Picker International, Inc.

Technicare Corporation

Gary G Jarkewicz

Hugh T Morgan

Stephen D Miller

Piotr J Maniawski

A method of scatter correction for use with gamma cameras includes the steps of detecting and producing a first count value indicative of gamma radiation falling within a first energy range generally associated with a radionuclide photopeak. Gamma radiation falling within second and third energy ranges is also detected and a corresponding count produced. The second and third ranges are above and below the photopeak, respectively. The location of the second and third energy ranges is determined based on the energy resolution of the gamma camera such that a predetermined percentage of the radiation falling within the second and third ranges results from primary radiation. The second and third energy ranges may be located such that they are non-contiguous with the first energy range. Based on the count of radiation falling within the second and third ranges, the scatter radiation falling within the first energy range can be estimated, and the first count value corrected. The method is suitable for use with radionuclides having multiple closely spaced photopeaks as well as with multiple widely spaced photopeaks.

Split window scatter correction

A head (10) of a nuclear medicine camera has a face defined by scintillation crystal (12) which is non-rectangular. In particular, it has symmetrically clipped corners (16). As the head scans from an initial position (32) to a final position (34), radiation originating from regions (72) and (82) are received by the detector head for a shorter duration than radiation from a corresponding point in the central region, due to the clipped corners. Particularly, for a path (74) that is shorter by 2W.sub.1 than a width W.sub.0 of the central portion, 2W.sub.1 /W.sub.0 fewer counts are received in region (82) from a radiation source of the same strength than would have been received in the central region. An edge enhancement circuit (70 ) boosts the number of radiation events counted in an image memory (54) in pixels corresponding to region (72) by 2W.sub.i /W.sub.0 and in region (82) by W.sub.i /W.sub.0. In the preferred on-line embodiment, the radiation event count adjustment is performed in conjunction with a uniform flood control correction which causes a gate (52) to accept or reject a preselected percentage of the radiation events received at each unit area of the scintillation crystal. The edge enhancement circuit adjusts the uniformity correction factors such that W.sub.i /W.sub.0 or 2W.sub.i /W.sub.0 more radiation events are kept for the edge regions (82, 72).

Uniformity correction of whole body images taken with non-rectangular

Real time acquisition of cardiac or other gated cyclical data using a scintillation camera with image formulation utilizing only such data that satisfied a preselected time frame for each cycle. The technique provides real time processing of gated data without the need for specialized hardware equipment or for post processing of the data. Unwanted information corresponding to cycles falling outside a preselected time frame are deleted in real time and hence do not contribute to the cumulative cardiac image.

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Willoughby, OH, United States of America

Gary G Jarkewicz