CN116660298A - Imaging method, device, storage medium and equipment based on cable scanning detection - Google Patents

Imaging method, device, storage medium and equipment based on cable scanning detection Download PDF

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Publication number
CN116660298A
CN116660298A CN202310577106.7A CN202310577106A CN116660298A CN 116660298 A CN116660298 A CN 116660298A CN 202310577106 A CN202310577106 A CN 202310577106A CN 116660298 A CN116660298 A CN 116660298A
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cable
flat panel
projection data
panel detector
smoothing
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李昆鹏
邱焓
倪松
段晓礁
刘建军
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Chongqing Zhence Science And Technology Co ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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Chongqing Zhence Science And Technology Co ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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Priority to CN202310577106.7A priority Critical patent/CN116660298A/en
Publication of CN116660298A publication Critical patent/CN116660298A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
    • G01N23/18—Investigating the presence of flaws defects or foreign matter
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/003—Reconstruction from projections, e.g. tomography
    • G06T11/005—Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T11/00—2D [Two Dimensional] image generation
    • G06T11/003—Reconstruction from projections, e.g. tomography
    • G06T11/006—Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/03—Investigating materials by wave or particle radiation by transmission
    • G01N2223/04—Investigating materials by wave or particle radiation by transmission and measuring absorption
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/40—Imaging
    • G01N2223/401—Imaging image processing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/60—Specific applications or type of materials
    • G01N2223/646—Specific applications or type of materials flaws, defects
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2211/00—Image generation
    • G06T2211/40—Computed tomography
    • G06T2211/421—Filtered back projection [FBP]

Abstract

The invention provides an imaging method, device, storage medium and equipment based on cable scanning detection. The imaging method comprises the following steps: equidistant sampling scanning is carried out on the cable to be tested along the radial source according to a preset path and preset intervals, and scanned original projection data are obtained through the flat panel detector; outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expanded projection data; performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data; and carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image. The invention solves the technical problem that the quality of the reconstructed image is difficult to be ensured while the internal defect structure of the cable is quickly reconstructed in the prior art.

Description

Imaging method, device, storage medium and equipment based on cable scanning detection
Technical Field
The present invention relates to the field of cable detection technologies, and in particular, to an imaging method, apparatus, storage medium, and device based on cable scanning detection.
Background
At present, aiming at the defect detection of the buffer layer of the crosslinked polyethylene high-voltage cable, visual defect images can be obtained through CT detection. But the cable cannot rotate when running, and the field environment is complex, so that the space is narrow, and the inspection is inconvenient. In the existing local STCT detection method (L-STCT) for detecting the defects of the high-voltage cable buffer layer, in the L-STCT scanning, an object and a detector are kept motionless, and a ray source makes equidistant translational motion along a straight line parallel to the detector so as to acquire projection data of different angles.
Because the bottom of the cable is scanned and imaged, the rays emitted by the micro Jiao Dianshe line source at each position cannot cover the whole object, and the projection acquired by the detector is transversely truncated. The iterative algorithm has higher flexibility in the problems of limited angle and related pathological inversion of cut-off, but the iterative reconstruction process is long in time consumption and low in efficiency. The direct reconstruction of truncated and limited angle projection data by a filtered back-projection reconstruction algorithm (FBP) introduces artifacts in the reconstructed image that affect the identification and detection of defects.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides an imaging method based on cable scanning detection, which solves the technical problem that the quality of a reconstructed image is difficult to be ensured while the internal defect structure of a cable is quickly reconstructed in the prior art.
In a first aspect, the present invention provides an imaging method based on cable scan detection, applied to a scanning system comprising a radiation source and a flat panel detector; the imaging method comprises the following steps:
equidistant sampling scanning is carried out on the cable to be tested along the radial source according to a preset path and preset intervals, and scanned original projection data are obtained through the flat panel detector;
outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expanded projection data;
performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
and carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
Further, the positions of the preset paths and the flat panel detectors are adjusted, so that an interested region of the cable to be tested is positioned at a central point Q of a scanning space formed by the ray source and the flat panel detectors; establishing a rectangular coordinate system by taking the point Q as an origin, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) is acquired, where δ represents the local coordinates of the focal position of the radiation source and u represents the local coordinates of the detector unit.
