CN111973205B - Multilayer X-ray detector image processing method and terminal - Google Patents
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Abstract
The invention provides an image processing method and a terminal of a multilayer X-ray detector, which are used for acquiring a multi-energy image of an object to be measured, wherein the multi-energy image is a plurality of images respectively obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multilayer flat plate structure; fusing a plurality of log-transformed multi-energy images to obtain a fused image; determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image; obtaining an image analysis result according to the fusion image and the subtraction image; according to the method and the terminal provided by the invention, the multi-layer X-ray detector is arranged, the multi-energy image is obtained through one-time exposure, the obtained image is subjected to logarithmic transformation and then is fused, the gray level of the image and the thickness of the object to be detected have a linear relation, the image can be subjected to subtraction according to the weight determined by the target, the information of the object to be detected can be more accurately and pertinently obtained, and the readability of the multi-energy image is improved.
Description
Technical Field
The invention relates to the field of image processing, in particular to an image processing method and a terminal of a multilayer X-ray detector.
Background
The multi-energy X-ray detection technology at least collects 2 images which are respectively high-energy and low-energy, and realizes specific detection through a corresponding dual-energy subtraction technology; the technology is widely applied to the fields of medical treatment, nondestructive testing and the like, and can specifically realize the functions of chest piece bone and meat separation, bone density detection, metal detection and the like; the traditional multi-energy X-ray detection technology generally adopts a structure of a single X-ray bulb tube and a single detector, the bulb tube is operated to emit rays with different kV (such as high, medium and low kV), the detector acquires multi-energy images under corresponding kV, and the acquired images can be subjected to dual-energy subtraction and other technologies to acquire images with specific requirements.
The traditional multi-energy detection technology enables the bulb tube to emit rays with different kV in the process of acquiring multi-energy images, respectively acquires the multi-energy images under the corresponding kV, and the multi-energy images are not exposed simultaneously in the process of acquiring the images, so that the multi-energy images have motion difference when moving objects are shot (such as chest X-ray films are shot, the chest fluctuates along with respiration), the phenomenon of motion artifacts can occur after the images are subjected to dual-energy subtraction, and the radiation dose can be increased after the images are acquired for multiple times.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the multi-layer X-ray detector image processing method and the terminal are provided, processing of the multi-energy image acquired by one-time exposure is achieved, and readability of the multi-energy image is improved.
In order to solve the technical problem, the invention adopts a technical scheme that:
a multi-slice X-ray detector image processing method, comprising the steps of:
s1, obtaining a multi-energy image of an object to be measured, wherein the multi-energy image is a plurality of images respectively obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multi-layer flat plate structure;
s2, fusing a plurality of log-transformed multi-energy images to obtain a fused image;
s3, determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image;
and S4, obtaining an image analysis result according to the fusion image and the subtraction image.
In order to solve the technical problem, the invention adopts another technical scheme as follows:
a multi-layered X-ray detector image processing terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the computer program:
s1, obtaining a multi-energy image of an object to be measured, wherein the multi-energy image is obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multi-layer flat plate structure;
s2, fusing a plurality of log-transformed multi-energy images to obtain a fused image;
s3, determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image;
and S4, obtaining an image analysis result according to the fusion image and the subtraction image.
The invention has the beneficial effects that: the X-ray detector with the multi-layer flat plate structure can acquire a plurality of multi-energy images by single exposure, the multi-energy images are subjected to logarithmic transformation, gray values of the images are linearly related to the thickness of the object to be measured, information of the object to be measured can be acquired more clearly, the weighting coefficient is determined according to the preset target, the images in a target area can be further highlighted, the images can be acquired by single exposure, a plurality of fusion images and subtraction images with high readability can be acquired, the utilization rate of X-ray photons is greatly improved, and the absorption dose of the object to be measured irradiating the X-ray is reduced.
