Hardening correction method, apparatus, and storage medium

Abstract

The application provides a hardening correction method, device and storage medium for a CBCT system. The method comprises the following steps: adjusting the width of an imaging ray beam to a preset width value; then respectively collecting a first air image and a first phantom image of a correction phantom, and obtaining a first correction parameter according to the first air image and the first phantom image; adjusting the projection position of the imaging ray beam on a detector plane, and respectively collecting a second air image and a second phantom image; wherein the included angle between the imaging ray beam for collecting the second phantom image and the projection of the imaging ray beam for collecting the first phantom image on the detector plane is not 0, and a second correction parameter is obtained according to the second air image and the second phantom image; finally, a hardening correction parameter is determined according to the first correction parameter and the second correction parameter. The application can improve the overall uniformity of the three-dimensional reconstruction image and thus improve the image quality, and can better assist doctors in diagnosis and treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical image processing, in particular to a hardening correction method and device and a storage medium. BACKGROUND

[0002] With the continuous improvement of imaging quality, X-ray imaging equipment is more and more widely used, among which, CBCT (Cone Beam Computed Tomography) system has been widely used in clinical medicine and scientific research due to its small effective dose and high imaging quality. However, due to the divergence of the ray source in three-dimensional space of the CBCT system, the attenuation ability of X-rays, and the scattering of the measured body, the CBCT system is not completely consistent with the ideal model in actual application, which is manifested as the existence of artifacts in the reconstructed image, such as geometric artifacts, scattering artifacts, metal artifacts, cone beam artifacts, and hardening artifacts. Among them, the hardening artifact is caused by beam hardening when the X-rays pass through the measured body.

[0003] Specifically, the X-rays generated by the X-ray ball tube of the CBCT system are multi-energy X-rays with continuous energy spectrum, and the attenuation abilities of X-rays with different energies in the energy spectrum are different when passing through the same material. Therefore, when passing through the measured body, the proportion of low-energy X-rays in the energy spectrum gradually decreases, and the proportion of high-energy X-rays gradually increases, causing beam hardening. The measured body of the medical CBCT system is generally the human body, which presents an approximate ellipsoid geometric shape with a thick middle and thin sides. Beam hardening will cause the reconstructed image to appear a cup-shaped artifact with a dark middle and a bright periphery. This cup-shaped artifact is the hardening artifact. The hardening artifact often leads to a decrease in the uniformity of the image and thus affects the quality of the reconstructed image. Therefore, in order to improve the quality of the reconstructed image to better assist doctors in diagnosis and treatment, it is necessary to correct the hardening artifact.

[0004] In the prior art, the correction parameter is often obtained in the following way to reduce the adverse effects of the hardening artifact on the quality of the reconstructed image: under the same conditions, an air image and a phantom image are collected, and the hardening correction parameter is obtained according to the corresponding line integral when the phantom image is obtained and the corresponding line integral when the simulation is performed through simulation. However, it is found in practice that the hardening correction parameter obtained in this way has errors, which affects the overall uniformity of the three-dimensional reconstructed image, and the image quality needs to be further improved.

[0005] It should be noted that the information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0006] The present application aims at the problem that the hardening correction parameter obtained by the hardening correction method in the prior art has errors, which affects the overall uniformity of the three-dimensional reconstruction image, and provides a hardening correction method, device and storage medium, which can reduce the influence of scattered X-rays on the corrected hardening parameter, thereby improving the overall uniformity of the three-dimensional reconstruction image, improving the quality of the three-dimensional reconstruction image, and better assisting doctors in diagnosis and treatment.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a hardening correction method for a CBCT system, the CBCT system comprising a detector; the hardening correction method comprising:

[0008] adjusting the width of an imaging ray beam to a preset width value;

[0009] respectively acquiring a first air image and a first phantom image of a correction phantom;

[0010] obtaining a first correction parameter according to the first air image and the first phantom image;

[0011] adjusting the projection position of the imaging ray beam on the detector plane, and respectively acquiring a second air image and a second phantom image of the correction phantom; wherein the included angle between the projection of the imaging ray beam for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam for acquiring the first phantom image on the detector plane is not 0;

[0012] obtaining a second correction parameter according to the second air image and the second phantom image;

[0013] determining a hardening correction parameter according to the first correction parameter and the second correction parameter.

[0014] Optionally, the CBCT system comprises a beam limiter; the adjusting the width of the imaging ray beam to a preset width value comprises:

[0015] opening the beam limiter to a narrow slit with a width of a first value, so that the width of the imaging ray beam is the preset width value; wherein the projection area of the imaging ray beam on the detector is located within the projection area of the correction phantom on the detector.

[0016] Optionally, the hardening correction method comprises: keeping the correction phantom stationary, and rotating the beam limiter or simultaneously rotating the beam limiter and the detector, so that the included angle between the projection of the imaging ray beam for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam for acquiring the first phantom image on the detector plane is not 0.

[0017] Optionally, the adjusting the width of the imaging ray beam to a preset width value comprises:

[0018] Optionally, the second number is selected as the height of the correction phantom so that the width of the imaging ray beam used for acquiring the first phantom image is the preset width value.

[0019] Optionally, the hardening correction method comprises: keeping the beam limiter and the detector stationary, and rotating the correction phantom so that the projection of the imaging ray beam used for acquiring the second phantom image on the detector plane is not 0 between the projection of the imaging ray beam used for acquiring the first phantom image on the detector plane.

