WO2022198729A1 - 一种x射线层析成像系统 - Google Patents

一种x射线层析成像系统 Download PDF

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Publication number
WO2022198729A1
WO2022198729A1 PCT/CN2021/087423 CN2021087423W WO2022198729A1 WO 2022198729 A1 WO2022198729 A1 WO 2022198729A1 CN 2021087423 W CN2021087423 W CN 2021087423W WO 2022198729 A1 WO2022198729 A1 WO 2022198729A1
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ray
dimensional
receiving end
voxel
projection
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PCT/CN2021/087423
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English (en)
French (fr)
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蔡宗远
周卫东
戴兴武
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上海涛影医疗科技有限公司
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Publication of WO2022198729A1 publication Critical patent/WO2022198729A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/025—Tomosynthesis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
    • A61B6/5211—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data
    • A61B6/5223—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data generating planar views from image data, e.g. extracting a coronal view from a 3D image
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
    • A61B6/5211—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data
    • A61B6/5229—Devices using data or image processing specially adapted for radiation diagnosis involving processing of medical diagnostic data combining image data of a patient, e.g. combining a functional image with an anatomical image

Definitions

  • the invention relates to the technical field of medical imaging, in particular to an X-ray tomography imaging system.
  • X-ray tomography imaging system By controlling the X-ray source and the flat panel detector to continuously move in the same direction in the vertical or horizontal direction, and during the movement, pulse shooting can be performed at specified time intervals, so as to achieve continuous shooting of any designated area of the subject's body, so as to obtain the subject.
  • Several X-ray plane images of the inspection area are processed to construct a three-dimensional image of the inspected area.
  • Tomosynthesis is an imaging technique using standard X-ray equipment, digital flat panel detectors, to generate tomographic images from very low dose projections obtained from different angles. These images are parallel to the plane of the detector. The tube is projected from multiple angles at discontinuous positions to obtain images. By moving and superimposing the projected images, the tomographic image of an object at any set height can be reconstructed. For example, in the large flat-panel gastrointestinal machine Shimadzu SONIALVISION safire II shown in Figures 1 and 2, continuous multi-slice high-definition tomographic images are obtained under one scan.
  • an object of the present invention is to provide an X-ray tomography system.
  • the X-ray transmitting end and the X-ray receiving end are continuously moved in the same direction in the vertical or horizontal direction.
  • X-ray pulses are continuously emitted to the imaging area located between the transmitting end and the receiving end, forming several distributions of different angles.
  • the present invention can break through the limitation of the existing Tomosynthesis system on the three-dimensional imaging area to a great extent.
  • a tomographic X-ray imaging system comprising: an X-ray imaging module, a two-dimensional image receiving module, and a three-dimensional image reconstruction module;
  • the X-ray imaging module is configured to use an X-ray imaging device to acquire multi-angle two-dimensional images of the designated inspection part of the object to be imaged;
  • the two-dimensional image receiving module is configured to receive the multi-angle two-dimensional images of the designated inspection site acquired in the X-ray imaging module;
  • the three-dimensional image reconstruction module is configured to reconstruct a three-dimensional image from a plurality of the two-dimensional images of different angles by using any image reconstruction algorithm including a translation-superposition method, a filtered back-projection method, and an iterative reconstruction method. , the voxel data formed in the imaging area.
  • the X-ray imaging equipment adopted specifically includes:
  • the X-ray emission terminal is used to emit X-rays to the designated inspection site;
  • the X-ray receiving end is used for receiving X-rays after the X-rays emitted by the X-ray transmitting end pass through the designated inspection site, and the X-ray receiving end and the X-ray transmitting end are parallel and synchronized during imaging Movement, during the movement process, the designated inspection site is irradiated with pulses at a certain time interval. With the relative movement of the X-ray emitting end, the X-ray receiving end and the designated inspection site, the X-rays in the X-ray The projection imaging on the ray receiving end is constantly changing, and the two-dimensional images of several different angles are obtained.
  • the X-ray imaging device uses any one of two forms, including standing and lying down, to image the designated inspection site.
  • the X-ray imaging device when the X-ray imaging device performs imaging in a standing form, the X-ray imaging device further includes: a vertical transmission mechanism;
  • the vertical transmission mechanism is used for fixing the X-ray transmitting end and the X-ray receiving end, and using a motion control system to realize the simultaneous operation of the X-ray transmitting end and the X-ray receiving end;
  • the vertical transmission mechanism may include one or two vertical transmission units; when there is one vertical transmission unit, the X-ray transmitting end and the X-ray receiving end are fixed by means including a C-shaped arm , form a stable C-shaped structure fixed on the vertical transmission unit, and use a motion control system to control the up and down movement of the C-shaped structure; when there are two vertical transmission units, the X-ray emitting end and the The X-ray receiving end is fixed on the two vertical transmission units, and a motion control system is used to control the X-ray transmitting end and the X-ray receiving end to run simultaneously.
  • the vertical transmission mechanism adopts any form including a column type and a suspension type.
  • the X-ray imaging device when the X-ray imaging device performs imaging in the form of lying flat, the X-ray imaging device further includes: a C-arm and a hospital bed;
  • the C-arm is configured to fix the X-ray emitting end and the X-ray receiving end in an opposite manner
  • the hospital bed configured to provide the subject to be imaged to lie down
  • At least one of the C-shaped arm and the hospital bed can move horizontally.
  • the specific reconstruction mode is:
  • the space where the designated inspection site is located is discretized into several rectangular parallelepiped units of the same size, denoted as voxels; wherein, a group of rectangular planes of the voxels are parallel to the X-ray receiving end, and all the centers of mass in the voxels absorb X-rays
  • the voxel center coordinate V(x, y, z) represents the voxel spatial position, x represents the voxel horizontal position, y represents the voxel vertical height position, and z represents the voxel’s distance to the X-ray receiving end;
  • Image reconstruction is to solve the problem of all or part of the voxel X-ray absorptivity A(x, y, z) of the specified inspection site, including translation-superposition method, filtered back-projection method, and iterative reconstruction method, specifically: :
  • H j represents the height position of the jth X-ray emitting end
  • D represents the vertical distance from the X-ray emitting end to the X-ray receiving end, assuming that the X-ray emitting end and the X-ray receiving end move
  • a total of N rays penetrate the voxel V(x i , y i , z 0 )
  • the X-ray emitting end at height H j emits X-rays to penetrate the voxel to obtain the projection data P j , which can be obtained by
  • the translation-superposition method in the following formula is used to obtain the target voxel absorptivity A(x i , y i , z k ):
  • the X-ray emitting end generates cone-beam X-rays, and performs linear projection sampling on the space of the designated inspection site. However, when the X-ray emitting end is at a certain height, the X-rays emitted are not parallel to each other. After rearrangement, a parallel projection environment is formed, and the filtered back projection method can be used.
