241 results about "Gamma photon" patented technology

A method for acquiring PET images with reduced time coincidence window limits includes obtaining a preliminary image of a patient within a radiation field of view (FOV), determining the spatial location of the patient within the FOV based on the preliminary image, calculating a different time coincidence window based on the spatial location of the patient for each possible pair of oppositely disposed detectors, scanning the patient with a PET scanning system to detect a pair of gamma photons produced by an annihilation event, determining whether the detection of the pair of gamma photons occurs within the time coincidence window, accepting the detected event only if the detection of the gamma photons occurs within the time coincidence window, calculating the spatial location of accepted annihilation event, and adding the calculated spatial location of the annihilation event to a stored distribution of calculated annihilation event spatial locations representing the distribution of radioactivity in the patient.

The invention provides a radioactive substance detection method, a radioactive substance detection device and a radioactive substance detection system based on a gamma camera. The detection method comprises the following steps of: receiving gamma photons incident from all directions of a target angle plane (alpha, beta) defined by radioactive substances by using the gamma camera; generating gamma photon energy spectrums and projection data of the radioactive substances; and reconstructing the projection data by using a 'maximum likelihood estimation' statistical iterative algorithm to obtain a gamma radiation image with quantitative information. By the method, the spatial resolution and the signal to noise ratio of the gamma radiation image are increased, spaces of the radioactive substances are positioned, the radiation dose is measured, nuclide types of the radioactive substances are identified, and the radioactive activity is measured.

A positron emission tomography detector for a multilayer scintillation crystal comprises a plurality of layers of scintillation crystals, a photoelectric detector system and an algorithm system, wherein the multilayer scintillation crystals comprises n layers of array scintillation crystals and m layers of continuous scintillation crystals, both n and m are integers which are greater than or equal to 1, the sum of n and m is smaller than or equal to 10, the array scintillation crystals are formed by arraying strip-type scintillation crystals along the width and length directions, the continuous scintillation crystals are scintillation crystals which have uncut inner parts, the array scintillation crystals and the continuous scintillation crystals are sequentially coupled along the height direction of the strip-type scintillation crystals to form the multilayer scintillation crystals, and the bottoms of the continuous scintillation crystals are coupled with the photoelectric detector system. The positron emission tomography detector can more accurately obtain the position and the time of energy deposition of gamma photon in the scintillation crystal, and has higher detection efficiency of the gamma photon, the spatial resolution, the time resolution and the flexibility of a positron emission tomographic imaging system can be improved when the positron emission tomography detector is applied to the positron emission tomographic imaging system, and further, the imaging quality of the system can be improved.

An on-line energy coincidence method for an all-digital PET system, comprising: a detection module conducting information collection on a scintillation pulse, forming a single event data frame and sending the single event data frame to an upper computer (S1); the upper computer conducting two-bit position distribution statistics on an incident gamma photon event and conducting position spectrum partition (S2); performing statistics on an energy distribution spectrum of each crystal bar, so as to acquire an energy correction value (S3); the detection module uploading a crystal bar partition data table and an energy peak correction data table (S4); starting information collection of on-line energy correction (S5); when an event is coming, according to a two-dimensional coordinate thereof, from the crystal partition table, searching for a crystal bar number corresponding thereto, and then, according to the crystal bar number, searching for an energy correction value from the energy correction table (S6); and sending data passing the energy coincidence to the upper computer (S7). The method achieves fully automatic and fast on-line energy coincidence, and not only achieves the requirements of the variable structure PET for the fully automatic and fast correction, but also filters useless data in a transmission medium to a greater degree at the same time, thereby achieving the purpose of increasing a valid data bandwidth.

The invention relates to an NaI (TI) scintillation detector gamma energy spectrum high-resolution inversion analysis process and method based on a gauss response matrix. The analysis process comprises the steps of spectral line pretreatment, peak searching and peak boundary treatment, resolution ratio ruling, background subtraction, gauss response matrix generation and inversion analysis. According to the feature of an NaI (TI) scintillation detector and the physical property of the spectrum forming process, response, in the detector, of different energy gamma photons corresponds to different full widths at half maximum of a photo peak, and the photo peak is approximate to a gauss function in shape. The parameters of the full widths at half maximum of a spectral line are extracted, the background is subtracted from the full widths at half maximum adaptively, the universal gauss response matrix between a radioactive source and a gamma spectrum is constructed, and finally the response matrix is used for inversion analysis of other gamma instrument spectrums measured by the NaI (TI) scintillation detector. The result analyzed through the method is an energy point corresponding to the measured spectral line under the response matrix or is approximate to the solution of a physical spectral line in theory, and the ability of the method to analyze the spectral line is obviously improved.

