Abstract: A data reducer for a scintillation camera is applied when photomultiplier tubes in an array thereof generate output signals following a flash of light from a scintillator. The output signal from a given photomultiplier tube is connected to an integrating preamplifier circuit. Each output signal is connected to an analog to digital converter, to a row amplifier circuit and to a column amplifier circuit. The signal from the analog to digital converter is provided via a bus to a data processor. The output signal of the data processor is set according to operational requirements, and then provided to a digital to analog converter. The signal from the row amplifier circuit is provided to a row summing circuit. The signal from the column amplifier circuit is provided to a column summing circuit. The respective signals from the row summing circuit and the column summing circuit are provided to an energy analyser. The energy analyser ensures that the signal is the result of a gamma event.

Abstract: A radiation detector emits a signal containing pulses produced by each radiation event being detected. The pulses tend to decay and may overlap the pulse from a subsequent radiation. In order to prevent such pulse overlap a circuit is provided to clip the signal pulses. The circuit incorporates an analog delay line which produces a delayed, inverted and attenuated reflection of the original detector signal. The reflection signal is combined with the original detector signal to cancel remnants of each pulse lasting longer than the predefined delay period.

Abstract: The invention relates to a process for determining the position of an event with respect to a set of N photodetectors, comprising the following after digitization of the signal output by each photodetector: calculate an uncorrected position of the event, determine the distance of each photodetector from the uncorrected position, calculate a corrected value of the contribution of each photodetector as a function of the distance from P0, calculate a new position P1, as a function of the corrected contributions of the photodetectors and their position. Another purpose of the invention is a device for embodiment of the process.

Abstract: A radiation detector D comprises: a scintillator 1, a main light guide 4, a wavelength shift fiber 5 passing through the main light guide 4, and an auxiliary light guide 2 provided between the scintillator 1 and the main light guide 4. The scintillator 1 is designed to emit scintillation light in response to incoming radiation. The main light guide 4 is surrounded by a plane 4a of incidence, for allowing the scintillation light to be incident thereon, and a reflecting surface for inwardly reflecting the scintillation light entering the plane 4a of incidence. The wavelength shift fiber 5 is designed to absorb the scintillation light entering the main light guide 4 to re-emit the scintillation light as fluorescent pulses of a longer wavelength to allow the re-emitted fluorescent pulses to simultaneously leave both ends 5a, 5b.

Abstract: The invention relates to a process and a device for determining the position P0 of an event with respect to a set of N photodetectors, inducing a signal in the N photodetectors. This process comprises the following steps: a) digitize the signal output by each photodetector; calculate the energy of the signal output by each photodetector, b) calculate the contribution of the column to the total energy, to the X value of the center of gravity of the event and to the Y value of the center of gravity of the event, for each column, c) determine the total energy induced by the event and the coordinates of the center of gravity of the event with respect to the N photodetectors.

Abstract: Method and apparatus for determining a position of an event. The system processes signals from an assembly of N photodetectors and includes a signal generator for producing a signal representing the value of the maximum, or the energy, of a pulse delivered by the photodetector and is digitized. It also includes a signal generator for producing a threshold-exceeded signal for each photodetector when the amplitude of the signal representing the value of the maximum, or the energy, of the digitized pulse is greater than the threshold. It also includes a signal generator common to the photodetectors, for delivering a signal representing a position of an event as a function of the threshold-exceed signals. This device can be used with gamma cameras.

Abstract: Gamma cameras and positron (PET) cameras use scintillation detectors to detect radiation from the body. However, when the number of radiation particles that strike the detector is very high, the chance that signals from two or more individual particles will pile up in the detector (to produce one erroneous, larger signal) is high. This problem is common to all applications using scintillation detectors. The present invention discloses methods and apparatus to prevent and correct for this problem. Results from a circuit according to the present invention show at least a 10 fold improvement in the maximum detection-rate limit over the conventional method.

Abstract: A system and method of reducing pile-up errors in multi-crystal tomography applications. In a system with multi-crystal gamma ray detectors having scintillating crystals with different decay constants, the problem of signal pile-up is avoided by taking energy samples during a fast integration time and stopping the integration process if the sampling indicates that the event occurred in the crystal with the faster decay time, and continuing the integration process if the sampling indicates that the event occurred in the crystal with the slower decay time.

