CN117670662A - Signal processing method, device and equipment based on interpolation algorithm - Google Patents
Signal processing method, device and equipment based on interpolation algorithm Download PDFInfo
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Abstract
The disclosure provides a signal processing method, device and equipment based on an interpolation algorithm, which can be applied to the field of medical images. The method comprises the following steps: determining an mth projection angle and an nth projection angle from the P projection angles; determining an mth scattering signal and an nth scattering signal corresponding to the mth projection angle and the nth projection angle, respectively; respectively processing an mth projection angle, an nth projection angle and an ith to-be-interpolated angle between the mth projection angle and the nth projection angle by using a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith to-be-interpolated angle weight factor; obtaining a distance weight factor according to a first interval angle degree between the ith angle to be interpolated and the mth projection angle and a second interval angle degree between the ith angle to be interpolated and the nth projection angle; and processing the angle weight factor, the distance weight factor and the scattering signal based on an interpolation algorithm, and generating an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
Description
Technical Field
The disclosure relates to the field of medical image equipment, in particular to a signal processing method, device and equipment based on an interpolation algorithm.
Background
Cone beam computed tomography (cone beam computed tomography, CBCT) systems have the advantages of easy integration, single-turn three-dimensional imaging, high cost performance, and open architecture, and are widely used in clinic. In CBCT scanning, an increase in the scanning volume in the imaging field of view can lead to an increase in the proportion of scatter signals in the measured projection signals, which in turn can lead to severe scatter artifacts in the reconstructed image, greatly affecting the CBCT image quality. In order to obtain a high quality CBCT image, scatter correction is required for all measured projection signals.
In clinical practice, the projection signals used for CBCT reconstruction are typically hundreds or even thousands of angles. If the scattered signals of all angles are obtained through simulation, a large amount of simulation time is required; by inserting a blocking plate between the X-ray tube and the scanned object to measure the scatter signal, it is possible to estimate the scatter signal without using the blocking plate, but the larger the number of angles of the measured scatter signal, the higher the X-ray dose to the scanned object, and the larger the influence to the patient.
Disclosure of Invention
In view of the above, the present disclosure provides a signal processing method, apparatus and device based on an interpolation algorithm.
According to a first aspect of the present disclosure, there is provided a signal processing method based on an interpolation algorithm, including:
determining an mth projection angle and an nth projection angle from the P projection angles, wherein P is more than m, P is more than n, and at least one angle to be interpolated is arranged between two adjacent projection angles in the P projection angles;
determining an mth scattering signal and an nth scattering signal corresponding to the mth projection angle and the nth projection angle, respectively, wherein the scattering signals are generated by radiation irradiating an imaged object, and each scattering signal corresponds to one projection angle;
respectively processing an mth projection angle and an nth projection angle and an ith to-be-interpolated angle between the mth projection angle and the nth projection angle by utilizing a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith to-be-interpolated angle weight factor, wherein m < i < n;
obtaining a distance weight factor according to a first interval angle degree between the ith angle to be interpolated and the mth projection angle and a second interval angle degree between the ith angle to be interpolated and the nth projection angle;
and processing the angle weight factor, the distance weight factor and the scattering signal based on an interpolation algorithm, and generating an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
According to an embodiment of the present disclosure, processing an mth projection angle with a sine function to obtain an mth angle weight factor includes:
processing the mth projection angle by using a sine function to obtain an mth sine value;
and obtaining an mth angle weight factor corresponding to the mth projection angle according to the sum of the product of the mth sine value and the first factor and the second factor.
According to an embodiment of the present disclosure, obtaining a distance weight factor according to a first angular interval between an i-th angle to be interpolated and an m-th projection angle and a second angular interval between the i-th angle to be interpolated and the n-th projection angle, includes:
obtaining a first interval value according to the sum of the square of the first interval angle number and the square of the second interval angle number;
and obtaining a distance weight factor according to the ratio between the square of the first interval angle number and the first interval value.
According to an embodiment of the present disclosure, the signal processing method further includes:
measuring a projection signal corresponding to the ith angle to be interpolated;
and generating a corrected projection signal according to the difference value between the projection signal corresponding to the ith angle to be interpolated and the corresponding scattering signal.
According to an embodiment of the present disclosure, generating a corrected projection signal from a difference between a projection signal corresponding to an i-th angle to be interpolated and a corresponding scatter signal, includes:
Processing the corrected projection signal corresponding to the ith angle to be interpolated according to a noise reduction algorithm so as to conveniently reduce the noise of the corrected projection signal and obtain a noise reduction projection signal;
and carrying out image reconstruction according to the noise reduction projection signals to obtain a corrected CBCT image.
