similar image forming apparatus. The spatial distortion correction method accurately and precisely determines distortion correction factors in an off-line test measurement and analysis phase prior to actual on-line diagnostic use. The distortion correction factors are initially determined from image event data that is obtained during the test measurement phase by orthogonal line pattern images. Data from a uniform field flood image is also utilized during the test measurement phase to refine and modify the distortion correction factors utilizing the gradient of a function of the field flood image data. Scintillation camera image repositioning apparatus is provided and includes a memory having the correction factors stored therein in a predetermined array.