A method, system, and storage medium for hardening correction

Abstract

The embodiment of the specification provides a hardening correction method, system and storage medium, the method comprises the following steps: based on the imaging equipment, scanning each thickness scanning object in at least one different thickness scanning object, obtaining first scanning data; setting a small gap formed by a shield in the radiation area of the imaging equipment, and based on the imaging equipment, scanning each thickness scanning object, obtaining second scanning data of each thickness scanning object; based on the first scanning data and the second scanning data, obtaining the corresponding non-spectral signal of each thickness scanning object; for each thickness scanning object, correcting the first scanning data based on the non-spectral signal, and obtaining corrected scanning data; based on the corresponding corrected scanning data of each thickness scanning object, determining the corresponding hardening correction coefficient of the imaging equipment.

Description

TECHNICAL FIELD

[0001] The present specification relates to the field of CT imaging, and in particular, to a hardening correction method, system and storage medium. BACKGROUND

[0002] Computed Tomography (CT) technology is a non-destructive testing technology, which can reconstruct an image based on scan data corresponding to attenuated radiation after a radiation beam passes through a scan object. The image reconstruction algorithm of CT assumes that the radiation beam is monochromatic radiation. Monochromatic radiation is a radiation composed of photons with the same energy. However, the radiation beam is actually a wide beam, continuous energy spectrum and polychromatic radiation. When the radiation beam passes through the scan object, the low-energy photons have weak penetration ability, large attenuation and are easily absorbed by the scan object; the high-energy photons have strong penetration ability, small attenuation and are easily passed through the scan object, resulting in an increase in the proportion of high-energy photons in the attenuated radiation after passing through the scan object, a change in the energy spectrum and an increase in the average energy. The image reconstruction algorithm is based on the calculation of the equivalent energy of the single energy of the attenuated radiation, so that the equivalent energy is higher than the actual energy, the corresponding signal intensity is higher, the projection value of the reconstructed image is smaller, the CT value of the central region of the reconstructed image is lower, the cup-shaped artifact is formed, the hardening effect is produced and the image quality is reduced. Therefore, it is necessary to perform hardening correction on the imaging device. The hardening correction technology can use different thicknesses of substances to perform scanning, fit the measured projection values of different thicknesses with the theoretical projection values, obtain the hardening correction coefficient, and then realize the hardening correction.

[0003] However, the actual measured projection value is also affected by other factors. For example, the non-energy spectrum signal produced by the scattered radiation can also form a cup-shaped artifact on the image, affecting the measurement of the scan data.

[0004] Therefore, a hardening correction scheme is needed, which can effectively evaluate the non-energy spectrum signal produced by interference factors such as scattering and defocusing, thereby improving the accuracy of the actual scan data and improving the accuracy of the hardening correction. SUMMARY

[0005] One or more embodiments of the present specification provide a hardening correction method. The hardening correction method comprises: obtaining first scan data based on the imaging device scanning each thickness scan object in at least one different thickness scan object; setting a shield forming a small gap in the radiation region of the imaging device, and obtaining second scan data of each thickness scan object based on the imaging device scanning each thickness scan object; obtaining a non-energy spectrum signal corresponding to each thickness scan object based on the first scan data and the second scan data; for each thickness scan object, correcting the first scan data based on the non-energy spectrum signal to obtain corrected scan data; and determining a hardening correction coefficient corresponding to the imaging device based on the corrected scan data corresponding to each thickness scan object.

[0006] The one or more embodiments of the specification provide a hardening correction system, comprising: a first data acquisition module configured to acquire first scan data based on scanning each thickness scan object in at least one different thickness scan object by an imaging device; a second data acquisition module configured to set a small gap forming shield in a radiation region of the imaging device and acquire second scan data of each thickness scan object based on scanning each thickness scan object by the imaging device; a non-spectrum signal acquisition module configured to acquire a non-spectrum signal corresponding to each thickness scan object based on the first scan data and the second scan data; a correction module configured to correct the first scan data based on the non-spectrum signal to acquire corrected scan data for each thickness scan object; and a correction coefficient determination module configured to determine a hardening correction coefficient corresponding to the imaging device based on the corrected scan data of each thickness scan object.

