172 results about "Metal Artifact" patented technology

A method and apparatus include acquisition of a view dataset based on x-rays received by a detector corresponding to a energy level, reconstruction of an initial image using the view dataset, the initial image comprising a plurality of metal voxels at respective metal voxel locations, and generation of a metal mask corresponding to the plurality of metal voxels within the initial image. The method and apparatus also include forward projection of the metal mask onto the view dataset to identify metal dexels in the view dataset, performance of a weighted interpolation based on the identified metal dexels to generate a completed view dataset, reconstruction of a final image using the completed view dataset, the final image comprising a plurality of image voxels corresponding to the metal voxel locations, and replacement of a portion of the plurality of image voxels corresponding to the metal voxel locations with smoothed metal values.

A method for reducing artifacts in an original computed tomography (CT) image of a subject, the original (CT) image being produced from original sinogram data. The method comprises detecting an artifact creating object in the original CT image; re-projecting the artifact creating object in the original sinogram data to produce modified sinogram data in which missing projection data is absent; interpolating replacement data for the missing projection data; replacing the missing projection data in the original sinogram data with the interpolated replacement data to produce final sinogram data; and reconstructing a final CT image using the final sinogram data to thereby obtain an artifact-reduced CT image.

The invention relates to a Computerized Tomography (CT) image uniformization metal artifact correction method based on four-order total-variation shunting, wherein solving is carried out on the basis of a convexity splitting method to achieve metal artifact correction. The CT image uniformization metal artifact correction method includes the specific steps of collecting data, reconstructing images, dividing metal zones, calculating priori images, obtaining re-projection of the metal zones and the priori images, uniformizing projection data, performing four-order total-variation equation correction, reversely uniformizing the corrected data, reconstructing images again and restoring the image metal zones. The CT image uniformization metal artifact correction method can effectively remove metal artifacts, well maintains structural information of metals and the periphery of the metals, and limits secondary artifact from appearing to the maximum extent and the like.

The invention provides a computerized tomography (CT) image metal artifact correction method, a computerized tomography (CT) image metal artifact correction device and a computerized tomography (CT) apparatus. The computerized tomography (CT) image metal artifact correction method comprises the following steps that: a metal projection range caused by an interference object is determined according to an original image corresponding to original projection data; diagnosis object projection data after the removal of the interference object are obtained based on metal projection data in the metal projection range, and after that, the original projection data are corrected and a model image is constructed based on the diagnosis object projection data; and secondary correction is performed on the original projection data according to the projection data of the model image, and reconstruction is performed based on corrected target projection data and according to clinically-used scanning and image construction conditions so as to obtain a metal artifact-free target image, and therefore, the purpose of metal artifact correction can be achieved. According to the computerized tomography (CT) image metal artifact correction method of the invention, the original projection data are adopted as a correction object, and therefore, the spatial resolution and low-contrast ability of a processed image can be ensured; and the original projection data completely contain all information of the interference object, and therefore, the introduction of a new artifact can be avoided.

The invention discloses an attenuation filter-based metal artifact removing mixed reconstruction method for CT images. When a CT acquires data, if a scanned object contains a metal object with high absorption coefficients which comprises a tissue attenuation coefficient and a metal attenuation coefficient to cause projection data jump, the scanned object is considered to be destructive and should be corrected; thus, the metal artifact is greatly weakened during FPB reconstruction. The method comprises the following steps: after determining a metal projection area, performing adaptive attenuation adjustment and filter on the determined metal area; reconstructing an entire image through the FBP, performing EM iterative reconstruction on the metal area by using the primary projection data, and correcting the metal area after the adaptive attenuation filter and reconstruction; and compensating the metal projection area. The numerical simulation CT experiments prove that the method can effectively remove metal artifacts and well keep the information of the metal and the surrounding tissue of the metal. Particularly under the condition of multiple metal objects, the method has low calculation complexity and high practical value.

Approaches are disclosed for removing or reducing metal artifacts in reconstructed images. The approaches include creating a metal mask in the projection domain, interpolating data within the metal mask, and perform a reconstruction using the interpolated data. In certain embodiments the metal structure is separately reconstructed and combined with the reconstructed volume.

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.

Various methods and systems for spectral computed tomography imaging are provided. In one embodiment, a method comprises acquiring a first projection dataset and a second projection dataset, detecting a location of metal in the first projection dataset, applying corrections to the first and second projection datasets based on the location of the metal, and displaying an image reconstructed from the corrected first and second projection datasets. In this way, metal artifacts may be substantially reduced in dual or multi-energy CT imaging.