  • the X-ray emission end at a certain height can be uniquely determined by the spatial direction angle.
  • the range of the ray direction angle depends on the field of view of the radiation source. For X-rays
  • the spatial direction angle ( ⁇ , ⁇ ) and the field of view angle ⁇ of the radiation source are:
  • W represents the height dimension of the X-ray receiving end
  • D represents the vertical distance from the X-ray emitting end to the X-ray receiving end
  • the X-ray emitting end can emit the same value in the process of vertically moving to different heights H i .
  • the direction angle ray l( ⁇ , ⁇ , H i ) can form a set of rays L that perform parallel linear scans on the space of the specified inspection site, and satisfy:
  • the spatial voxel absorptivity A(x, y, z) and the three-dimensional projection data P(x, y, z) have:
  • a F ( ⁇ x , ⁇ y , ⁇ z ) T F ( ⁇ x , ⁇ y , ⁇ z ) ⁇ P F ( ⁇ x , ⁇ y , ⁇ z )
  • P F , T F , and A F represent the three-dimensional Fourier transform of P, T, and A, respectively.
  • the following filters can be designed to realize the spatial filtering of three-dimensional projection data:
  • T′ F T s ( ⁇ x , ⁇ y ), T P ( ⁇ z ) ⁇ T I ⁇ T F
  • T I , T P , T S , and T' F represent the approximation of the inverse matrix of T F respectively, the modulation filter function in the z direction, the modulation filter function in the xy plane, the actual filter back-projection function, in the Fourier space
  • the 3D projection data is filtered and back-projected, and the 3D volume data to be reconstructed can be obtained through inverse Fourier transform:
  • A(x, y, z) FT -1 (T s ⁇ T P ⁇ T I ⁇ T F ⁇ P F )
  • the reconstruction method includes algebraic iterative reconstruction method.
  • the target reconstruction object is set as discrete volume data, and each voxel is a homogeneous material, and the following reconstruction is established The relationship between the data and the projected image:
  • matrix A is the system matrix, which is determined by the overall imaging equipment
  • matrix T is the image data to be solved
  • P is the projection data
  • N in the matrix is the number of detection units
  • M is the number of voxels
  • the goal of algebraic iterative reconstruction is Solve the above equations, and iteratively correct the target reconstructed image by using the error between the projection data and the real data.
  • the iterative formula is as follows:
  • ⁇ is the relaxation factor, which is adjusted according to the desired reconstruction speed and accuracy.
  • the above formula only considers the error of one ray. Considering all the ray-to-voxel images, the following iterative formula for joint iterative reconstruction can be used to solve:
  • the X-ray emitting end is a bulb.
  • the X-ray receiving end is a flat panel detector.
  • system of the present invention also includes an image cutting module
  • the image cutting module is configured to acquire pixel values of a specific plane in the three-dimensional image when a slice image on a specific plane in the three-dimensional image needs to be acquired, so as to obtain the slice images of different slices.
  • the present invention provides an X-ray tomography system, which not only effectively utilizes the advantages of Tomosynthesis technology in three-dimensional imaging, such as high shooting efficiency and lower dose than CT, but also breaks through the limitation of the three-dimensional imaging range of Tomosynthesis, and satisfies the need for longer imaging on the human body.
  • the continuous pulse shooting and three-dimensional imaging of the area meet the needs of specific clinical diagnosis scenarios including the full length of the human body, the full length of the spine or the full length of the lower limbs.
  • the X-ray tomography system of the present invention realizes that the X-ray transmitting end and the X-ray receiving end move continuously and in the same direction along the vertical or horizontal direction.
  • X-ray pulses form several two-dimensional plane images distributed in the entire imaging area at different angles; and obtain voxel data from multiple two-dimensional images distributed in the entire imaging space at different angles through the image reconstruction algorithm, and reconstruct the three-dimensional image.
  • Image when a slice of a specific plane needs to be obtained, the pixel value of the voxel data in the specific plane is obtained through the multi-plane cutting algorithm, and slice images of different slices are obtained.
  • the present invention can break through the limitation of the existing Tomosynthesis system on the three-dimensional imaging area to a great extent.
  • Figure 1 is a schematic diagram of a wheelchair patient with a large flat-panel gastrointestinal machine Shimadzu SONIALVISION safire II;
  • Figure 2 is a schematic diagram of a stretcher patient photographed by the large flat gastrointestinal machine Shimadzu SONIALVISION safire II;
  • FIG. 3 is an overall structural diagram of a tomographic X-ray imaging system of the present invention.
  • Fig. 4 is the schematic diagram of the multi-angle photographing of the designated inspection site according to the present invention.
  • FIG. 5 is a schematic diagram of the present invention for multi-angle photography of a designated inspection site
  • FIG. 6 is a schematic diagram of an X-ray imaging device in a standing mode of the present invention.
  • FIG. 7 is a schematic diagram of the X-ray imaging device in the lay-flat mode in which the hospital bed 15 is movable and the C-shaped arm 14 is stationary according to the present invention
  • FIG. 8 is a schematic diagram of the X-ray imaging device in the flat-lying mode in which the C-shaped arm 14 is movable and the patient bed 15 is stationary according to the present invention
  • FIG. 9 is a schematic diagram of the X-ray imaging apparatus in the lay-flat mode in which both the C-shaped arm 14 and the patient bed 15 are movable according to the present invention.
  • first”, “second”, etc. are used for descriptive purposes only, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as “first”, “second”, etc., may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more.
  • the terms “installed”, “connected” and “connected” should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements.
  • installed should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements.
  • this embodiment provides a tomographic X-ray imaging system, including: an X-ray imaging module 1 , a two-dimensional image receiving module 2 , and a three-dimensional image reconstruction module 3 ;
  • the X-ray imaging module 1 is configured to use an X-ray imaging device to acquire multi-angle two-dimensional images of a designated inspection part of an object to be imaged.
  • the X-ray imaging module is a two-dimensional image acquisition module at the front end of the present invention, which collects multi-angle two-dimensional images for a designated inspection site to provide data support for subsequent three-dimensional image reconstruction.
  • the present invention does not impose specific restrictions on the X-ray imaging equipment used by the X-ray imaging module, and only needs to be able to collect multi-angle two-dimensional images of a designated inspection site.
  • the adopted X-ray imaging equipment specifically includes:
  • the X-ray emitting end 11 is used for emitting X-rays to the designated inspection site;
  • the X-ray receiving end 12 is configured to receive X-rays after the X-rays emitted by the X-ray emitting end pass through the designated inspection site, and at the same time, the X-ray receiving end and the X-ray emitting end are parallel and parallel during imaging. Synchronous movement, during the movement, the designated inspection site is irradiated with pulses at a certain time interval. With the relative movement of the X-ray emitting end 11, the X-ray receiving end 12 and the designated inspection site, the X-rays are The projection imaging on the X-ray receiving end 12 is constantly changing, and the two-dimensional images of several different angles are obtained.
