Abstract: A method and apparatus for collecting transmission information utilizing a large field of view of a detector and for collecting emission data using a small field of view window of the same detector. The system employs the large field of view of a scintillation detector in order to collect transmission data for the entire body being scanned. Such a technique improves the quantitative capability of emission data by acquiring non-truncated attenuation factors. The emission data of a small field of view window is collected so that high resolution image pixels are used for processing the emission data (e.g., of a particular body organ). Since a large field of view is used for collecting the transmission data, the imaging pixels for transmission data are of lower resolution than the emission data. The emission data can be collected using a roving zoom technique during an ECT scan.

Abstract: A mechanism and method for performing transmission and emission scanning sessions with two line sources and two detectors wherein two sliding transmission detection windows are employed to differentiate between transmission and emission photons. Transmission and emission data can be collected simultaneously. This system provides that the dual transmission detection windows are each associated with a particular line source and move in synchronization with the associated line source. Further, the two line sources and the two detector windows all move in synchronization in the direction of the long axis of the object being scanned and at any given position all are within a given spatial plane that is transverse to the long axis of the object. In this configuration, the system can effectively reduce the amount of cross-talk detected by a detector (e.g., cross-talk being scattered photon radiation detected by a given detector but not originating from the detector's associated line source).

Abstract: A variable filter arrangement wherein differently sized and shaped filters are automatically selected and installed from a collection of filters housed within a configuration for use with a radiation source. The line source is typically used for transmission scanning to collect attenuation correction factors. A line source is utilized in the preferred embodiment and a series of filters (e.g., differently sized "bow-tie" filters) are rotatably attached to a central junction so that a particular filter can be rotated into an installed position. When installed, the filter acts to attenuate the radiation emitted from the line source to reduce radiation emitted on an otherwise unobstructed area of a scintillation detector. Differently sized filters are advantageously used to accommodate differently sized patents and also to accommodate different unobstructed parts of a detector for different angles of rotation during an ECT transmission scan.

Abstract: A method of reducing the effects of Compton scattered photons detected in a gamma ray detection arrangement includes the steps of receiving data responsive to energy states of the detected photons and storing the data in memory locations corresponding to predetermined image grid points, grouping the stored data, whereby a coarser grid having fewer image grid points is produced, calibrating the gamma ray detection arrangement by utilizing a spectral shape corresponding to a calibration function which is expected to correspond to a first data set corresponding to unscattered ones of the detected photons, processing the stored data for at least selected ones of the predetermined grid points employing minimization of a function which includes a product of an energy regularization term times an energy regularization parameter, as well as a spatial regularization term times a spatial regularization parameter, for separating the stored data into the first data set corresponding to unscattered ones of the detected ph

Abstract: A system for removing the effects of Compton scattering in systems such as tomographic scanning and radioisotope imaging arrangements, which detect gamma rays, utilizes the smoothness of the Compton component over the image to reduce computing time. Data responsive to energy states of the photons which are detected are received and values corresponding thereto are stored in at least one memory location. In some embodiments, where imaging is the ultimate function of the gamma ray detection system, the data correspond to predetermined image grid points. Also, the data which is stored is processed so as to be separated into a first data set corresponding to unscattered ones of the detected photons and a second data set corresponding to scattered ones of the detected photons. The gamma ray detection arrangement is calibrated by acquiring a spectral shape corresponding to unscattered photons. The processing utilizes non-linear least squares fitting analysis.