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: Methods and apparatus for tuning scintillation detectors. An output of a first light is equalized with an output of a neighboring, second light. The outputs are measured by one or more light detectors shared by the first and second lights. Outputs of a plurality of light detectors are equalized using the equalized output of the first light.

Abstract: A method for operating a coincidence imaging system is provided. The method includes receiving samples from a detector output and determining an intersection of a first line corresponding to a baseline portion of the detector output samples and a second line corresponding to a pulse rise portion of the detector output samples.

Abstract: A method of calibrating detectors in a detector ring of a PET scanner, each detector including a plurality of crystals, the PET scanner having a field of view, is disclosed. The method comprises collecting timing data indicative of coincidence events occurring between each pair of crystals within the field of view. The method further comprises determining a detector adjustment value for each detector, determining a crystal adjustment value for each crystal in each detector, and discretizing the crystal adjustment value for each crystal to produce a discretized crystal adjustment value for each crystal. Lastly, the method comprises calibrating each detector by applying the discretized crystal adjustment value for each crystal in each detector to the collected timing data indicative of coincidence events.

Abstract: Methods and apparatuses for obtaining position and energy information without pileup. Signal integration, which is triggered by a present event, stops when a subsequent event is detected. A weighted value for estimating the total energy in a scintillation is calculated, which includes the energy of the current event and a residual energy from previous events. Remnant correction is used to calculate a pile-up free energy from two consecutive weighted values. An analog filter may be applied to reduce noise. Dynamic digital weighting of integrated values, and/or digital integration may be used during data processing. Pileup can be avoided in conjunction with several types of applications, including multi-zone detector applications and coincidence detection applications. High-resolution timing techniques are also disclosed that facilitate one's ability to avoid pileup.

Abstract: A method and apparatus for calibrating PET PMTs includes conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold. If the threshold is exceeded the steps of conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold would be repeated and if the threshold is not exceeded then the calibration procedure would be ended.

Abstract: A method of calibrating detectors in a detector ring of a PET scanner, each detector including a plurality of crystals, the PET scanner having a field of view, is disclosed. The method comprises collecting timing data indicative of coincidence events occurring between each pair of crystals within the field of view. The method further comprises determining a detector adjustment value for each detector, determining a crystal adjustment value for each crystal in each detector, and discretizing the crystal adjustment value for each crystal to produce a discretized crystal adjustment value for each crystal. Lastly, the method comprises calibrating each detector by applying the discretized crystal adjustment value for each crystal in each detector to the collected timing data indicative of coincidence events.

Abstract: A gamma camera having a system for performing a quality control procedure with minimal to no intervention from a user of the camera. In one aspect, the gamma camera includes a relatively weak radioactive source positioned at a fixed or known location relative to the gamma camera scintillation crystal and positioned so that the entrance window side of the crystal is facing the source, wherein the photons emitted from the source have an energy that is below the energy of photons used for diagnostic imaging. The response of the gamma camera photo-multiplier tubes to the absorption events caused by the radioactive source when the camera is idle can be compared to a baseline response to determine whether one or more of the PMTs need to be adjusted.

Abstract: Methods and apparatus for tuning scintillation detectors. An output of a first light is equalized with an output of a neighboring, second light. The outputs are measured by one or more light detectors shared by the first and second lights. Outputs of a plurality of light detectors are equalized using the equalized output of the first light.

Abstract: A gamma camera having a system for performing a quality control procedure with minimal to no intervention from a user of the camera. In one aspect, the gamma camera includes a relatively weak radioactive source positioned at a fixed or known location relative to the gamma camera scintillation crystal and positioned so that the entrance window side of the crystal is facing the source, wherein the photons emitted from the source have an energy that is below the energy of photons used for diagnostic imaging. The response of the gamma camera photo-multiplier tubes to the absorption events caused by the radioactive source when the camera is idle can be compared to a baseline response to determine whether one or more of the PMTs need to be adjusted.

Abstract: Methods and apparatuses for obtaining position and energy information without pileup. Signal integration, which is triggered by a present event, stops when a subsequent event is detected. A weighted value for estimating the total energy in a scintillation is calculated, which includes the energy of the current event and a residual energy from previous events. Remnant correction is used to calculate a pile-up free energy from two consecutive weighted values. An analog filter may be applied to reduce noise. Dynamic digital weighting of integrated values, and/or digital integration may be used during data processing. Pileup can be avoided in conjunction with several types of applications, including multi-zone detector applications and coincidence detection applications. High-resolution timing techniques are also disclosed that facilitate one's ability to avoid pileup.

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 method and apparatus for calibrating PET PMTs includes conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold. If the threshold is exceeded the steps of conducting a calibration procedure and determining whether a number of photons absorbed by a corresponding crystal exceeds a count threshold would be repeated and if the threshold is not exceeded then the calibration procedure would be ended.

