Abstract: A device and a method for computer tomography are described, in which an uncorrected volume image and a correction volume image are overlaid by the user after selection of a weighting function. This enables manual correction to be undertaken even after the correction of interference effects, such as x-ray scattering or beam hardening.

Abstract: A method and apparatus for correcting scattering in SPECT I-123 imaging. The method generally includes: accessing list mode data for a plurality of pixels corresponding to a first SPECT I-123 image generated using a gamma camera; generating a raw energy spectrum for at least some of the pixels utilizing the acquired list mode data; acquiring a gamma camera model corresponding to the gamma camera; utilizing the gamma camera model and an iterative algorithm to apply a first scattering correction to the raw energy spectrum; utilizing a Compton window to apply a second scattering correction to the raw energy spectrum; and generating a correction table with the corrected raw energy spectrum.

Abstract: Correction of scintillation event data from a nuclear medicine imaging system for effects of pulse pile-up is carried out by separating event data packets into total energy and individual detector energy data packets, executing pile-up correction algorithms on each of the separated packets simultaneously using a pipeline processing architecture, and reassembling the corrected data packets into corrected scintillation event data packets. Pulse tail correction information for each individual detector is stored in a storage medium for a present event and immediately preceding event for which correction information exists, which allows individual detector correction information to be retrieved by using a look-up procedure, thereby enabling correction to be performed within a single processor cycle.

Abstract: Correction of time-of-flight (TOF) PET data for scattered radiation explicitly models the TOF of the annihilation photon pairs along their individual scattered paths, yielding a distinct, accurate estimated scatter contribution for each time offset bin of the measured TOF data. This is accomplished by extending the single scatter simulation algorithm to include a new detection efficiency function ?TOF,n.

Abstract: A high performance imaging system for diffuse optical tomography is disclosed. A dense grid utilizing sources, e.g., light emitting diodes (“LEDs”), that achieve high performance at high speed with a high dynamic range and low inter-channel crosstalk are complemented by a system of discrete, isolated receivers, e.g., avalanche photodiodes (“APDs”). The source channels have dedicated reconfigurable encoding control signals, and the detector channels have reconfigurable decoding, allowing maximum flexibility and optimal mixtures of frequency and time encoding and decoding. Each detector channel is analyzed by dedicated, isolated, high-bandwidth receiver circuitry so that no channel gain switching is necessary. The resulting improvements to DOT system performance, e.g., increased dynamic range and decreased crosstalk, enable higher density imaging arrays and provide significantly enhanced DOT image quality.

Abstract: Image quality deterioration due to a drop in resolution or lowering of S/N ratio while reducing the amount of data stored during a 3D data acquisition process, and shortening the time from the start of an examination to the end of imaging. The method and apparatus of this invention perform, in parallel with the 3D data acquisition process, addition of sinograms, reading of subsets of the sinograms having been added, and image reconstruction. Consequently, the amount of data stored is reduced, and the time from the start of an examination to the end of imaging is shortened. At the same time, since 3D iterative reconstruction is not accompanied by conversion from 3D data to 2D data, a drop in resolution due to errors occurring with the conversion from 3D data to 2D data is avoided. The 3D iterative reconstruction can directly incorporate processes such as an attenuation correction process. It is thus possible to avoid also a lowering of S/N ratio resulting from an indirect incorporation of such processes.

Abstract: Attenuation correction in SPECT studies such as cardiac function imaging is carried out using an iterative statistically-based transmission projection reconstruction algorithm that is capable of modeling overlapping transmission beams from a line source array of radiation emitters. Downscatter between emission and transmission photons is additively corrected for in the algorithm. Optimal line source spacing techniques and source collimation angle selection are derived to improve performance and reduce cost.

Abstract: A method of locating an event with a gamma camera (12) of an emission computed tomography (ECT) scanner (10) is provided. The gamma camera (12) includes a matrix of sensors (22) situated to view the event. The sensors (22) have respective outputs that are responsive to the event. The method includes: identifying a first sensor in the matrix that has in response to the event a highest output relative to the other sensors in the matrix (step (B2)); identifying a number of second sensors in the matrix that are closest neighbors to the first sensor (step (B3)); combining into a total output a number of outputs from the identified sensors, the number of outputs being at least one (1) and less than the number of all the identified sensors (step (B4)); and, determining a threshold value which is a percentage of the total output (step (B4)).

