Abstract: In a method for measuring detected radiation, an analog data signal is converted to a digital data signal having aperiodic data pulses varying with intensity of the analog data signal. A time signal indicative of data intervals is produced. The data pulses are counted. A data count is stored in a start location and a corresponding time value is stored in a start location each time a data pulse occurs until a measured data interval starts. After a next data interval is detected, the data count is stored in an end location and a corresponding time value is stored in an end location when the next data pulse occurs. An average intensity of the detected radiation for the measured data interval is determined from the stored data counts and time values. A CT scanner (10) for measuring detected radiation includes a channel circuit (56), a storage circuit (60), a control circuit (58), and a processor (62).

Abstract: A data acquisition system (DAS) (30) for a computed tomography (CT) scanner (12) includes a two-dimensional array (32) of detectors (34) which is arranged to detect x-rays produced by the CT scanner (12). Each detector (34) is divided into two sub-detectors (34a, 34b) along an axial direction (z). A high-speed switching circuit (40) combines selected adjacent sub-detector outputs (34a, 34b), e.g. combining a sub-detector n alternately with sub-detectors (n?1) and (n+1). The high-speed switching circuit (40) switches its configuration between DAS measurements to produce interlaced DAS output signals along the axial direction (z).

Abstract: A data acquisition system (DAS) (30) for a computed tomography (CT) scanner (12) includes a two-dimensional array (32) of detectors (34) which is arranged to detect x-rays produced by the CT scanner (12). Each detector (34) is divided into two sub-detectors (34a, 34b) along an axial direction (Z). A high-speed switching circuit (40) combines selected adjacent sub-detector outputs (34a, 34b), e.g. combining a sub-detector n alternately with sub-detectors (n−1) and (n+1). The high-speed switching circuit (40) switches its configuration between DAS measurements to produce interlaced DAS output signals along the axial direction (Z).

Abstract: A multi-modality diagnostic imaging system includes a first imaging subsystem (A), such as a computed tomographic (CT) system, for performing a first imaging procedure on a subject. A second imaging subsystem (B), such as a nuclear medicine system (NUC), performs a second imaging procedure on a subject. The second imaging subsystem (B) is remote from the first imaging system (A). A patient couch (28) supports a subject. A patient transfer subsystem (C) transfers a patient couch (28) between the first imaging subsystem (A) and the second imaging subsystem (B). The first and second imaging subsystems (A, B) can be operated concurrently to perform different imaging procedures on different subjects supported by separate patient couches. Data generated by the first imaging subsystem (A) can be used to correct emission data generated by the second imaging subsystem (B).

Abstract: A toroidal x-ray tube (I) is supported (II) for rotation about a horizontal axis (170), translation along a vertical axis (172), and translation along a horizontal axis (174). The x-ray tube includes a toroidal housing (A), an annular anode (B), and a cathode (0) which rotates a beam of electrons around the annular anode. A plurality of parallel connected voltage sources (90.sub.1, 90.sub.2, . . . , 90.sub.n) provide a sufficiently high bias voltage between the electron source and the anode that x-rays are generated. The x-ray beam passes through a compensator crystal (62), an annular window (20), a collimator (132), through a subject received in a central bore (26) of the x-ray tube, and impacts an arc segment of radiation detectors (130). The x-ray detectors are stationarily mounted outside of the plane of the annular window (FIGS. 2 and 7), nutate into the plane of the windows opposite of the origin of the x-ray beam (FIG. 6 ), rotate in part (FIG. 9 ) or rotate in full (FIG.

Abstract: A CT scanner (10) includes a radiation source (12) mounted for rotation about a scan circle (14). A ring of radiation detectors (30) includes narrow detectors (30.sub.n) and wide detectors (30.sub.w). The narrow and wide detectors are separately sampled (42.sub.n, 42.sub.w) and operated on with different digital filters (50.sub.n, 50.sub.w). The wider detectors have a more limited frequency response (32) which typically includes an out of phase response portion (36); whereas, the output signal from the narrow detetector has a higher frequency response (34), i.e. better resolution. The filters (50.sub.n, 50.sub.w) are selected to yield optimum signal to noise ratio. When the data is merged (60), the resultant data has a modulation transfer function with response (62) which has a higher frequency component or improved resolution relative to response (70) that would be obtained from detectors of uniform width of the average of the narrow and detector widths.

