273 results about "Ct reconstruction" patented technology

A multispectral X-ray imaging system uses a wideband source and filtration assembly to select for M sets of spectral data. Spectral characteristics may be dynamically adjusted in synchrony with scan excursions where an X-ray source, detector array, or body may be moved relative to one another in acquiring T sets of measurement data. The system may be used in projection imaging and / or CT imaging. Processed image data, such as a CT reconstructed image, may be decomposed onto basis functions for analytical processing of multispectral image data to facilitate computer assisted diagnostics. The system may perform this diagnostic function in medical applications and / or security applications.

A multispectral X-ray imaging system uses a wideband source and filtration assembly to select for M sets of spectral data. Spectral characteristics may be dynamically adjusted in synchrony with scan excursions where an X-ray source, detector array, or body may be moved relative to one another in acquiring T sets of measurement data. The system may be used in projection imaging and / or CT imaging. Processed image data, such as a CT reconstructed image, may be decomposed onto basis functions for analytical processing of multispectral image data to facilitate computer assisted diagnostics. The system may perform this diagnostic function in medical applications and / or security applications.

A technique is provided for CT reconstruction for use in CT metrology. The boundary based CT reconstruction method includes the steps of initializing a boundary of an object to obtain a boundary estimate, defining a forward model based on the boundary estimate, linearizing the forward model to obtain a system matrix and implementing an iterative image reconstruction process using the system matrix to update the boundary estimate.

The application relates to a system and a method for the phase-contrast imaging by use of X-ray gratings. The system comprises an X-ray device, a first absorption grating, a second absorption grating, a detection unit, a data processing unit and an imaging unit, wherein the X-ray device transmits an X-ray bundle to a detected object; the first and second absorption gratings are positioned in the direction of the X-ray bundle; the X-ray refracted by the detected object forms an X-ray signal with variable intensity through the first absorption grating and / or the second absorption grating; the detection unit receives and converts the X-ray with variable intensity into an electrical signal; the data processing unit processes and extracts refraction-angle information in the electrical signal, and utilizes the refraction-angle information to figure out pixel information; and the imaging unit constructs images of the object. In addition, the system and the method can also realize CT imaging by using a rotating structure to rotate the object so as to obtain refraction angles in a plurality of projection directions and the corresponding images, and use CT reconstruction algorithm to figureout refraction-index fault images of the detected object. According to the invention, the phase-contrast imaging of approximate decimeter-magnitude viewing fields under incoherent conditions can be realized by use of common X-ray machines or multi-seam collimator such as source gratings, as well as two absorption gratings.

A method for reconstructing image data from measured sinogram data acquired from a CT system is provided. The CT system is configured for industrial imaging. The method includes pre-processing the measured sinogram data. The pre-processing includes performing a beam hardening correction on the measured sinogram data and performing a detector point spread function (PSF) correction and a detector lag correction on the measured sinogram data. The pre-processed sinogram data is reconstructed to generate the image data.

A computed tomography (CT) reconstruction method includes implementing an iterative image reconstruction process for CT metrology of an object, wherein the iterative reconstruction process utilizes accurate forward projection. During each of a plurality of iterations, a reconstructed image is constrained by utilizing prior outer edge information obtained from a modality in addition to CT, and then transformed to a projection domain so as to generate a calculated sinogram. A correction image is determined based on the calculated sinogram and a measured sinogram.

A technique is provided for CT reconstruction for use in CT metrology. The boundary based CT reconstruction method includes the steps of initializing a boundary of an object to obtain a boundary estimate, defining a forward model based on the boundary estimate, linearizing the forward model to obtain a system matrix and implementing an iterative image reconstruction process using the system matrix to update the boundary estimate.

The invention discloses a multi-energy-spectrum CT image reconstruction method based on projection estimation, wherein the method is used for reconstruction of density images of various base materials of a measured object. The method comprises the steps of directly reconstructing energy images of the measured object from collected multicolor projection data according to a traditional single-energy CT reconstruction method, calculating the line integral of each energy image in the radial directions of all other energy spectrums, estimating multicolor projections of a current energy spectrum in the directions, obtaining the multicolor projections with the consistent geometrical parameters, calibrating a various base material division function, dividing the estimated multicolor projections with the consistent geometrical parameters into the line integrals of the various base materials, and reconstructing the corresponding density images of the various base materials through the line integrals of the various base materials. The multi-energy-spectrum CT image reconstruction method based on projection estimation is simple, practical and suitable for multi-energy-spectrum CT image reconstruction when the geometrical parameters of the multicolor projections are not consistent. Compared with the prior art, the multi-energy-spectrum CT image reconstruction method has the advantage that high-quality images can be reconstructed only by estimating the multicolor projections with the consistent geometrical parameters through the measured projection data.