Further, performing outward expansion smoothing on the original projection data along two ends of the flat panel detector to obtain outward expansion projection data, including:
determining M' columns of virtual smooth data according to the dimension MXN of the original projection data, wherein M is the number of detector unit arrays in each row;
performing spread smoothing by a smoothing function g (x) =cosx, wherein
Obtaining the outward expansion projection data:
further, performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data, including:
defining N' rows of virtual smooth data according to the dimension M multiplied by N of the original projection data; wherein N is the sampling point number of the ray source;
performing spread smoothing by a smoothing function g (x) =cosx, whereinObtaining inner expansion projection data;
wherein x is n ＝(n-1)*Δβ；
Further, performing filtered back projection reconstruction on the interior-expanded projection data to obtain a reconstructed tomographic image, including:
reconstructing the original projection data after the external expansion smoothing process and the internal expansion smoothing process by the following formula:
h is the distance of the original flat panel detector; l is the distance from the origin Q to the preset path of the ray source; delta is the local coordinate of the focal position of the radiation source; u is the local coordinates of the detector unit; s is half of a preset path length; d is half the width of the flat panel detector.
Further, the length of the preset path is equal to the width of the flat panel detector to obtain a central point Q of a scanning space formed by the ray source and the flat panel detector;
acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line;
acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment;
and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
Further, the positions of the preset paths and the flat panel detectors are adjusted, so that an interested region of the cable to be tested is positioned at a central point Q of a scanning space formed by the ray source and the flat panel detectors; comprising the following steps:
based on the model of the cable to be tested, confirming the center of the radial cross section of the cable to be tested at the position to be tested and the position of the buffer layer;
adjusting a preset path and a flat panel detector to enable the center of the radial cross section of the position to be detected to be positioned right below the Q point;
confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested;
and according to the offset distance, adjusting the preset path and the flat panel detector to enable the buffer layer of the radial cross section of the position to be measured to be positioned at the Q point.
Further, the preset interval includes: confirming the length of a preset path based on the diameter of the cable to be tested; and acquiring preset acquisition points, and confirming preset intervals according to the length of the preset path.
In a second aspect, the present invention provides an imaging device based on cable scan detection, the device comprising:
the data acquisition module is connected with the flat panel detector and is used for acquiring the equidistant sampling scanning of the ray source along the cable to be detected according to a preset path and a preset interval and acquiring the scanned original projection data through the flat panel detector;
the outward expansion smoothing module is used for outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expansion projection data;
the inner expansion smoothing module is used for carrying out inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
and the image reconstruction module is used for carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
Further, the data acquisition module includes:
the position adjusting module is positioned between the ray source and the flat panel detector and is used for adjusting the preset path and the position of the flat panel detector so that the region of interest of the cable to be tested is positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; establishing a rectangular coordinate system by taking the point Q as an origin, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) are acquired, where δ is the local coordinate of the focal position of the radiation source and u is the local coordinate of the detector unit.
Further, the spread smoothing module includes:
the external expansion virtual smoothing module is used for determining M' column virtual smoothing data according to the dimension MxN of the original projection data, wherein M is the number of detector unit arrays in each row;
a spreading module for performing spreading smoothing by a smoothing function g (x) =cosx, wherein
Obtaining the outward expansion projection data:
further, the inner expansion smoothing module includes:
the internal expansion virtual smoothing module is used for defining N' row virtual smoothing data according to the dimension M multiplied by N of the original projection data; wherein N is the sampling point number of the ray source;
an inner spreading module for performing outer spreading smoothing by a smoothing function g (x) =cosx, whereinObtaining inner expansion projection data;
wherein x is n ＝(n-1)*Δβ；
Further, the image reconstruction module includes:
the filtering back projection module is used for reconstructing the original projection data after the external expansion smoothing processing and the internal expansion smoothing processing through the following formula:
h is the distance of the original flat panel detector; l is the distance from the origin Q to the preset path of the ray source; delta is the local coordinate of the focal position of the radiation source; u is the local coordinates of the detector unit; s is half of a preset path length; d is half the width of the flat panel detector.
