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A Trajectory-Based Method for Removing Metal Artifacts in CT Images

A technology for metal artifacts and CT images, applied to the original projection data of CT images to locate the trajectory of newly introduced artifacts, research and implementation of artifact removal methods

Active Publication Date: 2016-08-31
BEIJING UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In other words, most images containing metal artifacts will introduce such artifacts more or less, even the classic NMAR algorithm has such shortcomings
There are no very targeted algorithms to remove these artifacts

Method used

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  • A Trajectory-Based Method for Removing Metal Artifacts in CT Images

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Embodiment Construction

[0078] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0079] image 3 A flow chart of the method according to the invention is schematically shown.

[0080] 1) According to the tomographic scanning of a certain part of the human body by the CT machine, a piece of original scanning data is obtained, which is called the original sinogram S orign (Such as Figure 4 ). The method starts at step 1, where a first reconstruction is performed on the original data, resulting in the original (unrectified) image I orign (Such as Figure 5 ).

[0081] 2) Threshold segmentation:

[0082] ①In step 2-1, for I orign Medium pixel value I orign Tissue threshold segmentation >5000 to get metal mask image I metal (Such as Figure 6 ). Then, after dilation, the original metal mask is etched to remove spots and fill voids.

[0083] ② In step 2-2, perform multi-threshold segmentation to obtain image I prior...

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Abstract

The invention is a trajectory-based method for removing metal artifacts in CT images. In the classic NMAR metal artifact removal algorithm, it is inevitable to introduce new artifacts between metal and high-density tissue (bone, metal). After the metal area interpolation in the NMAR algorithm, this method adds a special repair method for overlapping areas in multiple high-density tissue projections, and mainly uses a method based on pixel projection trajectory interpolation. First, the projection trajectory of each high-density tissue pixel is obtained by forward projection; then, the interval overlapping with other high-density tissue on the trajectory is repaired, and the above repair process is repeated for all high-density tissue pixels to obtain the final repaired sinusoid picture. Based on the classic NMAR algorithm, this method adds a trajectory-based interpolation method, which greatly reduces the introduction of new artifacts in the reconstructed image. A large number of results show that the metal artifact removal effect of the repaired image is better.

Description

technical field [0001] The invention relates to a method for reducing metal artifacts in computed tomography (CT), in particular to the original projection data of a CT image to locate the trajectory of newly introduced artifacts, and then to research and implement the artifact removal method. Background technique [0002] In radiation therapy, on the one hand, for patients with metal implants (such as dental fillings, alloy femoral heads, such as figure 1 ) patients generally have severe shadowing artifacts. This condition is very common with tumors in the brain or prostate. On the other hand, doctors usually use small metal markers to locate tumors, which also introduce metal artifacts. In tumor radiation therapy, the accuracy of tumor location and radiation dose distribution provided by computed tomography (CT) images is very important, so it is necessary to reduce the influence of metal artifacts. [0003] figure 2 is a flowchart of the prior art NMAR method. [00...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T5/00A61B6/03
Inventor 毋立芳颜凤辉曹航明侯亚希冯泽猛
Owner BEIJING UNIV OF TECH