Abstract: A representative positron emission tomography (PET) calibration system includes a PET scanner having a ring detector, a phantom that is placed at approximately the center of the ring detector, and a time alignment calibration manager that is coupled to the PET scanner. The time alignment calibration manager detects coincidence events from the phantom, calculates position of time of flight events from the ring detector based on the detected coincidence events, and calculates time offsets for the ring detector using a mean value calculation based on the calculated position of the time of flight events.

Abstract: The present invention provides a method for estimating crystal efficiency in a PET detector that takes axial compression into account. It does so via an iterative methodology in which a ?-map is first generated and then is used to obtain a solution for the equation L ? ( ? i ) = ? n ? N ? ? y n ? log ? ? i , j ? span ? ? g ij ? ? i ? ? j ? x ij - ? i , j ? span ? ? g ij ? ? i ? ? j ? x ij , wherein gij is a geometric factor for LOR(i,j), ?i and ?j are the efficiencies for crystal i and crystal j, and xij is the line integral of the source distribution along LOR(i,j). Once efficiencies are determined, they are used to calibrate the PET detector.

Abstract: A method for co-registering attenuation data of MR coils in a MR/PET imaging system with PET emission data includes computing a likelihood of PET emission data on a grid in a parameter space based on an algorithm, wherein the algorithm defines L(?, ?body, ?coils{p}) as a log-likelihood of measured PET data, where ? is an emitter distribution (image), ?body is a known linear attenuation coefficient (LAC) distribution of the body from MRI, ?coils is a linear attenuation coefficient map of MRI coils, and {p} is a set of parameters governing the position of each coil, wherein if ?coils is assumed, then ? can be reconstructed and forward projected and L can be computed. The method includes adjusting the estimated position of the MR coils to maximize the likelihood of emission data based on the computed L.

Abstract: A method for determining quality of sinograms produced by a medical imaging device. The method may include placing a uniform phantom object in the field of view of the medical imaging device; acquiring one or more phantom sinograms of the uniform phantom object; establish a set of parameters for the acquired one or more phantom sinograms; and determine, based on pre-set ranges of the parameters, the quality of sinograms produced by the medical imaging device. The parameters may be one or more parameters of a group of parameters consisting of block uniformity, block efficiency, randoms rate, scanner efficiency, and scatter ratio.

Abstract: A method for calibrating an imaging system includes coincident detecting scatter radiation events from a calibration source located within a bore of the imaging system. The scatter radiation events are subsequently used to compute calibration time offsets for each detector channel in the imaging system. Each detector channel is then calibrated with respective calibration time adjustments.

Abstract: A time-of-flight PET nuclear imaging device (A) includes radiation detectors (20, 22, 24), electronic circuits (26, 28, 30, 32) for processing output signals from each of detectors (20), a coincidence detector (34), a time-of-flight calculator (38) and image processing circuitry (40). A calibration system (48) includes an energy source (50, 150) which generates an electrical or optical calibration pulse. The electrical calibration pulse is applied at an input to the electronics at an output of the detector and the optical calibration pulse is applied to a preselected point adjacent a face of each optical sensor (20) of the detectors. A calibration processor (52) measures the time differences between the generation of the calibration pulse and the receipt of a trigger signal from the electronic circuitry by the coincidence detector (34) and adjusts adjustable delay circuits (44, 46) to minimize these time differences.

Abstract: A detector includes a sonde having a housing and comprising a scintillator disposed within the housing and a calibration source coupled to the scintillator to fluoresce the scintillator at a known wavelength of electromagnetic radiation. The detector further includes an electromagnetic radiation sensing device coupled to the scintillator and disposed within the housing and a first programmable/re-programmable processing module (PRPM) coupled to the electromagnetic radiation sensing device and disposed within the housing. The PRPM is programmed to process signals from the electromagnetic sensing device based on a user-defined analysis mode selected from the group of modes consisting of filtering, windowing, discriminating, and counting.

Abstract: A medical imaging system is provided including a positron emission tomography (PET) imaging apparatus and a computed tomography (CT) imaging apparatus. The CT imaging apparatus includes a rotatable gantry. A radioactive source loader is attached to the rotatable gantry to rotate therewith. The radioactive source loader further includes a radioactive source to calibrate the PET imaging apparatus.