[0007] The one or more embodiments of the specification provide a computer readable storage medium storing computer instructions, wherein when a computer reads the computer instructions in the storage medium, the computer executes a hardening correction method. BRIEF DESCRIPTION OF DRAWINGS

[0008] The specification will be further described in the manner of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same numbers represent the same structures, wherein:

[0009] Figure 1 is a schematic diagram of an application scenario of a hardening correction system according to some embodiments of the specification;

[0010] Figure 2 is an exemplary block diagram of a hardening correction system according to some embodiments of the specification;

[0011] Figure 3 is an exemplary flowchart of a hardening correction method according to some embodiments of the specification;

[0012] Figure 4A is a schematic diagram of an imaging device according to some embodiments of the specification;

[0013] Figure 4B is a schematic diagram of a detector according to some embodiments of the specification;

[0014] Figure 5A and Figure 5B is a schematic diagram of moving a small gap on a shield according to some embodiments of the specification;

[0015] Figure 6 is a schematic diagram of setting N small gaps on a shield according to some embodiments of the specification;

[0016] Figure 7 is an example flowchart of acquiring non-spectral signals corresponding to each thickness scanning object in the entire radiation region according to some embodiments of the present specification. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present specification, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some examples or embodiments of the present specification, and for those skilled in the art, the present specification can also be applied to other similar scenarios without creative labor on the basis of these drawings. Unless it is clear from the language environment or otherwise stated, the same reference numbers in the drawings represent the same structures or operations.

[0018] It should be understood that the "system", "device", "unit" and / or "module" used herein is a method for distinguishing different components, elements, parts, sections or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0019] As shown in the specification and claims, unless the context clearly indicates otherwise, the words "one", "a", "an", and / or "the" do not refer to the singular, but can also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.

[0020] Flowcharts are used in the present specification to illustrate the operations performed by the system according to the embodiments of the present specification. It should be understood that the preceding or subsequent operations are not necessarily performed in sequence. On the contrary, each step can be processed in reverse order or simultaneously. At the same time, other operations can also be added to these processes, or one or more steps of the operation can be removed from these processes.

[0021] Figure 1 is a schematic diagram of an application scenario 100 of a hardening correction system according to some embodiments of the present specification.

[0022] The hardening correction system can obtain the hardening correction parameters corresponding to the imaging device by implementing the methods and / or processes disclosed in the present specification. As shown in Figure 1 The hardening correction system can include an imaging device 110, a processing device 120, a terminal device 130, a network 140, and / or a storage device 150, etc.

[0023] The components of the hardening correction system can be connected in one or more various ways. Just as an example, as shown inFigure 1 As shown, the imaging device 110 can be connected to the processing device 120 through the network 140. As another example, the imaging device 110 can be directly connected to the processing device 120 (as shown by the dashed bidirectional arrow connecting the imaging device 110 and the processing device 120). As a further example, the storage device 150 can be connected to the processing device 120 directly or through the network 140. As a further example, the terminal device 130 can be connected to the processing device 120 directly (as shown by the dashed bidirectional arrow connecting the terminal device 130 and the processing device 120) and / or through the network 140.

[0024] The imaging device 110 can be a multi-modality scanning device including a Computed Tomography (CT) device. In some embodiments, the imaging device 110 can include a radiation source and a detector. In some embodiments, the radiation source can emit a radiation beam to a scan object. For example, an X-ray beam. In some embodiments, the detector can receive the radiation beam passing through the scan object and convert the radiation beam passing through the scan object into a signal.

