CN113989400A - CT image generation method and device, electronic equipment and computer storage medium - Google Patents
CT image generation method and device, electronic equipment and computer storage medium Download PDFInfo
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Abstract
The application discloses a CT image generation method, a device, electronic equipment and a computer storage medium, wherein the method comprises the following steps: calibrating an original CT projection image of a detected object to obtain first attenuation projection data; reconstructing the first attenuation projection data to obtain a first image; segmenting the first image to obtain a second image; carrying out orthographic projection processing on the second image to obtain second attenuation projection data; generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data; correcting the first attenuation projection data by using a polynomial fitting function to obtain third attenuation projection data; the third attenuation projection data is reconstructed to generate a CT image of the object. According to the embodiment of the application, a good ring artifact removing effect can be obtained on the basis of keeping the detail structure of the original CT image.
Description
Technical Field
The present application relates to the field of image processing technologies, and in particular, to a method and an apparatus for generating a CT image, an electronic device, and a computer storage medium.
Background
The CT image generation technology obtains projection data of an object in a certain angle range through relative motion of the detected object and a detector, and reconstructs the projection data into three-dimensional data of the detected object through an algorithm. During image acquisition, there is a certain degree of degradation in the projection data due to the problems of non-uniformity and non-linearity of the detector cell response. After the degraded projection data are reconstructed by the algorithm, artifacts are generated in the reconstructed image, which affects subsequent image processing and analysis. Therefore, the CT image generation process should remove the artifact information of the image as much as possible. Although the prior art ring artifact removing method can correct the ring artifact, the original information of some images is lost in the data processing process, so that the reconstructed images have the problems of image blurring and quality reduction.
Therefore, there is a need for an image generation method that can remove the ring artifact of the CT image and simultaneously protect the original information of the image from being lost as much as possible.
Disclosure of Invention
The embodiment of the application provides a method and a device for generating a CT image, electronic equipment and a computer storage medium, which can obtain a good ring artifact removing effect on the basis of keeping the detail structure of the original CT image.
In one aspect, an embodiment of the present application provides a method for generating a CT image, including:
calibrating an original CT projection image of a detected object to obtain first attenuation projection data;
reconstructing the first attenuation projection data to obtain a first image;
segmenting the first image to obtain a second image, wherein each part of the second image corresponds to different materials of the detected object, and the numerical value of each part of the second image is related to the ray attenuation coefficient of the corresponding material;
carrying out orthographic projection processing on the second image to obtain second attenuation projection data;
generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data;
correcting the first attenuation projection data using the polynomial fitting function to obtain third attenuation projection data;
reconstructing the third attenuation projection data to generate a target CT image.
In another aspect, an embodiment of the present application provides a CT image generation apparatus, including:
the calibration module is used for calibrating the original CT projection image of the detected object to obtain first attenuation projection data;
a first reconstruction module, configured to reconstruct the first attenuation projection data to obtain a first image;
the segmentation processing module is used for segmenting the first image to obtain a second image, wherein each part of the second image corresponds to different materials of the detected object, and the numerical value of each part of the second image is related to the ray attenuation coefficient of the corresponding material;
the orthographic projection processing module is used for carrying out orthographic projection processing on the second image so as to obtain second attenuation projection data;
a generating module for generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data;
a correction module for correcting the first attenuation projection data using the polynomial fitting function to obtain third attenuation projection data;
a second reconstruction module for reconstructing the third attenuation projection data to generate a target CT image.
In another aspect, an embodiment of the present application provides an electronic device, including: a processor and a memory storing computer program instructions.
The processor, when executing the computer program instructions, implements the CT image generation method provided by the embodiments of the present application.
In another aspect, an embodiment of the present application provides a computer storage medium, on which computer program instructions are stored, and the computer program instructions, when executed by a processor, implement the CT image generation method provided by the embodiment of the present application.
According to the CT image generation method, the CT image generation device, the electronic equipment and the computer storage medium, a first image obtained by reconstructing first attenuation projection data can be segmented according to material information of each part of a detected object to obtain a second image; because the material information of each part of the detected object can reflect the boundary information of each part of the detected object, the structure information of the detected object can be reflected, and therefore, the second image and the second attenuation projection data obtained by orthographic projection processing according to the second image can both retain the structure information of the detected object; then, the first attenuation projection data is corrected by using the second attenuation projection data, and the structural information of the detected object can be reserved. Therefore, the CT image is reconstructed by using the corrected third attenuation projection data, and the ring artifact of the CT image can be removed on the basis of keeping the original image detail structure.
