Abstract: The disclosure relates generally to a method of three dimensional (3D) tomographic volume reconstruction for computed tomography (CT) using vector processors and more specifically to an optimized implementation which pre-computes back projection weights and perspective geometry data associated with a given CT device as down-sampled tables. The down-sampled perspective geometry data and the weight table are interpolated dynamically as part of the volume reconstruction process for an object scanned using the given CT device.

Abstract: The disclosure relates generally to a method of three dimensional (3D) tomographic volume reconstruction for computed tomography (CT) using vector processors and more specifically to an optimized implementation which pre-computes back projection weights and perspective geometry data associated with a given CT device as down-sampled tables. The down-sampled perspective geometry data and the weight table are interpolated dynamically as part of the volume reconstruction process for an object scanned using the given CT device.

Abstract: The invention provides in one aspect methods and apparatus for use with C-arm and other CT systems, e.g., with non-rigid geometries. In such systems, by way of example, calibration can be performed to determine the exact position of the x-ray source and the exact orientation of the detector where each projection measurement is made. Next, a weighting coefficient can be determined for the voxels in each plane of a reconstruction volume at every possible projection. Finally, the order in which to process the voxels during image reconstruction can be determined. Following an actual CT scan procedure in which scans are obtained of a volume to be constructed, a system according to these and related aspects of the invention can use an optimal, pre-calculated processing method, while utilizing offsets and weighting coefficients determined during calibration, for performing backprojection image reconstruction.

Abstract: The invention provides in one aspect methods and apparatus for use with C-arm and other CT systems, e.g., with non-rigid geometries. In such systems, by way of example, calibration can be performed to determine the exact position of the x-ray source and the exact orientation of the detector where each projection measurement is made. Next, a weighting coefficient can be determined for the voxels in each plane of a reconstruction volume at every possible projection. Finally, the order in which to process the voxels during image reconstruction can be determined. Following an actual CT scan procedure in which scans are obtained of a volume to be constructed, a system according to these and related aspects of the invention can use an optimal, pre-calculated processing method, while utilizing offsets and weighting coefficients determined during calibration, for performing backprojection image reconstruction.

Abstract: The invention provides in one aspect methods and apparatus for use with C-arm and other CT systems, e.g., with non-rigid geometries. In such systems, by way of example, calibration can be performed to determine the exact position of the x-ray source and the exact orientation of the detector where each projection measurement is made. Next, a weighting coefficient can be determined for the voxels in each plane of a reconstruction volume at every possible projection. Finally, the order in which to process the voxels during image reconstruction can be determined. Following an actual CT scan procedure in which scans are obtained of a volume to be constructed, a system according to these and related aspects of the invention can use an optimal, pre-calculated processing method, while utilizing offsets and weighting coefficients determined during calibration, for performing backprojection image reconstruction.

Abstract: The invention provides improvements in reconstructive imaging of the type in which a volume is reconstructed from a series of measured projection images (or other two-dimensional representations) generated by projection of a point x-ray source (or other radiation source), positioned at a distinct focus, through the volume to a plane at which the respective projection image is acquired (“detector plane”). In one aspect, the improvements are with respect to back-projecting a two-dimensional representation lying in the detector plane (representing, for example, a difference between an originally-acquired measured projection image and a subsequently-generated estimate thereof) to generate three-dimensional representation (which can be used, for example, to update an estimate of the volume).

Abstract: An apparatus for controlling sequential (DMA) transfers between a plurality of buffer memories and a data translation device. Each buffer has an overrun has an overrun area associated with it. Prior to transfers from the buffers to the data translation device, the buffer memories are first "threaded" together by loading the overrun area of a first buffer with data from the next buffer. During the DMA transfer, when the first buffer becomes empty a request is made to the computer to restart the DMA operation on the next sequential buffer, but while the interrupt is being serviced data is continually being transferred out of the first buffer's overrun area. Alternatively, for transfers from the data translation device to the buffers, after the first buffer is full, an interrupt is generated and incoming data is stored in the first buffer's overrun area while the interrupt is being serviced. After the interrupt is serviced data is stored in the next sequential buffer.

Abstract: Apparatus controls sequential direct memory access (DMA) transfers between a plurality of buffer memories and a data translation device. Each buffer memory has an overrun area associated with it. Prior to transfers from the buffer memories to the data translation device, the buffer memories are first "threaded" together by loading the overrun area of a first buffer memory with data from the next buffer memory. During the DMA transfer, when the first buffer memory becomes empty a request is made to a computer to restart the DMA operation on the next sequential buffer, but while the request is being serviced, data is continually being transferred out of the first buffer's overrun area. Alternatively, for transfers from the data translation device to the buffer memories, after the first buffer memory is full, an interrupt is generated and incoming data is stored in the first buffer memory's overrun area while the interrupt is being serviced.