Further, the data acquisition module further includes:
the center determining module: acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line; acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment; and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
Further, the position adjustment module includes:
the cable model acquisition module is used for confirming the center of the radial cross section of the position to be tested of the cable to be tested and the position of the buffer layer based on the model of the cable to be tested;
the position confirming module is used for confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested;
the adjusting module is used for adjusting the preset path and the flat panel detector to enable the center of the radial cross section of the position to be detected to be located right below the Q point; and according to the offset distance, adjusting the preset path and the flat panel detector to enable the buffer layer of the radial cross section of the position to be detected to be positioned at the Q point.
Further, the data acquisition module further includes:
the path confirming module is used for confirming the length of a preset path based on the diameter of the cable to be tested;
the interval confirming module is used for acquiring preset acquisition points and confirming preset intervals according to the length of the preset paths.
In a third aspect, the present invention provides a computer readable storage medium storing at least one instruction for execution by a processor to implement a cable scan detection based imaging method.
In a fourth aspect, the present invention provides a computer device comprising a processor and a memory; the memory stores at least one instruction for execution by the processor to implement a cable scan detection-based imaging method.
Compared with the prior art, the invention has the following beneficial effects:
the method comprises the steps of performing outward expansion smoothing on original projection data along two ends of a flat panel detector to obtain outward expansion projection data; and the angle of sampling the edge of the outward expansion projection data; and (3) performing inner expansion smoothing on the outer expansion projection data to obtain inner expansion projection data, so that limited angles and truncation artifacts are restrained. Meanwhile, the filtering back projection method can rapidly improve the reconstruction efficiency of the image. The technical problem that in the prior art, the quality of the reconstructed image is difficult to ensure while the internal defect structure of the cable is quickly reconstructed is solved.
Drawings
Fig. 1 is a method step diagram of an embodiment of the present invention.
FIG. 2 is a two-dimensional geometric model of a scanning system according to another embodiment of the present invention.
FIG. 3 is a schematic diagram of a cable simulation phantom according to another embodiment of the invention.
Fig. 4 is a schematic diagram of a smoothing process of original projection data according to another embodiment of the present invention.
FIG. 5 is a comparison of reconstructed tomographic images obtained by three methods for the same cable phantom in accordance with another embodiment of the present invention.
Fig. 6 is a comparison of reconstructed tomographic images obtained by three methods for two types of cables, respectively, according to another embodiment of the present invention.
Figure 7 is a reconstructed tomographic image of a plurality of position cross-sections of two types of cables by the present method according to another embodiment of the present invention,
fig. 8 is a schematic diagram of a computer device according to another embodiment of the invention.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.
Example 1:
as shown in fig. 1, an imaging method based on cable scan detection (hereinafter referred to as LFBP) is applied to a scanning system, which includes a radiation source and a flat panel detector (L-STCT); the imaging method comprises the following steps:
s1: equidistant sampling scanning is carried out on the cable to be tested along the radial source according to a preset path and preset intervals, and scanned original projection data are obtained through the flat panel detector;
s2: outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expanded projection data;
s3: performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
s4: and carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
The specific implementation manner of the embodiment comprises the following steps:
the scanning system in the embodiment comprises a ray source and a flat panel detector, and a cable to be tested is positioned between the ray source and the flat panel detector; adjusting the preset path and the position of the flat panel detector to enable the region of interest of the cable to be tested to be positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; comprising the following steps: acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line; acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment; and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
Multiple experiments show that the imaging effect at the Q point is the best for a scanning system, so that the region of interest is placed at the Q point so that the imaging effect is the best; comprising the following steps: based on the model of the cable to be tested, confirming the center of the radial cross section of the cable to be tested at the position to be tested and the position of the buffer layer; the radial cross section structures of the cables of different types are different, namely the positions and the thicknesses of the buffer layers are different, so that the positions and the centers of the corresponding buffer layers can be obtained according to the types of the cables.