Abstract: Methods and apparatus for correcting for at least one of deadtime losses and random coincidences in a positron emission tomography (PET) medical imaging device having a plurality of detectors at successive locations circumferentially spaced about a viewing area, the method comprising, receiving signals indicative of positron-electron annihilation events occurring along a line of response between pairs of detectors for a plurality of predetermined time segments of data acquisition of the events, calculating a correction sinogram for each predetermined time segment from data acquired during each respective single time segment, calculating corrected counts in the correction sinogram for each time segment, calculating a time-weighted correction sinogram for each time segment, combining the time-weighted correction sinogram to generate an acquisition sinogram, and generating an image from the acquisition sinogram.

Abstract: The present invention includes an apparatus and corresponding method for temperature correction and count rate expansion of inorganic scintillation detectors. A temperature sensor is attached to an inorganic scintillation detector. The inorganic scintillation detector, due to interaction with incident radiation, creates light pulse signals. A photoreceiver processes the light pulse signals to current signals. Temperature correction circuitry that uses a fast light component signal, a slow light component signal, and the temperature signal from the temperature sensor to corrected an inorganic scintillation detector signal output and expanded the count rate.

Abstract: An image pick-up apparatus and an image pick-up system constructed to prevent occurrence of random noise in a photographed image due to a random noise component produced in a reference supply circuit. An image pick-up apparatus has an area sensor driven by matrix driving, and a reference supply circuit for supplying a reference voltage for driving of the area sensor, and the reference voltage is supplied through a low-pass filter (LPF) coupled to the reference supply circuit. Further, a cutoff frequency of the low-pass filter is preferably determined so that an effective value of noise of the reference voltage having passed through the low-pass filter becomes not more than one-tenth of an effective value of random noise produced in pixels of the area sensor.

Abstract: An image pick-up apparatus and an image pick-up system constructed to prevent occurrence of random noise in a photographed image due to a random noise component produced in a reference supply circuit. An image pick-up apparatus has an area sensor driven by matrix driving, and a reference supply circuit for supplying a reference voltage for driving of the area sensor, and the reference voltage is supplied through a low-pass filter (LPF) coupled to the reference supply circuit. Further, a cutoff frequency of the low-pass filter preferably is determined so that an effective value of noise of the reference voltage having passed through the low-pass filter becomes not more than one-tenth of an effective value of random noise produced in pixels of the area sensor.

Abstract: The energy E of a signal pulse P inputted to an energy measurement apparatus 1 for measurement, and corresponding to the total integrated intensity, is calculated in an energy calculation unit 10 from the integrated signal intensity Q acquired by a gate integrator 32, and from the pulse interval T measured by a pulse interval measurement unit 23. At this time, pileup correction is performed using at least one of the integrated signal intensity or the energy, and the pulse interval of the signal pulse inputted prior to the signal pulse for measurement. By this means, the correct energy E, with the effect of pileup eliminated, can be determined with good precision. Hence a method and apparatus for energy measurement are realized which enable correct and precise measurement of the energy of individual signal pulses, even when the pulse interval between signal pulses is short.

Abstract: The present invention provides an analysis of displacement by calculating the phase variance image P? (k, l) between Fourier transformed images of paired images S1 (n, m) and S2 (n, m) to determine the center of gravity of ? peak appearing on the invert Fourier transform image of the images. The present invention provides numerous advantages such as a precision of displacement analysis of a fraction of pixel to thereby allow to improve the precision of focal analysis, or reduced number of pixels required to achieve the same precision, evaluation of reliability of the analysis by using the ? peak intensity, influence of varying background reduced by using a phase variance component. The improved performance by the present invention allows any operator skilled or not to achieve a best focusing.