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In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a CT image generation method provided herein;
FIG. 2 is a schematic gray level histogram of a CT raw projection image according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a CT image generation method according to an embodiment of the present application;
FIG. 4 is a CT raw projection image provided by an embodiment of the present application;
FIG. 5 is a target CT image obtained by processing the original CT projection image shown in FIG. 4 by the CT image generation method shown in FIG. 3;
FIG. 6 is a schematic diagram of another embodiment of a CT image generation method according to an embodiment of the present application;
FIG. 7 is a target CT image obtained by processing the original CT projection image shown in FIG. 4 by the CT image generation method shown in FIG. 6;
FIG. 8 is a schematic diagram of another embodiment of a CT image generation method according to an embodiment of the present application;
FIG. 9 is a target CT image obtained by processing the original CT projection image shown in FIG. 4 by the CT image generation method shown in FIG. 8;
FIG. 10 is a schematic structural diagram of a CT image generation apparatus according to an embodiment of the present application;
fig. 11 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
Features and exemplary embodiments of various aspects of the present application will be described in detail below, and in order to make objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are intended to be illustrative only and are not intended to be limiting. It will be apparent to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present application by illustrating examples thereof.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiment of the application provides a CT image generation method, a CT image generation device, electronic equipment and a computer storage medium. First, a CT image generation method provided in an embodiment of the present application will be described below.
Fig. 1 is a flowchart illustrating a CT image generation method according to an embodiment of the present application.
As shown in fig. 1, the CT image generation method of the present application includes:
103, segmenting the first image to obtain a second image, wherein each part of the second image corresponds to different materials of the detected object, and the numerical value of each part of the second image is related to the ray attenuation coefficient of the corresponding material;
104, performing orthographic projection processing on the second image to obtain second attenuation projection data;
and step 107, reconstructing the third attenuation projection data to generate a target CT image.
The CT image generation method of the present application may be implemented by the CT image generation device of the present application.
Referring to step 101, a CT image generation apparatus calibrates an original CT projection image of a detected object to obtain first attenuation projection data.
The detected object is a structural member which is composed of one or more materials and the material type and density of each part are known.
The original CT projection image is a projection image P of N objects in a certain angle range acquired by a CT system through the relative motion of a detected object and a detectorn。
The original CT projection image is an actual image acquired by the CT system, and includes projection data of the detected object and possibly interference data such as artifact information.
The first attenuation projection data is projection data after the original CT projection image is calibrated, and may also be original attenuation projection data.
The image calibration may be performed by using the no-load image calibration or the zero-point image calibration, or may be performed by using both the no-load image and the zero-point image calibration, and may further include other image calibration methods, which are not limited in this application.
Referring to step 102, the CT image generation device may reconstruct the first attenuation projection data using a CT image reconstruction algorithm to obtain a first image.
For example: the CT image generation device reconstructs the first attenuation projection data by using an FDK algorithm to obtain a first image.
The first image is an original reconstructed image of the object which is reconstructed by the CT image generation apparatus from the first attenuation data. The first image is three-dimensional volume data composed of M tomographic images.
Referring to step 103, the CT image generating device segments the first image to obtain a second image, wherein each portion of the second image corresponds to a different material of the detected object, and the numerical values of each portion of the second image are related to the ray attenuation coefficient of the corresponding material.
The CT image generation device may segment the first image according to the material information of the detected object to obtain a second image.
The object material information includes the material type, density, structure, etc. of the object.
The parts of the second image correspond to different materials of the detected object, and the ray attenuation coefficients corresponding to the detected object materials in the parts of the second image can be obtained through calculation.
In the embodiment of the present application, the radiation attenuation coefficient of the material corresponding to the detected object may be obtained by the following method:
calculating the ray attenuation of different materials according to the ray energy spectrum f (E) and the material informationCoefficient mui。
The attenuation coefficient of the radiation corresponding to the material of the object to be detected is the sum of the products of the size of the unit pixel of the object to be detected and the line attenuation coefficient of the radiation corresponding to the unit pixel.