As shown in fig. 2, the preset path and the flat panel detector are adjusted so that the center of the radial cross section of the position to be measured is located right below the Q point; confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested; according to the offset distance, adjusting a preset path and the flat panel detector to enable a buffer layer of a radial cross section of a position to be detected to be positioned at a Q point; τ in fig. 2 is the offset distance.
Establishing a rectangular coordinate system by taking a point Q as an origin o, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) are acquired, where δ is the local coordinate of the focal position of the radiation source and u is the local coordinate of the detector unit.
Based on the coordinate system constructed as described above, the coordinates of the flat panel detector unit during scanning can be expressed as:
the coordinates of the focal spot of the source of radiation can be expressed as
Wherein delta is the local coordinate of the focal position of the ray source, u is the local coordinate of the detector unit, d is half of the width of the flat panel detector, s is half of the length of the moving track of the ray source, h and l respectively represent the distance from the origin o to the detector and the distance from the ray source track to the origin o, and the two are
h＝Fd/(s+d)； (3)
l＝Fs/(s+d)； (4)
F represents the distance of the source trajectory from the detector. In the scanning system, any ray can form an included angle with the y-axisAnd the distance r of the ray from the origin of coordinates o. The integral of the attenuation coefficient f (x, y) of each point along the path along the ray is the projection specified by the ray:
in an L-STCT scanning system, any ray can be uniquely specified by (delta, u), and has
According to the geometrical relationship shown in figure 2,the corresponding relation of the coordinates with (delta, u) is
According to equation (7), it is desirable to acquire projection data of at least 180 deg. to achieve accurate reconstruction, the delta is required to be within a range of (- +. ++ infinity A kind of electronic device. However, in the actual scanning process, the moving distance 2s of the ray source is necessarily limited, and imaging is a limited angle problem. At the same time, the radiation source emits radiation at each location that covers only a portion of the cable due to the oversized cable diameter.
Classical parallel-beam FBP reconstruction algorithms can be expressed as
Wherein the method comprises the steps ofIs inclined toThe slope filter convolves the kernel function. According to formulae (7) and (8) +.>Jacobian to (δ, u):
substituting the formula (13) and the formula (6) into the formula (11) and simplifying the formula to obtain
Equation (12) is the FBP reconstruction equation for fan beam scanning, but directly reconstructing the limited angle and truncated projection data using equation (12) can introduce serious streak artifacts in the reconstructed image.
Therefore, before performing the filtered back projection reconstruction, the present embodiment sequentially performs the outer expansion smoothing and the inner expansion smoothing on the original projection data, including:
defining M and N as the number of detector unit arrays and the number of sampling points of the ray source in each row, wherein the dimension of the original projection data p (delta, u) is M multiplied by N, and the extrapolated M' column virtual smooth data is defined. The smoothing function is g (x) =cosx, whereIn the data expansion smoothing process, first, the leftmost column of data p (, u) of the original data is extracted respectively 1 ) And the rightmost column of data p (·, u) M ) Performing the spread smoothing process can be expressed as:
wherein x is m ＝(m-1)Δγ，The smoothed data may be represented as
It can be seen from this that the partial virtual data is added on the basis of the original data in the data expansion smoothing process. And secondly, carrying out inward expansion smoothing on projection data along the sampling direction of the ray source so as to inhibit artifacts caused by limited angle imaging.
Defining interpolation N' data for smoothing, and the smoothed data can be expressed as
Wherein x is n ＝(n-1)*Δβ，Therefore, the data interpolation smoothing processing does not increase the data amount, and only the smoothing processing is performed on the original data. After two times of data smoothing processing, the data preprocessing is completed. As shown in fig. 4, a process of data smoothing processing is illustrated. Fig. 4 (a) shows the original acquired data p= (δ, u), which is smoothed by despreading to obtain the dataAs shown in FIG. 4 (b), further, an inner expansion smoothing is performed on the basis of this to obtain final data +.>As shown in fig. 4 (c).