Abstract: A method of and apparatus for automatically calibrating a computed tomography (“CT”) scanning system (100) is provided including providing (405) a calibration object (130) substantially centered on a translating table (120) for passing through the CT system (100). The system (100) scans (410) the calibration object (130) and provides (420) a preliminary representation such as a display (500) of a sorted sinogram of the object (130). From that preliminary representation, the system (100) determines intercept-related and/or slope-related values for at least a portion (510, 520, 530 or 540) of the preliminary representation and uses these values to calculate (440) one or more predetermined calibrations values.

Abstract: A representative positron emission tomography (PET) system includes a positron emission tomography detector having one or more silicon photomultipliers that output silicon photomultipliers signals. The PET system further includes a calibration system that is electrically coupled to the silicon photomultipliers. The calibration system determines a single photoelectron response of the silicon photomultipliers signals and adjusts a gain of the silicon photomultipliers based on the single photoelectron response.

Abstract: A method for correcting energy values of pulses from a nuclear medicine camera for errors due to Analog to Digital conversion shift includes determining a relationship between a subset of samples selected from a set of samples from the pulse, the relationship being expressed in the form of a code. A conversion table is accessed which provides a list of codes and corresponding conversion factors. The conversion factor for the closest code to that of the subset of samples is selected from the table and applied to an integration of the set of samples to correct the energy value of the pulse.

Abstract: Method for correction of the temperature dependency of a light quantity L emitted by a light emitting diode (LED), being operated in pulsed mode with substantially constant pulse duration tP, and measured in a light detector, using a predetermined parameter X, correlated to the temperature T of the LED in a predetermined ratio, whereby a correction factor K is determined from the parameter X, preferably using a calibration table, especially preferred using an analytic predetermined function, whereby the measured emitted light quantity L is corrected for the temperature contingent fluctuations of the emitted light quantity, whereby the parameter X is determined from at least two output signals of the LED, which are related to each other in a predetermined manner.

Abstract: Methods and systems are provided for radioactive imaging of a test subject. At least one detector is operative to detect a radiation type associated with the subject. A test bed supports the test subject. A collimator assembly is positioned between the test bed and the at least one detector. The collimator assembly is not mechanically coupled to the at least one detector.

Abstract: Radiation analysis devices include circuitry configured to determine respective radiation count data for a plurality of sections of an area of interest and combine the radiation count data of individual ones the sections to determine whether a selected radioactive material is present in the area of interest. An amount of the radiation count data for an individual section is insufficient to determine whether the selected radioactive material is present in the individual section. An article of manufacture includes media comprising programming configured to cause processing circuitry to perform processing comprising determining one or more correction factors based on a calibration of a radiation analysis device, measuring radiation received by the radiation analysis device using the one or more correction factors, and presenting information relating to an amount of radiation measured by the radiation analysis device having one of a plurality of specified radiation energy levels of a range of interest.

Abstract: An image from a gamma camera, e.g., from a radiopharmaceutical, is corrected for scatter. The image is approximated by estimating the center of the organ and supposing a Guassian response that is scatter-corrected.

Abstract: A calibration system for a combined Positron Emission Tomography (PET)/Computed Tomography scanner system, may have a support structure carrying a rotation motor driving a phantom, wherein the phantom has at least two phantom rods and the rods are positioned such that they are neither parallel nor connected to each other.

Abstract: Detector efficiency data is generated for a positron emission tomography scanner (2) including a single photon source by conducting a blank scan acquisition procedure using the single photon source. The acquired detection count data is processed using an efficiency estimation algorithm to calculate data efficiencies of individual detectors in the detector array (8). In one embodiment, the detection count data is output as artificial coincidence count data and the efficiency estimation algorithm operates on the artificial coincidence count data. The method can be used in a non-rotating scanner or a rotating scanner.

