CN114004745A - CT (computed tomography) horizontal scanning image reconstruction method, system, equipment and readable storage medium - Google Patents
CT (computed tomography) horizontal scanning image reconstruction method, system, equipment and readable storage medium Download PDFInfo
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Abstract
The invention provides a CT (computed tomography) flat-scan image reconstruction method, a system, equipment and a readable storage medium, which relate to the field of medical image processing and comprise the following steps: calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table; creating a CT flat scan data set, and acquiring a weight coefficient set corresponding to the flat scan collimator in a storage table; acquiring corresponding weight coefficients according to each voxel position and the rotation angle at which the ray is positioned based on the flat scanning data set so as to perform back projection weighted summation to acquire a voxel value at the detector position; the detector moves in the Z direction relative to the scanning object in the flat scanning process, voxel values of the detector at all positions of the scanning object in the Z direction are calculated, three-dimensional images are generated according to the voxel values of all detector positions and are sequentially spliced to obtain reconstructed images, and the problems that a large amount of computing resources are consumed in the image reconstruction process, and the requirements on computer hardware configuration are high are solved.
Description
Technical Field
The invention relates to the field of medical image processing, in particular to a CT (computed tomography) flat scan image reconstruction method, a system, equipment and a readable storage medium.
Background
With the continuous development of imaging technology, medical imaging diagnosis plays an extremely important role in modern medical treatment, plays an important role in clinical diagnosis, teaching and scientific research and the like, and CT flat scan is also called common scan, which refers to scan without iodine-containing contrast agent in veins. After a CT (computed tomography) horizontal scanning data set is obtained, data needs to be reconstructed, and a large amount of computing resources occupied by reconstruction of a three-dimensional image restrict the reconstruction of the image rate and influence the clinical use efficiency.
In the process of parallel scan data reconstruction, the corresponding voxel value is obtained mainly by using the weighted sum of parallel conjugate rays, but the used weighting coefficients are calculated in real time, so that the ratio of calculation resources is more than half.
Disclosure of Invention
In order to overcome the above technical defects, the present invention provides a CT flatscan image reconstruction method, system, device and readable storage medium, which are used to solve the problems of consuming a large amount of computing resources, having low efficiency and having high requirements for computer hardware configuration during image reconstruction.
The invention discloses a CT (computed tomography) flat scan image reconstruction method, which comprises the following steps of:
calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table;
the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the positions of the rays at a rotation angle;
creating a CT flat-scan data set, determining a flat-scan collimator, and acquiring a weight coefficient set corresponding to the flat-scan collimator in a storage table;
acquiring a detector position and each voxel position of a scanned object under the detector position based on the flat scanning data set, and acquiring corresponding weight coefficients in a weight coefficient set matched and corresponding to the flat scanning collimator according to each voxel position and the rotation angle of the ray position so as to perform back projection weighted summation to acquire a voxel value under the detector position;
and moving the detector in the Z direction relative to the scanning object in the flat scanning process, calculating voxel values of the detector at all positions of the scanning object in the Z direction, generating three-dimensional images according to the voxel values of all detector positions, and sequentially splicing to obtain a reconstructed image.
Preferably, the method includes calculating a set of weight coefficients corresponding to each collimator in a collimator group to generate a storage table, including the following steps:
acquiring a collimator in a collimator group, and acquiring opening parameters of the collimator and the Z-direction length of a detector module;
a ray at a rotation angle passes through any voxel position to a detector unit on a detector module, the Z position of the detector unit on the detector module is recorded as a detection position, the distance between the detection position and a central detector unit on the detector module is obtained, and a weight coefficient corresponding to the voxel position is calculated according to the distance and a detector module shape adjusting parameter;
normalizing the parallel conjugate weight coefficients based on the weight coefficients corresponding to all pixel positions to obtain a weight coefficient set corresponding to the collimator;
and calculating each collimator in the collimator group until a weight coefficient set corresponding to all the collimators is obtained so as to generate a storage table.
Preferably, the distance of the detection position from a central detector unit on the detector module is acquired, including the following:
the distance of the detection position from the central detector unit on the detector module is calculated according to the following formula,
wherein q isiIs a distance, ziA detection position of the ray i, wherein the detection position is a position in a Z direction on the detector module when the ray passes through a voxel position to a detector unit on the detector module, ZcentIs the Z-direction position of the central detector unit on the detector module, and dz is the Z-direction length of the detector module.