According to an embodiment of the present disclosure, the noise reduction algorithm includes at least one of:
local filtering algorithm, least square method, gaussian filtering algorithm, median filtering, mean filtering and iterative noise reduction method.
According to an embodiment of the present disclosure, performing image reconstruction from the noise-reduced projection signal includes:
processing the noise-reduced projection signal according to an image reconstruction algorithm, the image reconstruction algorithm comprising at least one of:
an analytic reconstruction algorithm, an iterative reconstruction algorithm and a deep learning reconstruction method.
A second aspect of the present disclosure provides a signal processing apparatus based on an interpolation algorithm, including:
the first determining module is used for determining an mth projection angle and an nth projection angle from P projection angles, wherein P is more than m, P is more than n, and at least one angle to be interpolated is arranged between two adjacent projection angles in the P projection angles;
a second determining module, configured to determine an mth scattering signal and an nth scattering signal corresponding to an mth projection angle and an nth projection angle, where the scattering signals are generated by irradiating an imaged object with radiation, and each scattering signal corresponds to a projection angle;
The first processing module is used for respectively processing the mth projection angle and the nth projection angle and the ith interpolation angle between the mth projection angle and the nth projection angle by utilizing a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith interpolation angle weight factor, wherein m < i < n;
the second processing module is used for obtaining a distance weight factor according to a first interval angle number between the ith angle to be interpolated and the mth projection angle and a second interval angle number between the ith angle to be interpolated and the nth projection angle;
the generating module is used for processing the angle weight factor, the distance weight factor and the scattering signal based on the interpolation algorithm and generating an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
A third aspect of the present disclosure provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to perform the signal processing method described above.
A fourth aspect of the present disclosure provides a computer-readable storage medium having stored thereon executable instructions that, when executed by a processor, cause the processor to perform the above-described signal processing method.
According to the signal processing method, the device and the equipment based on the interpolation algorithm, the mth scattering signal and the nth scattering signal which correspond to the mth projection angle and the nth projection angle are processed through the interpolation algorithm, so that the scattering signals of all angles to be interpolated between the two projection angles can be obtained, further, the scattering signals of all angles of the scanned object can be rapidly and accurately estimated by using the scattering signals of a small number of angles, the ray scanning dosage of the scanned object is reduced, and the simulation efficiency of the scattering signal correction is improved.
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The foregoing and other objects, features and advantages of the disclosure will be more apparent from the following description of embodiments of the disclosure with reference to the accompanying drawings, in which:
fig. 1 schematically illustrates a schematic view of a head mold position offset direction according to an embodiment of the present disclosure;
FIG. 2 schematically illustrates a flow chart of a signal processing method based on an interpolation algorithm according to an embodiment of the disclosure;
FIG. 3 schematically illustrates a plot of relative intensity of scattered signals along projection angles, obtained by Monte Carlo simulation, in accordance with an embodiment of the present disclosure;
FIG. 4 schematically illustrates a plot of experimentally measured relative intensities of scattered signals along projection angles, in accordance with an embodiment of the present disclosure;
FIG. 5 schematically illustrates a schematic diagram of head mold image contrast in accordance with an embodiment of the present disclosure;
fig. 6 schematically illustrates a block diagram of a signal processing apparatus based on an interpolation algorithm according to an embodiment of the present disclosure; and
fig. 7 schematically illustrates a block diagram of an electronic device of a signal processing method based on an interpolation algorithm according to an embodiment of the disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expressions should generally be interpreted in accordance with the meaning as commonly understood by those skilled in the art (e.g.," a system having at least one of A, B and C "shall include, but not be limited to, a system having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
In practicing the present disclosure, it is found that in clinical practice, projection signals for CBCT reconstruction typically have hundreds or even thousands of angles. If the scattered signals of all angles are obtained through simulation, a large amount of simulation time is required; by inserting a blocking plate between the X-ray tube and the scanned object to measure the scattering signal, the scattering signal can be estimated when the blocking plate is not used, but the larger the angle number of the measured scattering signal is, the higher the X-ray dose to the scanned object is, and the influence to the patient is larger, so that a signal processing method based on an interpolation algorithm is urgently needed.
In view of this, embodiments of the present disclosure provide a signal processing method and apparatus based on an interpolation algorithm. The method comprises the following steps: determining an mth projection angle and an nth projection angle from the P projection angles; determining an mth scattering signal and an nth scattering signal corresponding to the mth projection angle and the nth projection angle, respectively; respectively processing an mth projection angle, an nth projection angle and an ith to-be-interpolated angle between the mth projection angle and the nth projection angle by using a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith to-be-interpolated angle weight factor; obtaining a distance weight factor according to a first interval angle degree between the ith angle to be interpolated and the mth projection angle and a second interval angle degree between the ith angle to be interpolated and the nth projection angle; and processing the angle weight factor, the distance weight factor and the scattering signal based on an interpolation algorithm, and generating an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
In the technical scheme of the invention, the related user information (including but not limited to user personal information, user image information, user equipment information, such as position information and the like) and data (including but not limited to data for analysis, stored data, displayed data and the like) are information and data authorized by a user or fully authorized by all parties, and the processing of the related data such as collection, storage, use, processing, transmission, provision, disclosure, application and the like are all conducted according to the related laws and regulations and standards of related countries and regions, necessary security measures are adopted, no prejudice to the public welfare is provided, and corresponding operation inlets are provided for the user to select authorization or rejection.