Using the preprocessed data for reconstruction, equation (12) may be further expressed as:
and (3) reconstructing through a formula (16) to obtain a reconstructed tomographic image of the interior of the cable to be detected.
In this embodiment, in order to verify the effectiveness of the above scheme, a simulation experiment was designed, a simulation model body as shown in fig. 3 was designed with two types of cables, 110kV and 220kV, as experimental objects, and a simulation defect was designed according to practical situations. The size of the simulation die body is 512 pixels×512 pixels;
the size of the designed reconstructed tomographic image is 300 pixels multiplied by 300 pixels in the simulation process; quantitative evaluation by acquiring root mean square error RMSE and structural similarity SSIM in an image comprises:
wherein: f is a reconstructed image;is a standard image; m and N are the rows and columns of the reconstructed image, respectively; sigma (sigma) f And->The sum of standard deviations of the reconstructed image and the standard image is covariance; c (C) 1 And C 2 Is a constant term.
The parameters in the simulation are as follows:
table 1 simulation experiment parameters
The reconstructed tomographic image is obtained by adopting an FBP method, an SIRT method and a method provided by the scheme (the method is marked as LFBP in the drawing in the embodiment) respectively, and a result shown in the figure is obtained;
as can be seen from fig. 5, the reconstructed tomographic image obtained by the FBP method shows obvious truncation artifacts and limited angle artifacts (indicated by arrows in fig. 5 (a)), which interfere with defect identification; the quality of the reconstructed tomographic image obtained by the scheme and the SIRT method is better than that obtained by the FBP method; truncation artifacts and limited angle artifacts are suppressed.
Further comparing the quantization indexes of the reconstructed tomographic image obtained by the FBP method, the SIRT method and the scheme, the quantization indexes are as follows:
table 2 reconstructed image quantization index
As can be seen from table 2, the reconstructed image quality of this scheme is close to SIRT and significantly better than that of FBP reconstructed images.
Table 3 three methods reconstruct time comparisons
As can be seen from table 3, the reconstruction time of the analytical reconstruction methods FBP and LFBP was found to be 42 times faster than the SIRT reconstruction. Since the calculation time is additionally increased in the smoothing process of the external expansion smoothing of the original projection data, the reconstruction time of the scheme is increased compared with that of the FBP method directly reconstructing the original data, but the difference of only 0.04s is almost negligible. By combining the comparison of the reconstructed image quality and the reconstruction time, the scheme can be found that the reconstruction efficiency is guaranteed to be equivalent to that of FBP, and the imaging quality is equivalent to that of SIRT iterative reconstruction.
FIG. 6 shows the result of constructing the experimental platformAnd->The cable uses the reconstructed results of FBP, SIRT and LFBP methods respectively; the results indicate that LFBP and FBP reconstruction efficiencies are comparable and significantly higher than SIRT algorithms. Because of the problems of truncation and limited angles of projection data, the direct use of the FBP algorithm for reconstruction causes serious truncation artifacts and limited angle artifacts, and the identification of cable defects is interfered. SIRT reconstruction results effectively inhibit truncation artifacts and strengthen cable junctionsThe degree of recognition of the structure, but the limited angle artifacts cannot be further processed. The LFBP reconstruction result shows that not only the truncation artifact is effectively suppressed, but also the limited angle artifact is weakened, and the influence of the limited angle artifact on the real geometric structure is reduced.
Fig. 7 illustrates a pair using LFBP methodsAnd->The results of the reconstruction of the sections of the cable at the various locations are shown by the arrows indicating the detected buffer layer ablation hole defects. The reconstructed cable local section structure is clear and visible, which shows that the method can well inhibit the artifact, thereby effectively detecting the defect and further verifying the effectiveness of the method.
