78 results about "Lines of response" patented technology

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

An imaging system comprises: a ring of positron emission tomography (PET) detectors; a PET housing at least partially surrounding the ring of PET detectors and defining a patient aperture of at least 80 cm; a coincidence detection processor or circuitry configured to identify substantially simultaneous 511 keV radiation detection events corresponding to electron-positron annihilation events; and a PET reconstruction processor configured to reconstruct into a PET image the identified substantially simultaneous 511 keV radiation detection events based on lines of response defined by the substantially simultaneous 511 keV radiation detection events. Radiation planning utilizing such an imaging system comprises: acquiring PET imaging data for a human subject arranged in a radiation therapy position requiring a patient aperture of at least about 80 cm; reconstructing said imaging data into a PET image encompassing an anatomical region to undergo radiation therapy; and generating a radiation therapy plan based on at least the PET image.

An imaging system comprises: a ring of positron emission tomography (PET) detectors; a PET housing at least partially surrounding the ring of PET detectors and defining a patient aperture of at least 80 cm; a coincidence detection processor or circuitry configured to identify substantially simultaneous 511 keV radiation detection events corresponding to electron-positron annihilation events; and a PET reconstruction processor configured to reconstruct into a PET image the identified substantially simultaneous 511 keV radiation detection events based on lines of response defined by the substantially simultaneous 511 keV radiation detection events. Radiation planning utilizing such an imaging system comprises: acquiring PET imaging data for a human subject arranged in a radiation therapy position requiring a patient aperture of at least about 80 cm; reconstructing said imaging data into a PET image encompassing an anatomical region to undergo radiation therapy; and generating a radiation therapy plan based on at least the PET image.

Methods and systems for imaging a patient are provided. The method includes determining a location of a volume of interest within the patient and acquiring a plurality of frames of emission data, at least one frame including the volume of interest. The method further includes determining a time-of-flight (TOF) information of at least a portion of the annihilations detected along a line of response between corresponding coincidence detectors and generating an image of the patient from the emission data using the determined TOF information.

The invention provides a PET (Polyethylene terephthalate) three-dimensional image reconstruction method and device. The method comprises the following steps: initializing a three-dimensional image to cause the pixel value of a pixel, which is positioned on a three-dimensional matrix in a first coordinate system (X, Y, Z), of the initialized three-dimensional image to be f1(x,y,z); selecting one line-of-response subset from a plurality of line-of-response subsets obtained from a detector; successively selecting line-of-response groups from the selected line-of-response subset, and independently carrying out preset operation to each selected line-of-response group, wherein the preset operation comprises the step of obtaining the pixel value g1(s,t,z) of each pixel of the first pixel group which is positioned in a second coordinate system (S,T,Z) and corresponds to the selected according to the pixel value f1(x,y,z) of the pixel in the first coordinate system (X, Y, Z), and the pixels of the first pixel group are positioned on a plurality of lines of response corresponding to the selected line-of-response group. Three-dimensional image reconstruction efficiency can be improved.

An image reconstruction method comprising accepting coincidence datat from either a data file or in real time from a pair of detector heads, culling event data that is outside a desired energy range, optionally saving the desired data for each detector position or for each pair of detector pixels on the two detector heads, and then reconstructing the image either by backprojection image reconstruction or by iterative image reconstruction. In the backprojection image reconstruction mode, rays are traced between centers of lines of response (LOR's), counts are then either allocated by nearest pixel interpolation or allocated by an overlap method and then corrected for geometric effects and attenuation and the data file updated. If the iterative image reconstruction option is selected, one implementation is to compute a grid Siddon retracing, and to perform maximum likelihood expectation maiximization (MLEM) computed by either: a) tracing parallel rays between subpixels on opposite detector heads; or b) tracing rays between randomized endpoint locations on opposite detector heads.

The invention relates to an image reconstruction method for a dual panel position-emission tomography (PET) detector. The image reconstruction method for the dual panel PET detector comprises the following steps: conducting simulation on image process of a dual panel PET detection structure by using simulation software; recording line of response (LOR) information corresponding to all coincidence events and voxels where annihilation events lay; judging the type of one coincidence event according to positions of photon pairs in the annihilation events, considering the coincidence event as a true coincidence event if the occurring positions of the pair of photons corresponding to the coincidence event are consistent, considering the coincidence event as a random coincidence event if the occurring positions are inconsistent and removing the random coincidence event; expanding the range of the voxels; obtaining a compressed system response matrix through calculation by using symmetry of the structure the dual panel PET detector; reconstructing an image by using the obtained system response matrix. The image reconstruction method for the dual panel PET detector can be widely in the image reconstruction of the PET detector with the dual panel PET detection structure.

