Abstract: According to one embodiment of the invention, a variable length correlation method is provided for compensating for body motions and heart creep in a sequence of image frames obtained by single-photon emission computed tomograph (SPECT) myocardial perfusion imaging. Abrupt body motions, gradual body motions, and heart upward creep are detected and corrected in the sequence of image frames, based on varying correlation lengths. A linear transformation is used to compensate for appearance changes of the heart under different acquisition angles so as to achieve high accuracy of motion detection and correction. The detecting and correcting step is applied in the two-dimensional image domain. The method also includes the steps of detecting and excluding high intensity, non-heart regions in a particular image frame so that non-heart motions such as bowel gas, spleen, and liver motions are excluded from being involved in the motion detection and correction procedure.

Abstract: A combination PET/single photon (SPECT or planar) nuclear imaging system utilizes a pair of dedicated PET detectors and at least one dedicated single photon detector mounted on a single gantry. The single photon detector is a solid-state detector, such as CZT, and the PET detectors are made of a high effective Z material, such as LSO or BGO. Simultaneous PET/single photon imaging studies can be carried by the single system. The solid-state detectors also may be removable and mountable on a separate, dedicated single photon imaging gantry.

Abstract: A gamma ray imaging detector for nuclear medical imaging includes an array of photodiode detectors provided on opposite surfaces of a scintillating crystal. By measuring the relative distribution of detection signal intensities produced by each photodiode in each array, it becomes possible to measure the depth of interaction of a gamma ray absorption event along the Z axis direction of the crystal in addition to its spatial position in the X-Y plane of the crystal and its absorption energy. The value of the measured depth of interaction is subsequently used in refining the calculation of the spatial location and improving the performance characteristics of the imaging detector.

Abstract: A scintillation camera is provided with a scintillation crystal assembly having multiple crystal layers for interacting with various photon energy levels. The camera performs imaging of conventional nuclear medicine radioisotopes as well imaging of high energy isotopes used in PET (Positron Emission Tomography) applications. The multiple crystal layers have the effect of doubling the sensitivity of the camera to high energy photons, while retaining the performance characteristics needed for conventional low energy photon imaging.

Abstract: A method of obtaining scatter-corrected images from a nuclear imaging apparatus such as a gamma-ray camera involves the use of a calibration step which measures the energy spectrum response of the apparatus to unscattered gamma-ray events as a function of spatial location, and a correction step which deconvolves the unscattered distribution from a distribution measured in the presence of scatter by using the calculated calibration response function. The method eliminates the necessity of performing a spatially dependent energy correction for detected radiation image events.

Abstract: A scintillation camera is provided with multiple linearity correction maps which are accessed as a function of the value of the energy of a detected radiation event, so as to separately correct for spatial dislocation errors in multiple energy ranges as a function of detected position. The correction maps may be obtained by direct measurement of nonlinearities for each of the desired energy ranges individually, or sets of corrections for some energy ranges may be obtained by extrapolation calculation from correction factors which have been obtained by direct measurement.

Abstract: A Compton scatter camera for nuclear medical imaging includes an annular scattered photon detector disposed around a first scattering detector and shielded from the field of view of incident gamma photons. Scattered photons detected by the annular detector are thus scattered through angles greater than those of a conventional Compton scatter geometry. Sensitivity and count rate capability is thus significantly increased over the conventional scatter camera, so as to present the possibility for a commercially feasible Compton scatter camera to be realized.

Abstract: A gamma ray imaging detector is disclosed for use in nuclear medicine applications. The imaging detector includes a single scintillation detector crystal which converts absorbed gamma rays into a plurality of scintillation photons. The scintillation detector crystal emits scintillation light with a spectral distribution for which most of the yield corresponds to wavelengths longer than 475 nanometers and is preferably a thallium doped cesium iodide crystal. An array of photodiodes are arranged along one side of the crystal to receive the scintillation photons which generate an electrical output signal proportional to the number of scintillation photons received by the photodiode. Diodes with low capacitance and electrical noise, such as silicon drift photodiodes, are employed so that the signal generated by the photodiode as a result of the received scintillation photons is readily detectable above the electrical noise from the photodiodes.