The signal processing method based on the interpolation algorithm of the disclosed embodiment will be described in detail below with reference to fig. 1 to 5.
Fig. 1 schematically shows a flowchart of a signal processing method based on an interpolation algorithm according to an embodiment of the present disclosure.
As shown in fig. 1, the method 100 includes operations S110 to S150.
In operation S110, an mth projection angle and an nth projection angle are determined from P projection angles, wherein P > m, P > n, and at least one angle to be interpolated is disposed between two adjacent projection angles of the P projection angles.
In operation S120, an mth scattering signal and an nth scattering signal corresponding to each of the mth projection angle and the nth projection angle are determined, wherein the scattering signals are generated by radiation irradiating the imaged object, each of the scattering signals corresponding to one of the projection angles.
In operation S130, the mth projection angle and the nth projection angle, and the ith to-be-interpolated angle between the mth projection angle and the nth projection angle are processed by using a sine function, respectively, to obtain an mth angle weight factor, an nth angle weight factor, and an ith to-be-interpolated angle weight factor, where m < i < n.
In operation S140, a distance weight factor is obtained according to the first angular interval between the i-th angle to be interpolated and the m-th projection angle and the second angular interval between the i-th angle to be interpolated and the n-th projection angle.
In operation S150, the angle weight factor, the distance weight factor, and the scattering signal are processed based on the interpolation algorithm, and an i-th interpolation scattering signal corresponding to the i-th angle to be interpolated is generated.
In accordance with embodiments of the present disclosure, projection signals for multiple projection angles need to be acquired during imaging using cone beam computed tomography (cone beam computed tomography, CBCT). In each projection angle, the ray includes two components: an initial ray and a scattered ray. The primary radiation produces primary radiation signals to form an image, the scattered radiation produces scattered radiation signals to produce noise or image artifacts, and the projection signals comprise primary radiation signals and scattered radiation signals.
According to an embodiment of the present disclosure, the radiation irradiates the imaged object, and the scatter signals are present in projection signals at any angle, each scatter signal corresponding to one projection angle.
According to the embodiment of the disclosure, at least one angle to be interpolated is disposed between two adjacent projection angles from the P projection angles, for example, two mth projection angles and an nth projection angle are arbitrarily determined from the P projection angles, and one or more angles to be interpolated are included between the mth projection angle and the nth projection angle.
According to an embodiment of the present disclosure, an mth scattered signal is formed by deflection at an mth projection angle; the nth scattered signal is deflected at an nth projection angle; the ith interpolated scatter signal is deflected by the ith angle to be interpolated.
According to an embodiment of the present disclosure, the mth angular weight factor characterizes an angular weight factor of the mth scattered signal; the nth angular weight factor characterizes an angular weight factor of the nth scattered signal; the ith angle weight factor to be interpolated characterizes the angle weight factor of the ith interpolated scatter signal.
According to an embodiment of the present disclosure, the distance weight factor characterizes a change in the number of angular intervals between the i-th interpolated scatter signal to the m-th scatter signal and the n-th scatter signal, respectively.
According to an embodiment of the present disclosure, an ith scattered signal, an nth scattered signal, an mth angle weight factor, an nth angle weight factor, an i-to-be-interpolated angle weight factor, and a distance weight factor are processed using an interpolation algorithm to generate an ith interpolated scattered signal.
According to the embodiment of the disclosure, the mth scattering signal and the nth scattering signal corresponding to the mth projection angle and the nth projection angle are processed through the interpolation algorithm, so that scattering signals of all angles to be interpolated between the two projection angles can be obtained, and further, scattering signals of all angles of the scanned object can be rapidly and accurately estimated by using a small amount of scattering signals of the angles, the radiation scanning dosage of the scanned object is reduced, and the simulation efficiency of correcting the scattering signals is improved.
Fig. 2 schematically illustrates a schematic diagram of a head mold position offset direction according to an embodiment of the present disclosure.
As shown in fig. 2, when the head mold moves in the positive x and y directions, the offset is a positive value; when the head mould moves along the negative directions of the x and y axes, the offset is negative.