The invention discloses an improved eliminating method of tapered beam CT reconstruction image annular false shade, comprising the steps as follows: the invention changes the annular false shade of reading CT reconstruction image into a straight line through a method of coordinate change, then takes a one-dimension filter parallel with the false shade as a mask to search a middle image regularly line by line and acquire sample space, at the same time calculates out the variance about the pixel value of each sample space, acknowledges the false shade according to whether the variance is less than the preset valve value, substitutes the pixel value of each sample space with the average pixel value between the point and two upper and lower false shades in the ordinate axis direction in order to eliminate the annular false shade, and finally changes the middle image free from the false shade to be under the original frame of axes to gain a corrected image.

The utility model discloses a beam hardening correction method of cone beam CT based on registration model simulation, which acquires multi-color projection data through circle locus cone beam CT scanning to a spare part. After acquiring CT images of sequence slices by cone beam CT reconstitution to the multi-color projection, the contour of certain pieces of the images are extracted so that a measurement point formed a plurality of closed contour lines is acquired. Projection simulation is processed after the registration of the measurement point and the CAD model of the part, and then the length of the part passing through the part at every imaging point is acquired. A hardening curve that passes through the original point is acquired by nonlinear fitting and a straight line that passes through the original point is acquired by linear fitting. The beam hardening constructed defect of the cone beam CT is corrected according to the hardening curve and the rectifying straight line. The utility model is flexible in application, and can approximately corrected through multi-color projection to unique color projection, and the beam hardening artifacts is reduced obviously after correction.

A CT scanning system including a gantry operable to rotate about a rotation axis, and a plurality of X-ray imagers mounted on the gantry, each X-ray imager including a radiation source and a detector, wherein the radiation source is operative to emit a radiation beam (e.g., a cone beam) and the detector is positioned to receive the radiation beam so as to acquire partial projections set of an object through which the beams pass, wherein a union of the partial projections sets forms a projection set sufficient for CT reconstruction of the object.

The invention relates to a metal artifact correcting method of a cone-beam CT (computed tomography) system. The metal artifact correcting method of the cone-beam CT system comprises the steps of separating a metal projection image M (x, y) from an original orthographic projection image f(x, y), reconstructing the metal projection image M (x, y) to obtain a CT reconstruction image XMetal of the metal part, reducing the metal projection image M (x, y) of the original orthographic projection image f(x, y) to obtain a projection image fres(x, y) without the metal part, reconstructing the projection image fres(x, y) without the metal part to obtain a CT (computed tomography) image Xres without the metal part, and adding a CT (computed tomography) image Xmetal of the metal part with the CT (computed tomography) image Xres without the metal part to obtain a final CT (computed tomography) reconstruction image Xcorrection after the correction of a metal artifact. Coordinates are not changed in the metal artifact correcting method, so that the image space resolution is not lost, and the image quality is enhanced.

The invention provides a high-efficiency registration method aimed at a CT and optical scanning tooth model, and belongs to the field of computer oral cavity recovery. The method comprises the steps of (1) data preparation in which 3D visualization is carried out on CT data of the oral cavity to obtain a CT reconstructed tooth image, visualization is carried out on optical scanning data of the tooth crown and gum part to obtain an optical scanning tooth crown image, and the CT reconstructed tooth image and the optical scanning tooth crown image are arranged in the unified world coordinate system; (2) initial registration in which characteristic points are selected manually to process the CT reconstructed tooth image and the optical scanning tooth crown image and further to obtain an initial registration model; and (3) accurate registration in which characteristic points are selected automatically to process the initial registration model and further to obtain an accurate registration model. Problems in registration data with scale transformation and different resolution are solved, and a registration result is high in convenience speed and low in registration error.

A CT scanning system including a gantry operable to rotate about a rotation axis, and a plurality of X-ray imagers mounted on the gantry, each X-ray imager including a radiation source and a detector, wherein the radiation source is operative to emit a radiation beam (e.g., a cone beam) and the detector is positioned to receive the radiation beam so as to acquire partial projections set of an object through which the beams pass, wherein a union of the partial projections sets forms a projection set sufficient for CT reconstruction of the object.

An x-ray imaging technology, performing an x-ray dark-field CT imaging of an examined object using an imaging system which comprises an x-ray source, two absorbing gratings G1 and G2, an x-ray detector, a controller and a data processing unit, comprising the steps of: emitting x-rays to the examined object; enabling one of the two absorbing gratings G1 and G2 to perform phase stepping motion within at least one period range thereof; where in each phase stepping step, the detector receives the x-ray and converts it into an electric signal; wherein through the phase stepping of at least one period, the x-ray intensity at each pixel point on the detector is represented as an intensity curve; calculating a second moment of scattering angle distribution for each pixel, based on a contrast of the intensity curve at each pixel point on the detector and an intensity curve without presence of the examined object; taking images of the object at various angles, then obtaining an image with scattering information of the object in accordance with a CT reconstruction algorithm.