Abstract: A method and apparatus for determining the centre photodetector in a planar array of photodetectors of a gamma scintillation camera is provided. The analog signals generated by a plurality of photomultiplier tubes (PMT) following a scintillation event, are digitized, integrated, and stored in a first memory. A first comparison means is used to divide the set of PMT logical signals into groups. Each group comprises an arbitrary number of PMTs. The PMT logical signals within a group are combined into pairs and compared to select the highest intensity value for each individual group. Subsets of local PMT highest intensity values are created. A second comparison means is used to receive the subsets of local PMT highest values, combine them into pairs, compare the paired signals, and record the selected signals in a second memory, until a PMT with the maximum intensity value or a centre PMT is obtained.

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 method and apparatus for selectively integrating PMT channel signals in a gamma camera system are described. A trigger word is decoded to determine which of multiple PMT channels are affected by a given scintillation event. When two scintillation events overlap both spatially and temporally, only those channels which are affected by both events stop integrating in response to the second event. Pre-pulse pile-up is corrected by removing the tail of a preceding pulse from a current pulse using an approximation of the tail of the preceding pulse based upon the instantaneous energy of the current pulse and the current countrate. Extrapolation of the tail of the current pulse may also be performed in essentially the same manner.

Abstract: A method and apparatus for improving the image quality of positron emission tomography is disclosed. This is achieved by analysing individual photomultiplier tubes for true events. The apparatus includes a photomultiplier tube for generating a photomultiplier tube signal. A series of pull up resistors generates a code signal identifying the photomultiplier tube. A clock generates a time stamp to the photomultiplier tube signal. A bus buffer generates an encoded signal. A position computing device calculates the position of the photomultiplier tube. An image computer generates an image from a plurality of encoded signals. A display displays the image. Analysing data from individual photomultiplier tubes results in smaller areas and smaller amounts of data to be processed. This then permits smaller time franm windows to be used. The use of time stamps also permits data before and after an event to be recorded.

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 gamma camera comprising essentially and in order from the front outer or gamma ray impinging surface: 1) a collimator, 2) a scintillator layer, 3) a light guide, 4) an array of position sensitive, high resolution photomultiplier tubes, and 5) printed circuitry for receipt of the output of the photomultipliers. There is also described, a system wherein the output supplied by the high resolution, position sensitive photomultipiler tubes is communicated to: a) a digitizer and b) a computer where it is processed using advanced image processing techniques and a specific algorithm to calculate the center of gravity of any abnormality observed during imaging, and c) optional image display and telecommunications ports.

Abstract: System and apparatus for locating sources of radiation emanating from predetermined radionuclides. The apparatus incorporates a large window display utilizing icon imagery to identify counting functions such as target count and background. A variety of radionuclide modes of operation can be selected by the operator and the system automatically defaults to detector bias selection and window reference voltage selection in correspondence with the elected radionuclide. A bar graph readout apprises the user of the amount of time or count level remaining in a target or background procedure and the flashing of icon identifiers occurs during such procedures. Pulse validation is improved by the utilization of a discriminator which evaluates pulse width.

Abstract: A detector including opposed detector heads having anode signal processors which perform a sliding box car integration of each PMT anode signal, corrects for baseline shifts and pileup from the tails of previous events, vary the length of the box car based on the time between events, and use a peak detection circuit to reduce the dependence of the integrated value on timing differences between the asynchronous events and the synchronous ADC conversion is described. The outputs of anode processors are combined to provide the X and Y coordinates, and the energy E, of an event. The outputs from each head processor are then combined in a coincidence processor to provide the corrected positions and energies of coincidence events. The above described detector heads function at a high count rate with minimum dead time and pileup.

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: A method for correcting the temporal relationships between event detection pulses generated by a PET scanner system, the method including, for each pulse, identifying the impact point of an associated photon on a scanner surface area and based on the impact point, selecting a compensation delay for the pulse and delaying the pulse by the compensation delay. The invention also includes an apparatus for practicing the method.