According to an embodiment of the present disclosure, the scatter signal is present in the projection signal of any angular measurement. In the process of scanning an imaged object by CBCT, the change relation between the intensity of a scattering signal and the projection angle can be further simulated or measured along with the offset of the head mould of the imaged object along the x-axis direction and the y-axis direction.
Fig. 3 schematically illustrates a plot of relative intensity of scattered signals along projection angles from a monte carlo simulation according to an embodiment of the present disclosure.
As shown in fig. 3, the CBCT imaging system is simulated by the monte carlo simulation method, all projection angles are recorded each time the head mode is shifted in the CBCT scanning process, each curve on the distribution diagram represents a change rule of the relative intensity of the scattered signal along the projection angle when the head mode is shifted, the horizontal axis represents the projection angle, and the vertical axis represents the relative intensity of the scattered signal.
According to an embodiment of the present disclosure, the values of x and y each represent the distance in mm along the x-axis and y-axis between the center of the head phantom and the center of the imaging field of view.
According to the embodiment of the disclosure, for example, when the head mould is shifted by x=15 and y=15, the change rule of the relative intensity of the scattering signal along the projection angle in the shift is shown on a curve.
According to the embodiment of the disclosure, the simulation result shows that when the position of the head model is shifted, the relative strength of the scattering signal is still related to the projection angle, so that the scattering signal in the direction of the projection angle can be deduced based on an interpolation algorithm in the condition that the position of the scanned object is uncertain.
Fig. 4 schematically illustrates a distribution of experimentally measured relative intensities of scattered signals along a projection angle, in accordance with an embodiment of the present disclosure.
As shown in fig. 4, a distribution diagram of the relative intensity of the scattered signal along the projection angle is obtained by an experimental measurement method, the horizontal axis represents the projection angle, the vertical axis represents the relative intensity of the scattered signal, and the values of x and y each represent distances between the center of the head phantom and the center of the imaging field of view along the x-axis and the y-axis in mm.
According to embodiments of the present disclosure, experimental measurements have found that the relationship between the relative intensities of the scatter signals and the projection angles approximately conforms to the form of a sinusoidal function, indicating that interpolation of the scatter signals in the projection angle direction can be guided according to a function related to the projection angle.
According to an embodiment of the present disclosure, processing an mth projection angle with a sine function to obtain an mth angle weight factor includes:
processing the mth projection angle by using a sine function to obtain an mth sine value;
and obtaining an mth angle weight factor corresponding to the mth projection angle according to the sum of the product of the mth sine value and the first factor and the second factor.
According to the embodiment of the disclosure, the mth projection angle is processed by using a sine function to obtain a sine value, and a second factor is added according to the product of the sine value and the first factor to obtain an angle weight factor corresponding to the mth projection angle.
In one embodiment, the mth angle weight factorThe calculation formula is shown as (1):
wherein θ m An angle value representing the mth projection angle, a representing a first factor determined by the imaging system, and b representing a second factor determined by the imaged object.
According to embodiments of the present disclosure, for example, a takes on a value of 0.3 and b takes on a value of 0.5.
According to an embodiment of the present disclosure, the mth angle weightFactors ofIt may also be measured or simulated from the intensity distribution of the scattered signal along a known projection angle in the imaging system.
According to the embodiments of the present disclosure, the calculation process of the nth angle weight factor and the ith angle weight factor to be interpolated is the same as above, and will not be described herein.
According to an embodiment of the present disclosure, obtaining a distance weight factor according to a first angular interval between an i-th angle to be interpolated and an m-th projection angle and a second angular interval between the i-th angle to be interpolated and the n-th projection angle, includes:
obtaining a first interval value according to the sum of the square of the first interval angle number and the square of the second interval angle number;
and obtaining a distance weight factor according to the ratio between the square of the first interval angle number and the first interval value.
According to an embodiment of the present disclosure, a first interval value is obtained from a sum between squares of a first interval angle number and squares of a second interval angle number; and obtaining a distance weight factor according to the ratio between the square of the first interval angle number and the first interval value.
In one embodiment, the distance weight factor ω d,i The calculation formula is shown as (2):
wherein D is m,i Characterizing a first angular interval between the ith to-be-interpolated angle and the mth projection angle, D n,i Characterizing a second angular interval between the ith to-be-interpolated angle and the nth projection angle, m<i<n。
According to an embodiment of the present disclosure, for example, the angle degree of the mth projection angle is 20 °, the angle degree of the nth projection angle is 70 °, the angle degree of the ith angle to be interpolated is 40 °, then S m,i Has a value of 20, D n,i Has a value of 30.