The invention discloses a multi-energy-spectrum CT imaging method and an imaging system. The multi-energy-spectrum CT imaging method comprises the following steps: scanning the object to be detected, and reconstructing the density image of a basic material so as to finally obtain the electron density and equivalent atomic number distribution of the object to be detected or linear attenuation coefficient distribution of the object under the radiation of mono-energetic X-rays. The multi-energy-spectrum CT reconstruction method comprises the following steps: assigning an initial value for the density image of a basic material to be reconstructed; carrying out orthographic projection on an estimated image so as to obtain a projection estimated value; estimating the error of the reconstructed image; updating the image by utilizing the estimated error of the reconstructed image, and repeating the steps mentioned above until the reconstructed density image is convergent. The multi-energy-spectrum CT imaging system comprises a scanning module, a reconstruction module, and a statistics module, wherein the reconstruction module comprises an initializing module, a projecting module, a correcting module, and an updating module.

A system and method for baggage screening at security checkpoints. A CT scanner system processes x-ray data to locate and eliminate non-contraband without a full CT reconstruction of the entire bag. The CT scanner system utilizes lineogram data to disqualify objects of insufficient size, density, or mass as potential threats. Objects can be inspected with CT reconstruction. The CT scanner is capable of obtaining CT data and projection images. Multiple CT scanning systems can be multiplexed together, and each CT scanning system is in communication with a review station. Baggage scanning may also be based on security intelligence inputs such as CAPPS to increase throughput.

The invention discloses a computer tomographic scanning imaging device, which comprises a variable dose CT scanning module used for adjusting the tube voltage of the X ray source in real time according to changes of effective thickness of an object to be detected in the X ray transillumination direction in the scanning process, implementing the circular locus X-CT scanning to the object to be detected according to the adjusted tube voltage of the X ray source, and sending the scanned projection images to a CT reconstruction module; and the CT reconstruction module is used for reconstructing CT according to the received projection images so as to obtain tomographic images of the object to be detected. The invention meanwhile discloses a computer tomographic scanning imaging method. The device and method of the invention are applicable to objects under detection with any complex structure, and will not be influenced by changes of effective thickness of the object to be detected in X ray transillumination direction.

The invention relates to the technical field of CT and provides an X-ray CT image enhancement method based on double energy spectrums. In order to realize image fusion and enhancement of two images and compensate defects of a single image, the invention adopts the technical scheme as follows: the X-ray CT image enhancement method based on double energy spectrums comprises the following steps: scanning to obtain multiple sets of dark field images and calculating the average value of dark fields; moving a sample out of a view field, and respectively obtaining N sets of bright field images under high voltage and low voltage; calculating projected images under the high voltage and low voltage; unifying projection data under the high voltage and low voltage to a dimension according the gray level unifying principle; performing wavelet decomposition on N sets of corrected high and low energy projected images at the same position, and performing image fusion through the wavelet transform method; performing CT reconstruction through the utilization of fused projected images. The X-ray CT image enhancement method is mainly used for CT equipment design and manufacturing.

A method for registration of ultrasound device in three dimensions to a C-arm scan, the method including acquiring a baseline volume, acquiring images in which the ultrasound device is disposed, locating the device within the images, registering the location of the device to the baseline volume, acquiring an ultrasound volume from the ultrasound device, registering the ultrasound volume to the baseline volume, and performing fusion imaging to display a view of the ultrasound device in the baseline volume.

The present invention relates to a method for correcting transmission image or projection data used for CT reconstruction, wherein when measured, a workpiece to be measured is arranged between an X-ray resource emitting X-ray radiation and an X-ray detector receiving the X-ray radiation. Furthermore, the invention also relates to a method for determining parameters of computer faultage radiography by using imaging an image with as possible as high quality and distinct difference on the detector according to the prepared transmission image. The invention also relates to an apparatus for determining the structure and / or geometry shape of objects by using measuring system, preferably computer faultage radiography measuring system, wherein the measuring system comprises at least one radiation resource, at least one radiation detector and at least one rotation shaft.

A method for reconstructing image data from measured sinogram data acquired from a CT system is provided. The CT system is configured for industrial imaging. The method includes pre-processing the measured sinogram data. The pre-processing includes performing a beam hardening correction on the measured sinogram data and performing a detector point spread function (PSF) correction and a detector lag correction on the measured sinogram data. The pre-processed sinogram data is reconstructed to generate the image data.

