General Electric Company

Ge Medical Systems Global Technology Company, LLC

John Jay Williams

David Leo McDaniel

Charles William Stearns

Alexander Ganin

Kelly Alan Stonger

Ravindra Mohan Manjeshwar

Floribertus Philippus Martinus Heukensfeldt Jansen

Michael Joseph Cook

Mark Kenneth Limkeman

Yiping Shao

Dershan Luo

Mark P Feilen

Edwin L Oswalt

Gang Cheng

Jonathan Alan Murray

Lars M Pedersen

Xiaoquan Zhao

John E Watkiss

A method of determining component misalignment in a multi-modality imaging system includes imaging a plurality of target objects with a first modality unit to generate a tomographic image data set and imaging the plurality of targets with a second modality unit to generate an emission image data set. The method also includes determining a location of the target objects in the emission image data set to produce emission target object location coordinates, calculating a positional alignment vector for each target object based on the emission target object location coordinates, and aligning the multi-modality imaging system based on the positional alignment vectors.

Method and apparatus for aligning a multi-modality imaging system

Methods and systems for calibrating a positron emission tomography (PET) system are provided. The method includes determining at least one non-acquisition time period for the PET system. The method further includes automatically acquiring calibration data during the at least one non-acquisition time period.

Method and system for calibrating a positron emission tomography system

Methods and systems for controlling a positron emission tomography (PET) system are provided. The method includes receiving timing information from a PET system during an imaging scan using the PET system. The method further includes processing the received timing information and timing bias information relating to the PET system to control the PET system.

Method and system for positron emission tomography image reconstruction

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

Methods and apparatus for real-time error correction

The invention is directed to a method and apparatus for timing calibration in a PET scanner. According to one embodiment, the invention relates to a method for timing calibration in a PET scanner having a plurality of scintillator blocks. The method comprises: detecting, in a first scintillator block, a first radiation event, wherein the first scintillator block time-stamps the first radiation event; detecting, in a second scintillator block that is adjacent to the first scintillator block, a second radiation event that corresponds to the first radiation event, wherein the second scintillator block time-stamps the second radiation event; and determining a timing characteristic of the first scintillator block with respect to the second scintillator block based on a comparison between the time-stamps of the first radiation event and the second radiation event.

Method and apparatus for timing calibration in a PET scanner

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.

Crystal-based coincidence timing calibration method

The invention relates to a system and method for generating a detector position map for an array of detectors. The detector position map comprises a map which converts measured position coordinates from a detection event to the detector in the array which detected the detection event. The method comprises the steps of illuminating an array of detectors with a source of radiation to generate a histogram, the histogram comprising an event count as a function of two dimensions, the two dimensions corresponding to a face of the array of detectors, wherein the histogram comprises a plurality of first peaks; modifying the histogram to comprise a plurality of second peaks, wherein the second peaks have a greater degree of isolation from each other than the first peaks; and for each detector, determining a region on the detector position map which corresponds to the detector, each region being based on a position of one of the second peaks.

System and method for producing a detector position map

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.

Method for dynamic stabilization of PET detector gains

A method and apparatus for eliminating the picket fence effect in PET scanners where the scanner includes a master clock and an event processing circuit that generates time stamps during each clock cycle, the scanner also including a coincidence detector that compares the time stamps during each clock cycle to identify coincidence events, the method including the steps of, for consecutive master clock cycles, identifying an overlap period that includes a portion of a first of the master cycles adjacent a second of the master cycles, adding an overlap period that occurs during the overlap period to the second of the master cycles to generate an extended cycle, identifying overlap events that occur during the overlap period in the first of the master cycles, copying the overlap events to the overlap period in the extended second cycle and performing a comparison of the events in the extended cycle to identify coincidence event pairs

Technique for removal of picket fence effect in PET imaging systems

An x-ray alignment and measurement process including an x-ray source and a detection array. The detection array allows for the taking of images having a precisely known pixel size and location. Disposed between the x-ray source and the detection array is an object having a known size or position. The object is then imaged and the location and size of the object on the image can be determined and compared to the actual size or location. The calculation is performed on the multiple pixels in the image to mathematically determine the remaining unknown object location or size. For alignment purposes, any error in the location or size of the object can thus be corrected.

X-ray system alignment method and apparatus

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.

A PET scanner contains a positron emission event qualifier which prevents noise from being misinterpreted as such an event. A radiation detector signal indicates the intensity and duration of sensed gamma radiation. A comparator produces an intermediate signal when the radiation detector signal exceeds a predetermined threshold. A delay line delays the intermediate signal by an interval of time and blocks any pulses in the intermediate signal which are shorter than this interval. Typical noise in the intermediate signal is shorter in duration than this interval of time.

Radiation event qualifier for positron emission tomography

A PET scanner operates in a calibration mode to produce timing calibration sinograms. These sinograms are employed to calculate time delay adjustment values for each detector channel. These values are downloaded to data acquisition circuits in each detector channel to adjust the delay of event data pulses that indicate the occurrence of a coincidence event. The process is repeated until the downloaded time delay values are reduced below preset criteria.

Automated coincidence timing calibration for a pet scanner

An assembly is provided for improving operation of a radiation detection system which comprises a scintillation crystal 1, a photomultiplier tube 5 having a cathode maintained at a high negative voltage, a glass wall 3 positioned between the crystal and the tube, and structure 7 supporting the tube to receive a light signal from the crystal representing radiation received thereby. The assembly includes structure 4, 11 for applying the same high negative voltage to the crystal 1, and further includes structure 10 for electrically isolating the supporting structure 7 from the crystal 1 and glass wall 3, the supporting structure 7 being maintained at ground potential.

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Hartland, WI, United States of America

John Jay Williams