Toshiba Medical Systems Corporation

Kabushiki Kaisha Toshiba

Canon Medical Systems Corporation

Kent C Burr

Yi Qiang

Daniel Gagnon

Xiaoli Li

Zhengyan Wang

Peng Peng

Gin-Chung Wang

Huini Du

Jerry Wang

Karthikayan Balakrishnan

John S Jedrzejewski

Manabu Teshigawara

Gregory John Mann

Evren Asma

Wenyuan Qi

Gin Chung Wang

Jeffrey Kolthammer

Nikolay Markov

Madhuri Kaul

An apparatus and method are provided to correct for time-walk errors during photon detections (e.g., detecting gamma rays). A time-walk correction is determined using measurements of energy (or charge) that apply different time windows, enabling corrections accounting for variations in the ratio between fast and slow components in the detected pulse. For example, one time window can be used to integrate the leading end of the pulse, thereby predominantly measuring the fast component, while a second window is used to integrate a trailing end of the pulse to predominantly measure the slow component. Alternatively or additionally, low-pass and high-pass filters may select the slow and fast components, respectively. The time-walk correction is a function of multiple measurements representing different components (e.g., fast and slow) of the pulse shape.

Time-walk correction using multiple energy measurements

A PET scanner includes gamma-ray detector rings that form a bore through which an imaging subject is translated, a length of the bore defining an axial length of the PET scanner, the gamma-ray detector rings being movable along the axial length, the gamma-ray detector rings including gamma-ray detector modules therein, and processing circuitry configured to receive PET data associated with a plurality of transaxial slices of the imaging subject, the PET data including a first set of spatial information and timing information corresponding to a first data acquisition period for the gamma-ray detector modules in a first axial position and a second set of spatial information and timing information corresponding to a second data acquisition period for the gamma-ray detector modules in a second axial position, and reconstruct a PET image based on the first set of spatial and timing information and the second set of spatial and timing information.

Pet reconstruction for adjustable pet system

An apparatus for calibrating a detector, including acquiring an energy spectrum obtained from a scan using an X-ray tube as a source of radiation, estimating calibration parameters, such as a gain and an offset, for each of several channels of the detector by applying the acquired first energy spectrum to inputs of a trained neural network that outputs the calibration parameters, and calibrating each of the plurality of channels using the estimation parameters. The neural network is trained to produce target output calibration parameters, using two or more measurements selected from isotope peak positions, K-edge absorption features, or K-edge emission peaks.

PCCT energy calibration from X-ray tube spectra using a neural network

In a gamma-ray detector system, such as a PET detector, coincidence events between multiple detector elements can be caused by inter-detector scattering and/or energy escape of the multi-stage radiation background in the scintillator crystals. Because these types of coincidence events are more likely to happen between nearby elements, they can be measured, analyzed and ultimately used to identify arrangement errors of detector elements in a gamma-ray detector system.

Identifying arrangement errors of detector elements within a gamma-ray detector system

A method and apparatuses for a radiation detector apparatus, comprising a scintillator array comprising a plurality of scintillator crystals. The plurality of scintillator crystals includes a first scintillator crystal and a second scintillator crystal adjacent to the first scintillator crystal within the scintillator array. A photosensor array comprising a plurality of photosensors including a first photosensor configured to detect photons from the first scintillator crystal. A first separator positioned between the first scintillator crystal and the second scintillator crystal. First separator optically separates the first scintillator crystal and the second scintillator crystal such that the first photosensor detects photons from the first scintillator crystal and not from the second scintillator crystal.

Method and apparatus for improved photosensor light collection in a radiation detector

A circuit for receiving signals from a photodetector array arranged to detect signals generated by a crystal includes a plurality of summing circuits having weighting circuits, the summing circuits being configured to produce outputs corresponding to a total energy of the signals, a position of the signals in a first dimension of the photodetector array, a position of the signals in a second dimension of the photodetector array, and a radius of a charge distribution of the signals.

Summing circuit for positron emission tomography diagnostic apparatus

Optical sensors and optical markers are placed on components in a medical system to provide calibration and alignment, such as on a patient transportation mechanism and spatially separated medical diagnostic devices. Image processing circuitry uses the data captured by these optical devices to coordinate their movements and/or position. This enables scans that were captured in multiple medical diagnostic devices to be accurately aligned.

Optical markers for calibration/alignment of medical diagnostic devices

A method and system for providing improved timing calibration information for use with apparatuses performing Time of Flight Positron Emission Tomography scans. Relative timing offset, including timing walk, within a set of processing units in the scanner are obtained and corrected using a stationary limited extent positron-emitting source, and timing offset between the set of processing units is calibrated using an internal radiation source, for performing calibration.