Methods and systems for imaging by using a filter for Time-Of-Flight Positron Emission Tomography (TOF PET) are described. The described methods of imaging a patient by using a positron emission tomography (PET) system includes acquiring a plurality of frames of sinogram data, filtering the acquired sinogram data and back-projecting the filtered sinogram data to form an output image of the patient. The acquired sinogram data defines a line of response (LOR) and a time-of-flight (TOF) measurement that localizes positron annihilation within the patient. The filtering of the acquired sinogram data is performed using the TOF measurement.

The invention provides a nuclear medical imaging method and device for obtaining optimal images. The nuclear medical imaging method comprises a first determining step of determining a line of response set by the positions of a pair detector crystals, a defining step of defining an array of radiation points corresponding to the line of response, a second determining step of determining a solid angle with the bottom surface being surfaces of the pair of detector crystals defining the line of response for each point in the array of the radiation points corresponding to the line of response, a generating step of averaging the solid angle for generating an average solid angle, a third determining step of determining a position factor related to depth-of-interaction, and a calculation step of multiplying the reciprocal of the average solid angle by the position factor for calculating a geometric corrective factor for the line of response.

An iterative image reconstruction method used with an imaging system that generates projection data, the method comprises: collecting the projection data; choosing a polar or cylindrical image definition comprising a polar or cylindrical grid representation and a number of basis functions positioned according to the polar or cylindrical grid so that the number of basis functions at different radius positions of the polar or cylindrical image grid is a factor of a number of in-plane symmetries between lines of response along which the projection data are measured by the imaging system; obtaining a system probability matrix that relates each of the projection data to each basis function of the polar or cylindrical image definition; restructuring the system probability matrix into a block circulant matrix and converting the system probability matrix in the Fourier domain; storing the projection data into a measurement data vector; providing an initial polar or cylindrical image estimate; for each iteration; recalculating the polar or cylindrical image estimate according to an iterative solver based on forward and back projection operations with the system probability matrix in the Fourier domain; and converting the polar or cylindrical image estimate into a Cartesian image representation to thereby obtain a reconstructed image.

Methods and systems for imaging by using a filter for Time-Of-Flight Positron Emission Tomography (TOF PET) are described. The described methods of imaging a patient by using a positron emission tomography (PET) system includes acquiring a plurality of frames of sinogram data, filtering the acquired sinogram data and back-projecting the filtered sinogram data to form an output image of the patient. The acquired sinogram data defines a line of response (LOR) and a time-of-flight (TOF) measurement that localizes positron annihilation within the patient. The filtering of the acquired sinogram data is performed using the TOF measurement.

In a combined scanner, a main magnet (20) and magnetic field gradient coils (28) housed in or on a scanner housing (12, 18) acquires spatially encoded magnetic resonances in an imaging region (14). Solid state radiation detectors (50, 50', 50'') disposed in or on the scanner housing are arranged to detect gamma rays emitted from the imaging region. Time-of- flight positron emission tomography (TOF-PET) processing (52, 54, 58, 60, 62) determines localized lines of response based on (i) locations of substantially simultaneous gamma ray detections output by the radiation detectors and (ii) a time interval between said substantially simultaneous gamma ray detections. TOF-PET reconstruction processing (64) reconstructs the localized lines of response to produce a TOF-PET image. Magnetic resonance imaging (MRI) reconstruction processing (44) reconstructs the acquired magnetic resonances to produce an MRI image.