Abstract: The optical apparatus of the present invention comprises; an optical member such as a lens; a casing containing the optical member; a gas supply device that supplies gas at a predetermined flow rate to inside the casing; and a gas introduction mechanism that reduces the flow rate of the gas supplied to inside the casing to below the predetermined flow rate. The casing has an inlet through which gas is supplied from the gas supply device to the inside. The gas introduction mechanism comprises an impingement member which is disposed between the inlet and a surface of the optical member, and the gas introduced from the inlet impinges against the impingement member. As a result, contamination of the optical member due to gas introduced to inside the casing can be reduced.

Abstract: A nuclear camera system includes a detector (12) for receiving radiation from a subject (14) in an exam region (16). The detector (12) includes a scintillation crystal (20) that converts radiation events into flashes of light. An array of sensors (22) is arranged to receive the light flashes from the scintillation crystal (20). Each of the photomultiplier sensors (22) generates a respective sensor output value in response to each received light flash. A processor (26) determines when each of the radiation events is detected. At least one of an initial position and an energy of each of the detected radiation events is determined in accordance with respective distances (d1 . . . d19) from a position of the detected event to the sensors (22). An image representation is generated from the initial positions and energies.

Abstract: A method and apparatus for detecting radiation including x-ray, gamma ray, and particle radiation for radiographic imaging, and nuclear medicine and x-ray mammography in particular, and material composition analysis are described. A detection system employs fixed or configurable arrays of one or more detector modules comprising detector arrays which may be electronically manipulated through a computer system. The detection system, by providing the ability for electronic manipulation, permits adaptive imaging. Detector array configurations include familiar geometries, including slit, slot, plane, open box, and ring configurations, and customized configurations, including wearable detector arrays, that are customized to the shape of the patient. Conventional, such as attenuating, rigid geometry, and unconventional collimators, such as x-ray optic, configurable, Compton scatter modules, can be selectively employed with detector modules and radiation sources.

Abstract: A nuclear imaging apparatus includes a radiation detector comprising an array (18) of solid state detector elements (22) responsive to incident gamma radiation by emitting a current spike. A pixel correction processor (44) detects defective detector elements in the array and a flood correction circuit (66) corrects detected radiation events (70) based on sensitivity differences between a plurality of groupings of detector elements in the array. A reconstruction processor (76) reconstructs an image representation from the corrected radiation events (74).

Abstract: A gamma camera system and method are described which use multiple point sources to detect inaccuracies in detector translational and rotational alignment. In practice of the method of the preferred embodiment, three capillary tubes, each containing a drop of an isotope, are located in different planes and locations with respect to the axis of rotation of the detectors. A SPECT acquisition is performed and the point source projection data is processed to calculate the point source coordinates, from which center-of-rotation correction factors may be calculated. These correction factors are applied by mechanical and software adjustments to the gantry and acquisition systems of the camera to correct for both translational and rotational inaccuracies.

Abstract: A nuclear camera system includes a detector (12) for receiving radiation from a subject (14) in an exam region (16). The detector (12) includes a scintillation crystal (20) that converts radiation events into flashes of light. An array of sensors (22) is arranged to receive the light flashes from the scintillation crystal (20). Each of the photomultiplier sensors (22) generates a respective sensor output value in response to each received light flash. A processor (26) determines when each of the radiation events is detected. At least one of an initial position and an energy of each of the detected radiation events is determined in accordance with respective distances (d1 . . . d19) from a position of the detected event to the sensors (22). An image representation is generated from the initial positions and energies.

Abstract: A gamma camera system that increases the count rate by counting events that time-wise appear to be pile-up events but are spatially separated.

Abstract: An autoadjusting electron microscope in which an image processor derives a third image constituting an analysis image from first and second images of a specimen by Fourier-transforming the first and second images to produce Fourier-transformed first and second images, computing a phase variant image from the Fourier-transformed first and second images, and Fourier-transforming or inverse Fourier-transforming the phase variant image to obtain the third image. A computer determines an amount of displacement between the first image and the second image based on a peak appearing in the third image. An identifier determines whether a consistency between the first image and the second image is within a predetermined range based on a magnitude of the peak appearing in the third image. A transformer transforms results obtained by the computer and the identifier into an amount of defocus of an electron lens relative to the specimen.