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.

The invention relates to a positron emission tomography scanner and a conformity judgment and selection method. The scanner comprises a plurality of detectors. The method comprises the following steps: acquiring instance information of each detector; storing the instance information in the corresponding storage space; taking the time information of each instance information as address information of the storage space; acquiring a plurality of sign information according to each instance information, wherein each sign information shows times of detecting gamma photons in corresponding time; acquiring judgment and selection information according to each sign information, wherein the judgment and selection information represents the times of detecting the gamma photons in a preset conformed time window from the corresponding time information; ranking each judgment and selection according to the corresponding time information; checking the ranked judgment and selection information by utilizing sequence checking features in sequence; identifying the storage space that the conformed instance corresponds to; and outputting the instance information in the storage space that the conformed instance corresponds to. The positron emission tomography scanner and the conformity judgment and selection method provided by the invention have the advantages of rapid and efficient conformity judgment and selection and wide application range.

A phoswich device for determining depth of interaction (DOI) includes a wavelength shifting layer between first and second scintillators of different scintillation materials and having different decay time characteristics. The wavelength shifting layer allows a true phoswich device to be constructed where the emission wavelength of one scintillator is in the peak excitation band of the other scintillator, by shifting the scintillation light outside of this excitation band to prevent scintillation light of one scintillator from exciting a response in the other scintillator, thus enabling unique identification of the location of a gamma photon scintillation event. The phoswich device is particularly applicable to positron emission tomography (PET) applications.

The invention provides a detector for positron emission imaging equipment, and positron emission imaging equipment. The detector includes a scintillation crystal and at least one photoelectric sensor array, wherein the scintillation crystal is an integrated scintillation crystal, and is provided with a through hole; the through hole is used for accommodating an object waiting for imaging; the photoelectric sensor array is coupled with the scintillation crystal, and is used for detecting a visible photon which is generated when a gamma photon and the scintillation crystal react; and the gamma photon is generated through positron annihilation effect which occurs in the object waiting for imaging. The detector for positron emission imaging equipment enables the positron emission imaging equipment using the detector to be high in positioning accuracy of the gamma photon, to be high in sensitivity, to be weak in edge effect and to be low in mechanical design difficulty.

The invention disclosed herein is directed to scintillation detectors capable of detecting the position or depth of gamma photon interactions occurring within a scintillator, thereby improving the resolution of ring based positron emission tomography (PET) imaging systems. In one embodiment, the invention is directed to a scintillation detector that comprises at least one pair of side-by-side conjunct scintillation crystal bars having a shared interface between, and a solid-state semiconductor photodetector optically coupled to each output window of each individual scintillation crystal bar. The solid-state semiconductor photodetector includes an array of discrete sensitive areas disposed across a top surface of a common substrate, wherein each sensitive area contains an array of discrete micro-pixelated avalanche photodiodes, and wherein the output window of each scintillation crystal bar is optically coupled to each respective sensitive area in a one-on-one relationship.

The invention provides a reaction position positioning method and apparatus. The method includes receiving the energy information of the visible photon coupled to a scintillation crystal, detected by at least one photoelectric sensor array, and generated by the reaction of the gamma photon with the scintillation crystal, wherein the scintillation crystal is an integrated scintillation crystal and has a through hole for receiving an object to be imaged, and the gamma photon is generated by the positron annihilation effect in the object to be imaged; and determining the reaction position of the gamma photon in the scintillation crystal according to the received energy information, wherein the reaction position is represented by a cylindrical coordinate system. According to the invention, by providing a way for positioning the reaction position of the gamma photon for a positron emission imaging apparatus with the integrated scintillation crystal, the problem that a conventional position calculation method is not suitable for the improved positron emission imaging apparatus can be solved.

The invention discloses a method for obtaining a system response model of positron emission tomography, and a method and device for image reconstruction. The method for the image reconstruction of the positron emission tomography includes the steps of obtaining DOI response information of a gamma photon incident to a crystal strip array; generating a DOI response model according to the DOI response information according with a back-to-back gamma photon incidence crystal strip time tick decision; generating the system response model according to the DOI response model; carrying out the image reconstruction according to the system response model.