In one embodiment, the ith interpolated scatter signal S i The calculation formula is shown as (3):
wherein S is m Characterization of the mth scattered Signal, S n Characterization of the nth scattered signal, ω d,i The distance weight factor is characterized by the fact that,characterizing the mth angle weight factor,>characterizing the n-th angle weight factor,>and (5) representing an ith angle weight factor to be interpolated.
According to an embodiment of the present disclosure, the scatter signal may be a matrix corresponding to the detector size, an element in the matrix characterizing the scatter signal. For example, the matrix dimensions may be 1024 x 768 or 1024 x 1024.
According to the embodiment of the disclosure, an interpolation algorithm is utilized to process an angle weight factor, a distance weight factor and a scattering signal, and an ith interpolation scattering signal corresponding to an ith angle to be interpolated is generated.
In an embodiment, there are 600 projection angles, if the first projection angle and the last projection angle are taken for interpolation, the scattering signals of the remaining 598 angles to be interpolated are obtained, and because the signal frames are continuously changed, the error of the obtained result may be larger, so for 600 projection angles, the scattering signals of 8 projection angles can be obtained through simulation by using the Monte Carlo simulation method, and further according to the scattering signals of all angles to be interpolated in every two known adjacent projection angles, the scattering signals of the remaining 592 angles to be interpolated are finally calculated, and the error is lower.
According to the embodiment of the disclosure, the scattering signals of 8 projection angles can also be obtained by methods such as experimental measurement or analytical calculation.
According to the embodiment of the disclosure, considering the angle interval influence and the angle weight influence of all angles to be interpolated between two projection angles, finally, the angle weight factor, the distance weight factor and the scattering signal are processed through an interpolation algorithm, so that the scattering signals of all angles to be interpolated between two projection angles are obtained, and the scattering signals of all projection angles of the scanned object can be rapidly and accurately estimated by using a small number of scattering signals of the projection angles.
According to an embodiment of the present disclosure, further comprising:
measuring a projection signal corresponding to the ith angle to be interpolated;
and generating a corrected projection signal according to the difference value between the projection signal corresponding to the ith angle to be interpolated and the corresponding scattering signal.
According to an embodiment of the present disclosure, the projection signal is composed of an original projection signal and a scattered signal, and each projection angle corresponds to one projection signal and one scattered signal.
According to the embodiment of the disclosure, a projection signal corresponding to an ith to-be-interpolated angle is measured, and the projection signal corresponding to the ith to-be-interpolated angle and a scattering signal corresponding to the ith to-be-interpolated angle are subtracted to obtain a corrected projection signal corresponding to the ith to-be-interpolated angle.
In one embodiment, there are 600 projection angles, and the projection signal of each projection angle is measured, and the object to be imaged is required to be irradiated 600 times by rays; if the scatter signals of the remaining 592 angles to be interpolated are obtained from the scatter signals of the 8 projection angles, the object to be imaged needs to be irradiated with the radiation 8 times. The projection signals corresponding to each projection angle and the corresponding scattering signals are subtracted to obtain 600 corrected projection signals of the projection angles, so that the imaged object is irradiated with a total of required rays 608 times, and correction of each projection signal can be completed.
According to the embodiment of the disclosure, since noise or image artifact is generated by the scattered signals, each projection signal needs to be corrected, therefore, the projected signal and the scattered signal corresponding to each projection angle need to be measured or simulated, the scattered signals of all projection angles of the scanned object can be rapidly and accurately estimated by using the scattered signals of a small number of projection angles by using an interpolation algorithm, 1200 times of original radiation irradiation on the imaged object is reduced to 608 times, the radiation scanning dosage of the scanned object is greatly reduced, and the simulation efficiency of the scattered signal correction is improved.
According to an embodiment of the present disclosure, generating a corrected projection signal from a difference between a projection signal corresponding to an i-th angle to be interpolated and a corresponding scatter signal, includes:
processing the corrected projection signal corresponding to the ith angle to be interpolated according to a noise reduction algorithm so as to conveniently reduce the noise of the corrected projection signal and obtain a noise reduction projection signal;
and carrying out image reconstruction according to the noise reduction projection signals to obtain a corrected CBCT image.
According to the embodiment of the disclosure, the noise reduction algorithm is utilized to perform noise reduction processing on the corrected projection signals corresponding to all the projection angles, so as to obtain noise reduction projection signals.
According to an embodiment of the present disclosure, the noise reduction algorithm includes at least one of: local filtering algorithm, least square method, gaussian filtering algorithm, median filtering, mean filtering and iterative noise reduction method.
According to the embodiment of the disclosure, image reconstruction is performed on the noise reduction projection signals corresponding to all projection angles, and a corrected CBCT image is obtained.
According to an embodiment of the present disclosure, the noise-reduced projection signal is processed according to an image reconstruction algorithm comprising at least one of: an analytic reconstruction algorithm, an iterative reconstruction algorithm and a deep learning reconstruction method.