Example 2:
an imaging device based on cable scan detection, the device comprising:
the data acquisition module is connected with the flat panel detector and is used for acquiring the equidistant sampling scanning of the ray source along the cable to be detected according to a preset path and a preset interval and acquiring the scanned original projection data through the flat panel detector;
the outward expansion smoothing module is used for outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expansion projection data;
the inner expansion smoothing module is used for carrying out inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
and the image reconstruction module is used for carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
The data acquisition module comprises:
the position adjusting module is positioned between the ray source and the flat panel detector and is used for adjusting the preset path and the position of the flat panel detector so that the region of interest of the cable to be tested is positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; establishing a rectangular coordinate system by taking the point Q as an origin, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) are acquired, where δ is the local coordinate of the focal position of the radiation source and u is the local coordinate of the detector unit.
The spread smoothing module comprises:
the external expansion virtual smoothing module is used for determining M' column virtual smoothing data according to the dimension MxN of the original projection data, wherein M is the number of detector unit arrays in each row;
a spreading module for performing spreading smoothing by a smoothing function g (x) =cosx, wherein
Obtaining the outward expansion projection data:
the inner expansion smoothing module comprises:
the internal expansion virtual smoothing module is used for defining N' row virtual smoothing data according to the dimension M multiplied by N of the original projection data; wherein N is the sampling point number of the ray source;
an inner spreading module for performing outer spreading smoothing by a smoothing function g (x) =cosx, whereinObtaining inner expansion projection data;
wherein x is n ＝(n-1)*Δβ；
The image reconstruction module includes:
the filtering back projection module is used for reconstructing the original projection data after the external expansion smoothing processing and the internal expansion smoothing processing through the following formula:
h is the distance of the original flat panel detector; l is the distance from the origin Q to the preset path of the ray source; delta is the local coordinate of the focal position of the radiation source; u is the local coordinates of the detector unit; s is half of a preset path length; d is half the width of the flat panel detector.
The data acquisition module further comprises:
the center determining module: acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line; acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment; and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
The position adjustment module includes:
the cable model acquisition module is used for confirming the center of the radial cross section of the position to be tested of the cable to be tested and the position of the buffer layer based on the model of the cable to be tested;
the position confirming module is used for confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested;
the adjusting module is used for adjusting the preset path and the flat panel detector to enable the center of the radial cross section of the position to be detected to be located right below the Q point; and according to the offset distance, adjusting the preset path and the flat panel detector to enable the buffer layer of the radial cross section of the position to be detected to be positioned at the Q point.
The data acquisition module further comprises:
the path confirming module is used for confirming the length of a preset path based on the diameter of the cable to be tested;
the interval confirming module is used for acquiring preset acquisition points and confirming preset intervals according to the length of the preset paths.
Example 3:
embodiment 3 of the present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the cable scan detection-based imaging method in the above-described method embodiment. Wherein the storage medium may be a volatile or nonvolatile computer readable storage medium.
Example 4:
based on the same technical conception, a computer device is also provided. Referring to fig. 8, a schematic structural diagram of a computer device according to an embodiment of the present invention includes a processor, a memory, and a bus. The memory is used for storing execution instructions, and comprises a memory and an external memory; the memory is also called an internal memory, and is used for temporarily storing operation data in the processor and data exchanged with an external memory such as a hard disk, and the processor exchanges data with the external memory through the memory. The memory is specifically used for storing and executing a program logic code corresponding to a scanning control method of the ray source and/or a filtered back projection image reconstruction algorithm according to the embodiment of the invention, and is controlled and executed by the processor. That is, when the computer device is running, the processor and the memory communicate via the bus, such that the processor executes the application code stored in the memory, which in turn is used to control the complete reconstruction of the scan control method and/or the filtered backprojection image reconstruction algorithm of one of the embodiments. The processor may be an integrated circuit chip having signal processing capabilities. The processor may be a general-purpose processor, including a central processing unit, a network processor, etc.; but also digital signal processors, application specific integrated circuits, field programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The disclosed methods, steps, and logic blocks in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The memory may be, but is not limited to, random access memory, read-only memory, programmable read-only memory, erasable read-only memory, electrically erasable read-only memory, etc.