  • the projection imaging of the X-rays on the X-ray receiving end 12 keeps changing, and several multi-angle two-dimensional images are obtained.
  • the specific principle of the image is as follows: the X-ray emitting end 11 is a tube, and the emitted X-rays are scattered in a conical column with the tube as the center.
  • the X-ray emitting end 11 moves relative to the designated inspection site, there will be a X-rays of different angles are penetrated into the designated inspection part, which means that multiple two-dimensional images of different angles are shot for the designated inspection part.
  • the X-ray imaging device can image the designated examination site in any one of two forms including standing and lying down.
  • the X-ray imaging device further includes: a vertical transmission mechanism 13;
  • the vertical transmission mechanism 13 is used to fix the X-ray transmitting end 11 and the X-ray receiving end 12, and use a motion control system to realize the simultaneous operation of the X-ray transmitting end and the X-ray receiving end;
  • the vertical transmission mechanism 13 may include one or two vertical transmission units; when the vertical transmission unit 13 is one, the X-ray is fixed by means of a C-shaped arm (shown in the figure) The transmitting end 11 and the X-ray receiving end 12 form a stable C-shaped structure and are fixed on the vertical transmission unit 13, and a motion control system is used to control the up and down movement of the C-shaped structure; when the vertical transmission unit 13 is When there are two, the X-ray transmitting end 11 and the X-ray receiving end 12 are respectively fixed on the two vertical transmission units 13, and a motion control system is used to control the X-ray transmitting end and the X-ray receiving end run simultaneously.
  • any form including a column type and a suspension type can be adopted.
  • the X-ray imaging device when the X-ray imaging device performs imaging in the form of lying flat, the X-ray imaging device further includes: a C-shaped arm 14 and a hospital bed 15 ;
  • the C-shaped arm 14 is configured to fix the X-ray emitting end 11 and the X-ray receiving end 12 in an opposite manner;
  • the hospital bed 15 is configured to provide the object to be imaged to lie down;
  • At least one of the C-shaped arm 14 and the hospital bed 15 can move horizontally (as shown in FIG. 7 , the hospital bed 15 is movable, and the C-shaped arm 14 is stationary; as shown in FIG. 8 , the C-shaped arm 14 is movable, and the hospital bed 15 Not moving; as shown in Figure 9, both the C-arm 14 and the hospital bed 15 are movable).
  • the two-dimensional image receiving module 2 is configured to receive the multi-angle two-dimensional images of the designated inspection site acquired in the X-ray imaging module 1 .
  • the two-dimensional image receiving module 2 is configured to acquire and receive the multi-angle two-dimensional images of the designated inspection site captured by the X-ray imaging module 1, and provide the three-dimensional image reconstruction module 3 to the subsequent three-dimensional image reconstruction module 3 for reconstruction.
  • the three-dimensional image reconstruction module 3 is configured to use any image reconstruction algorithm including translation-superposition method, filtered back-projection method, and iterative reconstruction method to reconstruct a three-dimensional image from a plurality of the two-dimensional images of different angles.
  • Image the voxel data formed in the imaging area.
  • the specific reconstruction mode is:
  • the space where the designated inspection site is located is discretized into several rectangular parallelepiped units of the same size, denoted as voxels; wherein, a group of rectangular planes of the voxels are parallel to the X-ray receiving end, and all the centers of mass in the voxels absorb X-rays
  • the voxel center coordinate V(x, y, z) represents the voxel spatial position, x represents the voxel horizontal position, y represents the voxel vertical height position, and z represents the voxel’s distance to the X-ray receiving end;
  • Image reconstruction is to solve the problem of all or part of the voxel X-ray absorptivity A(x, y, z) of the specified inspection site, including translation-superposition method, filtered back-projection method, and iterative reconstruction method, specifically: :
  • H j represents the height position of the jth X-ray emitting end
  • D represents the vertical distance from the X-ray emitting end to the X-ray receiving end, assuming that the X-ray emitting end and the X-ray receiving end move
  • a total of N rays penetrate the voxel V(x i , y i , z 0 )
  • the X-ray emitting end is at a height H j and emits X-rays to penetrate the voxel to obtain the projection data P j , which can be obtained by
  • the translation-superposition method in the following formula is used to obtain the target voxel absorptivity A(x i , y i , z k ):
  • the X-ray emitting end generates cone-beam X-rays, and performs linear projection sampling on the space of the designated inspection site. However, when the X-ray emitting end is at a certain height, the X-rays emitted are not parallel to each other, and it is necessary to convert the X-rays. After rearrangement, a parallel projection environment is formed, and the filtered back projection method can be used.
  • the X-ray emission end at a certain height can be uniquely determined by the spatial direction angle.
  • the range of the ray direction angle depends on the field of view of the radiation source. For X-rays
  • the spatial direction angle ( ⁇ , ⁇ ) and the field of view angle ⁇ of the radiation source are:
  • W represents the height dimension of the X-ray receiving end
  • D represents the vertical distance from the X-ray transmitting end to the X-ray receiving end
  • the X-ray transmitting end can emit the same direction in the process of vertically moving to different heights Hi.
  • the angular ray l( ⁇ , ⁇ , Hi) can form a set of ray sets L that perform parallel linear scans on the space of the designated inspection site and satisfy:
  • a F ( ⁇ x , ⁇ y , ⁇ z ) T F ( ⁇ x , ⁇ y, ⁇ z ) PF ( ⁇ x , ⁇ y, ⁇ z )
  • P F , T F , and A F represent the three-dimensional Fourier transform of P, T, and A, respectively.
  • the following filters can be designed to realize the spatial filtering of three-dimensional projection data:
  • T′ F T s ( ⁇ x , ⁇ y ) ⁇ T P ( ⁇ z ) ⁇ T I ⁇ T F
  • T I , T P , T S , and T' F represent the approximation of the inverse matrix of T F respectively, the modulation filter function in the z direction, the modulation filter function in the xy plane, the actual filter back-projection function, in the Fourier space
  • the 3D projection data is filtered and back-projected, and the 3D volume data to be reconstructed can be obtained through inverse Fourier transform:
  • A(x, y, z) FT -1 (T s ⁇ T P ⁇ T I ⁇ T F ⁇ P F )
  • the reconstruction method includes algebraic iterative reconstruction method.