Abstract: A method is disclosed for stabilizing the gain of a PET detection system with a cooling unit. The method includes determining the temperature of at least one component of the PET detection system, comparing the actual gain with a reference value, and actuating the cooling unit to influence the temperature such that the gain tends to the reference value. In at least one embodiment, the reference value is determined by determining the temperature of the at least one component during a test measurement, determining the gain during the test measurement, determining a functional dependence of the gain on the temperature, and selecting the reference value based on the gain to be stabilized. Advantageously, in at least one embodiment the gain can be kept constant using the described method in a simple manner, with the influence of the temperature of the components being taken into account.

Abstract: A method for correcting a positron emission tomography (PET) emission image is described. The method includes obtaining a PET emission sinogram of an object, obtaining a computed tomography (CT) image for a scanned portion of the object, the object having a truncated portion outside a field of view (FOV) of a CT image, determining a correction set of CT data based on a measured set of CT data within the CT sinogram, generating modified attenuation correction factors from the measured and correction sets of CT data, and correcting the PET sinogram using the modified attenuation correction factors.

Abstract: A resolution-variable X-ray imaging device is provided and includes: a scintillator that receives an X-ray through a subject to emit fluorescence; and an imaging device comprising a plurality of pixels aligned at pixel intervals on a light receiving surface of the imaging device, each of the pixels receiving the fluorescence and converting the fluorescence into an electric signal. The imaging device has at least two areas of: a higher-resolution imaging area in which the pixels are aligned at a pixel interval; and a lower-resolution imaging area in which the pixels are aligned at a pixel interval longer than the pixel interval of the higher-resolution imaging area.

Abstract: A constant fraction discriminating circuit outputs timing information corresponding to an event corresponding to a detected photon for providing nuclear medicine imaging. The constant fraction discriminating circuit includes a stripline or microstrip delay element.

Abstract: Transaxial radionuclide imaging is implemented without relative rotation between detectors and a patient by employing a collimator comprising segments sharing a common central axis, each segment having a plurality of apertures extending therethrough, wherein the segments are angularly displaced from one another about the common central axis. Embodiments include SPECT systems comprising a polygonal detector having a collimator on at least two sides thereof. Embodiments further include collimators comprising six segments, each offset by an angle of 7 to 9°.

Abstract: A non-circular-orbit detection method and apparatus is disclosed. In some embodiments, the method includes: locating first and second detectors, displaced with respect to one another, a distance from a patient; moving the first and second detectors in a direction towards the patient until a first sensor senses a first point of the patient at a first sensing position; moving the first and second detectors in a second direction from the first sensing position until a second sensor senses a second point of the patient at a second sensing position; and moving the first and second detectors in a non-circular-orbit around the patient. Preferably, the method includes determining the non-circular-orbit based on, among other things, locations of the first point and the second point.

Abstract: The invention relates to a method and an x-ray examination unit for analyzing and representing x-ray projection images with an x-ray examination unit, where the function relation bU=ƒU?1(J˜/J0) is established between the attenuation value and a material-equivalent value as a function of the energy spectrum used, and for the purposes of projection representation, the magnitude of the material-equivalent value bU of a specific material is represented as an image value.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: A multiple point source test phantom is used for calibration of detector positioning of a nuclear medical imaging apparatus. An absolute coordinate system for the detectors is aligned to an image reconstruction space coordinate system by fitting a Gaussian surface to a peak of a center point source of said test phantom, and using displacement parameters as obtained from the fitted Gaussian surface to calculate a displacement correction parameter, which is used to move a patient bed of the imaging apparatus such that the image reconstruction space is aligned with the absolute coordinate system.

Abstract: A method for calibrating an imaging system includes coincident detecting scatter radiation events from a calibration source located within a bore of the imaging system. The scatter radiation events are subsequently used to compute calibration time offsets for each detector channel in the imaging system. Each detector channel is then calibrated with respective calibration time adjustments.

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: A medical imaging system is provided including a positron emission tomography (PET) imaging apparatus and a computed tomography (CT) imaging apparatus. The CT imaging apparatus includes a rotatable gantry. A radioactive source loader is attached to the rotatable gantry to rotate therewith. The radioactive source loader further includes a radioactive source to calibrate the PET imaging apparatus.