[0025] The processing device 120 can process data and / or information obtained from the imaging device 110, the terminal device 130, and / or the storage device 150. For example, the processing device 120 can acquire a signal from the imaging device 110 and acquire scan data based on the signal. As another example, the processing device 120 can acquire a non-spectral signal based on the scan data and acquire corrected scan data based on the non-spectral signal. As a further example, the processing device 120 can determine a hardening correction parameter based on the corrected scan data. In some embodiments, the processing device 120 can include a Central Processing Unit (CPU), a Digital Signal Processor (DSP), a System on a Chip (SoC), a Microcontroller Unit (MCU), etc. and / or any combination thereof. In some embodiments, the processing device 120 can include a computer, a user console, a single server or a server group, etc. The server group can be centralized or distributed. In some embodiments, the processing device 120 can be local or remote. For example, the processing device 120 can access information and / or data stored in the imaging device 110, the terminal device 130, and / or the storage device 150 via the network 140. As another example, the processing device 120 can directly connect the imaging device 110, the terminal device 130, and / or the storage device 150 to access the stored information and / or data. In some embodiments, the processing device 120 can be implemented on a cloud platform. As an example only, the cloud platform can include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, inter-cloud, multi-cloud, etc. or any combination thereof. In some embodiments, the processing device 120 or a part of the processing device 120 can be integrated into the imaging device 110.

[0026] The terminal device 130 can display scan data (e.g., first scan data, revised scan data) to a user. The terminal device 130 can include a mobile device 131, a tablet computer 132, a notebook computer 133, or the like, or any combination thereof. In some embodiments, the terminal device 130 can be part of the processing device 120.

[0027] The network 140 can include any suitable network that facilitates the exchange of information and / or data for the hardening correction system. In some embodiments, one or more components of the hardening correction system (e.g., the imaging device 110, the processing device 120, the storage device 150, the terminal device 130) can communicate information and / or data with one or more other components of the hardening correction system via the network 140. For example, the processing device 120 can obtain reference scan data from the storage device 150 via the network. For another example, the terminal device 130 can obtain scan data from the processing device 120 via the network 140. The network 140 can be and / or include a public network, a private network, a wide area network (WAN), a wired network, a wireless network, a cellular network, a frame relay network, a virtual private network, a satellite network, a telephone network, a router, a hub, a switch, a server computer, and / or any combination thereof. In some embodiments, the network 140 can include one or more network access points. For example, the network 140 can include wired and / or wireless network access points, such as base stations and / or Internet exchange points, through which one or more components of the hardening correction system can connect to the network 140 to exchange data and / or information.

[0028] The storage device 150 can store data, instructions, and / or any other information. In some embodiments, the storage device 150 can store data obtained from the imaging device 110, the terminal device 130, and / or the processing device 120. In some embodiments, the storage device 150 can include a mass storage, a removable storage, a volatile read / write memory, a read-only memory (ROM), or the like, or any combination thereof. In some embodiments, the storage device 150 can be executed on a cloud platform. In some embodiments, the storage device 150 can be connected to the network 140 to communicate with one or more other components of the hardening correction system (e.g., the imaging device 110, the processing device 120, the terminal device 130). One or more components of the hardening correction system can access data or instructions stored in the storage device 150 via the network 140. In some embodiments, the storage device 150 can be directly connected to or in communication with one or more other components of the hardening correction system (e.g., the imaging device 110, the processing device 120, the storage device 150, the terminal device 130). In some embodiments, the storage device 150 can be part of the processing device 120.

[0029] Figure 2is an exemplary block diagram of a hardening correction system according to some embodiments of the present specification.

[0030] In some embodiments, the hardening correction system 200 can comprise a first data acquisition module 210, a second data acquisition module 220, a non-spectral signal acquisition module 230, a correction module, and a correction coefficient determination module.

[0031] The first data acquisition module 210 can be configured to acquire first scan data based on scanning each thickness scan object in the at least one different thickness scan object by the imaging device.

[0032] The second data acquisition module 220 can be configured to set a small slit forming shield in a radiation region of the imaging device, and acquire second scan data of each thickness scan object based on scanning each thickness scan object by the imaging device. In some embodiments, the shield can comprise a shield region and a non-shield region. In some embodiments, the shield region can comprise a material that absorbs a radiation beam. In some embodiments, the non-shield region can form a small slit.