According to the embodiment of the disclosure, the corrected projection signal is subjected to noise reduction to obtain a noise reduction projection signal, and then image reconstruction is performed to obtain a high-quality CBCT image.
Fig. 5 schematically illustrates a schematic diagram of head mold image contrast according to an embodiment of the present disclosure.
As shown in fig. 5, the CBCT image without scattering signal, the uncorrected CBCT image, and the corrected and noise-reduced CBCT image are represented in this order from left to right in the head model image contrast map. The window width of the display is [ -100 ] 300] HU.
According to embodiments of the present disclosure, corrected and noise reduced CBCT images have low artifact, high accuracy, and higher image uniformity and contrast than uncorrected CBCT image values.
Based on the signal processing method based on the interpolation algorithm, the disclosure also provides a signal processing device based on the interpolation algorithm. The device will be described in detail below in connection with fig. 6.
Fig. 6 schematically shows a block diagram of a signal processing apparatus based on an interpolation algorithm according to an embodiment of the present disclosure.
As shown in fig. 6, the signal processing apparatus 600 based on the interpolation algorithm of this embodiment includes a first determination module 610, a second determination module 620, a first processing module 630, a second processing module 640, and a generation module 650.
The first determining module 610 is configured to determine an mth projection angle and an nth projection angle from P projection angles, where P > m, P > n, and at least one angle to be interpolated is set between two adjacent projection angles in the P projection angles. In an embodiment, the first determining module 610 may be configured to perform the operation S110 described above, which is not described herein.
A second determining module 620, configured to determine an mth scattering signal and an nth scattering signal corresponding to an mth projection angle and an nth projection angle, respectively, where the scattering signals are generated by radiation irradiating the imaged object, and each scattering signal corresponds to a projection angle. In an embodiment, the second determining module 620 may be configured to perform the operation S120 described above, which is not described herein.
The first processing module 630 is configured to process the mth projection angle and the nth projection angle, and the ith to-be-interpolated angle between the mth projection angle and the nth projection angle, respectively, by using a sine function, to obtain an mth angle weight factor, an nth angle weight factor, and an ith to-be-interpolated angle weight factor, where m < i < n. In an embodiment, the first processing module 630 may be configured to perform the operation S130 described above, which is not described herein.
The second processing module 640 is configured to obtain a distance weight factor according to a first angular interval between the i-th angle to be interpolated and the m-th projection angle and a second angular interval between the i-th angle to be interpolated and the n-th projection angle. In an embodiment, the second processing module 640 may be configured to perform the operation S140 described above, which is not described herein.
The generating module 650 is configured to process the angle weight factor, the distance weight factor, and the scattering signal based on an interpolation algorithm, and generate an ith interpolated scattering signal corresponding to the ith angle to be interpolated. In an embodiment, the generating module 650 may be configured to perform the operation S150 described above, which is not described herein.
According to the embodiment of the disclosure, the mth scattering signal and the nth scattering signal corresponding to the mth projection angle and the nth projection angle are processed through the interpolation algorithm, so that scattering signals of all angles to be interpolated between the two projection angles can be obtained, and further, scattering signals of all angles of the scanned object can be rapidly and accurately estimated by using a small amount of scattering signals of the angles, the radiation scanning dosage of the scanned object is reduced, and the simulation efficiency of correcting the scattering signals is improved.
According to an embodiment of the present disclosure, the first processing module 630 includes a first processing sub-module and a second processing sub-module.
And the first processing sub-module is used for processing the mth projection angle by utilizing a sine function to obtain an mth sine value.
And the second processing submodule is used for obtaining an mth angle weight factor corresponding to the mth projection angle according to the sum of the product of the mth sine value and the first factor and the second factor.
According to an embodiment of the present disclosure, the second processing module 640 includes a third processing sub-module and a fourth processing sub-module.
And the third processing submodule is used for obtaining the first interval value according to the sum of the square of the first interval angle number and the square of the second interval angle number.
And the fourth processing submodule is used for obtaining a distance weight factor according to the ratio between the square of the first interval angle number and the first interval value.
According to an embodiment of the present disclosure, the signal processing apparatus 600 further comprises a correction module comprising a measurement sub-module and a correction sub-module.
And the measurement submodule is used for measuring projection signals corresponding to the ith angle to be interpolated.
And the correction sub-module is used for generating a corrected projection signal according to the difference value between the projection signal corresponding to the ith angle to be interpolated and the corresponding scattering signal.
According to an embodiment of the present disclosure, the correction submodule includes a noise reduction unit and a reconstruction unit.
The noise reduction unit is used for processing the correction projection signal corresponding to the ith angle to be interpolated according to a noise reduction algorithm so as to conveniently reduce the noise of the correction projection signal and obtain a noise reduction projection signal.