The invention brings forward a method and device for measuring two-dimensional angle distribution of the radiation dose rate of a radioactive substance. The method comprises: a gamma camera detecting gamma photons incident from each direction of a defining object angle plane in an object area, and respectively recombining to form projection data and power spectrum data; reconstructing the projection data by use of an image reconstruction algorithm to obtain a radiation gamma image; based on this, obtaining the two-dimensional angle distribution of the fluence rate of the gamma photons incident from each direction in the object area; and according to incident photon energy, searching for corresponding conversion coefficients, and by use of the conversion coefficients, converting the two-dimensional angle distribution of the fluence rate of the gamma photons into the two-dimensional angle distribution of the dose rate of radiation of the radioactive substance to the position of the gamma camera. The measuring method provided by the invention realizes measurement of the two-dimensional angle distribution of the radiation dose rate of the gamma photons incident from the different directions in the object area by use of such devices as the gamma camera and the like.

The invention relates to a three-energy coal ash content online monitoring device which comprises a low-energy gamma source Am241, an intermediate-energy gamma source Cs137, and a lanthanum bromide detector for receiving the low-energy and intermediate-energy gamma rays, wherein gamma photons emitted by the low-energy gamma source Am241 and the intermediate-energy gamma source Cs137 irradiates the coal sample in a sample container; the output terminal of the lanthanum bromide detector is connected with the input terminal of a multi-channel data analysis spectrometer; the collected gamma energy spectrum information and the characteristic X-ray spectrum information are transmitted to a data processing and spectrum unscrambling system; and the data processing and spectrum unscrambling system is used for processing the data. The three-energy coal ash content online monitoring device can be used for coal sampling and automatic rapid detection of as-received coal vehicles without bypass belts, and can be mounted and detected only by slightly changing the structure of the rear end of the sample container.

The invention discloses a gradient type macromolecule-based neutron absorption grid tray material which comprises a fast neutron slow absorption layer, an intermediate energy neutron absorption layer and a heat neutron absorption layer, wherein the three absorption layers are formed by gradient lamination; a neutron absorption body material doped in the fast neutron slow absorption layer is a lithium fluoride, lithium hydride or boron carbide absorption body material; a neutron absorption body material doped in the intermediate energy neutron absorption layer is a samarium oxide neutron absorption body material; a neutron absorption body material doped in the heat neutron absorption layer is a gadolinium oxide or cadmium oxide neutron absorption body material. The invention also discloses a preparation method of the gradient type macromolecule-based neutron absorption grid tray material. The gradient type macromolecule-based neutron absorption grid tray material has the characteristics of high absorption efficiency, long service life, high mechanical property, simple technology and the like, has a certain absorption effect on gamma photons, can be used for spent fuel storage and neutron sources of other types and has a wide application prospect.

The invention provides a positron emission computer tomography system and belongs to the field of medical devices. The system comprises three gamma-ray detection devices, three front-end electronics devices, three data acquisition devices, an electromechanical control device and three control devices, wherein three gamma-ray detection devices are used for generating gamma photons to hit crystals to produce visible light and converting the visible light into electric signals; three front-end electronics devices are used for determining single case information according to electric signals of corresponding gamma-ray detection devices; three data acquisition devices are used for acquiring the single case information obtained by corresponding front-end electronics devices and processing the single case information to obtain coincidence case information; the electromechanical control device is connected with data acquisition devices and is used for controlling movement of machine assemblies under the control of data acquisition devices; and three control devices which are correspondingly connected with data acquisition devices one by one are used for receiving the coincidence case information transmitted by corresponding data acquisition devices, and positron emission tomography (PET) images are obtained through processing. By the aid of the positron emission computer tomography system, the scanning speed can be accelerated, and the application range of PET can be broadened.