Abstract: An imaging system acquires imaged data from a non-invasive examination of the subject. The data is transferred among various image processing agents on a data bus. A data acquisition agent receives the image data from the non-invasive examination and generates subsequent agent locations and transmits the subsequent agent locations and the packets of image data along the data bus. Various image processing agents each receive packets of data transmitted with that agent's location and performs imaging and processing operations on the data packets generating another agent location and thereafter transmitting the other agent location and process data packets along the data bus. The display agent receives the processed image data packets from one of the image processing agents via the data bus, stores the processed image data packets and communicates the process image data to a man-readable image display.

Abstract: A CT scanner (10) generates views of data such as equal angular increment detector fan views (FIG. 2A) which are convolved or filtered by an array processor (24). A combined backprojector and forward projector (28) backprojects the data from the array processor into an output memory (30) and forward projects lines of image representation data from an input memory (26) to the output memory. Each view representation may again be an equal angular increment detector fan format view (FIG. 2A), a parallel ray format view (FIG. 2B), an equal linear increment source fan format view (FIG. 2D), a source fan format view (FIG. 2C), an equal angular incremental detector fan format (FIG. 2E), an equal linear increment detector fan format (FIG. 2F), or an equal angular increment source fan format (FIG. 2G). In a backprojector mode, the projector is addressed by line and row addresses of a pixel of the output memory. A look-up table (76) and a multiplier (82) generate a weighting function W.

Abstract: A customized random access memory circuit is provided to allow the processing of extremely high amounts of data in an area of very small physical size. The chip contains a group of interconnected registers with a set of input ports and a set of output ports. The input ports have individual write enable signals to allow them to write to selected address locations. A switching circuit is provided to ensure that the proper data from the proper input port goes to the chosen address location. A first and second set of latches are provided where the first set of latches are connected to a multiplexor first and the second set of latches are connected to a second multiplexor. The chip also contains a cycle skipping chip to allow the data to maintain its position and not be transferred through at least one clock cycle. Selected data sets which are going to be outputted have the data internally swapped to prepare it for use in floating point operations.

Abstract: An array processor has been designed in a highly paralleled fashion thereby allowing extremely fast movement of data. Two 32-bit words come out of an internal data memory device. This data is fed into a register file. On the same clock cycle, three 32-bit results are coming out of an arithmetic unit. Those results feed back into the register file. Therefore, on a single clock cycle, five separate pieces of data are going into the register file. In the same clock cycle, other data coming out of the outputs of the register file feed data into two separate floating arithmetic adders and one floating arithmetic multiplier. The design of the present embodiment allows a constant flow of data to be supplied to the arithmetic unit thereby using the arithmetic unit to its maximum functioning ability.

Abstract: An improved computed tomography radiation detector is disclosed. One embodiment includes first and second layers of crystalline scintilation material mutually aligned in a path of x-rays to be detected, to receive the x-rays in sequence. The layer upstream in the x-ray path comprises a scintillation material having a relatively high efficiency for converting x-ray energy to light. The downstream one of the layers comprises a scintillation material having a relatively lower efficiency for x-ray/light conversion. A photodiode is positioned to view both scintillation layers simultaneously and to respond to scintillations in either or both. Scintillation crystal material surfaces can be coated with reflective material to enhance the effects of their scintillations. The photodiode thus combines x-ray indicating scintillations from both crystals while in analog form. The detector exhibits enhanced response to lower energy x-rays.

Abstract: Diagnostic mapping data representing a series of planar slices through a patient are generated by a CT or other multi-plane scanner (A) and stored in an image memory (32). To free the CT or other scanner for other patients, the mapping data and patient are transferred to a second location. At the second location, the patient is restrained in a digital radiographic imaging apparatus (B) in which data representing a shadowgraphic image is generated and stored in a reference memory (60). The transferred mapping data is stored in a second image memory (32') at the second site. A shadowgraphic image synthesizer (70) synthesizes an analogous shadowgraphic image from the diagnostic mapping data in the second image memory taken relative to a selected spatial position and angular orientation. The reference and synthesized shadowgraphic images are superimposed or otherwise concurrently displayed on a video display (64).