A single photon emission computed tomography system produces multiple tomographic images of the type representing a three-dimensional distribution of a photon-emitting radioisotope. The system has a base including a patient support for supporting a patient such that a portion of the patient is located in a field of view. A longitudinal axis is defined through the field of view. A detector module is adjacent the field of view and includes a photon-responsive detector. The detector is operable to detect if a photon strikes the detector. A photon-blocking member is positioned between the field of view and the detector. The blocking member has an aperture slot for passage of photons aligned with the aperture slot. A line of response is defined from the detector through the aperture. A collimating assembly includes a plurality of generally parallel collimating vanes formed of a photon attenuating material. The vanes are spaced apart so as to find a plurality of gaps, with the gaps each having a height. Each of the vanes has a front edge directed toward the field of view and a back edge directed towards the detector. The front-to-back depth of each of the vanes is greater than 10 times the height of the gaps. The plurality of vanes is disposed between the detector and the field of view such that only photons passing through one of the gaps can travel from the field of view to the detector. A displacement device moves either the detector module or the photon-blocking member relative to the other so that the aperture is displaced relative to the detector and the line of response is swept across at least a portion of the field of view.

A method of PET image reconstruction is provided that includes obtaining intra-patient tissue activity distribution and photon attenuation map data using a PET / MRI scanner, and implementing a Maximum Likelihood Expectation Maximization (MLEM) method in conjunction with a specific set of latent random variables, using an appropriately programmed computer and graphics processing unit, wherein the set of latent random variables comprises the numbers of photon pairs emitted from an electron-positron annihilation inside a voxel that arrive into two given voxels along a Line of Response (LOR), where the set of latent random variables results in a separable joint emission activity and a photon attenuation distribution likelihood function.

A PET scanner (20, 22, 24, 26) generates a plurality of time stamped lines of response (LORs). A motion detector (30) detects a motion state, such as motion phase or motion amplitude,of the subject during acquisition of each of the LORs. A sorting module (32) sorts the LORs by motion state and a reconstruction processor (36) reconstructs the LORs into high spatial, low temporal resolution images in the corresponding motion states. A motion estimator module (40) determines a motion transform which transforms the LORs into a common motion state. A reconstruction module (50) reconstructs the motion corrected LORs into a static image or dynamic images, a series of high temporal resolution, high spatial resolution images.

A positron emission scanner is disclosed having a timing compensation element which uses position information originating from a spatial locator element to compensate for travel time of timing signals. A method of constructing a PET image is also discussed in which a timing error function is convolved with an envelope function evaluated along a line of response to derive an emission event weight for use in image construction.

A method (70) of operation of a PET scanner (10) that determines the depth of interaction of the annihilation photons within the scintillator (32) in localizing a temporal photon pair along a line of response (LOR).

Methods and systems for imaging a patient are provided. The method includes determining a location of a volume of interest within the patient and acquiring a plurality of frames of emission data, at least one frame including the volume of interest. The method further includes determining a time-of-flight (TOF) information of at least a portion of the annihilations detected along a line of response between corresponding coincidence detectors and generating an image of the patient from the emission data using the determined TOF information.

A diagnostic imaging system comprises a plurality of radiation detectors (20) configured to detect radiation events emanating from an imaging region. The system comprises a calibration phantom (14) configured to be disposed in the imaging region spanning substantially an entire field of view and to generate radiation event pairs that define lines-of-response, wherein the calibration phantom is thin such that each LOR intersects the calibration phantom along its length, the thickness of the phantom being smaller than the length of the LORs. A calibration processor (24) receives input of the radiation detectors and calculates an incidence angle independent crystal delay tau i for each detector. The calibration processor (24) constructs a first look-up table for the timing correction of each LOR and a second look-up table for the angle depth of interaction correction for each crystal by combining tau i and eta i.

A method and system for reconstructing PET image data from a cylindrical PET scanner by incorporation of axial system response. The method includes the steps of: assuming the decomposition of axial components into individual line-of-response (LOR) contributions, approximating each LOR spreading in image space as depth-independent, implementing each LOR response, combining the LORs to produce large span projection data, implementing the back projector as a transposed matrix, and assembling the LOR projections and spans for each azimuthal angle.

The invention relates to a response spectrum method used for analyzing a floor system vibration response under the bounce load. The method comprises the steps that (1), a large number of curved lines of the single bounce load is connected to form an actual measured bounce load data base; (2), actual measured bounce load data are normalized and input into a standard excitation system, time-procedure analysis is carried out on the data, and an acceleration response spectrum of the actual measured bounce load is obtained through calculation of the data; (3), testers as objects are classified, outscourcing lines of response spectrums of the testers serve as the representative curved lines and are counted and fitted to construct integral piecewise function expressions of the designed response spectrums; (4), by means of the designed response spectrums, a value of a power response of each vibration mode of a floor system structure under the bounce load is calculated, combination is carried out according to the combined mode of a square method and a square root or complete square method, and finally the power response of the floor system is obtained. Compared with the prior art, the method can accurately and fast estimate the acceleration response of the floor system structure under the bounce load.