Abstract: A nuclear camera system is provided in which the energy spectrum peaks identified by a camera detector head are automatically adjusted to account for drift and other sources of inaccuracy. Histograms of events detected by the photomultiplier tubes of the detector head are acquired continuously and updated periodically. A system operator initiates the adjustment with an autopeaking command which causes the system to ascertain the validity of the histogram data and, if it is valid, to determine a peak energy level. The determined level is compared to a theoretical value for an isotope present and the comparison is used to adjust the gain applied to energy data of the detector head.

Abstract: A method and apparatus for calibrating PET PMTs, the method including, during a commissioning process, determining gain factors for each crystal in a detector unit that cause the peak energy level in a crystal energy spectrum to be equal to a target value and, during a calibration process, generating energy spectrums for each crystal in the unit, combining the gain factors and crystal spectrums to generate shifted crystal spectrums, combining the shifted spectrums to generate a unit spectrum, identifying the peak unit spectrum energy level and comparing the peak unit level to the target value to generate PMT adjustment levels.

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: The invention relates to an image correction method for an X-ray detector which includes a rear-mounted light source with improved correction of the after-image effects. The invention is based on the recognition of the fact that the so-called gain effects cannot be eliminated by means of known methods. The gain effects, however, give rise to an increase of the amplification by a few percents, and hence to a bright image with artefacts, already in the case of customary diagnostic X-ray doses. In accordance with the invention the gain effects are measured by acquisition of light source images by means of the build-in light source; the strength of the gain effect as well as a correction factor are determined pixel by pixel on the basis thereof. The pixel values of the bright image are corrected by means of the correction factor.

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 method and apparatus for calibrating PET PMTs, the method including, during a commissioning process, determining gain factors for each crystal in a detector unit that cause the peak energy level in a crystal energy spectrum to be equal to a target value and, during a calibration process, generating energy spectrums for each crystal in the unit, combining the gain factors and crystal spectrums to generate shifted crystal spectrums, combining the shifted spectrums to generate a unit spectrum, identifying the peak unit spectrum energy level and comparing the peak unit level to the target value to generate PMT adjustment levels.

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 method for calibration and/or quality assurance of nuclear medicine imaging, in which functional information of the organs to be studied is achieved by inserting radioactive solution emitting detectable radiation in the organs of a phantom simulating the organs to be studied and by detecting the radiation. The filling and emptying of the organs of the phantom to be studied is simulated by regulation of the detectable radiation from the phantom. The organs to be simulated by the phantom are in form of containers filled with radioactive solution, the apparatus further comprising movable isolating parts, like steel plates, between the containers and the gamma camera to isolate radiation from the containers to the camera. The invention is also concerned with an arrangement comprising the apparatus of the invention and a gamma camera.

Abstract: Disclosed is a is an improved flood source, and method of making the same, which emits an evenly distributed flow of energy from a gamma emitting radionuclide dispersed throughout the volume of the flood source. The flood source is formed by filling a bottom pan with a mix of epoxy resin with cobalt-57, preferably at 10 to 20 millicuries and then adding a hardener. The pan is secured to a flat, level surface to prevent the pan from warping and to act as a heat sink for removal of heat from the pan during the curing of the resin-hardener mixture.

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: An apparatus and method used to calibrate a gamma camera include an energy source and intensity selector and an energy weighting device. The energy source provides an energy output, such as an electrical current. The intensity selector is connected to the energy source and adjusts the energy output to a predetermined energy level that corresponds to an intensity of a predetermined radioactive source. The energy weighting device is also connected to the energy source and gamma camera, and the spatial compensator creates calibration signals from the energy output of the energy source. The calibration signals are supplied to the gamma camera and used during calibration of the gamma camera in lieu of energy signals produced by the gamma camera in response to a radioactive source.

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: 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 nuclear medicine imaging system includes the capability to correct for the deadtime, including the capability to correct for spatial variations in deadtime across the imaging surface of a detector. The imaging system includes one or more radiation detectors, each using a large, monolithic scintillation crystal. Each detector has deadtime associated with it. A given detector is used to acquire an energy profile of a patient based on emission radiation. The detector includes a number of timing channels. The energy profile is used to select a zone influence map indicating the extent of spatial overlap in response between the various timing channels. Emission data of the patient is then acquired during an emission scan. During acquisition of the emission data, a rate meter assigned to each timing channel samples the number of counts associated with each timing channel to acquire deadtime data.

Abstract: A PET scanner is disclosed which includes a gantry, a plurality of sets of detectors supported by the gantry, and a plurality of septa that are supported by the gantry and are constructed of material which blocks photons. The detectors in each set are disposed in a plane and positioned around a central axis that intersects the plane, and the plurality of sets of detectors are spaced along the central axis. The septa are spaced along the central axis to separate groups of two or more detector sets and block external photons from reaching the detectors. The PET scanner further includes a processor means for receiving signals produced by the detectors and indicating annihilation events occurring within a central region around the central axis, and for reconstructing an image from indicated annihilation events.

Abstract: A method for developing a set of gain correction coefficients corrected for structural noise to be used in correcting the digital values representing an image captured by a pixelated detector having a plurality of individual sensors. The gain correction coefficients are developed by first obtaining a first set gain correction coefficients using a flat exposure and adjusting the individual sensor gain output so that all sensors produce the same output value, and then applying a smoothing filter to the first set of gain correction coefficients to obtain a new set of corrected gain correction coefficients.