[0033] In some embodiments, the second scan data can be obtained by the imaging device irradiating each thickness scan object after the radiation beam of the imaging device passes through the small slit. In some embodiments, when the shield is set in the radiation region, the small slit can be parallel to the row direction of the detector in the imaging device. In some embodiments, for each thickness scan object, the second data acquisition module 220 can move the small slit to N positions in the channel direction of the detector of the imaging device along the channel direction. In some embodiments, N can be an integer greater than 1. In some embodiments, when the small slit is at each position of the N positions, the second data acquisition module 220 can cause the imaging device to scan each thickness scan object to acquire scan data corresponding to each position. In some embodiments, the shield can comprise N small slits arranged at intervals. In some embodiments, the second data acquisition module 220 can set the shield in the radiation region. In some embodiments, the second data acquisition module 220 can cause the imaging device to scan each thickness scan object to acquire scan data corresponding to the N positions. In some embodiments, the second scan data can comprise scan data at the N positions.

[0034] The non-spectral signal obtaining module 230 can be configured to obtain, based on the first scan data and the second scan data, a non-spectral signal corresponding to each thickness scan object. In some embodiments, the non-spectral signal obtaining module 230 can perform one or more operations of: obtaining, from the first scan data, scan data corresponding to N positions; obtaining, based on the scan data at the N positions in the first scan data and the scan data at the N positions in the second scan data, non-spectral signals at the N positions; and obtaining, based on the non-spectral signals at the N positions, a non-spectral signal corresponding to each thickness scan object within the entire radiation region.

[0035] The correction module 240 can be configured to correct, for each thickness scan object, the first scan data based on the non-spectral signal to obtain corrected scan data. In some embodiments, the correction module 240 can subtract the non-spectral signal from the first scan data to obtain the corrected scan data.

[0036] The correction coefficient determining module 250 can be configured to determine, based on the corrected scan data corresponding to each thickness scan object, a hardening correction coefficient corresponding to the imaging device. In some embodiments, the correction coefficient determining module 250 can determine reference scan data corresponding to each thickness scan object. In some embodiments, the correction coefficient determining module 250 can fit the reference scan data and the corrected scan data corresponding to each thickness scan object to determine the hardening correction coefficient corresponding to the imaging device.

[0037] Figure 3 is an exemplary flowchart of a hardening correction method according to some embodiments of the present specification. As shown in Figure 3 the flowchart 300 includes the following steps:

[0038] At step 310, first scan data is obtained based on scanning, by the imaging device, each thickness scan object in at least one different thickness scan object. Specifically, step 310 can be performed by the first data obtaining module 210.

[0039] As mentioned previously, the imaging device can be a Computed Tomography (CT) device or a multi-modal scanning device including a CT device. In some embodiments, the imaging device can include a radiation source and a detector. Figure 4A is a schematic diagram of an imaging device according to some embodiments of the present specification. As shown in Figure 4AAs shown, the positions of the ray source and the detector remain relatively unchanged, and are synchronously rotated around the rotation axis (parallel to the Z axis of the imaging device or the row direction of the detector) (e.g., point O in the figure). Among them, the tangent direction of the rotation of the detector is the channel direction of the detector (also known as the length direction), and the direction perpendicular to the channel direction in the detector plane is the row direction of the detector (also known as the width direction). In some embodiments, the detector can be composed of multiple detection elements.

[0040] Figure 4B is a schematic diagram of a detector according to some embodiments of the present specification. As shown, the detection elements are configured as multiple columns (such as m = 1000 columns) along the channel direction and multiple rows (such as n = 320 rows) along the row direction. In some embodiments, the detection elements can include but are not limited to gas ionization detectors, scintillator detectors, semiconductor detectors (such as photon counting detectors), etc. Figure 4B

[0041] In some embodiments, the scanning object can include but is not limited to an object, a phantom, etc. In some embodiments, the material of the scanning object can include but is not limited to one of water, plexiglass, and resin, etc. For example, the scanning object can be a water phantom. Different materials correspond to different hardening effects, so in some embodiments, the material of the scanning object can be determined based on the scanning requirements of the application stage.