The specific formula is as follows:
wherein, K is the number of segments of the energy spectrum f (E), j is the energy segment index, EjIs the energy of the radiation in the j energy segment,
for the i-th material to an energy of EjD is the size of a unit pixel in the original reconstructed image.
Radiation attenuation coefficients corresponding to the material of the object under examination can be assigned to the respective material of the parts of the second image.
Step 104 is involved, the CT image generation device carries out orthographic projection processing on the second image according to the parameters in the process of actually acquiring the CT projection image by the CT system, and second attenuation projection data are obtained.
The parameters of the CT system in the process of actually acquiring the CT projection images comprise the path from the ray source to the detection unit and the path angle information.
The second attenuation projection data is CT projection data predicted from the detected object material and structural information, and may also be referred to as theoretical attenuation projection data.
The orthographic projection process is a process of acquiring projection data by utilizing integral transformation in the CT scanning process.
Involving step 105, the CT image generation device generates a polynomial fitting function f (A) from the first attenuation projection data and the second attenuation projection datan)＝a0+a1An+…+amAn m。
The CT image generating apparatus may generate the polynomial fitting function directly using the first attenuation projection data and the second attenuation projection data, or may generate the polynomial fitting function from the processed data by preprocessing the first attenuation projection data and the second attenuation projection data.
A polynomial fit function may be used to correct the first attenuation projection data. The polynomial fitting function can be obtained by solving with least square method, which is used to solve the polynomial coefficient a satisfying the minimum mean square error0、a1、……am。
Involving step 106, the CT image generation device fits a function f (A) using a polynomialn) Namely, the correction function corrects the first attenuation projection data to obtain third attenuation projection data.
The third attenuation projection data is corrected attenuation projection data obtained by correcting the first attenuation projection data.
Fitting function f (A) with a polynomialn) For the first attenuation projection data
Correcting to obtain corrected attenuation projection data
The specific correction formula is as follows:
step 107 is involved in reconstructing the corrected attenuation projection data by the CT image generating device using a CT image reconstruction algorithm to obtain a corrected projection image.
The corrected projection image is a CT image with the ring artifact eliminated.
According to the CT image generation method, the CT image generation device, the electronic equipment and the computer storage medium, a first image obtained by reconstructing first attenuation projection data can be segmented according to material information of each part of a detected object to obtain a second image; because the material information of each part of the detected object can reflect the boundary information of each part of the detected object, the structure information of the detected object can be reflected, and therefore, the second image and the second attenuation projection data obtained by orthographic projection processing according to the second image can both retain the structure information of the detected object; then, the first attenuation projection data is corrected by using the second attenuation projection data, and the structural information of the detected object can be reserved. Therefore, the CT image is reconstructed by using the corrected third attenuation projection data, and the ring artifact of the CT image can be removed on the basis of keeping the original image detail structure.
Optionally, the calibrating the original CT projection image of the detected object to obtain the first attenuation projection data includes:
and correcting the original CT projection image by using a pre-acquired zero point image and a pre-acquired idle image of the detector unit to obtain the first attenuation projection data.
In one embodiment of the present application, the CT image generation device obtains N projection images P of the detected object at different positions acquired by the CT systemnAnd a no-load image F and a zero point image Z of the detector unit, respectively for the projection image P using the no-load image and the zero point image of the detector unitnCorrecting to obtain original attenuation projection data
The specific formula is as follows:
the zero point image is data of the detector under no radiation irradiation, and the no-load image is response of the detector under full radiation irradiation when no scanning object exists.
The zero-load calibration and the no-load calibration of the projection image can avoid the interference of the information of the image generation equipment to the image generation effect.
Optionally, the segmenting the first image to obtain a second image includes:
performing threshold segmentation on the first image according to the material type information of the detected object to obtain a second image; or,
and registering the point cloud data of the detected object with the first image, and segmenting the first image according to the structure diagram of the detected object to obtain a second image, wherein the structure diagram of the detected object comprises the point cloud data of the detected object.
In one embodiment of the present application, the CT image generation device determines a threshold value for image segmentation according to gray scale information of a detected object acquired in advance, and performs threshold segmentation on a first image according to the threshold value information to obtain a second image.