Drawings
FIG. 1 is a flowchart illustrating steps of a method for processing an image of a multi-slice X-ray detector according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an image processing terminal of a multi-layered X-ray detector according to an embodiment of the present invention;
FIG. 3 is a multi-layered X-ray detector of an embodiment of the present invention;
FIG. 4 is a schematic representation of an X-ray image of a breast of an embodiment of the present invention prior to subtraction;
FIG. 5 is a schematic illustration of a bone enhancement of a chest X-ray image in accordance with an embodiment of the present invention;
FIG. 6 is a schematic representation of chest X-ray image lung enhancement in accordance with an embodiment of the present invention;
description of reference numerals:
1. an X-ray bulb; 2. a multi-layered X-ray detector; 2-1, an upper detector; 2-2, a filtration layer; 2-3, a lower detector; 3. an object to be measured; 4. a multilayer X-ray detector image processing terminal; 5. a processor; 6. a memory.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
Referring to fig. 1, a method for processing an image of a multi-layered X-ray detector includes the steps of:
s1, obtaining a multi-energy image of an object to be measured, wherein the multi-energy image is a plurality of images respectively obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multi-layer flat plate structure;
s2, fusing a plurality of log-transformed multi-energy images to obtain a fused image;
s3, determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image;
and S4, obtaining an image analysis result according to the fusion image and the subtraction image.
From the above description, the beneficial effects of the present invention are: the X-ray detector with the multi-layer flat plate structure can acquire a plurality of multi-energy images by single exposure, the multi-energy images are subjected to logarithmic transformation, gray values of the images are linearly related to the thickness of the object to be measured, information of the object to be measured can be acquired more clearly, the weighting coefficient is determined according to the preset target, the images in a target area can be further highlighted, the images can be acquired by single exposure, a plurality of fusion images and subtraction images with high readability can be acquired, the utilization rate of X-ray photons is greatly improved, and the absorption dose of the object to be measured irradiating the X-ray is reduced.
Further, the S1 includes:
enabling an X-ray to pass through an object to be detected and a low-energy detector to obtain a low-energy image;
passing the X-rays through a filter layer placed between the low energy detector and a high energy detector such that the X-rays become high energy X-rays;
and enabling the high-energy X-ray to pass through a high-energy detector to acquire the high-energy image.
The above description shows that the multi-layer detector is used for allowing the X-ray to pass through once, and the energy of the X-ray is changed by means of the arrangement of the filtering layer, so that the multi-energy image is obtained by one-time exposure, the phenomenon of multi-energy image artifacts is avoided, and the multi-energy image is beneficial to subsequent processing.
Further, between S1 and S2, further comprising: and correcting the low-energy image to obtain a low-energy corrected image.
It can be known from the above description that, since the X-ray is not filtered when the low-energy image is generated, the low-energy X-ray is irradiated on the detector, and the high-energy X-ray is also irradiated to generate an error, which affects the subsequent image processing.
Further, the step of correcting the low-energy image to obtain a low-energy corrected image specifically comprises:
calculating a spectrum correction coefficient k:
in the above formula, mu is the linear attenuation coefficient of the X-ray of the filter layer, and l is the thickness of the filter layer;
correcting the low-energy image according to the frequency spectrum correction coefficient k and the high-energy image to obtain a low-energy correction image, specifically;
wherein, I l For the low-energy corrected image, I l prev For the low energy image, I h Is the high energy image.
According to the description, the characteristic that X rays are converted into high-energy X rays through the filtering layer when the high-energy image is obtained and the high-energy image is not influenced by the low-energy X rays is utilized, the low-energy image is corrected by utilizing the high-energy image, and meanwhile, the degree of attenuation of the X rays caused by the filtering layer is considered, so that the precision of the low-energy corrected image is further improved.
Further, S2 specifically is:
obtaining the logarithmically transformed high-energy image I log_h And the low-energy corrected image I after logarithmic transformation log_l ；
For the said I log_h And said I log_l Respectively performing gray scale stretching to obtain I logdst_h And I logdst_l ；
In particular, the method comprises the following steps of,
wherein maxGray =2 bits -1，bits、I dst 、I src 、I max And I min Respectively representing the number of bits of the high-energy image, the I logdst_h The above I log_h The above I log_h And said I and the maximum gray value of log_h The minimum gray value of (a); or respectively representing the number of bits of the low-energy image, the I logdst_l The said I log_l The said I log_l And said I and the maximum gray value of log_l The minimum gray value of (a);
fusing the I according to a preset weight logdst_h And said I logdst_l And obtaining the fusion image.
