Method for correcting projection pencil sclerosis based on CT data consistency

Abstract

The invention discloses a beam hardening correction method of CT projection data based on data dependency. The method is based on physics imaging model of medical X-ray, constructs a minimization solution problem between CT projection data, combines the minimization problem and obtains solution of intermediate parameter. For realizing more precise correction result, the method estimates reducing proportion of substance with high density in projection data according to primary correction construction result and CT reprojection. The invention is adaptable for realizing beam hardening correction function of various X-ray CT devices. Compared with the existing method only with water modeling correction, the method of the invention respectively considers differences of beam hardening effect of tissues with different density. Compared with the existing method of bone correction, the method of the invention can automatically adapted to different imaging subjects more flexibly and has better correction precision.

Description

technical field [0001] The invention belongs to the technical field of X-ray CT reconstruction imaging, and relates to a projection data beam hardening correction method based on CT data consistency. Background technique [0002] The principle of CT reconstruction is Radon transform and inverse transform theory. Its basis is that the projection data comes from a linear projection model. For example, for two-dimensional tomography, there is the following projection formula: [0003] p(θ,l)=∫ L(θ，l) f(x,y)dxdy (1) [0004] Where θ is the projection angle, l is the sampling point of the projection data, L(θ,l) is the ray penetration path, f(x,y) is the image function. [0005] Although CT technology has developed from the first generation to the fifth generation today, the scanning trajectory has changed from the earliest straight line to the current circular and spiral trajectory, and even any trajectory. The projection methods include fan and cone beams. The projection and ...

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Problems solved by technology

[0021] 3. There are individual differences for the same body part, so there may be problems with polynomial correction with uniform coefficients

The most typical one here is the epidural artifact in head CT. There is no ideal solution at present. In most CT equipment, it is necessary to rely on the doctor's clinical experience to judge and distinguish. In some other CT equipment, There is a solution to correct by post-processing methods, but there is a risk of inauthentic data reconstruction

[0022] 4. In order to overcome the above problems, bone correction is adopted, although it has a certain degree of self-adaptability, but there are also some important shortcomings, such as: it is very difficult to select the scale factor empirically, and the selection of the scale factor is suitable for the overall projection. Beam hardening correction performance has a significant impact on

As for the beam hardening correction related to the imaging object, if only the phantom correction method is used, it is theoretically impossible to be accurate

Although the bone correction method considers the imaging object to a certain extent, it is only an engineering solution to the problem and lacks strict theoretical support.

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