The gray information of the detected object can be obtained through a gray histogram of an original reconstructed image of the detected object.
As shown in fig. 2, the gradation histogram of the detected object includes gradation values and the number of pixel points corresponding to the gradation values.
In another embodiment of the present application, the CT image generation apparatus may further register the original projection image according to the point cloud data of the detected object, and perform image segmentation according to the structure diagram of the detected object.
The point cloud data of the detected object may be data in a three-dimensional coordinate system containing color and intensity information acquired by a 3D scanner or a camera or the like. The intensity information is related to the material of the object to be detected, the energy and wavelength of the radiation of the scanning instrument, and the like.
The structural diagram of the object to be detected includes information such as a material, a structure, and a boundary of the object to be detected. The structure diagram of the object to be detected may be a CAD image of the object to be detected, or may be other image data including information such as the material, structure, and boundary of the object to be detected.
According to the CT image generation method, the first image is segmented according to the material and structure information of the detected object, the original information of the detected object is reserved, and the original information is prevented from being lost.
Optionally, the threshold of the threshold segmentation is determined by gray scale information of the first image.
Optionally, the threshold of the threshold segmentation is determined by the following steps:
determining a gray peak value of each gray area according to the gray histogram of the first image;
determining the minimum gray value meeting a first preset condition in the gray histogram as a threshold value of the threshold segmentation;
the preset condition is that the number of pixel points corresponding to the gray value is smaller than the preset value of the number of pixel points corresponding to the previous gray peak value.
In one embodiment of the present application, a CT image generation device obtains a histogram of an original reconstructed image of an object to be detected, and determines peak information P of a gray value histogram of the original reconstructed imageiDetermining an index of peak information
The CT image generation device compares the gray value information, determines the gray value satisfying the preset threshold value that the number of pixel points corresponding to the gray value is smaller than the number of pixel points corresponding to the previous gray peak value in the gray histogram, and determines the index of the minimum gray value satisfying the condition
Threshold value TiIs composed of
The corresponding gray value. The specific formula is as follows:
the gray-level histogram of the original reconstructed image can be obtained by the hit function of MATLAB. The gray peak data is the pixel point number and the gray value corresponding to the peak value in the gray histogram, and the peak value of the gray histogram corresponds to the air and different materials of the detected object respectively. The preset threshold value can be determined according to actual requirements, and the preset threshold value is not limited in the application. For example: the preset threshold may take 0.05. The gray value corresponding to the threshold is larger than the gray value corresponding to the previous peak value in the gray histogram.
Optionally, the performing forward projection processing on the second image to obtain second attenuation projection data includes:
performing orthographic projection processing on the second image according to the path information from the ray source to the detector unit in the acquisition process of the original CT projection image to obtain second attenuation projection data
In one embodiment of the present application, the orthographic projection process is to calculate the ray attenuation coefficient μ corresponding to the ray passing through the segmented image in the path with the angle θ from the ray source to the detector unitiOn its way through the segmented image
Where d is the size of the unit pixel in the second image. The specific formula is as follows:
in the orthographic projection processing process of the embodiment, theoretical attenuation projection data of the detected object can be obtained, so that the original attenuation projection data can be corrected by using the theoretical attenuation data.
Optionally, the generating a polynomial fitting function according to the first attenuation projection data and the second attenuation projection data includes:
dividing the first attenuation projection data and the second attenuation projection data points to obtain a plurality of ratios;
removing abnormal data from the first attenuation projection data and the second attenuation projection data to obtain third attenuation projection data and fourth attenuation projection data, wherein the abnormal data are projection data which are in the first attenuation projection data and the second attenuation projection data and correspond to the ratio meeting a second preset condition;
polynomial fitting is performed on the third attenuation projection data and the fourth attenuation projection data to generate the polynomial fitting function.
In an embodiment of the present application, the CT image generation device generates a polynomial fitting function according to the original attenuation projection data and the theoretical attenuation projection data, and may preprocess the original attenuation projection data and the theoretical attenuation projection data to remove abnormal data.
Dividing the original attenuation projection data and the theoretical attenuation projection data point to obtain a plurality of ratios, and calculating standard deviation information of the ratios;
and removing abnormal data from the original attenuation projection data and the theoretical attenuation projection data according to the ratio and standard deviation information to obtain preprocessed original attenuation projection data and theoretical attenuation projection data.