[0020] Optionally, the hardening correction method further comprises: removing the penumbra region in the first phantom image and the penumbra region in the second phantom image.

[0021] The first correction parameter is obtained using the first air image and the first phantom image after the penumbra region is removed.

[0022] The second correction parameter is obtained using the second air image and the second phantom image after the penumbra region is removed.

[0023] Optionally, the projection of the imaging ray beam used for acquiring the second phantom image on the detector and the projection of the imaging ray beam used for acquiring the first phantom image on the detector have an included angle in the range of [30°, 90°].

[0024] Optionally, the hardening correction method comprises: two-dimensional fitting or two-dimensional interpolation of the first correction parameter and the second correction parameter to determine the hardening correction parameter.

[0025] To achieve the above-mentioned purposes, the application further provides a hardening correction device for a CBCT system, comprising:

[0026] An imaging ray beam width adjusting unit configured to adjust the width of the imaging ray beam to a preset width value;

[0027] A first image acquisition unit configured to acquire a first air image and a first phantom image of a correction phantom, respectively;

[0028] A first parameter acquisition unit configured to obtain a first correction parameter according to the first air image and the first phantom image.

[0029] An imaging ray beam angle adjusting unit is configured to adjust a projection position of the imaging ray beam on a detector plane, and to respectively acquire a second air image and a second phantom image of the correction phantom; wherein an included angle between a projection of the imaging ray beam for acquiring the second phantom image on the detector plane and a projection of the imaging ray beam for acquiring the first phantom image on the detector plane is not 0;

[0030] A second parameter acquiring unit is configured to acquire a second correction parameter according to the second air image and the second phantom image;

[0031] A correction parameter acquiring unit is configured to determine a hardening correction parameter according to the first correction parameter and the second correction parameter.

[0032] In order to achieve the above-mentioned purpose, the application further provides a readable storage medium, wherein the readable storage medium stores a computer program, and the computer program is executed by a processor to implement the hardening correction method.

[0033] Compared with the prior art, the hardening correction method, device and storage medium provided by the application have the following advantages:

[0034] The application provides a hardening correction method for a CBCT system, wherein the CBCT system comprises a detector. The hardening correction method comprises the following steps: firstly, adjusting the width of an imaging beam to a preset width value (for example, opening a beam limiter of the CBCT system to a narrow slit with a first value of the width; or selecting the height of the correction phantom to be able to make the width of the imaging beam be the preset width value); then, respectively acquiring a first air image and a first phantom image of the correction phantom, and obtaining a first correction parameter according to the first air image and the first phantom image; subsequently, adjusting the projection position of the imaging beam on the detector plane, and respectively acquiring a second air image and a second phantom image of the correction phantom; wherein the included angle between the projection of the imaging beam for acquiring the second phantom image on the detector plane and the projection of the imaging beam for acquiring the first phantom image on the detector plane is not 0, and a second correction parameter is obtained according to the second air image and the second phantom image; finally, determining a hardening correction parameter according to the first correction parameter and the second correction parameter. Thus, the hardening correction method provided by the application can limit the imaging beam in a preset width range, which is more convenient for selecting the correction phantom (in the prior art, if the phantom is too large, a large amount of scattered rays are generated, so that the hardening correction parameter obtained is inaccurate; if the phantom is too small, the correction parameter corresponding to the uncovered part cannot be obtained), and the hardening correction parameter is obtained without scattering correction, so that the efficiency of obtaining the hardening correction parameter is improved. Moreover, the influence of scattered X-rays on the hardening correction parameter can be effectively eliminated, and the hardening correction parameter is obtained according to the first correction parameter and the second correction parameter (for example, two-dimensional fitting), so that the overall uniformity of the three-dimensional reconstruction image is improved, the quality of the three-dimensional reconstruction image is improved, and the doctor is better assisted in diagnosis and treatment.

[0035] Since the hardening correction device and the storage medium provided by the application belong to the same inventive concept as the hardening correction method provided by the application, the hardening correction device and the storage medium provided by the application at least have all the advantages of the hardening correction method provided by the application. For details, please refer to the related description of the advantages of the hardening correction method in the foregoing, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The overall flowchart of the hardening correction method provided by the application is shown in the figure;

[0037] Figure 2 The position relationship between the beam limiter, the correction phantom and the detector when the first correction parameter is obtained in the hardening correction method provided by the first embodiment of the application is shown in the figure;

[0038] Figure 3The position relation example diagram of the collimator, the correction phantom and the detector when the second correction parameter is acquired for the hardening correction method provided by the embodiment one of the present application is shown in the following figure:

[0039] Figure 4 The position relation example diagram of the collimator, the correction phantom and the detector when the first correction parameter is acquired for the hardening correction method provided by the embodiment two of the present application is shown in the following figure:

[0040] Figure 5 The position relation example diagram of the collimator, the correction phantom and the detector when the second correction parameter is acquired for the hardening correction method provided by the embodiment two of the present application is shown in the following figure:

[0041] Figure 6 The structure schematic diagram of the hardening correction device provided by the embodiment three of the present application is shown in the following figure:

[0042] In the figure, the following signs are used:

[0043] Ball tube-110, imaging ray beam-111, collimator-120, narrow slit-121, detector-130;

[0044] Correction phantom-200;

[0045] Imaging ray beam width adjusting unit-310, first image acquiring unit-320, first parameter acquiring unit-330, imaging ray beam angle adjusting unit-340, second parameter acquiring unit-350, correction parameter acquiring unit-360. DETAILED DESCRIPTION