Preferably, the calculating a weighting coefficient corresponding to each voxel position according to the distance and the detector shape adjustment parameter includes the following steps:
calculating a weight coefficient corresponding to any voxel position according to the following formula:
wherein, w(α,z)Is a weight coefficient, qiFor distance, Q is the detector module shape adjustment parameter, and dz is the Z-direction length of the detector module.
Preferably, the normalizing operation is performed on the weight coefficients of the parallel conjugates, and includes the following steps:
determining the weight coefficient of the parallel conjugate according to the rotation angle of the ray, and carrying out normalization calculation according to the following formula:
wherein, w(α,z)，w(α+π,z)Is a pair of 180 deg. conjugated weight coefficients.
Preferably, after the generating the storage table, the following is included:
correspondingly storing the voxel positions and the weight coefficients of the rays under the rotation angles, and storing the voxel positions and the weight coefficients on a hard disk;
wherein the weight coefficient is stored in a format of
The storage space on the hard disk is N2And the multiplied by S multiplied by alpha multiplied by 4Bytes, N is the size of the scanned object in an XY plane, S is the row number of the detector units on the detector module, alpha is the circumferential scanning angle of the detector at one Z-direction position of the scanned object, and 4Bytes is used for storing data in a floating point number mode.
Preferably, the acquiring of the voxel value at the detector position according to the position of each voxel and the rotation angle at which the ray is located, in the weight coefficient set corresponding to the flat-scan collimator matching, to perform back projection weighted summation, includes the following:
the voxel values are calculated according to the following formula:
wherein the content of the first and second substances,
for the weight coefficients obtained from the memory table, p(α,l,z)The (x, y, z) is the geometric spatial position of the voxel of the scanned object, and l represents the position of the channel direction of the detector module.
The invention also provides a CT flat scanning image reconstruction system which is matched with the CT equipment for use and comprises:
the first processing module is used for calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table; the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the positions of the rays at a rotation angle;
the weight matching module is used for creating a CT flat scanning data set, determining a flat scanning collimator and acquiring a weight coefficient set corresponding to the flat scanning collimator in a storage table;
the calculation module is used for acquiring a detector position and each voxel position of a scanned object under the detector position based on the flat scanning data set, and acquiring corresponding weight coefficients in a weight coefficient set matched and corresponding to the flat scanning collimator according to each voxel position and the rotation angle of the ray position so as to perform back projection weighted summation to acquire a voxel value under the detector position;
and the second processing module is used for moving the detector relative to the scanning object in the Z direction in flat scanning, calculating voxel values when the detector is positioned at each position of the scanning object in the Z direction, generating three-dimensional images according to the voxel values at each detector position and sequentially splicing to obtain a reconstructed image.
The present invention also provides a computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the reconstruction method described above when executing the computer program.
The invention also provides a computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the reconstruction method described above.
After the technical scheme is adopted, compared with the prior art, the method has the following beneficial effects:
the CT flat scan image reconstruction method, the CT flat scan image reconstruction system, the CT flat scan image reconstruction equipment and the readable storage medium calculate the weighting coefficients in advance and store the weighting coefficients separately according to a preset format, after a CT flat scan module is obtained, corresponding weighting coefficients are obtained in a storage table according to the positions of all voxels and the rotating angles of the positions of rays and are used for back projection weighted summation, a three-dimensional image is generated based on the voxel values obtained by each circle scan and is spliced into a reconstructed image in sequence, all the weighting coefficients do not need to be repeatedly calculated again in image reconstruction, the weighting coefficients can be quickly obtained in a table look-up mode, calculation of the weighting coefficients is simplified, and the problems that a large amount of calculation resources are consumed in the image reconstruction process, the efficiency is low, and the requirement on computer hardware configuration is high are solved.