Abstract: A method of correcting errors in imaging data in a Gamma Camera including determining a first correction map based on one or both of (1) calculated corrections and (2) a first data acquisition, determining a second correction map based on a second data acquisition and correcting the imaging data based on the first and second correction maps. In a preferred embodiment of the invention, error correction is implemented using a neural network. Alternatively, a neural network can be used to perform the entire calculation of event position and/or energy.

Abstract: A nuclear medicine imaging device includes a radiation camera (10) including a plurality of photo multiplier tubes (28). Each photo multiplier tube (28) is configured with an analog to digital converter (30) which converts a detected scintillation event (50) to sampled digital values. A storage device (66) is preloaded with an estimator function which can be derived from a calibration scintillation events. A processor (14) in communication with both the camera (10) and the storage device (66), detects an event and combines the digital values which are sampled together to arrive at a total area or energy of the scintillation event. Alternately, if a second pulse (52) is detected before the first scintillation event (50) has ended, the area combining (A1) of the first event is stopped and a pulse tail is estimated (A2) from the estimator functions stored. This estimated tail is then added to the combined data values taken until the time of pile-up.

Abstract: A subject (10) is disposed adjacent a detector array (18) for the purposes of nuclear imaging. The subject (10) is injected with a radioactive isotope (14) and &ggr;-ray emissions indicative of nuclear decay are detected at the detector array (18) these signals are processed and reconstructed into an image representation of the anatomy of the subject (10). A dual level arbitration system orders detected signals for ease of processing and efficiency of reconstruction. The first level of the arbiter monitors a group of individual detectors (22). It locks out any signal that arrives from its group of detectors if a previous signal is still being analyzed. This avoids paralyzation of the system. The second level of the arbiter consists of a plurality of memories, one for each group of individual detectors (22) that store an address and energy of each processed signal.

Abstract: A nuclear medical diagnosis apparatus comprises a detector configured to detect gamma rays emitted from radioisotopes administered to a target object, a mechanism configured to move the detector with respect to the target object, a correcting unit configured to correct projection data, detected by the detector, on the basis of other projection data detected at a plurality of positions associated with a line which passes through a detection position of the projection data and crosses a detection surface of the detector at a predetermined angle, and a unit configured to generate a radioisotope density distribution on the basis of the corrected projection data.

Abstract: An image generation method in a scintillation camera relates to a scintillation camera having a collimator for collimating gamma rays, a scintillation crystal for generating a light scintillation upon receiving a gamma ray, an array of photomultiplier tubes for receiving the generated light scintillation and for generating electrical signals according to amount and position of light received, and a display comprising pixels for displaying an image corresponding to an interpretation of the electrical signals received by the photomultiplier tubes. The method for interpreting the electrical signals received from an array of photomultiplier tubes includes the steps of: receiving electrical signals from the array of photomultiplier tubes; applying a first algorithm to generate a first calculated event position; assigning the first calculated event position to a pixel; applying a second algorithm to generate a second calculated event position; assigning the second calculated event position to a pixel.

Abstract: A coded aperture is placed in proximity of a patient's body and a 2D coded image is acquired in conventional manner. The basic data-acquisition geometry is similar to that used in various coded-aperture systems. According to one aspect of the invention, additional coded images are acquired with different spacings between the aperture and the detector. Alternatively, additional coded images could be acquired with multiple movable apertures or by varying the location of the aperture relative to a patient. Another aspect of the invention resides in the recognition that presently available computer algorithms can process these multiple coded images in such a way as to estimate the integrals of the 3D object over a set of parallel cylindrical tubes extending through the volume of the target object. Such “tube integrals” can be thought of as the output of an ideal collimator where the sensitivity is confined to a tubular region of constant cross-section.

Abstract: A gamma camera for imaging radiation emitted from or transmitted by an object including a gamma camera head having a front input surface which produces signals, when a photon associated with the radiation is detected by the head, indicative of the position of the position of the detection on the input surface and at a given resolution in the absence of dithering of the head; and a dithering system which differentially translates the detector head or the object in at least one direction parallel to the input surface so that the dithering system translates the detector head or the object by an amount at least equal to the given resolution but less than 50 times the given resolution during acquisition of the signals.