[0046] The hardening correction method, device and storage medium of the present application are described in further detail below with reference to the accompanying drawings. The advantages and features of the present application will be more apparent from the following description. It should be noted that the drawings are very simplified and all use non-precise proportions, only for the purpose of facilitating, clarifying and assisting the description of the embodiments of the present application. For the purpose of making the objects, features and advantages of the present application more apparent and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. shown in the drawings of the present application are only used to cooperate with the content disclosed in the present description, to be understood and read by those skilled in the art, and are not used to limit the defined conditions for the implementation of the present application. Any modification of the structure, change of the proportional relationship or adjustment of the size, in the case of producing the same or similar effects and achieving the same or similar purposes as the present application, should still fall within the scope of the technology disclosed by the present application. The specific design features of the present application disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use to be applied and used. In the embodiments described below, the same reference signs are sometimes used in different drawings to represent the same parts or parts with the same function, and the repeated description is omitted. In the present specification, similar reference signs and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0047] In addition, if the method described herein includes a series of steps, and the order of the steps presented herein is not necessarily the only order in which the steps can be performed, and some of the described steps can be omitted and / or some other steps not described herein can be added to the method.

[0048] It has to be noted that, in the present document, the terms "first", "second", etc. merely serve the purpose of differentiation and do not require or imply any kind of ordering or sequence of the entities or actions associated therewith. Furthermore, the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusions, such that processes, methods, articles, or apparatuses that comprise a list of elements are not limited to those elements, but can include other elements not expressly listed or inherent to such processes, methods, articles, or apparatuses. Without further limitation, an element defined by an indefinite article "a" or "an" does not exclude the existence of more than one of such element in the process, method, article, or apparatus including the element. The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. The term "or" is generally employed in its sense including "and / or", the term "several" is generally employed in its sense including "at least two", and the term "at least two" is generally employed in its sense including "two or more". Furthermore, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or an indicated number of technical features.

[0049] It should be noted that the hardening correction method provided by the present application can be applied to the hardening correction device provided by the present application. Further, the hardening correction method and the hardening correction device provided by the present application can be deployed on a CBCT system or an electronic device. Still further, without making any improvement to the hardware of the CBCT system, only the hardening correction device deployed thereon or the hardening correction parameter obtained by using the hardening correction method provided by the present application in the process of reconstructing the image is needed to perform the hardening correction. Still further, the hardening correction device provided by the present application can be implemented in a software manner, a hardware manner or a combination of software and hardware, and the present application does not make any limitation in this regard. In addition, the present application does not make any limitation to the CBCT system, specifically, the CBCT system includes a ball tube that can provide a radiation beam (for example, X-ray), a beam limiter that controls the radiation beam irradiation field of the ball tube, a detector that receives the radiation beam passing through the scanning object and converts it into a corresponding signal, and an image reconstruction device that reconstructs the image according to the imaging data detected by the detector. More specifically, in some embodiments, the detector can be composed of a plurality of detection elements. For example, the detector can include 320000 (1000 columns x 320 rows) detection elements. In some embodiments, each detection element can receive the radiation beam passing through a position on the scanning object. In some embodiments, the detector can include but is not limited to a gas detector, a scintillator detector, a semiconductor detector, etc. The connection relationship, function, imaging principle, imaging process and image reconstruction process of the related imaging components such as the ball tube, the beam limiter and the detector of the CBCT system will not be described in detail here, and please refer to the prior art known by those skilled in the art for adaptive understanding. Similarly, the present application does not make any limitation to the electronic device, which can be a personal computer, a mobile terminal, etc., and the mobile terminal can be a mobile phone, a tablet computer, etc. with various operating systems.

[0050] In order to facilitate the understanding and description of the present application, before the specific embodiments of the hardening correction method, device and storage medium provided by the present application are described, the exploration process of the hardening correction method provided by the present application is briefly described as follows:

[0051] The hardening correction method in the prior art mainly comprises the following steps: first, under the same acquisition condition, an air image of a CBCT system and a phantom image of a correction phantom are acquired, and the line integral of X-rays passing through the correction phantom is determined according to the two groups of images; then, the acquisition process of the correction phantom is simulated according to the energy spectrum of the X-rays and the spatial condition of the CBCT system acquisition device, and a simulated line integral is obtained, when the simulated line integral image is consistent with the acquired line integral image, it is considered that the simulated parameters are consistent with the parameters when the phantom image is acquired; and third, a set of parameters is used to map the multi-energy spectrum attenuation characteristics of the simulation to the attenuation characteristics of single-energy X-rays, and the set of parameters is taken as the hardening correction parameter to perform hardening correction in the process of reconstructing the image.

[0052] However, research shows that this hardening correction method has the following problems: since the spatial distribution of the X-ray energy spectrum exists, if the size of the correction phantom is too small, the entire detector of the CBCT system cannot be covered, and the correction parameters corresponding to the uncovered part of the detector cannot be acquired; if the size of the correction phantom is large enough to cover the entire area of the detector, a large amount of scattered lines will be generated when the X-rays pass through the correction phantom, and the scattered lines will cause the line integral of the correction phantom calculated in the first step to be inaccurate, and further cause the hardening correction parameters to be inaccurate, thereby affecting the correction effect. Therefore, the image needs to be de-scattered by a scattering correction algorithm. However, the current scattering correction algorithm cannot completely and accurately remove the cup-shaped artifacts and stripe artifacts caused by the scattered lines, and the noise caused by the scattered lines cannot be removed by the scattering correction algorithm.