It can be known from the above description that the attenuation degree of the X-ray is related to the wavelength of the X-ray and the irradiated object, and when the X-ray passes through a uniform substance, the incident intensity is exponentially attenuated along with the increase of the thickness of the object, the image is preprocessed by logarithmic change, the low-gray-scale region of the image can be greatly stretched while the gray scale of the image is linearly related to the thickness of the object, so that the image presents more details, the image after logarithmic processing is subjected to gray scale stretching, the relation between the gray scale of the image and the thickness of the object to be measured can be clearer, the subsequent corresponding analysis and processing of the image are convenient, the image fusion can improve the signal-to-noise ratio of the image, the X-ray absorption dose of the object to be measured is reduced, and the quality of the obtained image is ensured.
Further, the S3 specifically is:
carrying out logarithmic transformation on the low-energy correction image to obtain I ln_l ；
Carrying out logarithmic transformation on the high-energy image to obtain I ln_h ；
The logarithm in the logarithmic transformation is a natural logarithm;
determining a weighting coefficient w according to a preset target;
obtaining the subtraction image I DE ＝I ln_h -w·I ln_l 。
According to the description, the logarithmic transformation is carried out by adopting the natural logarithm, the attenuation rule of the object after the X-ray is absorbed is met, the weighting coefficient is determined according to the preset target for subtraction, the preset target, namely the region of interest, can be highlighted through the corresponding algorithm, and the target information can be acquired more pertinently.
Further, the determining the weighting coefficient according to the preset target in step S3 specifically includes:
determining an interested area according to a preset target;
setting an initial value and a variation range of the weighting coefficient, and obtaining a standard deviation equation for calculating the standard deviation of the region of interest according to the initial value and the variation range;
determining the weighting coefficient which minimizes the standard deviation of the interested area according to the standard deviation equation.
It can be known from the above description that the weighting coefficient which minimizes the standard deviation is calculated by establishing the standard deviation equation, so that the degree of protrusion of the region of interest is further improved, and the information loss of the region of interest is reduced by determining the weighting coefficient by minimizing the standard deviation.
Further, the multi-energy images comprise a high-energy image, a medium-energy image and a low-energy image;
the S2 specifically comprises the following steps:
obtaining the logarithmically transformed high-energy image I log_h Logarithmically transformed mid-energy image I log_m And the low-energy image I after logarithmic transformation log_l；
For the said I log_h The above I log_m And said I log_l Respectively performing gray scale stretching to obtain I logdst_h 、I log_m And I logdst_l ；
Fusing the I according to a preset weight logdst_h The above I log_m And said I logdst_l And obtaining the fusion image.
The above description shows that not only can the dual-energy image, i.e., the high-energy image and the low-energy image, be processed, but also the three-energy image can be processed, and the processing of the multi-energy image can be expanded, so that the three-energy image can be fused, the information content in the image can be integrated more, and a new dimension is provided for the analysis of the image.
Further, the S3 specifically is:
determining a weighting coefficient according to a preset target, and subtracting the low-energy image and the high-energy image according to the weighting coefficient to obtain a first subtraction image;
subtracting the low-energy image and the intermediate-energy image according to the weighting coefficient to obtain a second subtraction image;
subtracting the intermediate-energy image and the high-energy image according to the weighting coefficient to obtain a third subtracted image;
and respectively taking the first subtraction image, the second subtraction image and the third subtraction image as three channels of the color map to synthesize the color map.
From the above description, when the three-energy images are subjected to subtraction, a plurality of subtraction images can be generated by combining two images, and the three subtraction images are respectively used as three channels of the color image, so that the color image can be synthesized, and the structure of the object to be detected in the image can be displayed more clearly.
Referring to fig. 2, a multi-layer X-ray detector image processing terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above steps when executing the computer program.