A 3D metal artifacts correction technique corrects the streaking artifacts generated by titanium implants or other similar objects. A cone-beam computed tomography system is utilized to provide 3D images. A priori information (such as the shape information and the CT value) of high density sub-objects is acquired and used for later artifacts correction. An optimization process with iterations is applied to minimize the error and result in accurate reconstruction images of the object.

The invention relates to an image postprocessing method for removing a metal artifact from a computed tomography (CT) image, which comprises the following steps of: converting an original CT image into a polar coordinate image from an orthogonal coordinate image; determining a metal projection region in the polar coordinate image; establishing a model in the polar coordinate image; performing model correction by adopting the model; correcting front and back projection errors brought into the model correction; and converting the polar coordinate image into the orthogonal coordinate image. According to a model establishing method provided by the invention, the good model can be established, and finally, a good correction result can be obtained; the errors brought in by front and back projection are corrected, so that the result after the correction is better, and the processing speed is ensured.

The invention provides a metal artifact correction method, comprising: first, employing a method based on a Markov random field model to divide metal areas, thereby solving the problem of inaccurate division of metal areas by a traditional metal artifact removal algorithm, and avoiding more secondary artifacts caused by inaccurate positioning of metal projection borders; and employing a prior interpolation algorithm to solve the problem of unsmooth borders of metal projection areas after linear interpolation; in addition, metal edge framework structure information is fed back to corrected projection data, thereby solving the problem that metal edge high contrast substance structures may be lost in correction results by a traditional interpolation algorithm.

The present invention discloses a computed tomography metal artifact correction method. The method comprises: inputting a to-be-corrected image; acquiring first projection data of the to-be-corrected image; performing first correction on the to-be-corrected image and acquiring second projection data according to a result of the first correction; performing a weighting process on the first and second projection data to acquire third projection data; and obtaining a corrected image according to the third projection data. The present invention further discloses a metal artifact correction apparatus. According to the method and the apparatus provided by the present invention, artifacts can be further reduced and the quality of images can be improved on the premise of reserving available information of original images.

The invention discloses a method for agrobacterium tumefaciens-mediated genetic transformation of sugarcane. The method comprises the steps: leading agrobacterium tumefaciens liquor carrying plant expression vectors to infect embryogenic callus of the sugarcane; and selecting and proliferating resistant calli to induce the resistant calli to obtain the resistant buds of the sugarcane, wherein matrix attachment region sequences are connected at two sides of a gene expression box of the plant expression vector. According to the method, MARs (metal artifact reduction) sequences are built at two sides of the gene expression box of the plant expression vector, thus greatly improving the exogenous gene transformation efficiency and seedling rate of the sugarcane, and being simple in process flow and low in cost.

An apparatus and a method for correcting a CT slice image for an image artifact (330) caused by the motion of a high attenuation part (140) in an object (135) of interest. The CT slice image is based on projection images (310a,b). The apparatus and method uses a footprint (315a,b) of the part in each of the projection images (310a,b).

The invention relates to a CT (Computerized Tomography) image metal track prediction and artifact reduction method based on integral cosine. Aiming at metal area part cutting in a metal artifact reduction algorithm, compared with a common threshold algorithm which uses original sinogram data to reestablish images, then cuts an image domain into metal pixels and finally projects the cut metal pixels onto a sinogram domain to position a metal track, the CT image metal track prediction and artifact reduction method based on integral cosine firstly obtains various projection tracks according to a cosine projection relationship, projections on each track are added and values which are greater than a threshold are regarded as values corresponding to metal, so that the metal track is obtained. The CT image metal track prediction and artifact reduction method based on integral cosine has the advantages that the original images are not required to be reestablished, the time is greatly saved, the accurate positioning of metal areas in images is kept as much as possible and artifacts introduced in the reestablished images are ensured to be as few as possible. According to results, the CT image metal track prediction and artifact reduction method can be used in a metal artifact reduction algorithm of CT medical images and the metal artifact reduction effect of the repaired images is better.

The present invention relates to a method of removing metal artifact from a CT image. The method comprises the steps of firstly carrying out the pre-processing via the image adaptive filtering to obtain an original reconstruction image from which the noise and a part of streak artifact are removed; then segmenting the original reconstruction image via a clustering method to obtain the areas of different tissues, establishing a model image, at the same time, carrying out the orthographic projection on a segmented metal area to obtain the position of the metal area in a projection domain; and then carrying out the orthographic projection on the model image to obtain the projection data of the model image, and then using the projection domain data of the model image to substitute for the projection domain data of the original reconstruction image according to the previously obtained position of the metal area in the projection domain; finally carrying out the filtering back projection on the repaired projection domain data to obtain a final corrected image. The method of the present invention reduces a real image accurately, enables the metal artifact to be removed effectively, and helps doctors to judge the states of illnesses accurately.