Abstract: A method of determining coincidence correction for a radiation detector in the presence of a radiation source symmetrical around the axis of the radiation detector, including: calculating the coincidence correction per the equation COI g = ϵ g ∫ ∫ ∫ ϵ ( g ) ⁢ x , y , z COI ( g )

Abstract: A process for identifying and rejecting pile-up pulses in a system is provided. Preferably, the process is applied to mine detection where time is at a premium. A thermal neutron activator sensor (TNA) trails a mine-detecting vehicle and is dwells over the coordinates of a target of interest for a short a time as possible. The TNA interrogates the object with slow neutrons, the required time being brief due to the use of a strong source coupled with a the process for analyzing the resultant high number and rate of pulses and rejecting piled-up pulses. Specifically, low energy pulses are removed and the remaining pulse is analyzed for its shape in comparison to the known shape of a non-piled-up pulse. The pulse is integrated using a gated integrator between a designated portion the pulse and for the whole pulse. For a normal pulse, the difference between the two integrations produces a repeatable baseline which is zeroed out to a null difference.

Abstract: A simultaneous acquisition process of a transmission image and an emission image with a gamma camera equipped with a detector (3), the detector (3) being opposite the patient (5) who has received an injection of a first radioactive isotope emitting gamma-ray photons (&ggr;2) in a first energy range (P1), the process including the movement of a radioactive source (4) behind the patient (5), the source (4) consisting of a second isotope emitting gamma-ray photons (&ggr;1) in a second energy range (P2), and the production, during the detection of an impact of a gamma-ray photon on the detector (3) of the coordinates of the impact of the photon on the detector and information relevant to the energy of the photon during the impact, the process having the particularity that it differentiates between the photon impacts according to their energy levels and the position of the impact in relation to the position of the source (4).

Abstract: A universal nuclear medicine imager (UNMI) enables planar, SPECT and PET studies. The UNMI is a “position sensitive” type of detector which has a relatively thick (e.g., {fraction (6/8)} in.) NaI(TI) crystal optically divided by a thin non-scintillating material into two half-thicknesses of ⅜ in. each. The UNMI detector uses a light collimator system to enable a depth of interaction (DOI) determination in addition to a two-dimensional location of gamma photons in the half-thicknesses of the crystal. The system includes a combination of a scintillating, optically more dense material with a non-scintillating, optically less dense material and uses the light refraction reflection law with PM tubes and coincidence circuits. For obtaining the optimal spatial resolution in planar and SPECT studies, a known DOI enables the use of only the lower ⅜ in.

Abstract: A gamma camera system includes a rotatable gantry supporting multiple detector heads each capable of receiving radiation from a region of interest of a subject disposed in an examination region. Each of the detector heads include a collimator which substantially defines the resolution and sensitivity of the respective detector head. At least two of the detector heads include collimators providing different resolution. Preferably, one of the collimators provides a detector head with substantially high resolution and another provides a detector head with substantially high sensitivity. An operator selectively combines image data detected by each of the multiple detector heads. If desired, the operator combine the image data from the multiple detector heads in a variety of manners to obtain images of various resolution and sensitivity from a single imaging procedure. The operator may also selectively weight the contribution that the image data from each of the detector heads has in the overall image.

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.

Abstract: A photomultiplier tube identifier is designed to identify a malfunctioning photomultiplier tube in a scintillation camera having an array of photomultiplier tubes. The photomultiplier tube identifier includes a photomultiplier tube for generating a photomultiplier tube signal. An amplifier/integrator generates an amplified/integrated signal from the photomultiplier tube signal. An analog to digital converter generates a digitized signal from the amplified/integrated signal. A series of pull up resistors generates a code signal identifying the photomultiplier tube. A bus buffer generates an encoded signal comprising the amplified/integrated signal followed by the code signal. A position computing device calculates the position of the photomultiplier tube. An image computer generates an image from a plurality of encoded signals. A display displays the image.