Referring to fig. 1 and fig. 3, a first embodiment of the present invention is:
in this embodiment, a multi-layer X-ray detector shown in fig. 3 may be used, the kV value of the X-ray emitted by the multi-layer X-ray detector may be set, an X-ray bulb 1 emits an X-ray with a corresponding kV value, the X-ray passes through an object to be detected 3 and then reaches a multi-layer X-ray detector 2, the multi-layer X-ray detector 2 converts the X-ray into visible light through a scintillator in an upper (low energy) detector 2-1, and then collects electrons through photoelectric conversion to obtain a low energy image; the residual X-ray passes through the filtering layer 2-2 and then is converted into high-energy X-ray, and a high-energy image is obtained through the lower-layer (high-energy) detector 2-3; the method specifically comprises the following steps:
s1, obtaining a multi-energy image of an object to be measured, wherein the multi-energy image is obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multi-layer flat plate structure;
in this embodiment, the method includes:
enabling an X-ray to pass through an object to be detected and a low-energy detector to obtain a low-energy image;
wherein a specific dose of X-rays can be set;
passing the X-rays through a filtering layer placed between the low energy detector and a high energy detector such that the X-rays become high energy X-rays;
passing the high-energy X-rays through a high-energy detector to obtain the high-energy image;
correcting the low-energy image to obtain a low-energy corrected image, specifically, calculating a spectrum correction coefficient k:
in the above formula, mu is the X-ray linear attenuation coefficient of the filtering layer, and l is the thickness of the filtering layer;
correcting the low-energy image according to the frequency spectrum correction coefficient k and the high-energy image to obtain a low-energy correction image, specifically;
wherein, I l For the low-energy corrected image, I l prev For said low energy image, I h Is the high-energy image;
s2, fusing a plurality of log-transformed multi-energy images to obtain a fused image;
specifically, obtaining the high-energy image I after logarithmic transformation log_h And the low-energy corrected image I after logarithmic transformation log_l ；
In an alternative embodiment, the log transformation is performed using a base 10 logarithm:
I log ＝a×log 10 I；
wherein,
maxGray＝2 bits -1；
in the above formula, I log And bits respectively represent the digits of the low-energy image (which can also be a low-energy correction image), the logarithmically transformed low-energy image and the low-energy image; or respectively representing the high-energy image, the high-energy image after logarithmic transformation and the digits of the high-energy image;
separately calculating the I log_h And said I log_l The histogram identifying the I log_h And said I log_l The pixel distribution of different gray values;
setting a threshold, determining the threshold proportion of pixels accumulated in a histogram of the image according to the width and the height of the image taking the pixels as units, accumulating the pixels with the corresponding proportion from the left side of the histogram, obtaining the maximum gray value of the image, accumulating the pixels with the corresponding proportion from the right side of the histogram, and obtaining the minimum gray value of the image, wherein the image is a low-energy image subjected to logarithmic transformation or a high-energy image subjected to logarithmic transformation;
if the ratio of the threshold value is set to be 0.01, the width of the image is h pixels, and the height of the image is w pixels, the threshold value of the pixel is h multiplied by w multiplied by 0.01, the pixels are accumulated from the left side of the histogram, and if the threshold value of the pixel is exceeded, the gray value corresponding to the exceeded pixel is the minimum gray value; accumulating pixels from the right side of the histogram, wherein if the pixel threshold value is exceeded, the gray value corresponding to the exceeded pixel is the maximum gray value;
for the said I log_h And said I log_l Respectively carrying out gray level stretching to respectively obtain I logdst_h And I logdst_l ；
In particular, the method comprises the following steps of,
wherein maxGray =2 bits -1，bits、I dst 、I src 、I max And I min Respectively representing the number of bits of the high-energy image, the I logdst_h The above I log_h The said I log_h Maximum gray value of and the value of log_h The minimum gray value of; or respectively representing the number of bits of the low-energy image, the I logdst_l The said I log_l The said I log_l Maximum gray value of and the value of log_l The minimum gray value of;
fusing the I according to a preset weight logdst_h And said I logdst_l Obtaining the fusion image;
in particular, the image I is fused fuse ＝I logdst_l +b×I logdst_h Wherein b is a weighting coefficient;
in an optional embodiment, b has a value ranging from 0 to 1;
in an optional implementation, the fused image may be enhanced, and specifically, the fused image may be processed by using methods such as laplacian pyramid decomposition, laplacian pyramid reconstruction, detail enhancement, gray scale stretching, and the like;
s3, determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image;
specifically, the low-energy corrected image is logarithmically transformed to obtain I ln_l (ii) a Carrying out logarithmic transformation on the high-energy image to obtain I ln_h (ii) a The logarithm in the logarithmic transformation is a natural logarithm; determining a weighting coefficient w according to a preset target; obtaining the subtraction image I DE ＝I ln_h -w·I ln_l ；
Determining the weighting coefficients according to the preset target specifically comprises:
determining an interested area according to a preset target;
setting an initial value and a variation range of the weighting coefficient, and obtaining a standard deviation equation for calculating the standard deviation of the region of interest according to the initial value and the variation range;
determining the weighting coefficient which minimizes the standard deviation of the region of interest according to the standard deviation equation;
and S4, obtaining an image analysis result according to the fusion image and the subtraction image.