[0042] In some embodiments, the at least one scanning object with different thicknesses can be multiple independent scanning objects with the same material and different thicknesses. Among them, the direction of the thickness is parallel to the exit direction of the radiation beam or perpendicular to the plane direction of the detector. For example, the multiple scanning objects with different thicknesses can be four water phantoms with thicknesses of 5 cm, 10 cm, 15 cm, and 20 cm, respectively. In some embodiments, the at least one scanning object with different thicknesses can be implemented based on a wedge-shaped scanning object. For example, the scanning object can be a wedge-shaped resin with a thickness of 20 cm on one side and a thickness of 5 cm on the other side, and different positions of the wedge-shaped resin can correspond to different thicknesses of the scanning object between 5 cm and 20 cm.

[0043] The first scanning data can be the original scanning data of the scanning object. In some embodiments, the first scanning data can be represented in a matrix. In some embodiments, the dimension of the first scanning data can be the same as the dimension of the detection elements on the detector. For example, the 1000 x 320 detector in the foregoing Figure 4B can obtain first scanning data with a dimension of 1000 x 320, where each element in the first scanning data can correspond to the scanning data received by a detection element.

[0044] ​In some embodiments, the first scan data can include, but are not limited to, any one of a first energy signal, a first projection value, and a first projection image.

[0045] The first energy signal can be a converted energy spectrum signal based on the attenuated rays passing through the scan object. Specifically, the attenuated rays incident on the detector, and the working medium (such as gas, scintillation crystal, and semiconductor, etc.) in different detection elements of the detector interact with each other, lose energy and produce ionization and / or excitation, and the detector converts the ionization or excitation effect into the first energy signal. In some embodiments, the first energy signal can be represented by a corresponding signal intensity. For example, the radiation beam passes through a water phantom with a thickness of 5 cm, the detector receives the attenuated rays passing through the water phantom, and converts them into the first energy signal I 1 1.

[0046] In some embodiments, different detection elements can receive attenuated rays of the radiation beam passing through different positions of the scan object, and convert them into corresponding energy spectrum signals in the first energy signal. For example, part of the radiation beam passes through position 1 of the water phantom with a thickness of 5 cm, detection element A receives the attenuated rays passing through position 1 of the water phantom, and converts them into the energy spectrum signal I 1 1 in the first energy signal I 1 1-1 Similarly, the first data acquisition module 210 can acquire corresponding signal I 1 1-2 , I 1 1-3 , I 1 1-4 , ….

[0047] The first projection value can be a value representing the degree of attenuation of the radiation beam passing through the scan object, which can be represented by the change in signal intensity before and after the attenuation of the radiation beam. In some embodiments, the first data acquisition module 210 can acquire the corresponding first projection value based on the first energy signal. Specifically, the first data acquisition module 210 can process the first energy signal according to formula (1) to acquire the corresponding first projection value.

[0048]

[0049] Where P1 is the first projection value, I1 is the first energy signal, I0 is the signal corresponding to the radiation beam without attenuation, and β is a constant.

[0050] Continuing the above example, the first data acquisition module 210 can acquire the corresponding first projection value P 1 1 based on the first energy signal I 1 1 of the water phantom with a thickness of 5 cm.

[0051] It can be understood that the smaller the first energy signal is, the greater the degree of attenuation of the radiation beam is, and the greater the first projection value is.

[0052] The first projection image can be an original image of the scanned object. In some embodiments, the first projection image can include, but is not limited to, a Joint Photographic Experts Group (JPEG) image format, a Tagged Image File Format (TIFF) image format, a Graphics Interchange Format (GIF) image format, a Kodak Flash PiX (FPX) image format, and a Digital Imaging and Communications in Medicine (DICOM) image format, etc.