Abstract: An improved medical diagnostic imaging method and apparatus. In both, Nuclear Magnetic Resonance and Computed Tomography imaging artifacts caused by the finite number of directions from which imaging data is obtained is minimized. An image is constructed and then modified by adjusting each image element with contributions from neighboring picture elements. When all picture elements have been so modified an improved image approximating a result that would have been achieved by interpolating and then reconstructing image data is obtained.

Abstract: An imaging method and apparatus having a new and improved data filter. In one application of the invention computed tomography number inaccuracies are avoided by use of a new filter function derived from discrete points of a truncated spatial domain convolution filter. The points from the truncated convolution filter are fourier transformed to yield a ramp filter with ripple in the spatial frequency domain. Data from a CT scan is filtered with this new filter function and back projected to produce images that do not exhibit CT number inaccuracies.

Abstract: An improved method for computed tomographic scanning is disclosed. A beam of electromagnetic radiation subtending an angle .phi. is alternately translated and rotated past a patient. The intensity of the beam is detected by an array after the radiation passes the patient and a reconstructed image created from the detected intensities. Each rotation of the array is through an angle less than the angle .phi. subtended by the array producing redundant intensity readings for similarly oriented beam paths through the patient. This redundant intensity data is modified according to a scheme which tends to reduce motion and misalignment artifacts within the patient.

Abstract: An improved method and apparatus for transaxial tomographic scanning of a patient. A scanning system is provided having a rotatably mounted X-ray radiation source/detector pair which orbits and radially scans the patient in the plane of orbit. The source provides a plurality of beams of radiation having axes in the orbital plane. The beams pass through the patient to an array of detectors each of which is aligned with one of the beams. Radiation intensity data is collected at predetermined orientations of each beam/detector pair as the assembly orbits about the patient. In a preferred embodiment the rotatably mounted source-detector pair is rotated as a unit through a preselected rotation angle .phi. about an axis effectively passing through the source. The axis and the source-detector pair connected to it are then orbited around the patient through an orbit angle .gamma. while maintaining the preselected rotation angle .phi.. The axis is orbited about an origin lying in the orbital plane.

Abstract: An improved radiation measuring and processing unit for a radiation scanning system precisely determines the average intensity of a beam of radiation as it impinges upon a radiation detector during a primary time period of predetermined duration. The unit computes the average intensity by detecting the average rate of a train of intensity representing pulses occurring during a secondary time period whose duration is determined according to the occurrences of the pulses within the primary time period. The system is preferably a transverse section, X-ray scanning system, and the radiation detector generates a data signal having a level indicative of the intensity of the beam of X-radiation after it passes through a subject. The measuring and processing unit includes a pulse generator, preferably in the form of a charge pump integrator, for converting the data signals into the train of data pulses having a repetition rate which varies according to the level of the data signal.

Abstract: A transverse section tomography system has an ultrahigh-speed data processing unit for performing back projection and updating. An X-ray scanner directs X-ray beams through a planar section of a subject from a sequence of orientations and positions. The data processing unit includes a scan storage section for retrievably storing a set of filtered scan signals in scan storage locations corresponding to predetermined beam orientations. An array storage section is provided for storing image signals as they are generated. The image signals are stored in array storage locations coordinated with a preselected array of points of the planar section. The image signals are each successively updated to eventually represent the density of the planar section at each of the selected array of points. The processing unit also includes array storage and scan storage address calculators.

Abstract: A dual axial scanner in a transverse tomography system collects nonredundant data throughout one or more substantially 360.degree. orbital scan paths with uniform motion about a patient. A set of N X-ray beams scans the patient in a manner to allow collection of two sets of non-redundant data corresponding to a pair of 180.degree. scans in each 360.degree. scan. Overall time to conduct the study is decreased, and the number of required accelerations and decelerations of the assemblies is minimized.Adjacent beams of radiation are separated by an angle .alpha., which is one degree in the preferred embodiment to provide a radiation field of ##EQU1## degrees on either side of a center of the radiation field. The source and detector assemblies are positioned prior to the first orbit such that the field center is offset a distance D from a center of orbit lying in the orbital plane. The source and detector assemblies are mounted for rotation through a rotation angle .phi..sub.

Abstract: A scintillation scanner having a visual image producing means coupled through a lost motion connection to the boom which supports the scintillation detector. The lost motion connection is adjustable to compensate for such delays as may occur between sensing and recording scintillations.