Dynamic regulation method for radial filter device in spiral multilayer CT (Computed Tomography) scanning

A technology of CT scanning and ray filtering, which is applied in the field of dynamic adjustment of ray filtering devices in multi-slice spiral CT scanning, can solve problems such as inefficient solutions, and does not take into account the three-dimensional reconstruction method of wide-body detectors, so as to achieve easy implementation and reduce Dosage, effect of high dose

Active Publication Date: 2011-07-06
NEUSOFT MEDICAL SYST CO LTD
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Problems solved by technology

However, this scheme only roughly puts forward the basic idea, the scheme is not efficient, and does not take into account the 3D reconstruction method that the wide body detector must apply

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  • Dynamic regulation method for radial filter device in spiral multilayer CT (Computed Tomography) scanning
  • Dynamic regulation method for radial filter device in spiral multilayer CT (Computed Tomography) scanning
  • Dynamic regulation method for radial filter device in spiral multilayer CT (Computed Tomography) scanning

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Embodiment Construction

[0061] The present invention starts from the mainstream two-dimensional and three-dimensional filtered back-projection reconstruction algorithms, and mathematically accurately calculates the range of projection data obtained by the detector at each Z position (the position corresponding to the ray projection view). On the basis of the ray usage rules, the linear approximation results that are relatively easy to achieve in machinery are given, so as to obtain the best guiding upper-slice switch seam scheme.

[0062] The inventive method comprises the following steps:

[0063] Coordinate transformation of the cone-shaped ray beam in the spiral scanning process of multi-slice CT into a wedge-shaped ray beam; the conversion of the cone-shaped ray beam into a wedge-shaped ray beam: in the plane where the CT equipment rack rotates Inside, according to the geometric relationship between the parallel beam and the fan beam, the fan beam geometric projection data of each layer of the co...

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Abstract

The invention relates to a dynamic regulation method for a radial filter device in spiral multilayer CT (Computed Tomography) scanning, which comprises the following steps: conducting coordinate transformation on taper ray bundles in the projected angle direction during the spiral scanning process of multilayer CT and converting the taper ray bundles into wedge-shaped rays bundles; under geometric condition of the wedge-shaped rays bundle, analyzing the condition that projective data obtained by a projective image at each scanning Z position is used for rebuilding the image, and then building an initial mathematical model at the position of maximum layer or minimum layer of ray, which is utilized by scanning each Z position; conducting extrapolation and numerical analysis on the initial mathematical model so as to simplify the initial mathematical model and obtain a linear approximation method; and summarizing the conclusions and obtaining a final linear switch seam scheme which can be used for mechanical control, thus realizing the dynamic regulation on the filter device in the spiral CT scanning. According to the invention, the increase of dosage is avoided caused by invalid ray of the image generated in the initial and finished stages in the spiral multilayer CT scanning.

Description

technical field [0001] The invention relates to CT scanning ray filtering technology, in particular to a dynamic adjustment method of a ray filtering device in multi-slice spiral CT scanning. Background technique [0002] When multi-slice CT (third generation) equipment performs helical scanning, no matter what reconstruction method is used, in order to ensure sufficient imaging data, it is necessary to start scanning before the imaging position, that is to say, there is a certain pre-scanning length. After the focus of the tube is aligned with the last imaging position in the Z direction, it will continue to walk for a certain distance before stopping scanning, which means that there is a certain length of overscanning. [0003] Most of the cone beam rays at the two distances of pre-scan and over-scan do not contribute to the reconstructed image, and only a small part is required for the reconstructed image, which undoubtedly causes a loss in dose. See figure 1 . The pos...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B6/03
Inventor 任毅赵江魏
Owner NEUSOFT MEDICAL SYST CO LTD
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