  • the target reconstruction object is set as discrete volume data, and each voxel is a homogeneous material, and the following reconstruction is established The relationship between the data and the projected image:
  • matrix A is the system matrix, which is determined by the overall imaging equipment
  • matrix T is the image data to be solved
  • P is the projection data
  • N in the matrix is the number of detection units
  • M is the number of voxels
  • the goal of algebraic iterative reconstruction is Solve the above equations, and iteratively correct the target reconstructed image by using the error between the projection data and the real data.
  • the iterative formula is as follows:
  • ⁇ is the relaxation factor, which is adjusted according to the desired reconstruction speed and accuracy.
  • the above formula only considers the error of one ray. Considering all the ray-to-voxel images, the following iterative formula for joint iterative reconstruction can be used to solve:
  • the X-ray emitting end is a bulb.
  • the X-ray receiving end is a flat panel detector.
  • system of the present invention further includes: an image cutting module 4;
  • the image cutting module 4 is configured to acquire pixel values of a specific plane in the three-dimensional image when it is necessary to acquire slice images on a specific plane in the three-dimensional image, so as to obtain the slice images of different slices .
  • the pixel value of any point in the entire three-dimensional space can be obtained.
  • the pixel value of the specific plane in the 3D image is acquired to obtain slice images of different slices.

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Abstract

一种X射线层析成像系统，包括：X射线成像模块(1)，被配置为采用一X射线成像设备获取待成像对象的指定检查部位的多角度的二维影像；二维影像接收模块(2)，被配置为接收在X射线成像模块(1)中获取到的指定检查部位的多角度的二维影像；三维影像重建模块(3)，被配置为采用图像重建算法将多张不同角度的二维影像，重建出三维影像，形成在成像区域内的体素数据。该X射线层析成像系统不仅有效利用了Tomosynthesis技术在三维成像方面拍摄效率高、比CT剂量低的优势，而且突破了Tomosynthesis三维成像范围的限制，满足对人体更长区域的连续脉冲拍摄和三维成像，满足包括人体全长、脊柱全长或下肢全长等特定临床诊断场景的需求。

Description

一种X射线层析成像系统 技术领域
本发明涉及医学成像技术领域，尤其涉及一种X射线层析成像系统。可通过控制X射线源和平板探测器沿垂直或水平方向连续同向移动，并在移动过程中，按指定时间间隔进行脉冲拍摄，从而实现对受试者全身任意指定区域持续拍摄，从而获得受检查区域若干张X射线平面影像。借助本发明中的三维重建算法，对所采集的若干张X射线平面图像进行处理，构建受检查区域的三维影像。
背景技术
断层合成(Tomosynthesis)是一种使用标准X射线设备的成像技术数字平板探测器从不同角度获得的极低剂量投影生成层析图像。这些图像平行于探测器的平面。球管在不连续的位置上多角度投照获取图像，通过移动和叠加投照的图像，任何设定高度的一个物体的断层图像均可以被重建出来。例如，如图1和图2所示的大平板胃肠机岛津SONIALVISION safireⅡ中，在一次扫描下获得连续多层面的高清晰断层图像。
但是，现有能够实现Tomosynthesis功能的X射线成像系统，其在进行层析图像采集时，有的采用平板探测器与射线源反向运动，伴随着射线源角度的旋转；有的采用平板探测器位置不变，射线源围绕平板探测器进行旋转。无论采用哪种现有技术，其三维成像范围都不大，难以满足人体更长区域的三维成像(如全身、全脊柱、全下肢等)，在临床应用上存在一定的局限性。
此外，现有的Tomosynthesis设备控制方式较复杂，机架结构设计与软 件控制成本较高。
发明内容
针对上述问题，本发明的目的在于提供一种X射线层析成像系统。实现X射线发射端和X射线接收端沿垂直或水平方向连续同向移动，在移动的过程中，向位于发射端和接收端中间的成像区域连续发射X脉冲射线，形成若干张不同角度的分布于整个成像区域的二维平面影像；并通过图像重建算法从多张不同角度的分布于整个成像空间的二维影像中获取体素数据，重建出三维影像；当需要获取特定平面的切片时，通过多平面切割算法，获取体素数据在特定平面内的像素值，得到不同断层的切片影像。本发明可在很大程度上突破现有Tomosynthesis系统在三维成像区域上的限制。
本发明的上述发明目的是通过以下技术方案得以实现的：
一种层析X射线成像系统，包括：X射线成像模块、二维影像接收模块、三维影像重建模块；
所述X射线成像模块，被配置为采用一X射线成像设备获取待成像对象的指定检查部位的多角度的二维影像；
所述二维影像接收模块，被配置为接收在所述X射线成像模块中获取到的所述指定检查部位的多角度的所述二维影像；