A method for reducing metal artifacts in a volume radiographic image reconstructs a first 3-D-image using measured projection images and forms a 3-D image metal mask that contains metal voxels. For each measured projection image, a projection metal mask is a projection of the 3-D image metal mask. A 3-D prior image contains voxels within the 3-D image metal mask. Voxel values of the first 3-D image outside the 3-D image metal mask are replaced with a value representative of air or soft tissue. Non-metal voxels of the 3-D prior image are modified according to a difference between a pixel value related to the nonmetal voxel and the corresponding pixel value in a calculated projection image. Composite projection images are formed by replacing measured projection image data for pixels within the projection metal mask with calculated projection image data. A metal artifact reduced 3-D image is reconstructed from composite projections.

A method and apparatus for reducing artifacts in image data generated by a computed tomography system is provided. The artifacts are due to the presence of a high density object in a subject of interest. CT data is acquired at a number of differing tilt angles. The data is then combined and reconstructed to generate an improved composite image substantially free of artifacts caused by the high density object.

A method and system provides medical image processing and 3-dimensional image construction of an examination subject. A user is enabled to selectively orient an x-ray imaging system having a variable 3-dimensional acquisition axis relative to an examination subject support for holding an examination subject. A non-planar image data acquisition path is set for the x-ray imaging system oriented around the variable 3-dimensional acquisition axis in response to user instruction. Acquisition of image data of the examination subject is initiated by the x-ray imaging system at a plurality of points along the non-planar image data acquisition path. A 3-dimensional image is constructed from the acquired image data such that any metal artifacts introduced by radio-opaque objects within the examination subject are minimized. The 3-dimensional image is displayed.

The invention provides a metal artifact correcting method and device for a CT image. Through restraint of a prior projection, Gaussian energy decrease treatment is performed on metal zone iteration of an original projection according to the original projection and a metal projection, and a preliminary uncorrected projection meeting conditions is obtained and a preliminary corrected image is obtained through back projection reconstruction. Smooth denoising is performed on the preliminary corrected image and then the preliminary corrected image is used for updating a prior image. Through iteration update of the prior image and obtaining updated prior image through performing projection on the prior image subjected to each process of update, with the constraint of the updated prior projection, the preliminary uncorrected project meeting conditions is obtained and the preliminary corrected image is obtained further. The preliminary corrected image meeting conditions is obtained and is fused with a metal image, and a final corrected image is obtained. The invention realizes metal artifact correction of the CT image effectively and avoids problems of insufficient smoothness of interpolation boundary of an interpolation method and long correcting time of an iteration method in the prior art.

The present invention provides a method and apparatus for reducing artifacts in CT image reconstruction. The method comprises obtaining an original reconstructed image and an original sinogram and determining a proportion of metal pixels in the original reconstructed image. If the proportion is greater than a first threshold value, then generating an expanded metal template based on the original reconstructed image, generating a metal-free, metal artifact reduced (MAR) image based on the expanded metal template and the original sinogram, and generating a final image based on the expanded metal template and the metal-free, MAR image. However, if the proportion of metal pixels is less than a second threshold value, then generating an expanded metal template based on the original reconstructed image, generating a metal-free, metal artifact reduced image based on a treatment, and generating a final image based on the expanded metal template and the metal-free, MAR image.

The invention relates to a conjugated carbon-iodine polymer, preparation thereof and application of the conjugated carbon-iodine polymer in preparation of a positioning marker, and belongs to the technical field of imaging markers. According to the brand-new imaging marker based on the conjugated carbon-iodine polymer disclosed by the invention, due to the conjugated structure, the polymer has very strong absorption in a visible light region, and the iodine content up to 84.1% corresponds to the superstrong imaging capability of the polymer. In the tumor operation process, based on double guidance of polymer image marking and naked eye observation, the marking can better assist in determining the cutting edge of the tumor, so that accurate cutting of the tumor is achieved, and damage to surrounding normal tissue is reduced as much as possible. In the tumor cyber knife treatment process, the polymer can replace a clinical gold mark to provide ray marking guidance, the ray imaging quality and more accurate radiation dose distribution are improved due to no metal artifacts, the relative stability of the marking position is improved due to good biocompatibility, and the radiotherapy side effect can be further reduced.