Abstract: An image is reconstructed based upon a filtered backprojection (FBP) technique using a reconstruction filter which is customized or shaped by parameters including a weight value that is determined for weighing projection data according to a predetermined noise model. The weight value is determined based upon rays or views in the projection data. A regularization term is also combined with the noise-weighted FBP.

Abstract: An image is reconstructed based upon a filtered backprojection (FBP) technique using a reconstruction filter which is customized or shaped by parameters including a weight value that is determined for weighing projection data according to a predetermined noise model. The weight value is determined based upon rays or views in the projection data. A regularization term is also combined with the noise-weighted FBP.

Abstract: A multi-view composite collimator includes a first parallel collimator segment having a plurality of collimator channels oriented at a first slant angle and a second parallel collimator segment adjacent to the first parallel collimator segment having a plurality of collimator channels oriented at a second slant angle different from the first slant angle and a bridging collimating element is provided between the first and second parallel collimator segments, wherein radiation can pass through the bridging collimating element.

Abstract: A SPECT system includes three gam camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. Camera head (22a) has a fan-beam collimator (24a) mounted on a radiation receiving face and generates fan-beam data indicative of the received emission radiation. The camera heads (22b) and (22c) each have a cone-beam collimator (24b), (24c) mounted respectively on their radiation receiving face and generate cone-beam data indicative of the received emission radiation. A transmission radiation source (26) is mounted opposite the camera head (22a) having the fan-beam collimator (24a). The fan-beam detector head (22a) further receives transmission radiation and generates fan-beam transmission radiation indicative thereof. A transmission data reconstruction processor (50) reconstructs the fan-beam transmission data.

Abstract: A subject (12) in an examination region is injected with a radioisotope that emits radiation. A detector head (18) receives emission radiation projections (28a) from the radioisotope and transmission radiation projections (28b) from a transmission radiation source (22) disposed opposite the subject from the detector head. A volume memory (50) stores an estimated volume image. For each actually collected image emission data projection set, a projector (52) reprojects a set of projection of the volume image from the image memory (50) along each of the same projection directions as the emission data projections. Each projection is rotated (80) and warped (82) such that rays which converge with the same angle as the convergence of the collimator on the detector head become parallel. The layers are each convolved with a point response function (84) weighted in accordance with a depth of the corresponding layer in the volume image and corresponding points are summed (92) to create a reprojected projection.

Abstract: A SPECT camera system has three detector heads (12a, 12b, 12c). Each of the detectors have a fan-beam collimator (14) disposed toward an examination region (10). The detectors receive radiation travelling along a fan of rays from an apex (x.sub.f,y.sub.f) to a planar face of the detectors. The detectors generate electronic data indicative of a location (x.sub.s,y.sub.s) on the detector at which a radiation event is received along a ray q.sub..beta. (s). The detectors in a selected orbit R(.beta.) around a subject within the examination region (10). A backprojector (56) includes a backprojection trajectory calculating processor (60) that calculates a trajectory through image space, hence through an image memory (58), corresponding to each radiation ray q.sub..beta. (s). The backprojector weights (68) each data value (x.sub.s,y.sub.s) with a weighting function, preferably a Jacobian J(r,.phi.,.beta.), and adds (64) each weighted data value to a corresponding memory cell of the image memory (58).

Abstract: A SPECT camera (A) includes a plurality of detector heads (12a, 12b, 12c) which rotate around an examination region (10). A reconstruction processor (50) reconstructs output projection data from the detector heads into a three-dimensional image representation which is stored in an image memory (62). Selected data from the image memory (62) is converted to a human-readable display on a video monitor (66). To adjust automatically for detector head misalignment, a calibration phantom (B) which has two orthogonal lines of scintillators (20.sub.1, 20.sub.2, 20.sub.3, 20.sub.4, 20.sub.5) arranged orthogonal to each other with a common scintillator in both lines is positioned in the examination region. As the detector heads rotate around the phantom, a misalignment parameter generator (40) generates the displacement distance of the actual rotation from the theoretical rotation axis (.zeta.

Abstract: Radiation passing through a cone beam collimator is received by a radiation detector (10) such as a gamma camera head, as the gamma camera head is moved in a helical orbit. Data g(n,u,v) collected during the helical orbit is scaled (42) to scaled data G(n,u,v). A first partial derivative .differential.G (n,u,v)/.differential.u is taken (46u) with respect to a horizontal direction and a second partial derivative .differential.G (n,u,v)/.differential.v is taken (46v) with respect to a vertical direction. The partial derivatives are linearly combined (48) by being multiplied by sine and cosine values of an angle .alpha. between the horizontal direction u and an arbitrary direction p in the detector plane to form partial derivatives .differential.G(n,u,v)/.differential.p. The coordinate system of the derivatives is converted (60) from the (n,u,v) coordinate system to an (n,.alpha.,p) coordinate system. The first derivatives are projected (62) i.e.

Abstract: A SPECT system includes three gamma camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. Transmission radiation from a transmission radiation source (30) is truncated to pass through a central portion of the subject but not peripheral portions and is received by one of the camera heads (22a) concurrently with the emission data. As the heads and radiation source rotate, the transmitted radiation passes through different parts or none of the peripheral portions at different angular orientations. An ultrasonic range arranger (152) measures an actual periphery of the subject. Attenuation properties of the subject are determined by reconstructing (90") the transmission data using an iterative approximation technique and the measured actual subject periphery.

Abstract: A SPECT system includes three gamma camera heads (22a), (22b), (22c) which are mounted to a gantry (20) for rotation about a subject (12). The subject is injected with a source of emission radiation, which emission radiation is received by the camera heads. A reconstruction processor (112) reconstructs the emission projection data into a distribution of emission radiation sources in the subject. Transmission radiation from a radiation source (30) passes through the subject and is received by one of the camera heads (22a) concurrently with the emission radiation. The transmission radiation data is reconstructed into a three-dimensional CT type image representation of radiation attenuation characteristics of each pixel of the subject. An attenuation correction processor (118) corrects the emission projection data to compensate for attenuation along the path or ray that it traversed. In this manner, an attenuation corrected distribution of emission sources is generated.

Abstract: Radiation passing through a cone-beam collimator is received by a radiation detector, such as a gamma camera head, as the gamma camera head is moved in a circular orbit and in a line orbit. Data collected during the circular orbit is stored (42c), transformed (50c) into the frequency domain and redundant data removed (52c, 52c), and transformed (56c) back to the spatial domain. The data collected during the line orbit is stored (42l). The line orbit data is transformed to the frequency domain and repeatedly filtered with a family of filter functions (52l, 54) to remove redundant data. Each filter function corresponds to a different row through the examination region. The filtered frequency domain slice data sets (62.sub.1, 62.sub.2, . . . , 62.sub.n) are transformed (56l) back to the spatial domain and transferred to a central portion of a spatial domain memory (58l). Empty memory cells of the memory (58l) are filled with zeros.