所述三维影像重建模块，被配置为采用包括平移-叠加法、滤波反投影法、迭代重建法在内的任意一种图像重建算法将多张不同角度的所述二维影像，重建出三维影像，形成在成像区域内的体素数据。
进一步地，在所述X射线成像模块中，采用的所述X射线成像设备具体 包括：
X射线发射端，用于向所述指定检查部位发射X射线；
X射线接收端，用于在所述X射线发射端发射的X射线穿过所述指定检查部位之后接收X射线，同时所述X射线接收端与所述X射线发射端在成像时平行且同步运动，在运动过程中以某一时间间隔脉冲照射所述指定检查部位，随着所述X射线发射端、所述X射线接收端与所述指定检查部位的相对运动，X射线在所述X射线接收端上的投影成像不停变化，得到若干不同角度的所述二维影像。
进一步地，还包括：所述X射线成像设备采用包括站立、平躺在内的两种任意一种形式对所述指定检查部位进行成像。
进一步地，当所述X射线成像设备采用站立的形式进行成像时，所述X射线成像设备，还包括：垂直传动机构；
所述垂直传动机构，用于固定所述X射线发射端和所述X射线接收端，并利用运动控制系统实现所述X射线发射端和所述X射线接收端同时运行；
其中，所述垂直传动机构可以包括一个或两个垂直传动单元；当所述垂直传动单元为一个时，采用包括C型臂在内的方式固定所述X射线发射端和所述X射线接收端，形成一稳定的C型结构固定于所述垂直传动单元上，采用运动控制系统控制所述C型结构上下运动；当所述垂直传动单元为两个时，分别将所述X射线发射端和所述X射线接收端固定于两个所述垂直传动单元上，采用运动控制系统控制所述X射线发射端和所述X射线接收端同时运行。
进一步地，还包括：所述垂直传动机构采用包括立柱型、悬吊型在内的任意一种形式。
进一步地，当所述X射线成像设备采用平躺的形式进行成像时，所述X射线成像设备，还包括：C型臂和病床；
所述C型臂，被配置为用于以相对的形式固定所述X射线发射端和所述X射线接收端；
所述病床，被配置为用于提供给所述待成像对象平躺；
其中，所述C型臂和所述病床中至少包括一个可以水平移动。
进一步地，所述三维影像重建模块，具体的重建模式为：
将所述指定检查部位所在的空间离散为若干大小相同的长方体单元，记为体素；其中，体素的一组长方形平面平行于所述X射线接收端，体素内所有质心对X射线吸收率相同，体素中心坐标V(x,y,z)表示体素空间位置，x表示体素水平位置，y表示体素垂直高度位置，z表示体素到所述X射线接收端的距离；
图像重建即求解所述指定检查部位全部或部分体素X射线吸收率A(x,y,z)的问题，包括平移-叠加法、滤波反投影法、迭代重建法在内的方法，具体为：
A：平移-叠加法，用K个等间距平行于所述X射线接收端的平面截取所述指定检查部位的所在空间，可以得到K个目标平面，每个所述目标平面内包含M个待求解体素，所述目标平面内的所有体素到所述X射线接收端的垂直距离相同，所述X射线发射端到所述X射线接收端的垂直距离相同，因此拍摄同一所述目标平面体素的放大率相同；
对于所述目标平面z＝z k内任意体素V(x i,y i,z k)在所述X射线接收器平面的投影v(x ij,y ij)有：
Figure PCTCN2021087423-appb-000001
Figure PCTCN2021087423-appb-000002
式中H j表示第j个所述X射线发射端的高度位置，D表示所述X射线发射端到所述X射线接收端的垂直距离，假设所述X射线发射端和所述X射线接收端运动全过程中，共有N条射线穿透体素V(x i,y i,z 0)，所述X射线发射端处于高度H j发出X射线穿透体素得到投影数据P j，则可通过下式中平移-叠加法求得目标体素吸收率A(x i,y i,z k):
Figure PCTCN2021087423-appb-000003
式中h j表示第j个所述X射线接收端的中心高度位置，遍历所述目标平面内所有待求解体素Vi，即可获得所述目标平面内全部待求解体素的X射线吸收率A i(i＝1,2,…,M)，遍历所有待求解的所述目标平面z＝z k(k＝1,2,…,K)，即可获得所述指定检查部位所在空间的三维体数据；
B)滤波反投影法，基于Rodon变换，在傅里叶空间上使用滤波函数处理投影数据，再将滤波后的投影数据反投影重建出目标体数据；
所述X射线发射端产生锥形束X射线，对所述指定检查部位的空间进行线性投影采样，但所述X射线发射端处于某一高度时发出的X射线互不平行，需要将X射线重排后形成平行投影环境，才可以使用滤波反投影法，所述X射线发射端处于某一高度发出X射线可由空间方向角唯一确定，射线方向角 范围取决于放射源视野大小，对于X射线空间方向角(φ,θ)与放射源视野角α有：
Figure PCTCN2021087423-appb-000004
Figure PCTCN2021087423-appb-000005
式中W表示所述X射线接收端的高度尺寸，D表示所述X射线发射端到所述X射线接收端的垂直距离，所述X射线发射端垂直运动到不同高度H i的过程中可以发出相同方向角射线l(φ,θ,H i)，可以构成一组对所述指定检查部位空间进行平行线性扫描的射线组L满足：
Figure PCTCN2021087423-appb-000006
对射线组L内所有射线投影数据进行重排，可以得到一维反投影环境；遍历所有方向角组合即可得到三维反投影环境I(φ，θ，H)，对于所述指定检查部位的三维空间体素吸收率A(x,y,z)与三维投影数据P(x,y,z)有：
Figure PCTCN2021087423-appb-000007
Figure PCTCN2021087423-appb-000008
经由三维傅里叶变换，可以得到：
A F(ω x，ω y，ω z)＝T F(ω x，ω y，ω z)·P F(ω x，ω y，ω z)
式中P F,T F,A F分别表示P,T,A的三维傅里叶变换，设计如下滤波器可以实现三维投影数据的空间滤波处理：
T′ F＝T s(ω x，ω y)，T P(ω z)·T I·T F
式中T I,T P,T S,T’ F分别表示T F逆矩阵的近似，z方向上的调制滤波函 数，x-y平面内的调制滤波函数，实际滤波反投影函数,在傅里叶空间中对三维投影数据进行滤波反投影，经由傅里叶逆变换即可得到待重建三维体数据：
A(x，y，z)＝FT -1(T s·T P·T I·T F·P F)
C：迭代重建法，对投影数据完备性不高的迭代法进行重建，重建方式包括代数迭代重建法，将目标重建物体设定为离散体积数据，且每个体素为均匀物质，建立如下的重建数据与投影影像的关系：
Figure PCTCN2021087423-appb-000009
其中，矩阵A为系统矩阵，为整体影像设备决定，矩阵T为待求解的图像数据，P为投影数据，矩阵中N为探测单元数，M为体素个数，代数迭代重建的目标即为求解上述方程组，通过采用投影数据与真实数据的误差对目标重建图像进行迭代修正，其迭代公式如下：
Figure PCTCN2021087423-appb-000010
其中γ为松弛因子，根据期望重建速度与精度进行调整，上式为只考虑一条射线的误差，综合考虑所有射线对体素的影像，可采用如下联合迭代重建的迭代公式进行求解：
Figure PCTCN2021087423-appb-000011
进一步地，所述X射线发射端为球管。
进一步地，所述X射线接收端为平板探测器。
进一步地，本发明的系统还包括影像切割模块；