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FIG. 1 is a schematic structural diagram of a CT scan-parallel image reconstruction method, system, device and readable storage medium according to a first embodiment of the present invention;
FIG. 2 is a schematic flowchart of a CT scan-parallel image reconstruction method, system, device and readable storage medium according to a first embodiment of the present invention;
fig. 3 is a schematic flow chart illustrating a process of calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table according to a CT plain scan image reconstruction method, system, device and readable storage medium according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a CT plain scan image reconstruction method, system, apparatus, and readable storage medium according to an embodiment of the present invention, in which a representative ray passes through a voxel position and strikes a detector module;
FIG. 5 is a schematic diagram illustrating distribution of weighting coefficients along the Z direction in an embodiment of a CT plain scan image reconstruction method, system, device and readable storage medium according to the present invention, wherein a point A is a weighting coefficient corresponding to a ray in FIG. 4;
FIG. 6 is a schematic diagram of a program module in a second embodiment of a CT flat-scan image reconstruction method, system, device and readable storage medium according to the present invention;
fig. 7 is a schematic diagram of a hardware structure of a computer device according to a third embodiment of the CT scan flat image reconstruction method, system, device, and readable storage medium of the present invention.
Reference numerals:
5-an image reconstruction system; 51-a first processing module; 52-weight matching module; 53-a calculation module; 54-a second processing module; 6-a computer device; 61-a memory; 62-processor.
Detailed Description
The advantages of the invention are further illustrated in the following description of specific embodiments in conjunction with the accompanying drawings.
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.
The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present disclosure. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for facilitating the explanation of the present invention, and have no specific meaning in themselves. Thus, "module" and "component" may be used in a mixture.
The first embodiment is as follows: the embodiment discloses a CT flat scan image reconstruction method, the CT flat scan operation needs to move a scanning object to a certain fixed position, then an X-ray source and a detector rotate 360 degrees around the scanning object, the scanning object moves a distance of a collimator opening size along a Z direction, 360-degree scanning is repeated, about 8 circles (16cm Z-direction coverage length) of head scanning of a 16-row (2cm collimator opening) CT is generally needed to be repeated, therefore, in the scheme, in order to reduce the calculation complexity in the image reconstruction process after scanning, a weight coefficient is calculated in advance, the weight coefficient used for back projection calculation in the flat scan process is repeatedly obtained every time of performing 360-degree scanning, it should be noted that, the above-mentioned performing 360-degree scanning is the operation of the detector on a certain position, the detector comprises a plurality of detector modules, and the detector modules comprise a plurality of detector units, specifically, the method comprises the following steps:
s100: calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table;
the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the positions of the rays at a rotation angle; i.e. the weight coefficients are related to the voxels on the scanned object and the rotation angle of the ray.
That is, in the above step, since the collimator with the appropriate aperture needs to be selected according to the actual usage scenario in the flat scanning process, each collimator is associated with a sub-storage table for storing the weight coefficient, the weight coefficient under the same collimator opening size only needs to use the same set of table lookup, and in the back projection calculation process of the reconstructed image, the corresponding sub-storage table is selected according to the aperture of the collimator first, and then the specific weight coefficient is searched according to the voxel position and the rotation angle at which the ray is located.
In the above steps, that is, the weight coefficients are calculated in advance and stored separately, and it is not necessary to repeatedly calculate each weight coefficient again in the subsequent process, so as to solve the problems of consuming a large amount of calculation resources, having low efficiency and having high requirements for computer hardware configuration in the process of reconstructing an image, specifically, a weight coefficient set corresponding to each collimator in a collimator group is calculated to generate a storage table, including the following steps:
s110: acquiring a collimator in a collimator group, and acquiring opening parameters of the collimator and the Z-direction length of a detector module;
in the above step, the corresponding sub memory table needs to be selected according to the aperture of the collimator, and the number of times of the horizontal scanning repeated by 360 ° needs to be determined according to the aperture of the collimator, which can be determined according to the opening parameter of the collimator, and it should be noted that the Z-direction length of the detector module is mainly used for determining the specific position where the ray reaches the detector module in the following step S120, so as to calculate the corresponding weight coefficient.