[0053] Based on the above research, the core idea of the present application is to provide a hardening correction method, device and storage medium to reduce the influence of scattered X-rays on the correction hardening parameters, thereby improving the overall uniformity of the three-dimensional reconstructed image, improving the quality of the three-dimensional reconstructed image, and better assisting doctors in diagnosis and treatment.

[0054] In order to realize the above idea, the present application provides a hardening correction method for a CBCT system, wherein the CBCT system comprises a detector. Specifically, please refer to Figure 1 which schematically shows the overall flowchart of the hardening correction method provided by the present application. From Figure 1 It can be seen that the hardening correction method provided by the present application comprises the following steps:

[0055] S100: adjusting the width of the imaging beam to a preset width value;

[0056] S200: acquiring a first air image and a first phantom image of a correction phantom, respectively;

[0057] S300: acquiring a first correction parameter according to the first air image and the first phantom image;

[0058] S400: adjusting a projection position of the imaging ray beam on the detector plane, and respectively acquiring a second air image and a second phantom image of the correction phantom; wherein an included angle between a projection of the imaging ray beam on the detector plane for acquiring the second phantom image and a projection of the imaging ray beam on the detector plane for acquiring the first phantom image is not 0;

[0059] S500: obtaining a second correction parameter according to the second air image and the second phantom image;

[0060] S600: determining a hardening correction parameter according to the first correction parameter and the second correction parameter.

[0061] Therefore, the hardening correction method provided by the present application can not only improve the efficiency of obtaining the hardening correction parameter by limiting the imaging ray beam within a preset width range, without the need for scattering correction, thereby improving the efficiency of obtaining the hardening correction parameter, but also effectively eliminate the influence of scattered X-rays on the hardening correction parameter, and further, the hardening correction parameter is obtained according to the first correction parameter and the second correction parameter (such as two-dimensional fitting), which can improve the overall uniformity of the three-dimensional reconstructed image and improve the quality of the three-dimensional reconstructed image, thereby better assisting doctors in diagnosis and treatment.

[0062] It should be noted that, as can be understood by those skilled in the art, the present application does not limit the order of adjusting the width of the imaging ray beam to a preset width value in step S100 and acquiring the first air image in step S200, for example, in some embodiments, the width of the imaging ray beam can be adjusted to a preset width first, and then the first air image and the first phantom image are acquired; in some other embodiments, the first air image can be acquired first, and then the width of the imaging ray beam is adjusted to a preset width. It is obvious that the step of acquiring the first phantom image of the correction phantom should be after adjusting the width of the imaging ray beam to a preset width value in step S100. Further, the present application does not limit the order of steps S300 and S400, in some embodiments, the first correction parameter can be calculated according to the first air image and the first phantom image, and in some other embodiments, the first correction parameter can be calculated after acquiring the first air image and the second phantom image.

[0063] In addition, those skilled in the art should understand that the first air image, the first phantom image, the second air image and the second phantom image should be acquired by using the same CBCT system and under the same acquisition protocol to ensure that the obtained hardening correction parameters are more accurate and reliable. Specifically, the acquisition protocol refers to the parameter settings of the CBCT system when acquiring the first air image, the first phantom image, the second air image and the second phantom image, including but not limited to scanning and reconstruction related parameters such as tube voltage, current and filtering parameters applied to the ball tube, scanning time, reconstruction interval and reconstruction parameters, etc.

[0064] In particular, the imaging radiation beam herein refers to a radiation beam used for reconstructing the first air image, the first phantom image, the second air image and the second phantom image.

[0065] Embodiment I

[0066] The embodiment provides a hardening correction method, and specifically, please continue to refer to Figure 1 in combination with Figure 2 and Figure 3 wherein, Figure 2 FIG. 1 is an example diagram of the positional relationship among the beam limiter, the correction phantom and the detector when the first correction parameter is obtained according to the hardening correction method provided in Embodiment I of the present application; Figure 3 FIG. 2 is an example diagram of the positional relationship among the beam limiter, the correction phantom and the detector when the second correction parameter is obtained according to the hardening correction method provided in Embodiment I of the present application. Figure 2 and Figure 3 It can be seen that the CBCT system includes a ball tube 110, a beam limiter 120 and a detector 130.

[0067] In this embodiment, the step S100 adjusts the width of the imaging radiation beam 111 to a preset width, specifically including:

[0068] The beam limiter 120 is opened to a narrow slit 121 with a first value, so that the width of the imaging radiation beam 111 is the preset width value; wherein the projection area of the imaging radiation beam 111 on the detector 130 plane is located within the projection area of the correction phantom 200 on the detector 130 plane. By configuring the beam limiter 120 as a narrow slit 121, only the X-rays passing through the narrow slit 121 can irradiate the correction phantom 200, thereby effectively reducing scattered X-rays, thereby laying a foundation for obtaining accurate first correction parameters.

[0069] For the convenience of understanding, the first air image and the first phantom image are acquired by taking the collimator 120 as a horizontal slit 121. However, it is obvious that this is not a limitation of the present application, and in other embodiments, the slit 121 can also have an angle with the horizontal direction. Further, the extension direction of the slit 121 is preferably parallel to the long side direction of the plane of the detector 130, so that the imaging ray beam 111 covers a larger range of the plane of the detector 130. It should be noted that, as can be understood by those skilled in the art, in some embodiments, the opening width of the slit 121 can be calculated according to the preset width, the position relationship between the detector 130, the placement position of the correction phantom 200 and the collimator 120. In actual application, the width of the slit 121 can also be reasonably set according to the system parameters of the CBCT system, such as any value between [5cm, 10cm].

