Correction method for ring artifact and arc artifact of computed tomography (CT) image
A CT image and correction method technology, applied in the field of image processing, can solve problems such as inability to locate ring artifacts, unstable detector pixels, and complex structures
Active Publication Date: 2012-06-27
SHENZHEN INST OF ADVANCED TECH CHINESE ACAD OF SCI
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In actual CT images, due to the complex structure of the scanned object, the difference between the brightness and the background at the ring artifact is often not obvious, so it is impossible to accurately locate the ring artifact simply based on the threshold and variance
[0005] At the same time, due to the instability of the detector pixel, the artifacts generated may not be circular but arc-shaped, and the existing methods cannot well eliminate the arc-shaped artifacts that have a great impact on imaging quality
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[0055] Such as figure 1 Shown is a flow chart of a ring artifact correction method for CT images. The CT image comes from m scan projection angles θ i Scanned m images with a resolution of n×n, where 0°i <360°, 1≤i≤m and is a positive integer.
[0056] In this embodiment, the scanning projection angle θ i Obtained by equally dividing the circle. Preferably, the scanning projection angle θ i Obtained by dividing the circumference into 360 equal parts.
[0057] The ring artifact correction method of CT image comprises the following steps:
[0058] Step S110, transform all the CT images into a Cartesian coordinate system with the detector pixel channel n as the abscissa and the projection angle θ as the ordinate, and obtain n×m first intermediate images R with a resolution of n×1 1 (n, θ i ).
[0059] In this embodiment, all CT images are transformed into a Cartesian coordinate system with the detector pixel channel n as the abscissa and the projection angle θ as the ordi...
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The invention discloses a correction method for the ring artifact and the arc artifact of a computed tomography (CT) image. According to a correction method for the ring artifact of the CT image, the ring artifact correction is carried out to a CT image which is not rebuilt, the phenomenon that the image quality is lowered because a coordinate is changed for multiple times is avoided; meanwhile, the CT image is successively subjected to data processing, such as the respective overlapped summation to the pixels of all lines, high-pass filtering, the averaging of the overlapped summation to the pixels of all lines and the like; ring artifact data can be accurately and reliably removed; and therefore, for the CT image rebuilt on the basis of processed projection data, the influence of the ring artifact can be eliminated. A correction method for the arc artifact of the CT image is characterized in that the image is divided into m subsets after the ring artifact is corrected; each subset is successively subjected to the data processing, such as the respective overlapped summation to the pixels of all lines, high-pass filtering to extract high-frequency ingredients, the averaging of the overlapped summation to the pixels of all lines and the like; the arc artifact data can be accurately and reliably removed; and therefore, for the CT image rebuilt on the basis of processed projection data, the influence of the arc artifact can be eliminated.
Description
【Technical field】 [0001] The invention relates to image processing technology, in particular to a method for correcting ring artifacts and arc artifacts of CT images. 【Background technique】 [0002] In CT systems, artifacts have always been an important factor restricting CT imaging. The so-called artifacts refer to components that do not exist in the real object that appear in the reconstructed image when the actual object is scanned. It is one of the important factors causing CT image distortion. Among them, the arc artifacts and ring artifacts of CT images are caused by the unsatisfactory response of detector pixels, and their existence leads to the degradation of CT image quality, which affects the subsequent processing and quantitative analysis of images. In clinical practice, because the artifact is similar to the pathological tissue on the image, it may lead to misdiagnosis. Therefore, it is necessary to remove or minimize this artifact. [0003] Compared with huma...
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IPC IPC(8): G06T5/00
Inventor 胡战利夏丹戎军艳桂建保邹晶张其阳蒋昌辉张成祥陈垚
Owner SHENZHEN INST OF ADVANCED TECH CHINESE ACAD OF SCI