所述影像切割模块，被配置为用于当需要获取所述三维影像中的特定平面上的切片影像时，获取特定平面在所述三维影像中的像素值，得到不同断层的所述切片影像。
与现有技术相比，本发明的有益效果是：
通过本发明提供了一种X射线层析成像系统，不仅有效利用了Tomosynthesis技术在三维成像方面拍摄效率高、比CT剂量低的优势，而且突破了Tomosynthesis三维成像范围的限制，满足对人体更长区域的连续脉冲拍摄和三维成像，满足包括人体全长、脊柱全长或下肢全长等特定临床诊断场景的需求。
本发明的X射线层析成像系统，实现了X射线发射端和X射线接收端沿垂直或水平方向连续同向移动，在移动的过程中，向位于发射端和接收端中间的成像区域连续发射X脉冲射线，形成若干张不同角度的分布于整个成像区域的二维平面影像；并通过图像重建算法从多张不同角度的分布于整个成像空间的二维影像中获取体素数据，重建出三维影像；当需要获取特定平面的切片时，通过多平面切割算法，获取体素数据在特定平面内的像素值，得到不同断层的切片影像。本发明可在很大程度上突破现有Tomosynthesis系统在三维成像区域上的限制。
附图说明
图1为大平板胃肠机岛津SONIALVISION safireⅡ的轮椅患者摄影示意图；
图2为大平板胃肠机岛津SONIALVISION safireⅡ的担架患者摄影示意 图；
图3为本发明一种层析X射线成像系统的整体结构图；
图4为本发明对指定检查部位多角度拍摄的示意图；
图5为本发明对指定检查部位多角度拍摄的原理图；
图6为本发明站立模式的X射线成像设备的示意图；
图7为本发明病床15可动，C型臂14不动的平躺模式的X射线成像设备的示意图；
图8为本发明C型臂14可动，病床15不动的平躺模式的X射线成像设备的示意图；
图9为本发明C型臂14和病床15均可动的平躺模式的X射线成像设备的示意图。
附图标记：
11、X射线发射端；12、X射线接收端；13、垂直传动单元；14、C型臂；15、病床；16、踏台。
具体实施方式
除非另作定义，在本说明书和权利要求书中使用的技术术语或者科学术语应当为本发明所属技术领域内具有一般技能的人士所理解的通常意义。
在本发明的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示 的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
此外，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。在本发明的描述中，除非另有说明，“多个”的含义是两个或两个以上。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以通过具体情况理解上述术语在本发明中的具体含义。
下面将参考附图并结合实施例来详细说明本发明。需要指出的是，在这些实施方式的具体描述过程中，为了进行简明扼要的描述，本说明书不可能对实际的实施方式的所有特征均作详尽的描述。
实施例
如图3所示，本实施例提供了一种层析X射线成像系统，包括：X射线成像模块1、二维影像接收模块2、三维影像重建模块3；
所述X射线成像模块1，被配置为采用一X射线成像设备获取待成像对象的指定检查部位的多角度的二维影像。
具体地，X射线成像模块为本发明前端的二维影像采集模块，以针对指定检查部位采集多角度的二维影像，为后续三维影像的重建提供数据支持。
需要说明的是，本发明对X射线成像模块所采用的X射线成像设备不做具体的限制，只需要能够采集到指定检查部位多角度的二维影像即可。
以下为具体的X射线成像设备的具体举例：
在所述X射线成像模块中，采用的所述X射线成像设备具体包括：
X射线发射端11，用于向所述指定检查部位发射X射线；
X射线接收端12，用于在所述X射线发射端发射的X射线穿过所述指定检查部位之后接收X射线，同时所述X射线接收端与所述X射线发射端在成像时平行且同步运动，在运动过程中以某一时间间隔脉冲照射所述指定检查部位，随着所述X射线发射端11、所述X射线接收端12与所述指定检查部位的相对运动，X射线在所述X射线接收端12上的投影成像不停变化，得到若干不同角度的所述二维影像。
如图4和5所示，当X射线发射端11和X射线接收端12与指定检查部位相对运动，X射线在X射线接收端12上的投影成像不停变化，得到若干多角度的二维影像的具体的原理为：X射线发射端11为球管，发射出的X射线以球管为中心呈锥形柱散射出去，当X射线发射端11相对于指定检查部位运动时，将会有不同角度的X射线打入指定检查部位，也就对指定检查部位拍摄出多个不同角度的二维影像。
进一步地，所述X射线成像设备可以采用包括站立、平躺在内的两种任意一种形式对所述指定检查部位进行成像。
如图6所示，为站立模式的X射线成像设备的示意图，当所述X射线成 像设备采用站立的形式进行成像时，所述X射线成像设备，还包括：垂直传动机构13；
所述垂直传动机构13，用于固定所述X射线发射端11和所述X射线接收端12，并利用运动控制系统实现所述X射线发射端和所述X射线接收端同时运行；
其中，所述垂直传动机构13可以包括一个或两个垂直传动单元；当所述垂直传动单元13为一个时，采用包括C型臂(图中为示出)在内的方式固定所述X射线发射端11和所述X射线接收端12，形成一稳定的C型结构固定于所述垂直传动单元13上，采用运动控制系统控制所述C型结构上下运动；当所述垂直传动单元13为两个时，分别将所述X射线发射端11和所述X射线接收端12固定于两个所述垂直传动单元13上，采用运动控制系统控制所述X射线发射端和所述X射线接收端同时运行。
进一步地，对于所述垂直传动机构13，可以采用包括立柱型、悬吊型在内的任意一种形式。
如图7-9所示，当所述X射线成像设备采用平躺的形式进行成像时，所述X射线成像设备，还包括：C型臂14和病床15；
所述C型臂14，被配置为用于以相对的形式固定所述X射线发射端11和所述X射线接收端12；
所述病床15，被配置为用于提供给所述待成像对象平躺；
其中，所述C型臂14和所述病床15中至少包括一个可以水平移动(如图7为病床15可动，C型臂14不动；如图8为C型臂14可动，病床15不动；如图9为C型臂14和病床15均可动)。
所述二维影像接收模块2，被配置为接收在所述X射线成像模块1中获取到的所述指定检查部位的多角度的所述二维影像。
具体地，二维影像接收模块2用于获取并接收X射线成像模块1中拍摄的指定检查部位的多角度的二维影像，并提供给后续的三维影像重建模块3进行三维影像的重建。
所述三维影像重建模块3，被配置为采用包括平移-叠加法、滤波反投影法、迭代重建法在内的任意一种图像重建算法将多张不同角度的所述二维影像，重建出三维影像，形成在成像区域内的体素数据。
进一步地，所述三维影像重建模块，具体的重建模式为：
将所述指定检查部位所在的空间离散为若干大小相同的长方体单元，记为体素；其中，体素的一组长方形平面平行于所述X射线接收端，体素内所有质心对X射线吸收率相同，体素中心坐标V(x,y,z)表示体素空间位置，x表示体素水平位置，y表示体素垂直高度位置，z表示体素到所述X射线接收端的距离；
图像重建即求解所述指定检查部位全部或部分体素X射线吸收率A(x,y,z)的问题，包括平移-叠加法、滤波反投影法、迭代重建法在内的方法，具体为：