It is to be understood that the structures illustrated in embodiment 4 and fig. 8 do not constitute a specific limitation on the computer apparatus. In actual use, the computer device may include more or fewer components than shown, or may combine certain components, or split certain components, or a different arrangement of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention.

Claims (18)

1. The imaging method based on cable scanning detection is characterized by comprising the following steps of: is applied to a scanning system, wherein the scanning system comprises a ray source and a flat panel detector; the imaging method comprises the following steps:
the method comprises the steps that equidistant sampling scanning is carried out on a cable to be detected along a preset path and at preset intervals by a ray source, and scanned original projection data are obtained through a flat panel detector;
outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expanded projection data;
performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
and carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
2. The cable scan detection based imaging method as recited in claim 1, wherein: adjusting the preset path and the position of the flat panel detector to enable the region of interest of the cable to be tested to be positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; establishing a rectangular coordinate system by taking the point Q as an origin, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) are acquired, where δ is the local coordinate of the focal position of the radiation source and u is the local coordinate of the detector unit.
3. The cable scan detection based imaging method as recited in claim 2, wherein: outward spread smoothing is carried out on the original projection data along the two ends of the flat panel detector to obtain outward spread projection data, and the outward spread projection data comprises:
determining M' columns of virtual smooth data according to the dimension MXN of the original projection data, wherein M is the number of detector unit arrays in each row;
performing spread smoothing by a smoothing function g (x) =cosx, wherein
Obtaining the outward expansion projection data:
4. a cable scan detection based imaging method as recited in claim 3, wherein: performing inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data, including:
defining N' rows of virtual smooth data according to the dimension M multiplied by N of the original projection data; wherein N is the sampling point number of the ray source;
performing spread smoothing by a smoothing function g (x) =cosx, whereinObtaining inner expansion projection data;
wherein x is n ＝(n-1)*Δβ；
5. The cable scan detection based imaging method as recited in claim 4, wherein: performing filtered back projection reconstruction on the interior-expanded projection data to obtain a reconstructed tomographic image, including:
reconstructing the original projection data after the external expansion smoothing process and the internal expansion smoothing process by the following formula:
h is the distance of the original flat panel detector; l is the distance from the origin Q to the preset path of the ray source; delta is the local coordinate of the focal position of the radiation source; u is the local coordinates of the detector unit; s is half of a preset path length; d is half the width of the flat panel detector.
6. The cable scan detection based imaging method as recited in claim 2, wherein: the length of the preset path is equal to the width of the flat panel detector; acquiring a central point Q of a scanning space formed by a ray source and a flat panel detector;
acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line;
acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment;
and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
7. The cable scan detection based imaging method as recited in claim 6, wherein: adjusting the preset path and the position of the flat panel detector to enable the region of interest of the cable to be tested to be positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; comprising the following steps:
based on the model of the cable to be tested, confirming the center of the radial cross section of the cable to be tested at the position to be tested and the position of the buffer layer;
adjusting a preset path and a flat panel detector to enable the center of the radial cross section of the position to be detected to be positioned right below the Q point;
confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested;
and according to the offset distance, adjusting the preset path and the flat panel detector to enable the buffer layer of the radial cross section of the position to be measured to be positioned at the Q point.
8. The cable scan detection based imaging method as recited in claim 1, wherein: a preset interval comprising:
confirming the length of a preset path based on the diameter of the cable to be tested;
and acquiring preset acquisition points, and confirming preset intervals according to the length of the preset path.
9. Imaging device based on cable scanning detects, its characterized in that: the device comprises:
the data acquisition module is connected with the flat panel detector and is used for acquiring the equidistant sampling scanning of the ray source along the cable to be detected according to a preset path and a preset interval and acquiring the scanned original projection data through the flat panel detector;
the outward expansion smoothing module is used for outward expanding and smoothing the original projection data along the two ends of the flat panel detector to obtain outward expansion projection data;
the inner expansion smoothing module is used for carrying out inner expansion smoothing on the outer expansion projection data along the projection angle to obtain inner expansion projection data;
and the image reconstruction module is used for carrying out filtering back projection reconstruction on the inner expansion projection data to obtain a reconstructed tomographic image.