S120: a ray at a rotation angle passes through any voxel position to a detector unit on a detector module, the Z position of the detector unit on the detector module is recorded as a detection position, the distance between the detection position and a central detector unit on the detector module is obtained, and a weight coefficient corresponding to the voxel position is calculated according to the distance and a detector module shape adjusting parameter;
in the above step, as an explanation, the detector is provided with a plurality of detector modules, the arrangement direction of the detector modules is the X direction, the direction perpendicular to the X direction and pointing to the center of the detector is the Y direction, each detector module is provided with a plurality of detector units, the detector units are sequentially arranged on the detector modules one by one, the arrangement direction of the detector units is the Z direction, and the detection position is a position where a voxel of a ray passing through a scanning object hits on the detector module, that is, the detection position is embodied on the position of the detector unit on the detector module.
Specifically, since the obtaining of the weighting factor is related to the voxel position, and more specifically, to the distance from the position on the detector module, where the ray strikes the detector module after passing through the voxel, to the central detector unit on the detector module, the obtaining of the distance from the detection position to the central detector unit on the detector module in the above steps includes the following steps:
the distance of the detection position from the central detector unit on the detector module is calculated according to the following formula,
wherein q isiIs a distance, ziA detection position of the ray i, wherein the detection position is a position in a Z direction on the detector module when the ray passes through a voxel position to a detector unit on the detector module, ZcentIs the Z-direction position of the central detector unit on the detector module, and dz is the Z-direction length of the detector module.
Further, based on the calculated distance between the detection position and the central detector unit on the detector module, the calculating the weight coefficient corresponding to each voxel position according to the distance and the detector shape adjustment parameter includes the following steps:
calculating a weight coefficient corresponding to any voxel position according to the following formula:
wherein, w(α,z)Is a weight coefficient, qiFor distance, Q is the detector module shape adjustment parameter, and dz is the Z-direction length of the detector module.
S130: normalizing the parallel conjugate weight coefficients based on the weight coefficients corresponding to all pixel positions to obtain a weight coefficient set corresponding to the collimator;
in this embodiment, most of the backprojection algorithms used in the CT flat-scan reconstruction utilize the weighted sum of the parallel conjugate rays to obtain the corresponding voxel value, so that the normalization operation needs to be performed on the weight coefficients of the parallel conjugates, and the parallel conjugate rays are the parallel rays that appear in pairs. Thus, the normalization of the weight coefficients of the parallel conjugates includes the following steps:
determining a parallel conjugate weight coefficient according to the rotation angle of the ray, and screening out the parallel conjugate weight coefficient based on the weight coefficient obtained according to the shape adjustment parameter of the detector module;
the normalization calculation is performed according to the following formula:
wherein, w(α,z)，w(α+π,z)Is a pair of 180 deg. conjugated weight coefficients.
S140: and calculating each collimator in the collimator group until a weight coefficient set corresponding to all the collimators is obtained so as to generate a storage table.
In the foregoing step, as described above, each collimator corresponds to one sub-storage table, and the sub-storage tables are combined to generate a storage table and stored separately, and further, in order to further facilitate acquisition, the storage table is stored in a hard disk or a preset address, specifically, after the storage table is generated in the foregoing step, the following operations are included:
correspondingly storing the voxel positions and the weight coefficients of the rays under the rotation angles, and storing the voxel positions and the weight coefficients on a hard disk; wherein the weight coefficient is stored in a format of
The storage space on the hard disk is N2xSxAlx4 Bytes, N is the size of the scanned object in the XY plane, S is the number of rows of detector units on the detector module, alpha is the angle of one circle of scanning of the detector at one Z-direction position of the scanned object, and 4Bytes is the angle of one circle of scanning in the circumferential directionThe data is stored in digital form.
Based on the above storage method, the weight coefficient set can be read into the hard disk during the reconstruction calculation process, the calculation of the weight coefficient is simplified, and the table is looked up according to the (x, y, z, alpha) coordinate to obtain the required weight coefficient.
S200: creating a CT flat-scan data set, determining a flat-scan collimator, and acquiring a weight coefficient set corresponding to the flat-scan collimator in a storage table;
in the above steps, when reconstructing an image, selecting a coefficient set under a corresponding collimator, and reading into a memory, it should be noted that, in the flat scanning process, the weight coefficients between circles are repeatedly calculated, and only the weight coefficients used in the reconstruction process of one circle need to be stored in a hard disk, and the weight coefficients can be quickly obtained by table lookup.