And the reconstruction unit is used for carrying out image reconstruction according to the noise reduction projection signals to obtain corrected CBCT images.
Any of the first determination module 610, the second determination module 620, the first processing module 630, the second processing module 640, the generation module 650 may be combined in one module to be implemented, or any of the modules may be split into a plurality of modules, according to an embodiment of the present disclosure. Alternatively, at least some of the functionality of one or more of the modules may be combined with at least some of the functionality of other modules and implemented in one module. According to embodiments of the present disclosure, at least one of the first determination module 610, the second determination module 620, the first processing module 630, the second processing module 640, the generation module 650 may be implemented at least in part as a hardware circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or as hardware or firmware in any other reasonable manner of integrating or packaging the circuits, or as any one of or a suitable combination of three of software, hardware, and firmware. Alternatively, at least one of the first determination module 610, the second determination module 620, the first processing module 630, the second processing module 640, the generation module 650 may be at least partially implemented as a computer program module, which when executed may perform the respective functions.
Fig. 7 schematically illustrates a block diagram of an electronic device of a signal processing method based on an interpolation algorithm according to an embodiment of the disclosure.
As shown in fig. 7, an electronic device 700 according to an embodiment of the present disclosure includes a processor 701 that can perform various appropriate actions and processes according to a program stored in a Read Only Memory (ROM) 702 or a program loaded from a storage section 708 into a Random Access Memory (RAM) 703. The processor 701 may include, for example, a general purpose microprocessor (e.g., a CPU), an instruction set processor and/or an associated chipset and/or a special purpose microprocessor (e.g., an Application Specific Integrated Circuit (ASIC)), or the like. The processor 701 may also include on-board memory for caching purposes. The processor 701 may comprise a single processing unit or a plurality of processing units for performing different actions of the method flows according to embodiments of the disclosure.
In the RAM 703, various programs and data necessary for the operation of the electronic apparatus 700 are stored. The processor 701, the ROM 702, and the RAM 703 are connected to each other through a bus 704. The processor 701 performs various operations of the method flow according to the embodiments of the present disclosure by executing programs in the ROM 702 and/or the RAM 703. Note that the program may be stored in one or more memories other than the ROM 702 and the RAM 703. The processor 701 may also perform various operations of the method flow according to embodiments of the present disclosure by executing programs stored in one or more memories.
According to an embodiment of the present disclosure, the electronic device 700 may further include an input/output (I/O) interface 705, the input/output (I/O) interface 705 also being connected to the bus 704. The electronic device 700 may also include one or more of the following components connected to the I/O interface 705: an input section 706 including a keyboard, a mouse, and the like; an output portion 707 including a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, a speaker, and the like; a storage section 708 including a hard disk or the like; and a communication section 709 including a network interface card such as a LAN card, a modem, or the like. The communication section 709 performs communication processing via a network such as the internet. The drive 710 is also connected to the I/O interface 705 as needed. A removable medium 711 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 710 as necessary, so that a computer program read therefrom is mounted into the storage section 708 as necessary.
The present disclosure also provides a computer-readable storage medium that may be embodied in the apparatus/device/system described in the above embodiments; or may exist alone without being assembled into the apparatus/device/system. The computer-readable storage medium carries one or more programs which, when executed, implement methods in accordance with embodiments of the present disclosure.
According to embodiments of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium, which may include, for example, but is not limited to: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this disclosure, a computer-readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. For example, according to embodiments of the present disclosure, the computer-readable storage medium may include ROM 702 and/or RAM 703 and/or one or more memories other than ROM 702 and RAM 703 described above.
Embodiments of the present disclosure also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowcharts. The program code means for causing a computer system to carry out the signal processing methods provided by the embodiments of the present disclosure when the computer program product is run on the computer system.
The above-described functions defined in the system/apparatus of the embodiments of the present disclosure are performed when the computer program is executed by the processor 701. The systems, apparatus, modules, units, etc. described above may be implemented by computer program modules according to embodiments of the disclosure.
In one embodiment, the computer program may be based on a tangible storage medium such as an optical storage device, a magnetic storage device, or the like. In another embodiment, the computer program may also be transmitted, distributed over a network medium in the form of signals, downloaded and installed via the communication section 709, and/or installed from the removable medium 711. The computer program may include program code that may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the foregoing.
In such an embodiment, the computer program may be downloaded and installed from a network via the communication portion 709, and/or installed from the removable medium 711. The above-described functions defined in the system of the embodiments of the present disclosure are performed when the computer program is executed by the processor 701. The systems, devices, apparatus, modules, units, etc. described above may be implemented by computer program modules according to embodiments of the disclosure.