The abnormal data is original attenuation projection data and the theoretical projection data, the ratio obtained by point division meets preset condition data, and the preset condition can be set according to actual needs, for example: the data deviating from the ratio mean by more than 2 times of the ratio standard deviation is not limited in the present application.
According to the CT image generation method, the abnormal values of the original attenuation projection data and the theoretical attenuation projection data are removed, so that noise interference in CT image generation can be better removed, and the correction quality of the CT image is improved.
The present application further provides a specific embodiment of the CT image generation method as follows:
fig. 3 shows a specific embodiment 1 of the method for generating a CT image according to the present application, and the generation result of the CT image is shown in fig. 5.
FIG. 4 shows a CT projection image acquired by a CT system, and the CT projection image shown in FIG. 4 is used as the original CT projection image in the following embodiments.
The specific embodiment of the CT image generation method shown in fig. 3 includes:
And 303, performing threshold segmentation on the first image according to the object material information to obtain a second image, wherein the threshold is determined by the gray histogram of the first image.
And step 304, calculating the ray attenuation coefficients of different materials according to the ray energy spectrum and the material types.
And step 306, performing orthographic projection on the second image according to ray paths of different angles actually acquired by the CT system to obtain second attenuation projection data.
And 307, using the first attenuation projection data and the second attenuation projection data to make a polynomial fitting function, and using a least square method to determine a polynomial coefficient when the mean square error is minimum.
And 308, correcting the first attenuation projection data by using the obtained polynomial fitting function to obtain third attenuation projection data.
And 309, reconstructing the third attenuation projection data by using an FDK algorithm to obtain a CT reconstructed image without the ring artifact.
Fig. 6 shows a specific embodiment 2 of the method for generating a CT image according to the present application, and the CT image generation result is shown in fig. 7.
The specific embodiment of the CT image generation method shown in fig. 6 includes:
And step 604, calculating the ray attenuation coefficients of different materials according to the ray energy spectrum and the material types.
And 606, performing orthographic projection on the second image according to ray paths of different angles actually acquired by the CT system to obtain second attenuation projection data.
And 608, using the first attenuation projection data and the second attenuation projection data after the abnormal data are removed to make a polynomial fitting function, and using a least square method to determine a polynomial coefficient when the mean square error is minimum.
And step 609, correcting the first attenuation projection data by using the obtained polynomial fitting function to obtain third attenuation projection data.
And 6010, reconstructing the third attenuation projection data by using an FDK algorithm to obtain a CT reconstructed image without the ring artifacts.
Fig. 8 shows another specific embodiment 3 of the CT image generation method provided by the present application, where a CT image generation result is shown in fig. 9, and the specific embodiment of the CT image generation method shown in fig. 8 includes:
And step 804, calculating the ray attenuation coefficients of different materials according to the ray energy spectrum and the material types.
In step 807, the first attenuation projection data and the second attenuation projection data point are divided to obtain a ratio, and the standard deviation of the ratio is calculated. And searching data with deviation more than two times of standard deviation from the mean value in the ratio, recording the index, and removing corresponding data in the first attenuation projection data and the second attenuation projection data.
And 808, using the first attenuation projection data and the second attenuation projection data after the abnormal data are removed to make a polynomial fitting function, and using a least square method to determine a polynomial coefficient when the mean square error is minimum.
And step 809, correcting the first attenuation projection data by using the obtained polynomial fitting function to obtain third attenuation projection data.
And 8010, reconstructing the third attenuation projection data by using an FDK algorithm to obtain a CT reconstructed image without the ring artifacts.
Fig. 10 is a schematic diagram of a CT image generation apparatus according to an embodiment of the present application. As shown in fig. 10, a CT image generation apparatus 1000 according to the present application includes:
a calibration module 1001, configured to calibrate an original CT projection image of a detected object to obtain first attenuation projection data;
a first reconstruction module 1002, configured to reconstruct the first attenuation projection data to obtain a first image;
a segmentation processing module 1003, configured to perform segmentation processing on the first image according to the material of the detected object and a corresponding ray attenuation coefficient to obtain a second image;
an orthographic projection processing module 1004, configured to perform orthographic projection processing on the second image to obtain second attenuation projection data;
a generating module 1005 for generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data;
a correction module 1006, configured to correct the first attenuation projection data by using the polynomial fitting function to obtain third attenuation projection data;
a second re-modeling block 1007 configured to reconstruct the third attenuation projection data to generate a target CT image.