[0053] Specifically, the first data acquisition module 210 can obtain the gray value of the corresponding pixel point based on the first projection value, thereby obtaining the first projection image. In some embodiments, the gray value of the pixel point at different positions in the first projection image can correspond to the detection element at different positions, and therefore, the more the number of detection elements of the detector is, the greater the resolution of the first projection image is.

[0054] Similarly to the 5cm-thick water phantom, the first data acquisition module 210 can obtain the first scanning data of the 10cm, 15cm, and 20cm-thick water phantom, respectively.

[0055] It can be understood that the first energy signal, the first projection value, and the first projection image are different forms of the first scanning data, and can be converted between each other.

[0056] In some embodiments, the first energy signal corresponding to the first scanning data can include a pure energy spectrum signal and a non-energy spectrum signal. The pure energy spectrum signal can be a signal converted by the detector based on the direct multi-color rays after attenuation. The non-energy spectrum signal can be a signal converted by the detector based on scattered rays, defocused rays, or other factors. Accordingly, in some embodiments, the first scanning data not only includes noise caused by the hardening effect, but also includes noise caused by scattered rays, etc. Therefore, it is necessary to further remove the influence of the non-energy spectrum signal in the first scanning data.

[0057] Step 320: setting a shield forming a small gap in the radiation region of the imaging device, and obtaining second scanning data of each thickness of the scanned object based on the imaging device scanning each thickness of the scanned object. Specifically, step 320 can be performed by the second data acquisition module 220.

[0058] The second scan data of each thickness scan object can be scan data corresponding to the pure energy spectrum signals of each thickness scan object at a plurality of positions along the detector row direction.

[0059] In some embodiments, the second scan data can include, but is not limited to, any one of the second energy spectrum signals, the second projection values and the second projection images, in contrast to the first scan data.

[0060] The second energy spectrum signals can be pure energy spectrum signals converted based on the attenuation of the radiation beams passing through the plurality of positions of the scan object.

[0061] The second projection values can be values representing the degree of attenuation of the radiation beams passing through the plurality of positions of the scan object.

[0062] The second projection images can be images of the plurality of positions of the scan object.

[0063] In some embodiments, the second energy spectrum signals, the second projection values and the second projection images can be different forms of the second scan data, and can be converted into each other. Detailed descriptions of the conversion between the second energy spectrum signals, the second projection values and the second scan data can be found in the first scan data, which will not be described herein.

[0064] In some embodiments, the second data acquisition module 220 can set a shield forming a small slit in the radiation region of the imaging device.

[0065] The radiation region of the imaging device can be the irradiation region of the radiation beams emitted by the radiation source. As shown in FIG. 1, the radiation region of the imaging device can include the region between the dashed lines l1 and l2. Figure 4A

[0066] The shield can be an object that blocks at least part of the radiation beams from passing through the scan object.

[0067] In some embodiments, the shield can be disposed in the radiation region, between the radiation source and the scan object.

[0068] In some embodiments, the edge of the shield with the smallest area can be tangent to the edge of the radiation beams. In some embodiments, the smallest area of the shield can be determined based on the distance between the shield and the radiation source and / or the distance between the shield and the detector. Specifically, the ratio of the smallest width and / or the smallest length of the shield to the width and / or the length of the detector can be equal to the ratio of the distance between the shield and the radiation source to the distance between the detector and the radiation source, and the ratio of the smallest area of the shield to the area of the detector can be equal to the square of the ratio of the distance between the shield and the radiation source to the distance between the detector and the radiation source. Exemplarily, as shown in FIG. 2, the smallest area of the shield can be equal to the area of the detector. Figure 4A ​As shown, the blocker 1 is at a distance d1 from the ray source, the detector is at a distance d from the ray source, the length of the detector is L, the width of the detector is W, and the area of the detector is S. The minimum length of the blocker The minimum width The minimum area It can be understood that the closer the blocker is to the ray source and the farther the blocker is to the detector, the smaller the minimum area is; otherwise, the larger the minimum area is. For example, as shown, the minimum area of the blocker 1 closer to the ray source is smaller than the minimum area of the blocker 2 closer to the detector. Figure 4A The minimum area

[0069] In some embodiments, the blocker can include a blocking region and a non-blocking region.