Abstract: A method of reducing artifacts caused by generation of unwanted photons by scattering (e.g., Compton scattered photons) in which a detected event is spatially convoluted with a spatial filter function. The filter function has a distribution of weights within the filter function that is dependent on the energy of the event for a same primary event energy.

Abstract: SPECT data is collected to produce a SPECT image and transmission CT projection data is collected to produce a transmission CT image. The contours of the body of a subject under examination is extracted from the SPECT image. Using data representing the contours of the body, a portion of the transmission CT projection data is approximated by a curve. The sum of the curve-approximated transmission CT projection data and the center of gravity of the transmission CT image are computed. The truncated portion is estimated from the sum of the transmission CT projection data and the center of gravity of the transmission CT image and the transmission CT projection data is then corrected. The correction of the transmission CT projection data involves producing (extrapolation) anew a curve represented by a quadratic polynomial for that region (truncated region) of the transmission CT projection data which has been approximated tentatively by an ellipse in order to determine the sum and the center of gravity.

Abstract: In positron emission imaging, coincident gamma ray pairs are acquired and processed to generate an image. Random gamma ray pairs in the acquired coincidence data degrade the quality of the resultant image. The coincident gamma ray pairs are re-paired to generate non-coincident gamma ray pairs. The non-coincident pairs are used to correct for randoms in the acquired coincidence data. Alternately, singles gamma rays may be detected and paired with non-coincident single gamma rays to generate non-coincident pairs. These pairs may be used to correct for randoms in the acquired coincidence data.

Abstract: A diagnostic apparatus for nuclear medicine capable of performing an operation of counting gamma rays for a TCT simultaneously with an operation of counting gamma rays for an SPECT has a SPECT counter for counting, as the number of photons, gamma rays passed through a SPECT energy window centered at a photoelectric peak of the SPECT gamma rays and a TCT counter for counting, as the number of photons, gamma rays passed through a TCT energy window centered at a photoelectric peak of the TCT gamma rays. The number of photons of the gamma rays passed through the SPECT energy window contains the number of photons of K-X rays generated due to a photoelectric effect produced by the TCT gamma rays in collimators of the detector. A K-X ray processor estimates the number of photons of mixed K-X rays on the basis of the number of photons counted at the TCT counter.

Abstract: A microcomputer usable for a long period of time even when disposed in a high dose radiation-exposed environment, and its access speed control method are provided. According to the microcomputer and the method, the total dose of radiation that the microcomputer receives is determined on the basis of detection signals from a radiation detecting element. Based on the determined total dose of radiation, and table data preset by tests and stored into a memory unit, a CPU controls an access speed. Moreover, the CPU, and the memory unit and a circuit interface unit that access the CPU are integrated on a single chip (ASIC) These units on the same chip are deteriorated and changed in the same direction, without fail, on exposure to radiation.

Abstract: A tomographic imaging system which images ionizing radiation such as gamma rays or x rays and which: 1) can produce tomographic images without requiring an orbiting motion of the detector(s) or collimator(s) around the object of interest, 2) produces smaller tomographic systems with enhanced system mobility, and 3) is capable of observing the object of interest from sufficiently many directions to allow multiple time-sequenced tomographic images to be produced. The system consists of a plurality of detector modules which are distributed about or around the object of interest and which fully or partially encircle it. The detector modules are positioned close to the object of interest thereby improving spatial resolution and image quality. The plurality of detectors view a portion of the patient or object of interest simultaneously from a plurality of positions.

Abstract: A method and apparatus for simultaneously acquiring imaging data at two different resolutions, a high resolution data set using for forming a diagnostic image and a plurality of low resolution data sets used for various purposes including high resolution data correction for patient movement and data errors and for observing dynamic physiological occurrences.

Abstract: According to the present invention, sub-windows using a TEW technique are centered to energies corresponding to 1/n and 1/m of maximal photon number in a standard energy spectrum without any scattering component. It is thus possible to improve a count coefficiency, while broadening a main window to a maximal possible extent, without underestimating the scattering component and crosstalk component.