S300: acquiring a detector position and each voxel position of a scanned object under the detector position based on the flat scanning data set, and acquiring corresponding weight coefficients in a weight coefficient set matched and corresponding to the flat scanning collimator according to each voxel position and the rotation angle of the ray position so as to perform back projection weighted summation to acquire a voxel value under the detector position;
specifically, in the above step, obtaining corresponding weight coefficients in a weight coefficient set corresponding to the flat-scan collimator according to each voxel position and a rotation angle at which the ray is located, so as to perform back projection weighted summation, and obtaining a voxel value at the detector position includes the following steps:
the voxel values are calculated according to the following formula:
wherein the content of the first and second substances,
for the weight coefficients obtained from the memory table, p(α,l,z)Are the pixel points of the detector module (x,y, z) is the geometric spatial position of the voxel of the scanned object, and l represents the position of the detector module channel direction.
In calculating the voxel value according to the above formula,
in order to directly search in a storage table according to the (x, y, z, alpha) coordinate, in order to improve the reconstruction speed, the method can be started from two aspects, namely, the computing power of a computer is increased, such as a multi-core CPU or a GPU with parallel computing capability; and secondly, the reconstruction speed is effectively improved by simplifying the calculation process of the weight coefficient, the method is different from the first aspect commonly used in the prior art, the implementation mode is realized based on the second aspect, the voxel values can be obtained by directly weighting and summing after the weight coefficient is obtained, the calculated amount is greatly simplified, and the reconstruction speed is effectively improved.
S400: and moving the detector in the Z direction relative to the scanning object in the flat scanning process, calculating voxel values of the detector at all positions of the scanning object in the Z direction, generating three-dimensional images according to the voxel values of all detector positions, and sequentially splicing to obtain a reconstructed image.
As an explanation, the flat scan reconstruction is to separately calculate a corresponding stereo image for each circle, and then to splice each other into a complete three-dimensional stereo image, so that the detector moves in the Z direction relative to the scan object, that is, after the relative position of the scan object and the detector changes, the X-ray source and the detector rotate 360 degrees around the scan object, that is, one circle of detection occurs, a voxel value is calculated for each weight, and based on this, a stereo image is generated, and the stereo images are spliced to form a complete reconstructed image.
Example two: the present embodiment provides a CT flatscan image reconstruction system 5, which is used in cooperation with a CT apparatus, and includes:
a first processing module 51, configured to calculate a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table; the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the positions of the rays at a rotation angle;
the first processing module 51 obtains a distance between the detection position and a central detector unit on the detector module, and calculates a weight coefficient corresponding to the voxel position according to the distance and a detector module shape adjustment parameter, wherein the detection position is a position in a Z direction on the detector module when a ray passes through any voxel position to a detector unit on the detector module.
The weight matching module 52 is configured to create a CT flat scan data set, determine a flat scan collimator, and obtain a weight coefficient set corresponding to the flat scan collimator in the storage table;
a calculating module 53, configured to obtain a detector position and each voxel position of the scanned object at the detector position based on the flat scan data set, and obtain corresponding weight coefficients in a weight coefficient set corresponding to the flat scan collimator according to each voxel position and a rotation angle at which a ray is located, so as to perform back projection weighted summation to obtain a voxel value at the detector position;
and the second processing module 54 is configured to move the detector in the Z direction relative to the scanned object during flat scanning, calculate a voxel value at each position of the detector in the Z direction of the scanned object, generate a stereo image according to the voxel values at each detector position, and sequentially stitch the stereo image to obtain a reconstructed image.
In this embodiment, the first processing module 51 calculates a set of weight coefficients corresponding to each collimator in the collimator set according to a preset formula in step S100 of an embodiment, and then calculates the set of weight coefficients according to a preset format
Storing on a hard disk, after obtaining a CT flat scanning module, screening out a sub-storage table consistent with the current collimator opening parameter by using a weight matching module 52, then obtaining corresponding weight coefficients in the sub-storage table according to each voxel position and the rotation angle of the ray position based on a calculating module 53, so as to perform weighted summation to obtain the voxel value obtained by the current circle detection, and scanning the object along the Z directionThe direction is moved by the collimator opening size distance and the 360 deg. scans (circle scans) are repeated, whereby the second processing module 54 generates a stereo image based on the voxel values obtained for each circle scan and successively splices into reconstructed images. Therefore, based on the steps, the pre-calculated weight coefficients are stored in a computer memory (on a hard disk or other storage addresses), the weight coefficient calculation process is simplified in a table look-up mode, and the coefficients are directly read to accelerate the reconstruction process.