The second embodiment of the invention is as follows:
a multi-slice X-ray detector image processing method, which is different from the first embodiment in that: for the multilayer X-ray detector shown in fig. 3, a filter layer similar to 2-2 and a detector similar to 2-3 can be continuously added below a lower detector 2-3 in the multilayer X-ray detector 2, and the composition of the filter layer is changed to generate X-rays with different energies, so that the acquisition of a multi-energy image is realized;
the S1 comprises: enabling X-rays to pass through a multi-layer X-ray detector to obtain a high-energy image, a medium-energy image and a low-energy image;
the S2 specifically comprises the following steps:
obtaining the logarithmically transformed high-energy image I log_h Logarithmically transformed intermediate energy image I log_m And the low-energy image I after logarithmic transformation log_l；
For the I log_h The above I log_m And the aboveI log_l Respectively carrying out gray level stretching to respectively obtain I logdst_h 、I log_m And I logdst_l ；
Fusing the I according to a preset weight logdst_h The said I log_m And said I logdst_l Obtaining the fusion image;
in particular, I fuse ＝I log_l +b×I log_h +c×I log_m B and c are weighting coefficients corresponding to the high-energy image and the medium-energy image respectively;
the S3 specifically comprises the following steps:
determining a weighting coefficient according to a preset target, and subtracting the low-energy image and the high-energy image according to the weighting coefficient to obtain a first subtraction image;
subtracting the low-energy image and the medium-energy image according to the weighting coefficient to obtain a second subtraction image;
subtracting the intermediate energy image and the high energy image according to the weighting coefficient to obtain a third subtraction image;
in an optional embodiment, the logarithmically transformed low-energy image and the logarithmically transformed high-energy image are subtracted according to the weighting coefficient to obtain a first subtracted image; subtracting the logarithmically transformed low-energy image and the logarithmically transformed medium-energy image according to the weighting coefficient to obtain a second subtraction image; subtracting the logarithmically transformed intermediate-energy image and the logarithmically transformed high-energy image according to the weighting coefficient to obtain a third subtraction image; wherein, the logarithm in the logarithmic transformation is a natural logarithm;
respectively taking the first subtraction image, the second subtraction image and the third subtraction image as three channels of a color image to synthesize the color image;
further comprising: continuously selecting two images from the first subtraction image, the second subtraction image and the third subtraction image respectively according to a preset weight to fuse to generate a first subtraction fusion image and a second subtraction fusion image; if the first subtraction image and the second subtraction image can be fused with a certain weight to generate a first subtraction fusion image, and the second subtraction image and the third subtraction image can be fused with a certain weight to generate a second subtraction fusion image;
by the dual-energy subtraction method, subtraction is performed according to the first subtraction fusion image and the second subtraction fusion image, and the specific X-ray spectrum identification degree of the object is improved.