According to embodiments of the present disclosure, program code for performing computer programs provided by embodiments of the present disclosure may be written in any combination of one or more programming languages, and in particular, such computer programs may be implemented in high-level procedural and/or object-oriented programming languages, and/or assembly/machine languages. Programming languages include, but are not limited to, such as Java, c++, python, "C" or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of remote computing devices, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet service provider).
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A signal processing method based on an interpolation algorithm, comprising:
determining an mth projection angle and an nth projection angle from P projection angles, wherein P is more than m and P is more than n, and at least one angle to be interpolated is arranged between two adjacent projection angles in the P projection angles;
Determining an mth scattering signal and an nth scattering signal corresponding to the mth projection angle and the nth projection angle, respectively, wherein the scattering signals are generated by radiation irradiation of an imaged object, and each scattering signal corresponds to one projection angle;
respectively processing the mth projection angle and the nth projection angle and an ith to-be-interpolated angle between the mth projection angle and the nth projection angle by using a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith to-be-interpolated angle weight factor, wherein m < i < n;
obtaining a distance weight factor according to a first interval angle number between the ith angle to be interpolated and the mth projection angle and a second interval angle number between the ith angle to be interpolated and the nth projection angle;
and processing the angle weight factor, the distance weight factor and the scattering signal based on an interpolation algorithm to generate an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
2. The method of claim 1, wherein processing the mth projection angle with a sine function results in an mth angle weight factor, comprising:
processing the mth projection angle by using a sine function to obtain an mth sine value;
And obtaining an mth angle weight factor corresponding to the mth projection angle according to the sum of the product of the mth sine value and the first factor and the second factor.
3. The method of claim 1, wherein deriving a distance weight factor from a first angular interval between the i-th to-be-interpolated angle and the m-th projection angle, and a second angular interval between the i-th to-be-interpolated angle and the n-th projection angle, comprises:
obtaining a first interval value according to the sum of the square of the first interval angle number and the square of the second interval angle number;
and obtaining the distance weight factor according to the ratio between the square of the first interval angle number and the first interval value.
4. The method of claim 1, further comprising:
measuring a projection signal corresponding to the ith angle to be interpolated;
and generating a corrected projection signal according to the difference value between the projection signal corresponding to the ith angle to be interpolated and the corresponding scattering signal.
5. The method of claim 4, wherein generating a corrected projection signal from a difference between the projection signal corresponding to the i-th angle to be interpolated and the corresponding scatter signal comprises:
Processing a correction projection signal corresponding to the ith angle to be interpolated according to a noise reduction algorithm so as to conveniently reduce the noise of the correction projection signal and obtain a noise reduction projection signal;
and carrying out image reconstruction according to the noise reduction projection signals to obtain a corrected CBCT image.
6. The method of claim 5, wherein the noise reduction algorithm comprises at least one of:
local filtering algorithm, least square method, gaussian filtering algorithm, median filtering, mean filtering and iterative noise reduction method.
7. The method of claim 5, wherein the image reconstruction from the noise-reduced projection signal comprises:
processing the noise-reduced projection signal according to an image reconstruction algorithm, the image reconstruction algorithm comprising at least one of:
an analytic reconstruction algorithm, an iterative reconstruction algorithm and a deep learning reconstruction method.
8. A signal processing apparatus based on an interpolation algorithm, comprising:
the first determining module is used for determining an mth projection angle and an nth projection angle from P projection angles, wherein P is more than m and P is more than n, and at least one angle to be interpolated is arranged between two adjacent projection angles in the P projection angles;
a second determining module, configured to determine an mth scattering signal and an nth scattering signal corresponding to the mth projection angle and the nth projection angle, where the scattering signals are generated by irradiating an imaged object with radiation, and each of the scattering signals corresponds to one projection angle;
The first processing module is used for respectively processing the mth projection angle, the nth projection angle and the ith to-be-interpolated angle between the mth projection angle and the nth projection angle by utilizing a sine function to obtain an mth angle weight factor, an nth angle weight factor and an ith to-be-interpolated angle weight factor, wherein m < i < n;
the second processing module is used for obtaining a distance weight factor according to a first interval angle number between the ith angle to be interpolated and the mth projection angle and a second interval angle number between the ith angle to be interpolated and the nth projection angle;
the generating module is used for processing the angle weight factor, the distance weight factor and the scattering signal based on an interpolation algorithm and generating an ith interpolation scattering signal corresponding to the ith angle to be interpolated.
9. An electronic device, comprising:
one or more processors;
storage means for storing one or more programs,
wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to perform the method of any of claims 1-7.
10. A computer readable storage medium having stored thereon executable instructions which, when executed by a processor, cause the processor to perform the method according to any of claims 1-7.
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