[0070] After the collimator 120 is taken as a slit 121, step S200 can be performed, that is, the first phantom image of the correction phantom 200 is acquired by using the same acquisition protocol as that for acquiring the first air image.

[0071] It should be noted that the present application does not limit the time of acquiring the first air image. As described above, the first air image can be acquired before the collimator 120 is taken as a slit 121, or the first air image can be acquired after the collimator 120 is taken as a slit 121.

[0072] Preferably, in one exemplary embodiment, step S300 calculates the first correction parameter (if the slit 121 extends along the horizontal direction, the first correction parameter is the row correction parameter) according to the acquired first air image and the first phantom image, specifically including: first, calculating the line integral LIHM of the first phantom image, ln(Ih0 / Ih1), wherein Ih0 is the first air image; Ih1 is the first phantom image. Then, according to the energy spectrum of X-rays, simulating the imaging image chain (including filtering, correction phantom 200, etc.) of the CBCT system for acquiring the first phantom image, simulating the line integral LIHC of X-rays after passing through the correction phantom 200, adjusting the X-ray energy spectrum and the size of the filter, so that the simulated line integral LIHC is consistent with the line integral LIHM of the first phantom image. Finally, according to the simulated image chain, the first attenuation curve of X-rays with energy spectrum distribution passing through different thicknesses of single material and the second attenuation curve of single energy X-rays passing through different thicknesses of single material are calculated, and the first attenuation curve is mapped to the second attenuation curve through an analytical equation, wherein the parameter Ph in the analytical equation is the first correction parameter of the CBCT system.

[0073] It should be noted that, as can be understood by those skilled in the art, the first correction parameter is only a correction parameter of a partial region of the detector 130 plane (i.e. a projection region of the correction phantom 200 on the detector 130 plane), rather than a correction parameter of the entire detector 130.

[0074] The present application does not limit the correction phantom 200, and specifically, the correction phantom 200 can be a uniform phantom composed of a single material. The material of which the correction phantom 200 is composed can include Teflon, propylene, polyethylene, or resin, etc. The shape of the correction phantom 200 can be a cylinder, a sphere, a cube, etc. The correction phantom 200 can contain a medium such as water or a water-equivalent plastic. Further, the correction phantom 200 can contain some local structures inside or on the surface, which can include holes, diagonal lines, letters, circles, etc. of different sizes. As a preference, the correction phantom 200 is a cylindrical PMMA phantom.

[0075] As a preference, in some exemplary embodiments, after step S200, there is further included: removing a penumbra region in the first phantom image. In this way, by removing the penumbra region, the accuracy of the correction parameter can be further improved. The size of the penumbra region can be determined according to the relevant parameters of the CBCT system, and more detailed contents can be found in the prior art known to those skilled in the art, which will not be described here.

[0076] Correspondingly, in step 300, the first correction parameter is obtained using the first air image and the first phantom image after the penumbra region is removed.

[0077] In one exemplary embodiment, step S400 of adjusting the projection position of the imaging ray beam 111 on the detector plane specifically includes: keeping the correction phantom 200 stationary, rotating the beam limiter 120 or simultaneously rotating the beam limiter 120 and the detector 130, so that the projection of the imaging ray beam 111 used to collect the second phantom image on the detector 130 plane is not 0 with the projection of the imaging ray beam 111 used to collect the first phantom image on the detector 130 plane.

[0078] Further, as a preference, the projection of the imaging ray beam 111 used to collect the second phantom image on the detector 130 plane is in the range of [30°, 90°] with the projection of the imaging ray beam 111 used to collect the first phantom image on the detector 130 plane. Correspondingly, in this embodiment, the angle range of rotating the beam limiter 120 or simultaneously rotating the beam limiter 120 and the detector 130 is preferably [30°, 90°].

[0079] Specifically, in the acquisition of the second air image and the second phantom image, the collimator 120 is rotated by 90° (correspondingly, the narrow slit 121 is adjusted from the horizontal direction to the vertical direction) is taken as an example for illustration. Please refer to Figure 3 Correspondingly, the second correction parameter obtained in step S500 according to the acquired second air image and the second phantom image is a column correction parameter. Similarly, the second correction parameter is similar to the first correction parameter, which is a correction parameter of only a part of the plane of the detector 130 (i.e., the projection region of the correction phantom 200 on the plane of the detector 130 after the rotation of the collimator 120), rather than a correction parameter of the entire detector 130.

[0080] In the acquisition of the second air image and the second phantom image, the collimator 120 and the detector 130 are preferably rotated simultaneously to keep the extension direction of the narrow slit 121 parallel to the long side direction of the plane of the detector 130, so that the imaging beam 111 covers a larger range of the plane of the detector 130.

[0081] More specifically, the basic principle of calculating the second correction parameter in step S500 according to the acquired second air image and the second phantom image is the same as that of calculating the first correction parameter. Please refer to the above description of calculating the first correction parameter according to the first air image and the first phantom image, which will not be described here.

[0082] Similarly to the principle of obtaining the first correction parameter, before step S500, there is also a step of removing the penumbra region in the second phantom image. Correspondingly, step S500 specifically includes a step of obtaining the second correction parameter using the second air image and the second phantom image after the removal of the penumbra region.