Optionally, the calibration module 1001 is specifically configured to correct the original CT projection image by using a pre-acquired zero point image and a pre-acquired idle image of the detector unit to obtain the first attenuation projection data.
Optionally, the segmentation processing module 1003 includes:
and the first segmentation unit is used for carrying out threshold segmentation on the first image according to the material type information of the detected object so as to obtain a second image.
Optionally, the segmentation processing module 1003 includes:
a registration unit, configured to register the point cloud data of the detected object with the first image;
and the second segmentation unit is used for segmenting the first image according to the structural diagram of the detected object to obtain a second image, wherein the structural diagram of the detected object comprises point cloud data of the detected object.
Optionally, the threshold of the threshold segmentation is determined by gray scale information of the first image.
Optionally, the CT image generating apparatus 1000 further includes:
the threshold value determining module is used for determining the gray peak value data of the first image in each gray area according to the acquired gray histogram of the first image; acquiring the minimum gray value meeting preset conditions in the gray histogram; the preset condition is the gray value of which the number of the pixel points corresponding to the gray value is smaller than the preset threshold value of the number of the pixel points corresponding to the previous gray peak value.
Optionally, the orthographic projection processing apparatus 1004 is specifically configured to:
and carrying out orthographic projection processing on the second image according to the path parameter information from the ray source to the detector unit in the process of acquiring the projection image by the original CT projection image CT system so as to obtain second attenuation projection data.
Optionally, the generating module 1005 may include:
a data processing unit for dividing the first attenuation projection data and the second attenuation projection data points to obtain a plurality of ratios; removing abnormal data from the first attenuation projection data and the second attenuation projection data to obtain third attenuation projection data and fourth attenuation projection data, wherein the abnormal data are projection data corresponding to the ratio meeting a preset condition in the first attenuation projection data and the second attenuation projection data;
a generating unit configured to perform polynomial fitting on the third attenuation projection data and the fourth attenuation projection data to generate the polynomial fitting function.
According to the CT image generation method, the CT image generation device, the electronic equipment and the computer storage medium, a first image obtained by reconstructing first attenuation projection data can be segmented according to material information of each part of a detected object to obtain a second image; because the material information of each part of the detected object can reflect the boundary information of each part of the detected object, the structure information of the detected object can be reflected, and therefore, the second image and the second attenuation projection data obtained by orthographic projection processing according to the second image can both retain the structure information of the detected object; then, the first attenuation projection data is corrected by using the second attenuation projection data, and the structural information of the detected object can be reserved. Therefore, the CT image is reconstructed by using the corrected third attenuation projection data, and the ring artifact of the CT image can be removed on the basis of keeping the original image detail structure.
Fig. 11 shows a hardware structure diagram of an electronic device provided in an embodiment of the present application.
The electronic device 1100 may include a processor 1101 and a memory 1102 in which computer program instructions are stored.
Specifically, the processor 1101 may include a Central Processing Unit (CPU), or an Application Specific Integrated Circuit (ASIC), or may be configured to implement one or more Integrated circuits of the embodiments of the present Application.
In a particular embodiment, the memory 1102 includes Read Only Memory (ROM). Where appropriate, the ROM may be mask-programmed ROM, Programmable ROM (PROM), Erasable PROM (EPROM), Electrically Erasable PROM (EEPROM), electrically rewritable ROM (EAROM), or flash memory or a combination of two or more of these.
The memory may include Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical/tangible memory storage devices. Thus, in general, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software comprising computer-executable instructions and when the software is executed (e.g., by one or more processors), it is operable to perform operations described with reference to the methods according to an aspect of the present disclosure.
The processor 1101 reads and executes the computer program instructions stored in the memory 1102 to implement any one of the CT image generation methods in the above-described embodiments.
It is to be understood that the present application is not limited to the particular arrangements and instrumentality described above and shown in the attached drawings. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present application are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications, and additions or change the order between the steps after comprehending the spirit of the present application.