The present invention discloses a multiple-nuclide gamma imaging system and method and belongs to the field of medical imaging. The multiple-nuclide gamma imaging system comprises a multiple-nuclide tracer injection module, a multi-nuclide scintillation crystal detector module, a configurable circuit module and an image reconstruction and imaging module. The multiple-nuclide gamma imaging method comprises the following steps: S1, starting the imaging system, setting acquisition time of the imaging system, and injecting 11C, 13N, 15O and 18F labeled compounds into an imaging object; S2, obtaining a decay event emission gamma pulse data set by positioning a gamma detector; S3, outputting an electrical signal (scintillation pulse) by a silicon photomultiplier; S4, conducting time discrimination, energy discrimination, data acquisition and coincidence processing by a detector; and S5, displaying images in a tomographic manner by a computer. The disclosed multiple-nuclide gamma imaging system and method can obtain more comprehensive data than the prior art, comprehensively analyze multi-molecule events and related influences, reduce requirements on the total gamma photon counting, reduce irradiation risks on organisms and improve a signal-to-noise ratio of reconstructed images.

The invention relates to a single photon fault imaging method and system, the method can acquire Gamma photons by a photomultiplier tube array through collision on a scintillation crystal to generate a fluorescent signal, the fluorescent signal is converted into a fluorescent digital signal by a data acquisition module, the fluorescent digital signal is sent into a positioning module to perform positioning calculation, the positioning data can be formed and all effective data can be converted into images, the algorithm adopted in the positioning calculation is maximum likelihood positioning algorithm guided by a mass center, at first the Gamma photon collision position can be calculated with a mass center method, then the Gamma photon collision positioning data can be formed by accurately estimating with local two-dimension maximum likelihood method in a selected scope; the system comprises the scintillation crystal, the photomultiplier tube array, the data acquisition module, the positioning module and an imaging module. The positioning accuracy of the invention is approximate to the maximum likelihood positioning method, thereby shortening the calculating time and reducing the requirements for the computer hardware and the memory space greatly.

A method for performing a measurement of a property downhole includes: using an instrument including an irradiator including a pulsed neutron generator, a moderator and a material including a high cross section for capturing thermal neutrons downhole, generating inelastic gamma photons from neutron interactions in the moderator and generating capture gamma photons from neutron interactions in the material; irradiating sub-surface materials proximate to the instrument with the inelastic gamma photons and the capture gamma photons; detecting radiation scattered by the sub-surface materials; and estimating the property according to the detected radiation. A system is also disclosed.

The invention discloses a method and a system for detecting material defects based on photonuclear reaction. The method comprises the following steps: scanning a detected material by a high-energy X-ray, wherein, the high-energy X-ray and target nuclide in the detected material can perform photonuclear reaction so as to generate positive electrons in the detected material; measuring Gamma-photon energy caused by annihilation of the positive electrons by utilizing a detector so as to obtain Gamma-photon energy spectrum broadening; and analyzing the Gamma-photon energy spectrum broadening so as to judge the defect situation of the detected material. In the method, the high-energy X-ray and the nuclide in the detected material perform photonuclear reaction so as to generate a positive electron source in the detected material, so that the problem that an external positive electron source can not detect the interior of the material can be solved.

A detector (100) for detecting neutrons includes a neutron reactive material (102) adapted to interact with neutrons to be detected and release ionizing radiation reaction products in relation to the interactions with neutrons. The detector also includes a first semiconductor element (101) being coupled with the neutron reactive material (102) and adapted to interact with the ionizing radiation reaction products and provide electrical charges proportional to the energy of the ionizing radiation reaction products. In addition electrodes are arranged in connection with the first semiconductor element (101) for providing charge collecting areas (106) for collecting the electrical charges and to provide electrically readable signal proportional to the collected electrical charges. The thickness of the first semiconductor element (101) is adapted to be electrically and/or physically so thin that it is essentially/practically transparent for incident photons, such as background gamma photons.

The invention discloses a multianode PS-PMT (position sensitive-photomultiplier tube) based detector signal readout method and system. The signal readout method comprises the following steps of: converting M*N array signals output by a detector into M channels of signals and N channels of signals on orthogonal directions by a symmetry charge distribution circuit; respectively carrying out amplification forming and digital integration processing on the M channels of signals and the N channels of signals to generate the integral numerical values of the processed M channels and N channels; transferring the integral numerical values of the processed M channels and N channels to a computer side; and calculating the position of the center of gravity in each channel direction with a local center of gravity method so as to determine the action position of a gamma photon on the detector. According to the scheme of the invention, noise brought by invalid channels can be eliminated in a process of obtaining the position information of a gamma example, and the positioning precision of the detector (especially a big-array output detector) is improved.