A：平移-叠加法，用K个等间距平行于所述X射线接收端的平面截取所述指定检查部位的所在空间，可以得到K个目标平面，每个所述目标平面内包含M个待求解体素，所述目标平面内的所有体素到所述X射线接收端的垂直距离相同，所述X射线发射端到所述X射线接收端的垂直距离相同，因此拍摄同一所述目标平面体素的放大率相同；
对于所述目标平面z＝z k内任意体素V(x i,y i,z k)在所述X射线接收器平面的投影v(x ij,y ij)有：
Figure PCTCN2021087423-appb-000012
Figure PCTCN2021087423-appb-000013
式中H j表示第j个所述X射线发射端的高度位置，D表示所述X射线发射端到所述X射线接收端的垂直距离，假设所述X射线发射端和所述X射线接收端运动全过程中，共有N条射线穿透体素V(x i,y i,z 0)，所述X射线发射端处于高度H j发出X射线穿透体素得到投影数据P j，则可通过下式中平移-叠加法求得目标体素吸收率A(x i,y i,z k):
Figure PCTCN2021087423-appb-000014
式中h j表示第j个所述X射线接收端的中心高度位置，遍历所述目标平面内所有待求解体素Vi，即可获得所述目标平面内全部待求解体素的X射线吸收率A i(i＝1,2,…,M)，遍历所有待求解的所述目标平面z＝z k(k＝1,2,…,K)，即可获得所述指定检查部位所在空间的三维体数据；
B)滤波反投影法，基于Rodon变换，在傅里叶空间上使用滤波函数处理投影数据，再将滤波后的投影数据反投影重建出目标体数据；
所述X射线发射端产生锥形束X射线，对所述指定检查部位的空间进行线性投影采样，但所述X射线发射端处于某一高度时发出的X射线互不平行， 需要将X射线重排后形成平行投影环境，才可以使用滤波反投影法，所述X射线发射端处于某一高度发出X射线可由空间方向角唯一确定，射线方向角范围取决于放射源视野大小，对于X射线空间方向角(φ,θ)与放射源视野角α有：
Figure PCTCN2021087423-appb-000015
Figure PCTCN2021087423-appb-000016
式中W表示所述X射线接收端的高度尺寸，D表示所述X射线发射端到所述X射线接收端的垂直距离，所述X射线发射端垂直运动到不同高度Hi的过程中可以发出相同方向角射线l(φ,θ,Hi)，可以构成一组对所述指定检查部位空间进行平行线性扫描的射线组L满足：
Figure PCTCN2021087423-appb-000017
对射线组L内所有射线投影数据进行重排，可以得到一维反投影环境；遍历所有方向角组合即可得到三维反投影环境T(φ,θ,H)，对于所述指定检查部位的三维空间体素吸收率A(x,y,z)与三维投影数据P(x,y,z)有：
Figure PCTCN2021087423-appb-000018
Figure PCTCN2021087423-appb-000019
经由三维傅里叶变换，可以得到：
A F(ω x，ω y，ω z)＝T F(ω x，ω y，ω z)·P F(ω x，ω y，ω z)
式中P F,T F,A F分别表示P,T,A的三维傅里叶变换，设计如下滤波器可以实现三维投影数据的空间滤波处理：
T′ F＝T s(ω x，ω y)·T P(ω z)·T I·T F
式中T I,T P,T S,T’ F分别表示T F逆矩阵的近似，z方向上的调制滤波函数，x-y平面内的调制滤波函数，实际滤波反投影函数,在傅里叶空间中对三维投影数据进行滤波反投影，经由傅里叶逆变换即可得到待重建三维体数据：
A(x，y，z)＝FT -1(T s·T P·T I·T F·P F)
C：迭代重建法，对投影数据完备性不高的迭代法进行重建，重建方式包括代数迭代重建法，将目标重建物体设定为离散体积数据，且每个体素为均匀物质，建立如下的重建数据与投影影像的关系：
Figure PCTCN2021087423-appb-000020
其中，矩阵A为系统矩阵，为整体影像设备决定，矩阵T为待求解的图像数据，P为投影数据，矩阵中N为探测单元数，M为体素个数，代数迭代重建的目标即为求解上述方程组，通过采用投影数据与真实数据的误差对目标重建图像进行迭代修正，其迭代公式如下：
Figure PCTCN2021087423-appb-000021
其中γ为松弛因子，根据期望重建速度与精度进行调整，上式为只考虑一条射线的误差，综合考虑所有射线对体素的影像，可采用如下联合迭代重建的迭代公式进行求解：
Figure PCTCN2021087423-appb-000022
以上是对三维重建算法的具体举例，还可以有其他的三维重建的方法均 可以应用于本发明，本发明不做具体的限制。
进一步地，所述X射线发射端为球管。
进一步地，所述X射线接收端为平板探测器。
进一步地，本发明的系统还包括：影像切割模块4；
所述影像切割模块4，被配置为用于当需要获取所述三维影像中的特定平面上的切片影像时，获取特定平面在所述三维影像中的像素值，得到不同断层的所述切片影像。
具体地，当经过三维影像重建模块3的三维重建之后，整个三维空间中的任意一个点的像素值均可以获取到。当需要获取三维影像中特定平面上的切片影像时，获取特定平面在三维影像中的像素值，得到不同断层的切片影像。
以上所述仅是本发明的优选实施方式，本发明的保护范围并不仅局限于上述实施例，凡属于本发明思路下的技术方案均属于本发明的保护范围。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理前提下的若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (10)

  1. 一种层析X射线成像系统，其特征在于，包括：X射线成像模块、二维影像接收模块、三维影像重建模块；
    所述X射线成像模块，被配置为采用一X射线成像设备获取待成像对象的指定检查部位的多角度的二维影像；
    所述二维影像接收模块，被配置为接收在所述X射线成像模块中获取到的所述指定检查部位的多角度的所述二维影像；
    所述三维影像重建模块，被配置为采用包括平移-叠加法、滤波反投影法、迭代重建法在内的任意一种图像重建算法将多张不同角度的所述二维影像，重建出三维影像，形成在成像区域内的体素数据。
  2. 根据权利要求1所述的层析X射线成像系统，其特征在于，在所述X射线成像模块中，采用的所述X射线成像设备具体包括：
    X射线发射端，用于向所述指定检查部位发射X射线；
    X射线接收端，用于在所述X射线发射端发射的X射线穿过所述指定检查部位之后接收X射线，同时所述X射线接收端与所述X射线发射端在成像时平行且同步运动，在运动过程中以某一时间间隔脉冲照射所述指定检查部位，随着所述X射线发射端、所述X射线接收端与所述指定检查部位的相对运动，X射线在所述X射线接收端上的投影成像不停变化，得到若干不同角度的所述二维影像。
  3. 根据权利要求2所述的层析X射线成像系统，其特征在于，还包括：所述X射线成像设备采用包括站立、平躺在内的两种任意一种形式对所述指定检查部位进行成像。
  4. 根据权利要求3所述的层析X射线成像系统，其特征在于， 当所述X射线成像设备采用站立的形式进行成像时，所述X射线成像设备，还包括：垂直传动机构；