10. The cable scan detection based imaging apparatus of claim 9, wherein: the data acquisition module comprises:
the position adjusting module is positioned between the ray source and the flat panel detector and is used for adjusting the preset path and the position of the flat panel detector so that the region of interest of the cable to be tested is positioned at the central point Q of the scanning space formed by the ray source and the flat panel detector; establishing a rectangular coordinate system by taking the point Q as an origin, wherein an X axis is parallel to the track of the ray source and points upwards, and a Y axis is directed to the center of the flat panel detector and is perpendicular to the flat panel detector; raw projection data p= (δ, u) are acquired, where δ is the local coordinate of the focal position of the radiation source and u is the local coordinate of the detector unit.
11. The cable scan detection based imaging apparatus of claim 10, wherein: the spread smoothing module comprises:
the external expansion virtual smoothing module is used for determining M' column virtual smoothing data according to the dimension MxN of the original projection data, wherein M is the number of detector unit arrays in each row;
a spreading module for performing spreading smoothing by a smoothing function g (x) =cosx, wherein
Obtaining the outward expansion projection data:
12. the cable scan detection based imaging apparatus of claim 11, wherein: the inner expansion smoothing module comprises:
the internal expansion virtual smoothing module is used for defining N' row virtual smoothing data according to the dimension M multiplied by N of the original projection data; wherein N is the sampling point number of the ray source;
an inner spreading module for performing outer spreading smoothing by a smoothing function g (x) =cosx, whereinObtaining inner expansion projection data;
wherein x is n ＝(n-1)*Δβ；
13. The cable scan detection based imaging apparatus of claim 12, wherein: the image reconstruction module includes:
the filtering back projection module is used for reconstructing the original projection data after the external expansion smoothing processing and the internal expansion smoothing processing through the following formula:
h is the distance of the original flat panel detector; l is the distance from the origin Q to the preset path of the ray source; delta is the local coordinate of the focal position of the radiation source; u is the local coordinates of the detector unit; s is half of a preset path length; d is half the width of the flat panel detector.
14. The cable scan detection based imaging apparatus of claim 10, wherein: the data acquisition module further comprises:
the center determining module: acquiring a straight line which passes through the center of the flat panel detector, which is close to one side surface of the ray source, and is parallel to a preset path of the ray source as a first reference line; acquiring two intersection points of a first reference line and edges at two ends of a flat panel detector, and connecting the two intersection points to acquire a reference line segment; and acquiring a point at the cross connection position of the two ends of the reference line segment and the preset path as a central point Q of the scanning space.
15. The cable scan detection based imaging apparatus of claim 14, wherein: the position adjustment module includes:
the cable model acquisition module is used for confirming the center of the radial cross section of the position to be tested of the cable to be tested and the position of the buffer layer based on the model of the cable to be tested;
the position confirming module is used for confirming the offset distance of the cable to be tested based on the position of the buffer layer in the cable to be tested;
the adjusting module is used for adjusting the preset path and the flat panel detector to enable the center of the radial cross section of the position to be detected to be located right below the Q point; and according to the offset distance, adjusting the preset path and the flat panel detector to enable the buffer layer of the radial cross section of the position to be detected to be positioned at the Q point.
16. The cable scan detection based imaging apparatus of claim 9, wherein: the data acquisition module further comprises:
the path confirming module is used for confirming the length of a preset path based on the diameter of the cable to be tested;
the interval confirming module is used for acquiring preset acquisition points and confirming preset intervals according to the length of the preset paths.
17. A computer-readable storage medium, characterized by: the storage medium stores at least one instruction for execution by a processor to implement the cable scan detection-based imaging method of any one of claims 1-8.
18. A computer device, characterized by: the computer device includes a processor and a memory; the memory stores at least one instruction for execution by the processor to implement the cable scan detection-based imaging method of any one of claims 1-8.
CN202310577106.7A 2023-05-19 2023-05-19 Imaging method, device, storage medium and equipment based on cable scanning detection Pending CN116660298A (en)

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