Timing calibration using internal radiation and external radiation source in time of flight positron emission tomography

A method and apparatus are provided for nonlinear energy correction of a gamma-ray detector using a calibration spectrum acquired from the background radiation of lutetium isotope 176 (Lu-176) present in scintillators in the gamma-ray detector. Further, by periodically acquiring Lu-176 spectra using the background radiation from the scintillators, the nonlinear energy correction can be monitored to detect when changes in the gamma-ray detector cause the detector to go out of calibration, and then use a newly acquired Lu-176 spectrum to update the calibration of the nonlinear energy correction as needed. The detector calibration is performed by comparing a reference histogram to a calibration histogram generated using the nonlinear energy correction, and adjusting the parameters of the nonlinear energy correction until the two histograms match. Alternatively, the detector calibration is performed by comparing reference and calibration values for specific spectral features, rather than for the whole Lu-176 spectrum.

Method and apparatus to use a broad-spectrum energy source to correct a nonlinear energy response of a gamma-ray detector

A method of imaging includes obtaining projection data for an object representing an intensity of radiation detected along a plurality of rays through the object, obtaining an outline of the object via a secondary imaging system, the secondary imaging system using non-ionizing radiation, determining, based on the outline, a model and model parameters for the object, calculating, based on the model and the model parameters, a volumetric attenuation map for the object, and reconstructing, based on the projection data and the volumetric attenuation map, an attenuation-corrected volumetric image.

Method and apparatus for computer vision based attenuation map generation

A method and apparatus are provided for positron emission imaging to calibrate energy measurements of a pixilated gamma-ray detector using energy calibration based on a calibration with a distribution energy signature (i.e., having more spectral features than just a single full-energy peak). The energy calibration can be performed using a deep learning (DL) network or a physics-based model. Using the DL network, a calibration spectrum is applied to either generate the measured-signal values of known energy values (e.g., spectral peaks for spectra of various radioactive isotopes) or the parameters of an energy-calibration function/model.

A method and apparatus are provided for positron emission imaging to calibrate timing of a pixelated gamma detector using multi-channel events. The apparatus can include processing circuitry configured to obtain calibration data representing a time and a position at which gamma rays are detected at a plurality of detector elements, and determine which gamma-ray detections of the calibration data correspond to multi-channel detections in which energy of a respective gamma ray is shared and detected by two or more of the plurality of detector elements. Additionally, the processing circuitry can be configured to determine a timing calibration of the plurality of detector elements by optimizing an objective representing agreement between time data of the multi-channel detections in the calibration data and the timing calibration.

Method and apparatus to calibrate timing of a detector using multi-channel events

A method and apparatus are provided for positron emission imaging to calibrate energy measurements of a pixilated gamma-ray detector using energy sharing events between channels of the detector. Due to conservation of energy, when the energy of a single gamma ray shared among multiple channels, the sum of measured energies across the respective channel must equal the original energy of the incident gamma ray. Further, the fractions of the original energy distributed to the respective channels can span the entire range of zero to the original energy. Thus, a single gamma-ray source (e.g., cesium isotope 137) can be used to continuously calibrate the nonlinear energy response of the detector over an entire range of interest.

Method and apparatus to use a single energy source to determine energy correction for a gamma detector

A method and apparatus are provided for positron emission imaging to correct a recorded energy of a detected gamma ray, when the gamma ray is scattered during detection. When scattering occurs, the energy of a single gamma ray can be distributed across multiple detector elements&#x2014;a multi-channel detection. Nonlinearities in the detection process and charge/light sharing among adjacent channels can result in the summed energies from the multiple crystals of a multi-channel detection deviating from the energy that would be measured in single-channel detection absent scattering. This deviation is corrected by applying one or more correction factors (e.g., multiplicative or additive) that shifts the summed energies of multi-channel detections to agree with a known predefined energy (e.g., 511 keV). The correction factors can be stored in a look-up-table that is segmented to accommodate variations in the multi-channel energy shift based on the level of energy sharing.

Method and apparatus to determine energy correction arising from multi-channel detection in a gamma detector exhibiting non-linear energy measurement and/or cross-talk among channels

An apparatus and method for testing scintillator arrays, e.g., crystal arrays for PET imaging. The apparatus includes, a two-sided tray arranged to hold scintillator arrays in either side and slide the arrays into a light-tight box having a radiation source beneath the arrays and photomultiplier tubes (PMTs) above the arrays. When arranged in the testing position with the arrays interposed between the radiation source and the PMTs, ambient light from outside the box is prevented from leaking into the box and high-voltage power is supplied to the PMTs. Otherwise, to prevent PMT damage, the high-voltage is off. The radiation source is an arrangement of sealed low-activity pieces of radioactive elements, thus minimizing requirements for radiation shielding and minimizing safety risks. The method calculates a flood map from scintillation data/counts and performs analysis according to predefined criteria, e.g., the peak-to-valley ratio, to flag arrays exhibiting inferior quality.

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Buffalo Grove, IL, United States of America

Kent C Burr