Abstract: A method and apparatus are provided for detecting scintillation events in a gamma camera detector using virtual photomultiplier tubes (PMTs). The gamma camera detector includes multiple real PMTs within the actual field of view of the detector as well as multiple virtual PMTs defined outside the actual field of view. In response to a scintillation event occurring near the edge of the field of view, one of the real PMTs responding to the event is identified. The event is then mapped to one or more virtual PMTs based on the identified real PMT. Data representing a response of the virtual PMT is then generated based on a response of a corresponding one of the real PMTs. Data representing responses of both the affected real PMTs and selected ones of the virtual PMTs are used in a centroid computation for the event, to increase the effective field of view of the detector.

Abstract: A method and apparatus for selectively integrating PMT channel signals in a gamma camera system are described. A trigger word is decoded to determine which of multiple PMT channels are affected by a given scintillation event. When two scintillation events overlap both spatially and temporally, only those channels which are affected by both events stop integrating in response to the second event. Pre-pulse pile-up is corrected by removing the tail of a preceding pulse from a current pulse using an approximation of the tail of the preceding pulse based upon the instantaneous energy of the current pulse and the current countrate. Extrapolation of the tail of the current pulse may also be performed in essentially the same manner.

Abstract: A method and apparatus for calibrating a programmable delay in a timing circuit of a gamma camera detector are provided. The programmable delay has an error, the value of which is to be determined. An input signal that is applied as input to the programmable delay is simultaneously applied as input to a precision fixed delay. The fixed delay has a delay value within the programmable range of the programmable delay, but has an error that is substantially smaller than that of the programmable delay. The output of the programmable delay is applied to one input of a decision circuit, and the output of the fixed delay is applied to another input of the decision circuit. The delay of the programmable delay is initially programmed to a value that is substantially greater than the delay of the fixed delay, and input pulses are then applied to both delays.

Abstract: A method for predicting PMT failure in a gamma camera by generating historical data for each PMT in a gamma camera indicating high voltage gain values at which each PMT causes autotune failure. The historical data is analyzed to predict PMT failure accurately thereby allowing PMT maintenance prior to failure actually occurring.

Abstract: In a gamma camera comprising a hollow-body scintillator crystal which is open at one end and has optoelectronic transducers disposed at its outer surface for sensing light signals generated by gamma radiation entering the scintillator crystal, a collimator with a pin hole is disposed at the open end of the scintillator crystal and has a cone-like projection with an apex where the pin hole is disposed. A number of such hollow scintillator crystals may be arranged on sheets with cone-like projections having pin hole apexes so as to be coaxial with the pin holes.

Abstract: A gamma ray detector for determining the position of gamma ray interactions has at least one module. Each module has a converter for converting gamma rays to charged particles, a scintillator for emitting light in response to charged particles produced by the converter, a photodetector to determine when light has been emitted from the scintillator, a two-coordinate position detector for determining the X and Y coordinates of charged particles interacting with the position detector, and a signal device for signaling the presence of emitted light in the photodetector and for activating the position detector.

Abstract: A high-energy photon imaging system includes an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector that includes a plurality of closely-packed detection modules. Each detection module includes a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold.

Abstract: A system for on-line monitoring the stability of a scintillation detector, comprises means providing two beams of gamma rays from a subsidiary source which are distinguishable because of their time relationship from the primary source. The two beams are of similar energies but are oriented in different directions, with one directed into the scintillation detector and one acting as a reference beam and directed to a reference beam counter. The ratio of the detector-count rate for the timed events to the reference count rate is compared to provide an indication of any drift in the scintillation detector.

Abstract: A process for processing signals delivered by a gamma camera including two detectors (23, 26, 28, 24, 27 and 29) on either side of a radioactive body (25), each of the detectors (23, 26, 28, 24, 27 and 29) producing analogue electric signals (x.sup.+, x.sup.-, y.sup.+, y.sup.- and w) consisting of pulses relevant to the impacts of gamma-ray photons (.gamma.' and .gamma.") on the detectors (23 and 24), the coordinates of the impact points being calculated from compressed signals, and the detection of the impact being performed in parallel by coincidence.