[0070] The blocking region can be a region in the blocker that can prevent the radiation beam from passing through the scanned object. In some embodiments, the blocking region can include a material that absorbs the radiation beam. For example, a lead plate, a tungsten plate, etc. Specifically, when the radiation beam irradiates the blocking region, the blocking region can absorb the radiation beam.

[0071] The non-blocking region can be a region that allows the radiation beam to pass through the scanned object. In some embodiments, the non-blocking region can form a small slit.

[0072] The small slit can be a gap with a certain width. In some embodiments, the width of the small slit can be determined based on the minimum scattering range of the scattered ray. Specifically, the width of the small slit can be smaller than the minimum scattering range. In some embodiments, the second data acquisition module 220 can determine the minimum scattering angle based on the ray source parameters, and determine the minimum scattering range according to the minimum scattering angle and the position of the blocker. For example, the minimum scattering range of the scattered ray is 1 cm, and the width of the small slit can be smaller than 1 cm, such as 0.5 cm.

[0073] In some embodiments, the small slit can be parallel to the row direction of the detector in the imaging device. Figure 5A And Figure 5B are schematic diagrams of moving the small slit on the blocker according to some embodiments of the present specification. As shown in Figure 5A The small slit g0 can be parallel to the row direction.

[0074] Some embodiments of the present specification set the direction of the small slit to be parallel to the row direction of the detector in the imaging device, which can ensure that the hardening effect of each row of detection elements on the detector can be corrected, and improve the accuracy of the hardening correction of the wider detector of the collimator.

[0075] In some embodiments, the shield can include a plurality of baffles. The plurality of baffles can include lead plates, tungsten plates, or the like. The plurality of baffles can be detachably disposed in the shield. The plurality of baffles can be disposed in the shield parallel to the detector row direction. In some embodiments, the slit can be moved by detaching baffles at different positions. In some embodiments, the slit can be moved by moving the baffles to different positions.

[0076] In some embodiments, two shield regions can be disposed on both sides of the radiation beam, each shield region corresponding to a baffle, and the gap between the two shield regions being the slit, which is the non-shield region. As shown in Figure 4A , the shield 1 can include a left shield region and a right shield region, and the slit between the left shield region and the right shield region being the non-shield region of the shield 1.

[0077] In some embodiments, the two shield regions can be fixed by, but not limited to, clamps, threaded connections, and clamping, etc.

[0078] In some embodiments, the size and / or position of the slit can be adjusted by changing the width of the two shield regions. For example, the size and / or position of the slit can be adjusted by replacing the left and / or right lead plates with different widths. For example, continuing with Figure 4A , the minimum area of the shield 1 has a width W min = 10 cm, when the width W f of the left shield region is 1 cm, the width W r of the right shield region is 8.9 cm, the width of the slit is 0.1 cm, and the position is 1 cm away from the left edge of the shield 1; when the width W f of the left shield region is 3 cm, the width W r of the right shield region is 6.9 cm, the width of the slit is 0.1 cm, and the position is 3 cm away from the left edge of the shield 1; when the width W f of the left shield region is 3 cm, the width W r of the right shield region is 5.8 cm, the width of the slit is 0.2 cm, and the position is 3 cm away from the left edge of the shield 1.

[0079] In some embodiments, a shield composed of a plurality of baffles can be disposed in the radiation beam, and the width of each baffle can be equal to the width of the slit. In some embodiments, the plurality of baffles can be spliced together by, but not limited to, clamps, threaded connections, and clamping, etc.