[0083] It should be noted that the first correction parameter and the second correction parameter are not limited in the present application. In some embodiments, the first correction parameter and the second correction parameter can be single-row and single-column parameters, and in other embodiments, the first correction parameter and the second correction parameter can also be multi-row and multi-column parameters.

[0084] In some exemplary embodiments, step S600 determines the hardening correction parameter according to the first correction parameter and the second correction parameter, specifically including:

[0085] The first correction parameter and the second correction parameter are two-dimensionally fitted or two-dimensionally interpolated to determine a hardening correction parameter. Thus, by two-dimensionally fitting or two-dimensionally interpolating, the correction parameter covering the whole plane of the detector 130 can be obtained, and the hardening correction parameter obtained by the hardening correction method provided by the present application has no influence of scattering when obtaining the first correction parameter and the second correction parameter, and thus, when the hardening correction parameter is used to correct the three-dimensional reconstruction image, the overall uniformity of the three-dimensional reconstruction image can be improved, and the image quality can be improved. It should be noted that the specific method of two-dimensionally fitting and two-dimensionally interpolating is not limited in the present application, for example, the two-dimensionally fitting can be polynomial fitting or fitting by other forms of functions.

[0086] In summary, the hardening correction method provided by the present embodiment can greatly reduce the scattered X-rays by opening the beam limiter 120 into a narrow slit 121 when collecting the image of the correction phantom 200, so that only the narrow beam of X-rays irradiates the correction phantom 200. Thus, the image collected by the narrow beam of X-rays can only support the generation of the X-ray beam hardening parameter within the narrow irradiation range, for example, the width of the narrow beam is a centimeters, and the effective range is a-b centimeters after removing the influence range b centimeters of the penumbra region, and thus, the first correction parameter Ph within a-b centimeters can be generated. In order to obtain the correction parameter outside a-b centimeters, in one embodiment, the detector 130 and the beam limiter 120 are rotated by 90 degrees, and then the image of the correction phantom 200 is collected, and the second correction parameter Pv generated at this time is still within a-b centimeters. However, the second parameter Pv and the first correction parameter Ph are perpendicular to each other, and according to the two-dimensional fitting of Pv and Ph, the final hardening correction parameter PHv can be obtained. Since the hardening correction parameter PHv has no influence of scattering, and covers the whole plane of the detector 130, the overall uniformity of the three-dimensional reconstruction image corrected by using the hardening correction parameter can be greatly improved.

[0087] Embodiment Two

[0088] The present embodiment provides another embodiment of the hardening correction method, and specifically, the hardening correction method provided by the present embodiment is different from the hardening correction method provided by the first embodiment in that the beam limiter 120 is opened into a narrow slit 121, and the hardening correction parameter is determined by rotating the beam limiter 120 and / or the detector 130. The hardening correction method provided by the present embodiment is determined by selecting the height of the correction phantom 200 and rotating the correction phantom 200.

[0089] Specifically, the steps S200, S300, S400 of collecting the second air image and the second phantom image of the correction phantom 200, S500 and S600 of the hardening correction method provided by the embodiment are similar to the steps S200, S300, S400 of collecting the second air image and the second phantom image of the correction phantom 200, S500 and S600 of the hardening correction method provided by the first embodiment. To avoid redundancy, the description is not expanded here. Only the differences from the first embodiment are described below, mainly including the step S100 of adjusting the width of the imaging ray beam 111 to a preset width value and the step S400 of adjusting the projection position of the imaging ray beam 111 on the detector plane.

[0090] More specifically, please refer to Figure 4 and Figure 5 wherein, Figure 4 is an example diagram of the positional relationship among the beam limiter 120, the correction phantom 200 and the detector 130 when the first correction parameter is acquired in the hardening correction method provided by the second embodiment of the present application. Figure 5 is an example diagram of the positional relationship among the beam limiter 120, the correction phantom 200 and the detector 130 when the second correction parameter is acquired in the hardening correction method provided by the second embodiment of the present application. In combination with Figure 1 and Figure 4 and Figure 5 It can be seen that in this embodiment, the step S100 adjusts the width of the imaging ray beam 111 to a preset width, specifically including:

[0091] The phantom with the second height value is selected as the correction phantom 200, so that the width of the imaging ray beam 111 used to collect the phantom image of the correction phantom 200 is the preset width value. In this way, the hardening correction method provided by the present embodiment can effectively reduce scattered X-rays by selecting the phantom with the second height value as the correction phantom 200, so that the width of the imaging ray beam 111 used to collect the phantom image of the correction phantom 200 is the preset width value, thereby laying a foundation for acquiring accurate first correction parameters.

[0092] For the convenience of understanding, the correction phantom 200 is horizontally placed when the first air image and the first phantom image are acquired. However, it is obvious that this is not a limitation of the present application, and in other embodiments, the correction phantom 200 can also have a certain angle with the horizontal direction. Further, the length direction of the correction phantom 200 is preferably parallel to the long side direction of the detector 130 plane, and the projection of the length direction of the correction phantom 200 on the detector 130 plane can cover the long side area of the detector 130 plane, so that the imaging ray beam 111 covers a larger range of the detector 130 plane. It should be noted that, as can be understood by those skilled in the art, in some embodiments, the height of the correction phantom 200 can be calculated according to the preset width, the position relationship between the detector 130, the placement position of the correction phantom 200 and the beam limiter 120, to determine the correction phantom 200. In actual application, the height of the correction phantom 200 can also be reasonably set according to the system parameters of the CBCT system, such as any value between [5cm, 10cm].