Abstract: A SPECT apparatus has a two-dimensional detector that detects radiations from RIs in a patient via a collimator. A correction processing unit corrects plural two-dimensional projection distributions with different projection angles, which are detected by the detector, on a three-dimensional frequency space according to plural correction functions corresponding to plural distances, respectively. Consequently, a fall in spatial resolution having dependency on distances between the respective RIs and the detector is reduced. A reconfiguring unit reconfigures a three-dimensional RI distribution from the plural two-dimensional projection distributions corrected.

Abstract: A method and system for calibrating a scintillation camera includes steps of constructing a pair of generic linearity coefficient (LC) matrices from a representative detector based on measurement of non-linearity; and transforming the pair of generic LC matrices according to measured pinhole locations from a lead mask to generate detector specific LC matrices.

Abstract: A method for calibrating an imaging system includes coincident detecting scatter radiation events from a calibration source located within a bore of the imaging system. The scatter radiation events are subsequently used to compute calibration time offsets for each detector channel in the imaging system. Each detector channel is then calibrated with respective calibration time adjustments.

Abstract: A nuclear medicine imaging system includes a bed having a direction of translation, a detector disposed rotationally about an axis of rotation substantially parallel to the direction of translation, and a radioactive line source disposed rotationally about the bed substantially opposite the detector at a first predetermined non-zero angle to the axis of rotation and a second predetermined non-zero angle to a plane of rotation of the detector. The bed may be translated along the along the direction of translation while the detector is rotated about the axis of rotation.

Abstract: A quality control system and method are provided for troubleshooting and performance testing of detectors in a Gamma camera that includes a field programmable gate array for forming digital words to be converted to a pulse, a test pattern generator for storing the digital words, a digital analog converter for converting the digital words into an analog voltage, an amplifier for amplifying and applying the analog voltage, and an analog multiplexor for accepting the analog voltage. The Gamma camera comprises a collimator, a scintillation crystal, a light guide, a photomultiplier tube, and an electronic circuit.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: A method for correcting attenuation in a positron emission tomography (PET) image includes acquiring images of tissue using a magnetic resonance imaging (MRI) system. The images of tissue are acquired by the MRI system at substantially the same time that sinogram data are acquired from the PET scanner. An attenuation correction sinogram is produced from the MR images and employed to correct the acquired sinogram data. PET images are then reconstructed from the corrected sinogram data.

Abstract: Methods and systems for imaging a patient are provided. The method includes scanning a patient and acquiring a plurality of frames of cine computed tomography (CT) images during one complete respiratory cycle. In one embodiment, a method is provided that includes selecting an organ of interest in the cine CT data and selecting a value for each pixel in the organ of interest that represents the maximum density measurement. An attenuation corrected positron emission tomography (PET) image is constructed based on the maximization of the pixel intensity of the organ of interest in the CT attenuation correction map. Incorrect attenuation correction values for PET images can be avoided by utilizing the CT attenuation correction map.

Abstract: A method and system for calibrating a time of flight (TOF) positron emission tomography (PET) scanner are provided. The method stores acquired scan data from detector pairs including data and timing information. The method further calculates an intensity distribution of emission sources based on the scan data and defines a timing pivot point based on a median of an intensity histogram. The method determines a timing correction for each detector based on the location of the timing pivot point. The positron emission tomography (PET) system further provides a plurality of detectors, used in performing imaging scans, and a processor. The processor is configured to determine a timing correction for each detector.

Abstract: Method for correction of the temperature dependency of a light quantity L emitted by a light emitting diode (LED), being operated in pulsed mode with substantially constant pulse duration tP, and measured in a light detector, using a predetermined parameter X, correlated to the temperature T of the LED in a predetermined ratio, whereby a correction factor K is determined from the parameter X, preferably using a calibration table, especially preferred using an analytic predetermined function, whereby the measured emitted light quantity L is corrected for the temperature contingent fluctuations of the emitted light quantity, whereby the parameter X is determined from at least two output signals of the LED, which are related to each other in a predetermined manner.