Example three:
in order to achieve the above object, the present invention further provides a computer device 6, where the computer device may include a plurality of computer devices, components of the CT flatbed image reconstruction system 5 in the second embodiment may be distributed in different computer devices 9, and the computer devices 9 may be smartphones, tablet computers, notebook computers, desktop computers, rack servers, blade servers, tower servers, or rack servers (including independent servers or a server cluster formed by a plurality of servers) that execute programs, and the like. The computer device of the embodiment at least includes but is not limited to: a memory 91, a processor 92 and a buffered CT flatscan image reconstruction system 5 communicatively connected to each other by a system bus. It should be noted that only a computer device having components is shown, but it should be understood that not all of the shown components are required to be implemented, and more or fewer components may be implemented instead.
In this embodiment, the memory 61 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application program required for at least one function; the storage data area may store a storage table containing weighting coefficients of a user at the computer device. Further, the memory 61 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory 61 optionally includes memory 61 located remotely from the processor, which may be connected to the PET system via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
Processor 62 may be a Central Processing Unit (CPU), controller, microcontroller, microprocessor, or other data Processing chip in some embodiments. The processor 92 is typically used to control the overall operation of the computer device. In this embodiment, the processor 62 is configured to execute the program code stored in the memory 61 or process data, for example, execute the CT-scan image reconstruction system 5, so as to implement the CT-scan image reconstruction method according to the first embodiment.
It is noted that only a computer device 6 having components 61-62 is shown, but it is understood that not all of the shown components are required to be implemented, and that more or fewer components may be implemented instead.
In this embodiment, the CT scout image reconstruction system 5 stored in the memory 61 can be further divided into one or more program modules, and the one or more program modules are stored in the memory 61 and executed by one or more processors (in this embodiment, the processor 62) to complete the present invention.
Example four:
to achieve the above objects, the present embodiment also provides a computer-readable storage medium including a plurality of storage media, such as a flash memory, a hard disk, a multimedia card, a card type memory (e.g., SD or DX memory, etc.), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read Only Memory (ROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), a Programmable Read Only Memory (PROM), a magnetic memory, a magnetic disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, which when executed by the processor 92 implements corresponding functions. The computer readable storage medium of the present embodiment is used for storing the CT scout image reconstruction system 5, and when being executed by the processor 92, the computer readable storage medium implements the CT scout image reconstruction method of the first embodiment.
It should be noted that the embodiments of the present invention have been described in terms of preferred embodiments, and not by way of limitation, and that those skilled in the art can make modifications and variations of the embodiments described above without departing from the spirit of the invention.
Claims (10)
1. A CT flat scan image reconstruction method is characterized by comprising the following steps:
calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table;
the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the rotation angles at which the rays are positioned; creating a CT flat-scan data set, determining a flat-scan collimator, and acquiring a weight coefficient set corresponding to the flat-scan collimator in a storage table;
acquiring a detector position and each voxel position of a scanned object under the detector position based on the flat scanning data set, and acquiring corresponding weight coefficients in a weight coefficient set matched and corresponding to the flat scanning collimator according to each voxel position and the rotation angle of the ray position so as to perform back projection weighted summation to acquire a voxel value under the detector position;
and moving the detector in the Z direction relative to the scanning object in the flat scanning process, calculating voxel values of the detector at all positions of the scanning object in the Z direction, generating three-dimensional images according to the voxel values of all detector positions, and sequentially splicing to obtain a reconstructed image.