    所述垂直传动机构，用于固定所述X射线发射端和所述X射线接收端，并利用运动控制系统实现所述X射线发射端和所述X射线接收端同时运行；
    其中，所述垂直传动机构可以包括一个或两个垂直传动单元；当所述垂直传动单元为一个时，采用包括C型臂在内的方式固定所述X射线发射端和所述X射线接收端，形成一稳定的C型结构固定于所述垂直传动单元上，采用运动控制系统控制所述C型结构上下运动；当所述垂直传动单元为两个时，分别将所述X射线发射端和所述X射线接收端固定于两个所述垂直传动单元上，采用运动控制系统控制所述X射线发射端和所述X射线接收端同时运行。
  5. 根据权利要求4所述的层析X射线成像系统，其特征在于，还包括：所述垂直传动机构采用包括立柱型、悬吊型在内的任意一种形式。
  6. 根据权利要求3所述的层析X射线成像系统，其特征在于，当所述X射线成像设备采用平躺的形式进行成像时，所述X射线成像设备，还包括：C型臂和病床；
    所述C型臂，被配置为用于以相对的形式固定所述X射线发射端和所述X射线接收端；
    所述病床，被配置为用于提供给所述待成像对象平躺；
    其中，所述C型臂和所述病床中至少包括一个可以水平移动。
  7. 根据权利要求2所述的层析X射线成像系统，其特征在于，所述三维影像重建模块，具体的重建模式为：
    将所述指定检查部位所在的空间离散为若干大小相同的长方体单元，记为体素；其中，体素的一组长方形平面平行于所述X射线接收端，体素内所有质心对X射线吸收率相同，体素中心坐标V(x,y,z)表示体素空间位置，x表示体素水平位置，y表示体素垂直高度位置，z表示体素到所述X射线接收端的距离；
    图像重建即求解所述指定检查部位全部或部分体素X射线吸收率A(x,y,z)的问题，包括平移-叠加法、滤波反投影法、迭代重建法在内的方法，具体为：
    A：平移-叠加法，用K个等间距平行于所述X射线接收端的平面截取所述指定检查部位的所在空间，可以得到K个目标平面，每个所述目标平面内包含M个待求解体素，所述目标平面内的所有体素到所述X射线接收端的垂直距离相同，所述X射线发射端到所述X射线接收端的垂直距离相同，因此拍摄同一所述目标平面体素的放大率相同；
    对于所述目标平面z＝z k内任意体素V(x i,y i,z k)在所述X射线接收器平面的投影v(x ij,y ij)有：
    Figure PCTCN2021087423-appb-100001
    Figure PCTCN2021087423-appb-100002
    式中H j表示第j个所述X射线发射端的高度位置，D表示所述X 射线发射端到所述X射线接收端的垂直距离，假设所述X射线发射端和所述X射线接收端运动全过程中，共有N条射线穿透体素V(x i,y i,z 0)，所述X射线发射端处于高度H j发出X射线穿透体素得到投影数据P j，则可通过下式中平移-叠加法求得目标体素吸收率A(x i,y i,z k):
    Figure PCTCN2021087423-appb-100003
    式中h j表示第j个所述X射线接收端的中心高度位置，遍历所述目标平面内所有待求解体素Vi，即可获得所述目标平面内全部待求解体素的X射线吸收率Ai(i＝1,2,…,M)，遍历所有待求解的所述目标平面z＝z k(k＝1,2,…,K)，即可获得所述指定检查部位所在空间的三维体数据；
    B)滤波反投影法，基于Rodon变换，在傅里叶空间上使用滤波函数处理投影数据，再将滤波后的投影数据反投影重建出目标体数据；
    所述X射线发射端产生锥形束X射线，对所述指定检查部位的空间进行线性投影采样，但所述X射线发射端处于某一高度时发出的X射线互不平行，需要将X射线重排后形成平行投影环境，才可以使用滤波反投影法，所述X射线发射端处于某一高度发出X射线可由空间方向角唯一确定，射线方向角范围取决于放射源视野大小，对于X射线空间方向角(φ,θ)与放射源视野角α有：
    Figure PCTCN2021087423-appb-100004
    Figure PCTCN2021087423-appb-100005
    式中W表示所述X射线接收端的高度尺寸，D表示所述X射线发射端到所述X射线接收端的垂直距离，所述X射线发射端垂直运动到不同高度Hi的过程中可以发出相同方向角射线l(φ,θ,Hi)，可以构成一组对所述指定检查部位空间进行平行线性扫描的射线组L满足：
    Figure PCTCN2021087423-appb-100006
    对射线组L内所有射线投影数据进行重排，可以得到一维反投影环境；遍历所有方向角组合即可得到三维反投影环境T(φ,θ,H)，对于所述指定检查部位的三维空间体素吸收率A(x,y,z)与三维投影数据P(x,y,z)有：
    Figure PCTCN2021087423-appb-100007
    Figure PCTCN2021087423-appb-100008
    经由三维傅里叶变换，可以得到：
    A F(ω x，ω y，ω z)＝T F(ω x，ω y，ω z)·P F(ω x，ω y，ω z)
    式中P F,T F,A F分别表示P,T,A的三维傅里叶变换，设计如下滤波器可以实现三维投影数据的空间滤波处理：
    T′ F＝T s(ω x，ω y)·T P(ω z)·T I·T F
    式中T I,T P,T S,T’ F分别表示T F逆矩阵的近似，z方向上的调 制滤波函数，x-y平面内的调制滤波函数，实际滤波反投影函数,在傅里叶空间中对三维投影数据进行滤波反投影，经由傅里叶逆变换即可得到待重建三维体数据：
    A(x，y，z)＝FT -1(T s·T P·T I·T F·P F)
    C：迭代重建法，对投影数据完备性不高的迭代法进行重建，重建方式包括代数迭代重建法，将目标重建物体设定为离散体积数据，且每个体素为均匀物质，建立如下的重建数据与投影影像的关系：
    Figure PCTCN2021087423-appb-100009
    其中，矩阵A为系统矩阵，为整体影像设备决定，矩阵T为待求解的图像数据，P为投影数据，矩阵中N为探测单元数，M为体素个数，代数迭代重建的目标即为求解上述方程组，通过采用投影数据与真实数据的误差对目标重建图像进行迭代修正，其迭代公式如下：
    Figure PCTCN2021087423-appb-100010
    其中γ为松弛因子，根据期望重建速度与精度进行调整，上式为只考虑一条射线的误差，综合考虑所有射线对体素的影像，可采用如下联合迭代重建的迭代公式进行求解：
    Figure PCTCN2021087423-appb-100011
  8. 根据权利要求2所述的层析X射线成像系统，其特征在于，还包括：所述X射线发射端为球管。
  9. 根据权利要求2所述的层析X射线成像系统，其特征在于，还包括：所述X射线接收端为平板探测器。
  10. 根据权利要求1所述的层析X射线成像系统，其特征在于，还包括：影像切割模块；
    所述影像切割模块，被配置为用于当需要获取所述三维影像中的特定平面上的切片影像时，获取特定平面在所述三维影像中的像素值，得到不同断层的所述切片影像。
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