An image-based super-resolution method using a cone-beam-based line-of-response (LOR) reconfiguration in a positron emission tomography (PET) image is provided. That is, an apparatus and method for reconfiguring a super-resolution PET image using a cone-beam-based LOR reconfiguration is provided.

The present disclosure relates to a positron emission tomography detector and a positron emission tomography system using the same. More particularly, the positron emission tomography detector includes: a lower detecting unit configured to have a plurality of detector modules disposed in a ring or polygonal shape; and an upper detecting unit configured to have a plurality of detector modules which are spaced apart from each other by a predetermined distance, or of which at least some are in contact with each other to be formed on the lower detecting unit, and formed in a conical shape which is tilted by a preset angle. By the configuration as described above, since the positron emission tomography detector and the positron emission tomography system using the same according to the present disclosure have a large number of effective lines of response (LOR) and increase geometric efficiency, it is possible to improve sensitivity.

The invention provides a PET image reconstruction method and device. The method comprises steps: as for any multi-coincidence data, corresponding multiple lines of response (LOR) are determined; the any multi-coincidence data are distributed to the corresponding multiple LOR: as for any LOR, according to a time difference between two single events corresponding to the LOR, the line integral valuecorresponding to the LOR is acquired, according to the ratio among the line integral values corresponding to the multiple LOR, the multi-coincidence data are distributed among the multiple LOR, and the multi-coincidence data distributed to any LOR are multiple distributed data in the LOR; as for any LOR, dual-coincidence data in the LOR and the multiple distributed data are added to obtain line ofresponse data; and a PET image is reconstructed according to the line of response data. Distribution of the multi-coincidence data in the LOR is more accurate, and the quality of the image reconstructed according to the coincidence data of the LOR is higher.

A PET event position calculation method using a combination angular and radial event map wherein identification of the radial distance of the event from the centroid of the scintillation crystal with which the event is associated as well as angular information is performed. The radial distance can be converted to a statistical confidence interval, which information can be used in downstream processing. More sophisticated reconstruction algorithms can use the confidence interval information selectively, to generate higher fidelity images with higher confidence information, and to improve statistics in dynamic imaging with lower confidence information.

A method and system for reconstructing PET image data from a cylindrical PET scanner by incorporation of axial system response. The method includes the steps of: assuming the decomposition of axial components into individual line-of-response (LOR) contributions, approximating each LOR spreading in image space as depth-independent, implementing each LOR response, combining the LORs to produce large span projection data, implementing the back projector as a transposed matrix, and assembling the LOR projections and spans for each azimuthal angle.

A partial-ring PET device, in which some of coincidence radiation detectors to be arranged in a ring shape around a field of view for detecting lines of response of annihilation radiations are missing, is compensated for a drop in image quality due to the missing of the coincidence radiation detectors by including single gamma-ray radiation detectors for detecting at least either one of the annihilation radiations as a single gamma-ray. This can reduce missing of projection angles and reduce artifacts in PET images.

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.

The invention discloses a method of improving PET (positron emission tomography) image reconstruction quality by constructing a virtual DOI (depth of interaction) and a corresponding system matrix. The method comprises the following steps: 1) virtual DOIs are divided: a scintillation crystal in a PET detector ring is divided into a plurality of regions which correspond to different DOIs; 2) the detection probability of a virtual DOI is calculated: the virtually-divided DOI regions are paired, and the probability of each pair being detected at a different signal source position is calculated; 3) a virtual LOR (Line of response) event in the virtual DOI is divided: one LOR event in one original pair of crystals is divided to multiple sub events in the virtual DOI; 4) a conventional system matrix is optimized: multiple factors that affect the image reconstruction quality are considered; 5) image reconstruction is carried out: a statistical iterative algorithm is used to reconstruct an image; and 6) a GPU platform is used for distributed operation, and the data processing time can be greatly reduced. Through the method disclosed in the invention, the resolution of PET-class equipment after image reconstruction can be greatly improved, the location of a tumor can be positioned accurately, and important clinical value and significance are achieved.