The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the present application are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. "computer-readable media" may include any medium that can store or transfer information. Examples of computer readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.
It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, the present application is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.
Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks. Such a processor may be, but is not limited to, a general purpose processor, a special purpose processor, an application specific processor, or a field programmable logic circuit. It will also be understood that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware for performing the specified functions or acts, or combinations of special purpose hardware and computer instructions.
As described above, only the specific embodiments of the present application are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present application, and these modifications or substitutions should be covered within the scope of the present application.
Claims (10)
1. A CT image generation method, comprising:
calibrating an original CT projection image of a detected object to obtain first attenuation projection data;
reconstructing the first attenuation projection data to obtain a first image;
segmenting the first image to obtain a second image, wherein each part of the second image corresponds to different materials of the detected object, and the numerical value of each part of the second image is related to the ray attenuation coefficient of the corresponding material;
carrying out orthographic projection processing on the second image to obtain second attenuation projection data;
generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data;
correcting the first attenuation projection data using the polynomial fitting function to obtain third attenuation projection data;
reconstructing the third attenuation projection data to generate a target CT image.
2. The CT image generation method as claimed in claim 1, wherein said calibrating the original CT projection image of the detected object to obtain the first attenuation projection data comprises:
and correcting the original CT projection image by using a pre-acquired zero point image and a pre-acquired idle image of the detector unit to obtain the first attenuation projection data.
3. The CT image generation method of claim 1, wherein said segmenting the first image to obtain the second image comprises:
performing threshold segmentation on the first image according to the material type information of the detected object to obtain a second image; or,
and registering the point cloud data of the detected object with the first image, and segmenting the first image according to the structure diagram of the detected object to obtain a second image, wherein the structure diagram of the detected object comprises the point cloud data of the detected object.
4. The CT image generating method according to claim 3, wherein the threshold value of the threshold value division is determined by gray scale information of the first image.
5. The CT image generation method of claim 4, wherein the threshold for the threshold segmentation is determined by:
determining a gray peak value of each gray area according to the gray histogram of the first image;
determining the minimum gray value meeting a first preset condition in the gray histogram as a threshold value of the threshold segmentation;
the preset condition is that the number of pixel points corresponding to the gray value is smaller than the preset value of the number of pixel points corresponding to the previous gray peak value.
6. The CT image generation method of claim 1, wherein said orthographically projecting the second image to obtain second attenuation projection data comprises:
and carrying out forward projection processing on the second image according to the path information from the ray source to the detector unit in the acquisition process of the original CT projection image so as to obtain second attenuation projection data.
7. The CT image generation method of claim 1 wherein generating a polynomial fit function from the first attenuation projection data and the second attenuation projection data comprises:
dividing the first attenuation projection data and the second attenuation projection data points to obtain a plurality of ratios;
removing abnormal data from the first attenuation projection data and the second attenuation projection data to obtain third attenuation projection data and fourth attenuation projection data, wherein the abnormal data are projection data which are in the first attenuation projection data and the second attenuation projection data and correspond to the ratio meeting a second preset condition;
polynomial fitting is performed on the third attenuation projection data and the fourth attenuation projection data to generate the polynomial fitting function.
8. A CT image generation apparatus includes;
the calibration module is used for calibrating the original CT projection image of the detected object to obtain first attenuation projection data;
a first reconstruction module, configured to reconstruct the first attenuation projection data to obtain a first image;
the segmentation processing module is used for segmenting the first image to obtain a second image, wherein each part of the second image corresponds to different materials of the detected object, and the numerical value of each part of the second image is related to the ray attenuation coefficient of the corresponding material;
the orthographic projection processing module is used for carrying out orthographic projection processing on the second image so as to obtain second attenuation projection data;
a generating module for generating a polynomial fitting function from the first attenuation projection data and the second attenuation projection data;
a correction module for correcting the first attenuation projection data using the polynomial fitting function to obtain third attenuation projection data;
a second reconstruction module for reconstructing the third attenuation projection data to generate a target CT image.
9. An electronic device, comprising: a processor and a memory storing computer program instructions;
the processor, when executing the computer program instructions, implements the CT image generation method of any of claims 1-7.
10. A computer storage medium having computer program instructions stored thereon which, when executed by a processor, implement the CT image generation method of any one of claims 1 to 7.
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