Referring to fig. 4 and 5, a third embodiment of the present invention is:
the specific application of the image subtraction in the multilayer X-ray detector image processing method is as follows:
setting the dosage of X-rays, acquiring a low-energy image and a high-energy image through single exposure, and correcting the low-energy image to obtain a low-energy corrected image; carrying out logarithmic transformation on the low-energy correction image to obtain I ln_l (ii) a Carrying out logarithmic transformation on the high-energy image to obtain I ln_h (ii) a Wherein, the logarithm in the logarithm transformation is a natural logarithm; determining a weighting coefficient w according to a preset target; obtaining the subtraction image I DE ＝I ln_h -w·I ln_l ；
Referring to fig. 4, a low-energy image of an unreduced chest X-ray film is shown, in which the right lung and the surrounding bones are shown, and if the right lung needs to be subjected to subtraction, i.e. the display of the enhanced bones, the upper box in fig. 4 is taken as a non-flat region of interest D;
calculating the standard deviation of the region in the subtraction image obtained under different w values
Referring to FIG. 5, w is limited to a value range of 0-1, and w with the smallest σ (w) is selected as the weighting factor and is substituted into I DE ＝I ln_h -w·I ln_l Obtaining a subtracted bone-enhanced image I DE_bone ；
If the bones need to be subtracted, namely the display of the right lung is enhanced, the upper square box in the two square boxes in the figure 4 is taken as a non-flat right lung interested area D s The lower square is used as the non-flat bone feelingRegion of interest D b Setting the range of w to be 0.01-1, setting the initial value to be 0.01, and setting the search step to be 0.01;
according to w and I DE ＝I ln_h -w·I ln_l Respectively calculating two interested areas D s And D d Is subtracted from the image I DE1 And I DE2 ；
Calculating the standard deviation of two interested areas
Referring to FIG. 6, w, which minimizes σ (w), is taken as a weighting coefficient in a limited range and is substituted into I DE ＝I ln_h -w·I ln_l Obtaining a lung enhancement image I after subtraction DE_bone 。
Referring to fig. 2, a fourth embodiment of the present invention is:
a multilayer X-ray detector image processing terminal 4 comprises a processor 5, a memory 6 and a computer program stored on the memory 6 and capable of running on the processor 5, wherein the processor 5 executes the computer program to realize the steps of the first embodiment, the second embodiment or the third embodiment.
In summary, the present invention provides an image processing method and a terminal for a multi-layer X-ray detector, which utilize the characteristics of X-rays, that is, when X-rays penetrate through a uniform object, a signal I = e -ul In the formula, u is the linear attenuation coefficient of the object, l is the thickness of the object, and after the signal I is subjected to logarithmic transformation, the gray scale can be linearly related to the thickness of the object, and the low-gray-scale area of the image can be greatly stretched, so that the subsequent further enhancement processing of the image is facilitated, the photon utilization rate of X-rays can be improved, and the absorbed dose of a patient can be reduced; the image obtained by the X-ray before passing through the filtering layer is corrected by utilizing the characteristics of the filtering layer according to the attributes of the filtering layer and the image obtained by the X-ray after passing through the filtering layer, so that the precision and readability of the image are improved; the weighting coefficient can be set according to the target, subtraction operation can be carried out according to the weighting coefficient and the multi-energy image, the information presentation definition of the target area can be greatly enhanced, and the non-target area is excludedThe interference of the image is enhanced, the readability of the image is enhanced, further, a low-energy image, a medium-energy image and a high-energy image are obtained, three subtraction images are generated, the images can be synthesized into a color image corresponding to three channels of the color image, the readability of the image is further improved, and under the condition that more filtering layers are arranged and more energy types of X-rays are formed, the multi-energy image generated by the filtering layers can be correspondingly processed, and the utilization rate of X-ray photons is further improved.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (7)
1. A multi-slice X-ray detector image processing method, comprising the steps of:
s1, obtaining a multi-energy image of an object to be measured, wherein the multi-energy image is obtained by X-rays with different energies generated after the X-rays pass through an X-ray detector with a multi-layer flat plate structure; the X-ray detector with the multilayer flat plate structure comprises a low-energy detector, a filtering layer and a high-energy detector, wherein the filtering layer is arranged between the low-energy detector and the high-energy detector;
s2, fusing a plurality of log-transformed multi-energy images to obtain a fused image;
s3, determining a weighting coefficient according to a preset target, and realizing subtraction according to the weighting coefficient and the multi-energy image to obtain a subtraction image;
s4, obtaining an image analysis result according to the fusion image and the subtraction image;
the S1 specifically comprises:
enabling the X-ray to pass through an object to be detected and a low-energy detector to obtain a low-energy image;
passing the X-rays through a filter layer placed between the low energy detector and a high energy detector such that the X-rays become high energy X-rays;
enabling the high-energy X-ray to pass through a high-energy detector to obtain a high-energy image;
still include between S1 and S2: correcting the low-energy image to obtain a low-energy corrected image;
correcting the low-energy image to obtain a low-energy corrected image, which specifically comprises the following steps:
calculating a spectrum correction coefficient k:
in the above formula, mu is the X-ray linear attenuation coefficient of the filtering layer, and l is the thickness of the filtering layer;
correcting the low-energy image according to the frequency spectrum correction coefficient k and the high-energy image to obtain a low-energy correction image, specifically;
wherein, I l For the low-energy corrected image, I l prev For said low energy image, I h Is the high energy image.