2. The reconstruction method according to claim 1, wherein calculating the set of weight coefficients corresponding to each collimator in a collimator group to generate a storage table comprises:
acquiring a collimator in a collimator group, and acquiring opening parameters of the collimator and the Z-direction length of a detector module; a ray at a rotation angle passes through any voxel position to a detector unit on a detector module, the Z position of the detector unit on the detector module is recorded as a detection position, the distance between the detection position and a central detector unit on the detector module is obtained, and a weight coefficient corresponding to the voxel position is calculated according to the distance and a detector module shape adjusting parameter;
normalizing the parallel conjugate weight coefficients based on the weight coefficients corresponding to all pixel positions to obtain a weight coefficient set corresponding to the collimator;
and calculating each collimator in the collimator group until a weight coefficient set corresponding to all the collimators is obtained so as to generate a storage table.
3. The reconstruction method according to claim 2, wherein obtaining the distance of the detection location from a central detector unit on a detector module comprises:
the distance of the detection position from the central detector unit on the detector module is calculated according to the following formula,
wherein q isiIs a distance, ziA detection position of the ray i, wherein the detection position is a position in a Z direction on the detector module when the ray passes through a voxel position to a detector unit on the detector module, ZcentIs the Z-direction position of the central detector unit on the detector module, and dz is the Z-direction length of the detector module.
4. The reconstruction method according to claim 2, wherein the calculating a weight coefficient corresponding to each voxel position according to the distance and the detector shape adjustment parameter comprises:
calculating a weight coefficient corresponding to any voxel position according to the following formula:
wherein, w(α,z)Is a weight coefficient, qiFor distance, Q is the detector module shape adjustment parameter, and dz is the Z-direction length of the detector module.
5. The reconstruction method according to claim 2, wherein the normalizing of the parallel conjugate weight coefficients comprises:
the weight coefficients of the parallel conjugates are determined from the angle of rotation at which the ray lies,
the normalization calculation is performed according to the following formula:
wherein, w(α,z)，w(α+π,z)Is a pair of 180 deg. conjugated weight coefficients.
6. The reconstruction method according to claim 1, comprising, after the generating of the storage table, the following:
correspondingly storing the voxel positions and the weight coefficients of the rays under the rotation angles, and storing the voxel positions and the weight coefficients on a hard disk;
wherein the weight coefficient is stored in a format of
The storage space on the hard disk is N2And the multiplied by S multiplied by alpha multiplied by 4Bytes, N is the size of the scanned object in an XY plane, S is the row number of the detector units on the detector module, alpha is the circumferential scanning angle of the detector at one Z-direction position of the scanned object, and 4Bytes is used for storing data in a floating point number mode.
7. The reconstruction method according to claim 1, wherein the acquiring of the voxel value at the detector position according to the respective voxel position and the rotation angle at which the ray is located in the weight coefficient set corresponding to the flat-scan collimator matching is performed for back-projection weighted summation, and comprises the following steps:
the voxel values are calculated according to the following formula:
wherein the content of the first and second substances,
for the weight coefficients obtained from the memory table, p(α,l,z)The (x, y, z) is the geometric spatial position of the voxel of the scanned object, and l represents the position of the channel direction of the detector module.
8. A CT flat scan image reconstruction system used in conjunction with a CT apparatus, comprising:
the first processing module is used for calculating a weight coefficient set corresponding to each collimator in a collimator group to generate a storage table; the weight coefficient set corresponding to any collimator comprises a plurality of weight coefficient subsets corresponding to the positions of the voxels of the scanned object, and each weight coefficient subset comprises a plurality of weight coefficients corresponding to the positions of the rays at a rotation angle; the weight matching module is used for creating a CT flat scanning data set, determining a flat scanning collimator and acquiring a weight coefficient set corresponding to the flat scanning collimator in a storage table;
the calculation module is used for acquiring a detector position and each voxel position of a scanned object under the detector position based on the flat scanning data set, and acquiring corresponding weight coefficients in a weight coefficient set matched and corresponding to the flat scanning collimator according to each voxel position and the rotation angle of the ray position so as to perform back projection weighted summation to acquire a voxel value under the detector position;
and the second processing module is used for moving the detector relative to the scanning object in the Z direction in flat scanning, calculating voxel values when the detector is positioned at each position of the scanning object in the Z direction, generating three-dimensional images according to the voxel values at each detector position and sequentially splicing to obtain a reconstructed image.
9. A computer device, characterized in that the computer device comprises a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the reconstruction method according to any one of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the reconstruction method according to one of the claims 1 to 7.
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