Abstract: Point source responses of pinhole apertures in a non-uniform grid mask used to spatially calibrate a gamma camera can be modeled as a two-dimensional Gaussian model function. Pinhole data from each pinhole location are added together to generate a complete Gaussian model of the flood image from the mask. The Gaussian model then is subjected to global and PMT-based pattern matching with an actual input flood image obtained using the mask, to obtain a transformed Gaussian model that is more accurately aligned with actual pinhole locations of the mask. The transformed Gaussian model then can be used in a peak detection process for calibration images, which are used to develop LC coefficients for the camera.

Abstract: A method for calibrating multi-headed high sensitivity and high spatial resolution dynamic imaging systems, especially those useful in the acquisition of tomographic images of small animals. The method of the present invention comprises: simultaneously calibrating two or more detectors to the same coordinate system; and functionally correcting for unwanted detector movement due to gantry flexing.

Abstract: A method and apparatus for calibrating the sensors of a radiation detector by collecting a radiation spectrum detected by the detector during an irradiation, calculating a peak energy location from the collected radiation spectrum, determining if the peak energy location is mislocated from a desired location; and adjusting the gain setting for the selected radiation sensor so that the peak energy location is no longer mislocated from the desired location.

Abstract: Rays incident upon a plurality of detection plates arranged along a normal direction are detected. A distance between the ray and the ray source is estimated based on the number of counted rays detected by each detection plate, and each interval distance of the detection plates. Moreover, the direction of the source of the ray is estimated based on each image obtained from each detection plate.

Abstract: A CT detector capable of energy discrimination and direct conversion is disclosed. The detector includes multiple layers of semiconductor material with the layers having varying thicknesses. The detector is constructed to be segmented in the x-ray penetration direction so as to optimize count rate performance as well as avoid saturation. The detector also includes variable pixel pitch and a flexible binning of pixels to further enhance count rate performance.

Abstract: A method and system for calibrating a Time of Flight Positron Emission Tomography (TOF PET) system are provided. The method includes storing acquired scan data from detector pairs. The acquired scan data includes image data and timing information. The method further includes reconstructing images using scan data. The method also includes determining a timing correction for each detector based on intensity distribution histograms of emission sources. The system includes a controller, which is configured to perform the above-mentioned method steps.

Abstract: Method and system are provided for calibrating a nuclear medical imaging apparatus for DC shift caused by gamma event afterglow pulses. Detector responses to weak and to high count rate radiation sources are compared with each other, and a zero correction value is incremented until the detector response is the same for the weak source and the high count rate source. The zero correction value is then stored as a static zero correction value, which multiplies a dynamic zero correction value obtained just prior to the occurrence of a gamma event, in order to remove the effects of DC shifts from the output energy signal Esum.

Abstract: A method for correcting at least one of pileup effects or charge sharing effects in multi-cell photon counting detectors includes determining a correction coefficient using a count rate of an entire spectrum and applying the determined correction to the counts recorded in an energy window of interest.

Abstract: A method for calibrating at least some individual light sensor elements of a linear sensor array of a scanner, wherein output values of first and second pluralities of elements are carried, respectively, by first and second output channels. A relative gain (Stored Gain) for each of such elements is calculated from a scan of a light calibration strip area of substantial uniformity. Output values of such elements are obtained from a scan of a light calibration strip area of unknown uniformity. An average is calculated of the obtained output values of the first elements (First Light Average) and an average is calculated of the obtained output values of the second elements (Second Light Average). A final gain for each first and second element is calculated using at least its Stored Gain and for second elements only also using the First and Second Light Averages.

Abstract: A method and system for normalization of a positron emission tomography system are provided. The method includes determining a plurality of block busy fractions for a positron emission tomography system and using the determined block busy fractions to provide correction during normalization of the positron emission tomography system.

Abstract: A method for calibrating a computed tomographic imaging apparatus having a gantry, a radiation source operable at a plurality of kVp's, and a detector array having a plurality of detector elements includes using a system detection function to estimate signals of each detector element that would have been detected through air and through a given thickness of water to determine estimated datasets. The estimated datasets are used to determine data pair sets each comprising a normalized water projection value and an ideal projection value for each detector element. The method further includes determining and storing a representation of a mapping function of the normalized water projections values to the ideal projection values in a memory of the computed tomographic imaging apparatus as a spectral calibration of the computed tomographic imaging apparatus.