[0093] Correspondingly, the step S400 adjusts the projection position of the imaging ray beam 111 on the detector 130 plane, specifically including: keeping the beam limiter 120 and the detector 130 unchanged, rotating the correction phantom 200, so that the projection of the imaging ray beam 111 for acquiring the second phantom image on the detector 130 plane is not 0 between the projection of the imaging ray beam 111 for acquiring the first phantom image on the detector 130 plane.

[0094] When the first air image and the first phantom image are acquired, the correction phantom 200 is preferably rotated by 90°, that is, the correction phantom 200 is rotated from horizontal placement to vertical placement.

[0095] When the width of the imaging ray beam 111 is controlled and the projection position of the imaging ray beam 111 on the detector 130 plane is adjusted using the correction phantom 200, whether the beam limiter 120 is opened into a narrow slit 121 is not limited, and in some embodiments, the beam limiter 120 can be opened into a narrow slit 121, but it is necessary to ensure that the X-rays passing through the narrow slit 121 can cover the correction phantom 200; in other embodiments, the beam limiter 120 can also be kept fully open.

[0096] Further, as can be understood by those skilled in the art, the above-mentioned embodiment one and embodiment two are only descriptions of preferred embodiments, and in other embodiments, the width of the imaging ray beam 111 can also be adjusted to a preset width value by other ways, or the correction parameters of multiple projection positions of the imaging ray beam 111 can be fitted. The present application does not limit this.

[0097] Embodiment three

[0098] The embodiment provides a hardening correction device for a CBCT system. Specifically, refer to Figure 6 which schematically shows a structural schematic diagram of the hardening correction device provided by the embodiment. It can be seen from Figure 6 that the hardening correction device provided by the embodiment comprises an imaging ray beam width adjusting unit 310, a first image acquiring unit 320, a first parameter acquiring unit 330, an imaging ray beam angle adjusting unit 340, a second parameter acquiring unit 350 and a correction parameter acquiring unit 360.

[0099] Specifically, the imaging ray beam width adjusting unit 310 is configured to adjust the width of the imaging ray beam to a preset width value. The first image acquiring unit 320 is configured to respectively acquire a first air image and a first phantom image of a correction phantom. The first parameter acquiring unit 330 is configured to acquire a first correction parameter according to the first air image and the first phantom image. The imaging ray beam angle adjusting unit 340 is configured to adjust the projection position of the imaging ray beam on a detector plane and respectively acquire a second air image and a second phantom image of the correction phantom; wherein the included angle between the projection of the imaging ray beam used for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam used for acquiring the first phantom image on the detector plane is not 0. The second parameter acquiring unit 350 is configured to acquire a second correction parameter according to the second air image and the second phantom image. The correction parameter acquiring unit 360 is configured to determine a hardening correction parameter according to the first correction parameter and the second correction parameter.

[0100] Since the basic principle of the hardening correction device provided by the embodiment is similar to that of the hardening correction method provided by each of the above embodiments, for more detailed content about determining the hardening correction parameter by the hardening correction device provided by the embodiment, refer to the related description of the hardening correction method provided by each of the above embodiments, which will not be described here. Further, since the hardening correction device provided by the embodiment and the hardening correction method provided by each of the above embodiments belong to the same inventive concept, the hardening correction device provided by the embodiment at least has all the advantages of the hardening correction method provided by each of the above embodiments, and the detailed content can be referred to the related description of the beneficial effects of the hardening correction method provided by each of the above embodiments, which will not be described here.

[0101] Embodiment four

[0102] The embodiment provides a readable storage medium, wherein the readable storage medium stores a computer program, and the computer program can realize the hardening correction method when the computer program is executed by a processor. Since the readable storage medium provided by the embodiment and the hardening correction method provided by each of the above embodiments belong to the same inventive concept, the readable storage medium provided by the embodiment has at least all advantages of the hardening correction method provided by each of the above embodiments, and the details are described in the related description of the advantages of the hardening correction method provided by each of the above embodiments, which will not be repeated here.

[0103] The readable storage medium of the embodiment of the application can adopt any combination of one or more computer-readable media. The readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared or semiconductor system, device or component, or any combination thereof. More specific examples (non-exhaustive list) of the computer-readable storage medium include: an electrical connection having one or more wires, a portable computer hard disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this paper, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or component.

[0104] The computer-readable signal medium can include a data signal propagating in a baseband or as a part of a carrier wave propagating in a baseband, wherein the computer-readable program code is carried. Such a propagating data signal can take various forms, including but not limited to an electromagnetic signal, an optical signal or any suitable combination thereof. The computer-readable signal medium can also be any computer-readable medium other than the computer-readable storage medium, which can send, propagate or transmit a program for use by or in combination with an instruction execution system, device or component.

[0105] Computer program code for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0106] In summary, compared with the prior art, the hardening correction method, device and storage medium provided by the present application have the following advantages:

[0107] The hardening correction method provided by the present application can improve the efficiency of obtaining the hardening correction parameter by limiting the imaging ray beam in a preset width range, without the need for scattering correction, thereby improving the efficiency of obtaining the hardening correction parameter, and effectively eliminating the influence of scattered X-rays on the hardening correction parameter. Furthermore, the hardening correction parameter is obtained according to the first correction parameter and the second correction parameter (such as two-dimensional fitting), which can improve the overall uniformity of the three-dimensional reconstruction image and improve the quality of the three-dimensional reconstruction image, thereby better assisting doctors in diagnosis and treatment.

