Abstract: A method of performing image reconstruction in a gamma camera system comprises the steps of performing a transmission scan of an object about a number of rotation angles to collect transmission projection data and performing an emission scan of the object about numerous rotation angles to collect emission projection data. The outer boundary of the object is then located based on the transmission projection data. Information identifying the boundary is then either stored in a separate body contour map or embedded in an attenuation map. The information identifying the boundary can be in the form of flags indicating whether individual pixels are inside or outside the boundary of the object. The emission projection data is then reconstructed, using the attenuation map if desired, to generate transverse slice images.

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: Radionuclide emission imaging is improved by correcting emission-transmission data for attenuation along calculated path lengths and through calculated basis material. X-ray transmission data are used to develop an attenuation map through an object which is then used in reconstructing an image based on emission data, Radiation detection circuitry is provided which has different operating modes in detecting the x-ray and emission photons passing through the object. An iterative process is used to reconstruct the radionuclide distribution using the radionuclide projection data and the attenuation map based on physical characteristics of the object being imaged. Subsets of the complete radionuclide projection data are used to reconstruct image subsets of the radionuclide distribution. The image subsets can be generated concurrently with the acquisition of the radionuclide projection data or following acquisition of all data.