2. The multi-slice X-ray detector image processing method according to claim 1, wherein S2 specifically is:
obtaining the logarithmically transformed high-energy image I log_h And the low-energy corrected image I after logarithmic transformation log_l ；
For the I log_h And said I log_l Respectively carrying out gray level stretching to respectively obtain I logdst_h And I logdst_l ；
In particular, the method comprises the following steps of,
wherein maxGray =2 bits -1，bits、I dst 、I src 、I max And I min Respectively representing the number of bits of the high-energy image, the I logdst_h The above I log_h The above I log_h And said I and the maximum gray value of log_h The minimum gray value of (a); or respectively representing the number of bits of the low-energy image, the I logdst_l The said I log_l The said I log_l And said I and the maximum gray value of log_l The minimum gray value of;
fusing the I according to a preset weight logdst_h And said I logdst_l And obtaining the fusion image.
3. The multi-slice X-ray detector image processing method according to claim 1, wherein S3 specifically is:
carrying out logarithmic transformation on the low-energy correction image to obtain I ln_l ；
Carrying out logarithmic transformation on the high-energy image to obtain I ln_h ；
The logarithm in the logarithmic transformation is a natural logarithm;
determining a weighting coefficient w according to a preset target;
obtaining the subtraction image I DE ＝I ln_h -w·I ln_l 。
4. The multi-slice X-ray detector image processing method according to claim 1, wherein the determining of the weighting coefficients according to the preset target in S3 specifically comprises:
determining an area of interest according to a preset target;
setting an initial value and a variation range of the weighting coefficient, and obtaining a standard deviation equation for calculating the standard deviation of the region of interest according to the initial value and the variation range;
determining the weighting coefficient which minimizes the standard deviation of the interested area according to the standard deviation equation.
5. The multi-slice X-ray detector image processing method as claimed in claim 1, wherein the multi-energy images comprise a high-energy image, a medium-energy image and a low-energy image;
the S2 specifically comprises the following steps:
obtaining the logarithmically transformed high-energy image I log_h Logarithmically transformed mid-energy image I log_m And the low-energy image I after logarithmic transformation log_l ；
For the I log_h The said I log_m And said I log_l Respectively carrying out gray level stretching to respectively obtain I logdst_h 、I logdst_m And I logdst_l ；
Fusing the I according to a preset weight logdst_h The said I logdst_m And said I logdst_l And obtaining the fusion image.
6. The multi-layered X-ray detector image processing method according to claim 5, wherein S3 specifically is:
determining a weighting coefficient according to a preset target, and subtracting the low-energy image and the high-energy image according to the weighting coefficient to obtain a first subtraction image;
subtracting the low-energy image and the intermediate-energy image according to the weighting coefficient to obtain a second subtraction image;
subtracting the intermediate energy image and the high energy image according to the weighting coefficient to obtain a third subtraction image;
and respectively taking the first subtraction image, the second subtraction image and the third subtraction image as three channels of the color map to synthesize the color map.
7. A multi-layered X-ray detector image processing terminal, comprising a memory, a processor and a computer program stored on the memory and operable on the processor, characterized in that the processor implements a multi-layered X-ray detector image processing method according to any one of claims 1 to 6 when executing the computer program.
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