Abstract: A system for determining a composition of radionuclides in, for instance, a mineral-containing material by detecting gamma and/or X-ray radiation emitted by the nuclides is disclosed. To that end, the system has a detector unit which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determine the composition mentioned. The signal processing system further has an A/D converter to which the electrical signals are applied and a first computer unit which further processes signals supplied by the A/D converter for the purpose of determining the composition mentioned.

Abstract: A method and apparatus for correcting for random coincidences in a gamma camera imaging system are provided, based on the distribution of the object to be imaged as well as the measured singles and coincidence rates. Gamma radiation emitted from the object is detected for multiple projection angles, including detection of a plurality of coincidence events, to generate an object profile. The singles rate and the coincidence rate are also measured for each of the projection angles. A randoms distribution representing random coincidences in the detected coincidence events is then determined, including computing a randoms profile as the convolution of the object profile and a Gaussian function.

Abstract: A method of calibrating multi-crystal, single block radiation detectors for use in positron emission tomography and other devices with multi-crystal, single block radiation detectors that are used to determine gamma ray distribution. The detector units are individually subjected to a gamma ray flood source wherein the gamma ray has an energy in excess of about 0.7 MeV, and preferably above about 1.0 MeV. Energies of up to about 10 MeV are usable with the calibration method, with higher energies giving rise to containment and handling problems because of the energy. The light produced within each of the crystals is converted to electrical signals through, for example, photomultiplier tubes. These signals are used to generate a lookup map, this map providing information as to the correct positioning and response of each crystal in the array of crystals of the block detector. The method is useful for detector blocks of of many sizes that are divided into arrays of a large number of crystals.

Abstract: Disclosed is an image detector of the type comprising an array of photosensitive dots and an additional light source. The disclosed device can be applied to particular advantage in the detection of radiological images. The image detector comprises a photosensitive matrix and an additional source positioned on opposite faces of a support. The matrix is exposed to a radiation known as an incident radiation, a part of which is not detected by the matrix. The detector furthermore comprises means to promote the transmission of an additional radiation produced by the additional source with respect to the undetected part of the incident radiation. An arrangement of this kind enables an improvement in the contrast of the image, especially at the low spatial frequencies.

Abstract: An apparatus for use with a gamma camera to increase count rate without causing dead time or pile up, the apparatus including a first processor optimized for simplicity and minimum dead time but with moderate to poor spatial resolution for generally determining the impact point of a photon on a scintillation crystal and a second digital processor which uses the general position information from the first processor to identify a subset of PMT intensity signals for further processing to identify the precise impact point location.

Abstract: A nuclear imaging radiation system including a gamma camera which, in one embodiment, includes a scintillation crystal, a collimator and an array of photomultiplier tubes, is described. The collimator is positioned adjacent a face of the crystal, and defines a field of view. The array of photomultiplier tubes is positioned adjacent an opposite face of the crystal, and selected tubes outside the field of view are disabled so that light events outside of the field of view are not processed.

Abstract: A high-energy photon imaging system including an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector comprising a plurality of closely-packed detection modules. Each detection module comprises a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold.

Abstract: A method for improving single photo emission computed tomography accuracy by determining photon impact locations within a detector field using PMT intensity signals from all PMTs in an array. The method includes determining the row and column of a PMT which is closest to an impacting photon, subtracting the sum of intensity signals to the left of the identified column from the sum of intensity signals to the right of the identified column generating a differentiated width signal, subtracting the sum of intensity signals above the identified row from the sum of intensity signals below the identified row to provide a differentiated length signal and correlating the differentiated width and length signals with length and width field curves to identify the impact location.

Abstract: A method of correcting coincidence data for random coincidences in a nuclear medicine imaging system is provided. The system includes a pair of detectors that are rotatable about an axis, with an object to be imaged disposed about the axis. During an imaging session, the detectors detect coincidence radiation emitted from the object at a plurality of angular stops relative to the axis. While rotating the detectors between stops, the detectors are reconfigured for single-photon data acquisition and are used to detect radiation in singles mode. The detected singles are rebinned into a plurality of randoms sinograms, which are used to correct the coincidence data.