Abstract: The present invention provides a novel apparatus for measuring the shape of various parts of anatomy, and alternatively capturing and digitizing an image of the part for the purpose of creating prosthetic or orthotic devices. Also provided are methods of measuring anatomical profiles involving physical contact with the body parts, and methods of manufacturing internal or external prosthetic and orthotic articles which mimic natural body parts in texture and motion characteristics, and in some cases, appearance.

Abstract: A method for calibrating photomultiplier tubes in a scintillation camera having a plurality of light sources includes the steps of: pulsing all light sources simultaneously; reading the output of each photomultiplier tube; comparing the output of each photomultiplier tube with an expected value; determining whether the output of each photomultiplier tube is within a first specified tolerance; and adjusting each photomultiplier tube if the output of the photomultiplier tube is not within the first specified tolerance.

Abstract: A method to be used with an imaging system, the system including two opposed cameras mounted for rotation among a plurality of acquisition angles about an imaging axis for acquiring imaging data throughout an arc about the axis, the cameras collecting data corresponding to an acquisition angle range including a plurality of flight path angles at each acquisition angle, the system also including a processor having a processor memory.

Abstract: A coincidence transmission source serves to detect coincident activity from a radiation source. The coincidence transmission source includes a detector dedicated to collecting attenuation data. A collimated radiation source and a detector are positioned with respect to a tomography device such that only a selected strip of the imaging detector of the tomograph is illuminated such that events unrelated to the attenuation are eliminated. The coincidence transmission source includes a collimator in which is disposed a radiation source. An opening is defined by the collimator for exposing a selected portion of the imaging detectors of the tomograph device. Positioned behind the radiation source, relative to the imaging detectors, is the dedicated attenuation detector. The attenuation detector and collimator are designed to illuminate only a strip of the imaging detector, thereby eliminating events not of interest in the attenuation measurement.

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 method for reducing required memory in a PET acquisition system processor wherein imaging data is collected and binned in a two dimensional histogram of coincident counts, the two dimensions being a flight path angle &thgr; and a distance R from the center of an imaging area, the method including the steps of determining when data acquired at a current acquisition angle will not include data corresponding to a specific flight angle and, when this is the case, storing the data corresponding to the specific flight angle on a secondary memory storage device independent of the processor memory. The method also includes a back projection method for using the stored data to construct an image and the invention includes an apparatus for performing the method.

Abstract: A combination PET/single photon (SPECT or planar) nuclear imaging system utilizes a pair of dedicated PET detectors and at least one dedicated single photon detector mounted on a single gantry. The single photon detector is a solid-state detector, such as CZT, and the PET detectors are made of a high effective Z material, such as LSO or BGO. Simultaneous PET/single photon imaging studies can be carried by the single system. The solid-state detectors also may be removable and mountable on a separate, dedicated single photon imaging gantry.

Abstract: An automatic pole-zero (APZ) adjustment circuit for an ionizing radiation spectroscopy system. An amplitude histogram of an acquired spectrum is obtained. The shape of a selected peak from the amplitude histogram is analyzed for peak shape distortion indicating the existence of undershoot or overshoot. An analog correction signal generated by a pole-zero adjustment network is added to cancel existing undershoot or overshoot, thereby minimizing distortion of the peak shape. In an alternate embodiment, the correction signal is a digital transformation algorithm applied to a programmable digital shaping filter, thereby digitally minimizing distortion of the peak shape.

Abstract: An apparatus for providing a radiation point source for testing PET scanner detector accuracy in an annular PET scanner which defines a scanning region, the apparatus including a supporter positioned axially adjacent a scanner, a support member which supports a radiation source at a distal end and is moveable between an extended position within the scanning region and a retracted position outside the scanning region and a motivator for rotating the support member about the scanning region when the support member is extended.

Abstract: An apparatus for photographing a radiographic image, has an image sensing system for obtaining a radiographic image; an image process system for correcting the radiographic image obtained by the image sensing system using input/output characteristics in units of pixels of the image sensing system, and outputting the corrected radiographic image; and a predetermined factor detecting unit for monitoring a predetermined factor value that ultimately influences the output from the image process system.

Abstract: A method of calibrating and using a radiation detector to quantify the radioactivity in or on a wide variety of objects, over a wide range of object sizes (points to hundreds of cubic meters), over a wide range of energies (e.g., 50-7000 keV photons), where the object can be at any location in a large sphere (e.g. 100 meter diameter) surrounding the detector, and where there can be various absorbers between the radioactive object and the detector (e.g., container, walls, air collimators), in which calibrations have been implemented and expanded following the method of Atrashkevich and Kolotov but without the use of radioactive sources and in minutes, and with no generation of radioactive waste. Such calibration technique can be applied to the quantiative analysis of a spectrum of radioactivity taken from a wide variety of in-situ or laboratory samples.

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.