Cone beam artifacts arise in circular CT reconstruction. The cone beam artifacts are substantially removed by reconstructing a reference image from measured data at circular source trajectory, generating synthetic data by forward projection of the reference image along a pre-determined source trajectory, which supplements the circular source trajectory to a theoretically complete trajectory, reconstructing a correction image from the synthetic data and substantially reducing the cone beam artifacts by generating a corrected image using the reference image and the correction image.

The invention provides a geometric parameter correction method for a static CT system. The static CT system is composed of a plurality of ray sources and one or more detectors, and geometric parameters are the geometric parameters of each ray source and the corresponding detector. The method includes the following steps that a, a correction body mold is placed in the static CT system which requires correction of the geometric parameters, and the correction body mold has a small marking ball; b, each ray source triggers rays once to obtain a plurality of projections; c, calculation is conductedto obtain the corrected geometric parameters of the entire static CT system according to the coordinate of the projection center point of the small marking ball in each projection and combination with the known coordinate of the small marking ball in a system to be corrected. The method can be applied to both an in vitro CT system and a living CT system, and all 10 geometric parameters of the CTsystem can be simultaneously corrected. In addition, only each ray source needs to carry out projection on the correction body mold once, and then all the geometric parameters required for CT reconstruction can be obtained.

The invention relates to a system and a method for X-ray grating contrast imaging. The system comprises an X-ray launching device, a first absorption grating, a second absorption, a detecting unit, a data processing unit and an imaging unit, wherein the X-ray launching device is used for launching X-ray beams to a detected article; the first absorption grating and the second absorption grating are positioned in the launching direction of the X-ray beams, and the X-ray refracted by the detected article forms X-ray signals with different intensity by the first absorption grating and the second absorption grating; the detecting unit is used for receiving the X-ray signals with changeable intensity and converting the X-ray signals into electric signals; and the data processing unit is used for processing and extracting the refraction angle information in the electric signals and calculating the pixel information through the refraction angle information; the imaging unit is used for constructing the image of the article. In addition, a rotating structure can also be utilized to rotate the article to realize a CT imaging mode so as to obtain refraction angles in a plurality of projection directions and the corresponding images and calculate the refraction index tomography image of the detected article by CT reconstruction algorithm. The system and the method adopt the common X-ray machine and the grating above a period of ten micron magnitude to realize the contrast imaging of a decimeter magnitude like viewing field.

A CT reconstruction of an object including a high-resolution object region of interest may be produced in an artefact-free manner by producing a first projection data set of a first region of the object that encloses the object region of interest and includes at least one projection recording of a first resolution, and a second projection data set of the object region of interest including at least a second projection recording of a second, higher resolution. The first and second projection data sets may be combined, in accordance with a combination rule, so as to obtain a CT reconstruction of the first region of the object having the first resolution and of the object region of interest having the second, higher resolution.

An x-ray imaging technology, performing an x-ray dark-field CT imaging of an examined object using an imaging system which comprises an x-ray source, two absorbing gratings G1 and G2, an x-ray detector, a controller and a data processing unit, comprising the steps of: emitting x-rays to the examined object; enabling one of the two absorbing gratings G1 and G2 to perform phase stepping motion within at least one period range thereof; where in each phase stepping step, the detector receives the x-ray and converts it into an electric signal; wherein through the phase stepping of at least one period, the x-ray intensity at each pixel point on the detector is represented as an intensity curve; calculating a second moment of scattering angle distribution for each pixel, based on a contrast of the intensity curve at each pixel point on the detector and an intensity curve without presence of the examined object; taking images of the object at various angles, then obtaining an image with scattering information of the object in accordance with a CT reconstruction algorithm.

The invention discloses a method for iteratively reconstructing double-energy spectrum CT base material images, and aims at reconstructing base material density images of tested objects. The method comprises the following steps of: scanning a tested object by using a double-energy spectrum CT system so as to obtain double-energy spectrum projection data of the tested object; respectively reconstructing a high / low-energy spectrum tested object images on the basis of high / low-energy spectrum projection data; calculating a linear combined image of the high / low-energy spectrum tested object images; solving a specific value image of a base material density image and the linear combined image, establishing a regularized constraint image reconstruction model by taking the condition of minimizinga total variation of the specific value image as a constraint condition, and iteratively reconstructing the base material density image of the tested object. According to the method, structure consistency among various double-energy CT reconstruction images is sufficiently utilized, so that the reconstruction noise amplified by base material decomposition is effectively reduced and the convergencespeed of iterative reconstruction of base material images is improved.