Abstract: Radiation from a subject (18) which is received by a scintillation crystal (12) interacts with the scintillation crystal to produce a burst of scintillation light photons. The depth distribution at which the interaction occurs varies in accordance with the energy of the received radiation. Low-energy radiation tends to interact at a shallow depth relative to a front face of the scintillation crystal and radiation with a high energy tends to interact relatively deeply into the crystal. A moment processor (20) processes electronic information from photomultiplier tubes (14) which view the scintillation crystal to generate zero-th moment or energy information, first moment or coordinate information and second moment or depth information. The event information is filtered (34, 62, 66, 82) in accordance with depth (26), e.g., sorted into acceptable/unacceptable information, information corresponding to each of two or more energies of radiation, and the like.

Abstract: An apparatus for measuring radiation at a region of interest inside a body is disclosed. The apparatus comprises a fiber optic equipped-catheter having a distal portion adapted to be inserted in a blood vessel. The apparatus further includes a luminescent scintillation material coupled to the fiber optic light pipe. The scintillation material is disposed in a distal portion of a lumen of the catheter and generates pulses of electromagnetic radiation in response to excitation by radiation rays. The apparatus further includes an index matching material disposed between the scintillation crystal and the fiber optic light pipe facilitating transmission of the pulses of electromagnetic radiation produced by the scintillation material to the fiber optic light pipe. A measuring assembly is coupled to the fiber optic light pipe to convert the pulses of radiation traversing the fiber optic light pipe to a measure of radiation in the region of interest.

Abstract: The detector of the present invention comprises a plurality of densely packed x-ray detectors arranged into an array. Each detector preferably comprises a scintillator element which is optically coupled to a photodetector element, preferably with a fiber optic link. Each photodetector element is preferably optically separate from adjacent photodetector elements. The detector array preferably includes integral alignment means to align the scintillator elements with the photodetector elements. The scintillator array elements are preferably formed from materials which possess a fast response and a minimum afterglow time.

Abstract: A camera for use in coincidence imaging includes detectors (10a, 10b) disposed about an examination region (12). Coincidence logic (14) determines whether gamma rays are detected by each of the detectors (10a, 10b) occur within a specified time interval. If so, the energy and positions of the detected events are determined. Energy discrimination circuitry (20a, 20b) associated with each detector (10a, 10b) determines if the detected events fall within a specified energy window. A list mode processor (22) generates a list of coincidence events. A rebinning processor (24) rebins the events, and a weight processor (26) weights each coincidence event based on the energy of the detected gamma rays.

Abstract: A device and a method for determining the interaction position and energy measurement of a radiation detector. A plurality of waveshifting optical fiber are positioned on the surface of a scintillator which is subjected to incident radiation causing the release of photons of a first wavelength from the scintillator which are absorbed by the optical fiber with a portion of the released photons being reemitted from one end of the fibers. The reemitted photons are measured and the centroid of the distribution of these measured photons is determined in order to provide an indication of the interaction position of incident radiation. A measurement of photons generated by the incident radiation which pass through the fibers but which are not transported down said fibers provide an indication of the energy of the incident radiation.

Abstract: A method of resampling of a sinogram from a fan beam SPECT includes the steps of angular resampling of the sinogram using frequency modulation, and thence transfers resampling of the sinogram using linear interpolation. This permits the use of parallel geometry algorithms in quantitative work without the expected degradation of resolution or the introduction of artifacts.

Abstract: The present invention provides an apparatus and method for enhancing the resolution of a Positron Emission Tomography (PET) image in a Nuclear Camera System that is configurable to performs both PET and SPECT imaging. The apparatus includes a crystal that interacts with a gamma ray to create a scintillation event within the surface of the crystal. The gamma rays that impinge the crystal have an incident angle that is limited by a field of view of the crystal. Positioned behind the crystal is a detector that responds to the light photons released by the scintillation event and registers a coordinate value of the scintillation event. Coupled to the detector is a resolution enhancer that generates an in-crystal plane displacement correction value for the coordinate value registered by the detector. The in-crystal plane displacement correction value is then combined with the coordinate value to compute the actual entry point of the gamma ray into the crystal.