[0108] The hardening correction device and storage medium provided by the present application belong to the same inventive concept as the hardening correction method provided by the present application, and therefore at least have all the advantages of the hardening correction method provided by the present application. For details, please refer to the relevant description of the advantages of the hardening correction method above. Here, they will not be repeated one by one.

[0109] It should be noted that the apparatus and method disclosed in the embodiments herein can also be implemented in other ways. The apparatus embodiments described above are merely exemplary, and the flowcharts and block diagrams in the accompanying drawings show only one possible implementation of the apparatus, method and computer program product according to the embodiments herein. In this regard, each block in the flowcharts and block diagrams can represent a module, a procedure, or a part of a program, which comprises one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementations, the functions noted in the boxes can occur out of the order noted in the flowcharts. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or in the reverse order, depending on the functionality involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by dedicated hardware-based systems that perform the specified functions or acts, or can be implemented by a combination of dedicated hardware and computer instructions.

[0110] In addition, each functional module in the various embodiments herein can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0111] The above description is merely illustrative of the embodiments of the present application, and is not intended to limit the scope of the present application in any way. Any modifications, changes, and improvements made to the present application by any person skilled in the art, based on the above description, are intended to fall within the scope of the present application. It is apparent that those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and changes fall within the scope of the present application and equivalent technology thereof, they are intended to be included in the present application.

Claims

1. A hardening correction method for a CBCT system, the CBCT system comprising a detector; characterized in that, The hardening correction method comprises: adjusting the width of the imaging ray beam to a preset width value by way one or way two; the way one is: opening the beam limiter of the CBCT system to a narrow slit with a first numerical value of width, so that the width of the imaging ray beam is the preset width value; the way two is: selecting a phantom with a second numerical value of height as a correction phantom, so that the width of the imaging ray beam used for acquiring the phantom image of the correction phantom is the preset width value; respectively acquiring a first air image and a first phantom image of the correction phantom; obtaining first correction parameters according to the first air image and the first phantom image; adjusting the projection position of the imaging ray beam on the detector plane, and respectively acquiring a second air image and a second phantom image of the correction phantom; wherein the included angle between the projection of the imaging ray beam used for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam used for acquiring the first phantom image on the detector plane is not 0; obtaining second correction parameters according to the second air image and the second phantom image; two-dimensional fitting or two-dimensional interpolation is performed on the first correction parameters and the second correction parameters to determine the hardening correction parameters.

2. The hardening correction method according to claim 1, characterized by, The projection area of the imaging ray beam on the detector plane is located in the projection area of the correction phantom on the detector plane.

3. The hardening correction method according to claim 2, characterized by, Comprise: keeping the correction phantom still, rotating the beam limiter or rotating the beam limiter and the detector at the same time, so that the included angle between the projection of the imaging ray beam used for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam used for acquiring the first phantom image on the detector plane is not 0.

4. The hardening correction method according to claim 1, characterized by, Comprise: keeping the beam limiter and the detector of the CBCT system still, and rotating the correction phantom, so that the included angle between the projection of the imaging ray beam used for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam used for acquiring the first phantom image on the detector plane is not 0.

5. The hardening correction method according to any one of claims 1 to 4, characterized in that, Also comprise: removing the penumbra area in the first phantom image and the penumbra area in the second phantom image; using the first air image and the first phantom image after removing the penumbra area to obtain the first correction parameters; using the second air image and the second phantom image after removing the penumbra area to obtain the second correction parameters.

6. The hardening correction method according to claim 5, characterized by, The included angle between the projection of the imaging ray beam used for acquiring the second phantom image on the detector and the projection of the imaging ray beam used for acquiring the first phantom image on the detector ranges from 30° to 90°.

7. A hardening correction device for a CBCT system, characterized in that The CBCT system comprises a detector; the hardening correction device comprises: An imaging ray beam width adjusting unit is configured to adjust the width of the imaging ray beam to a preset width value by a first mode or a second mode. The first mode is to open a beam limiter of the CBCT system to a narrow slit with a first value of width, so that the width of the imaging ray beam is the preset width value. The second mode is to select a phantom with a second value of height as a correction phantom, so that the width of the imaging ray beam for acquiring a phantom image of the correction phantom is the preset width value. A first image acquiring unit is configured to acquire a first air image and a first phantom image of a correction phantom respectively. A first parameter acquiring unit is configured to acquire a first correction parameter according to the first air image and the first phantom image. An imaging ray beam angle adjusting unit is configured to adjust the projection position of the imaging ray beam on a detector plane, and acquire a second air image and a second phantom image of the correction phantom respectively. An included angle between the projection of the imaging ray beam for acquiring the second phantom image on the detector plane and the projection of the imaging ray beam for acquiring the first phantom image on the detector plane is not 0. A second parameter acquiring unit is configured to acquire a second correction parameter according to the second air image and the second phantom image. A correction parameter acquiring unit is configured to perform two-dimensional fitting or two-dimensional interpolation on the first correction parameter and the second correction parameter, and determine a hardening correction parameter.

8. A readable storage medium, characterized by, The readable storage medium stores a computer program, and the computer program is executed by a processor to implement the hardening correction method in any one of claims 1 to 6.

Images