[0080] In some embodiments, the slit can be moved by detaching baffles at different positions. In some embodiments, the baffles that are not detached correspond to the shield region, and each detached baffle corresponds to a slit of the non-shield region. As shown inFigure 4A As shown, the small gap in the obstruction 1 can correspond to a baffle of the same area. After the baffle is removed, the small gap at the current position is formed. Furthermore, the baffle can be fixed to the obstruction 1, and the baffle at another position on the right can be removed, thereby forming a small gap at another position on the right, thus moving the small gap to the right.

[0081] In some embodiments, the width of the obstruction may be greater than the minimum width, such that when the obstruction is moved along the channel direction, the obstruction area can still prevent the radiation beam from passing through the scanned object.

[0082] In some embodiments, the relative positions between the occluded and unoccluded areas can be fixed. For example... Figure 5A As shown, the width of the obstruction 1 is the minimum width W. min Twice the size, or 20cm, the small slits in the unobstructed areas can be fixed in the middle of the obstruction.

[0083] In some embodiments, the position of the slit can be adjusted by moving the obstruction. For example, continuing with... Figure 5A For example, you can first place the right half of the obstruction within the radiation area, so that the small gap in the middle of the obstruction is placed at position 1 of the radiation area; then move the obstruction along the channel direction, placing the left half of the obstruction within the radiation area, so that the small gap in the middle of the obstruction is placed at position 5 of the radiation area.

[0084] Furthermore, in some embodiments, the second data acquisition module 220 can acquire second scan data for each thickness scan object based on the imaging device scanning each thickness scan object.

[0085] In some embodiments, the second scan data can be obtained by illuminating each thickness of the scanned object with a radiation beam from the imaging device after passing through a slit.

[0086] Specifically, when the radiation beam of the imaging device shines on the obstruction, part of the radiation beam is absorbed by the obstruction area, and part of the radiation beam passes through the slit and then shines on the object being scanned. After passing through the object being scanned, the radiation beam is attenuated. The detector can receive the attenuated rays and convert the attenuated rays into second scan data.

[0087] It is understandable that the small slit can limit the incident direction of the radiation beam passing through the obstruction to a small range. The probability of scattered rays in the radiation beam passing through the small slit is extremely low. Therefore, the scattered rays in the radiation beam after passing through the small slit can be basically filtered out, and the second scan data contains almost no noise data caused by scattered rays.

[0088] The hardening effect of the radiation beam varies at different locations; therefore, in some embodiments, the second scan data may include scan data from N locations, where N is an integer greater than 1.

[0089] In some embodiments, for each thickness scanned object, the second data acquisition module 220 can move the slit to N positions along the channel direction of the detector of the imaging device. As mentioned above, the second data acquisition module 220 can move the slit along the channel direction of the detector by changing the width of the left and right side blocking areas, or by moving the blocking objects along the channel direction of the detector. Figure 5A As shown, the second data acquisition module 220 can move the small slit g0 along the channel direction of the detector to position 1, position 2, position 3, position 4 and position 5 respectively.

[0090] In some embodiments, when the slit is in each of the N positions, the second data acquisition module 220 can enable the imaging device to scan each thickness of the scanned object to obtain the scan data corresponding to each position.

[0091] For example, continue with Figure 5A For example, the second data acquisition module 220 can acquire the second scan data corresponding to the attenuated rays passing through the 5cm water phantom after the radiation beam passes through the five positions: scan data 2-1, scan data 2-2, scan data 2-3, scan data 2-4, and scan data 2-5. Similarly, the second data acquisition module 220 can acquire the second scan data corresponding to the attenuated rays passing through the 10cm, 15cm, and 20cm water phantoms, respectively.

[0092] Some embodiments in this specification form a small slit in the obstruction, making the probability of scattered rays passing through the slit extremely low, thereby enabling the acquisition of pure energy spectrum signals using the small slit in a flexible and simple manner.

[0093] In some embodiments, for each thickness scan object, the slit can be moved along the channel direction of the detector by a certain width (e.g., the slit width) as the moving distance, and the second scan data corresponding to each thickness scan object can be obtained.

[0094] like Figure 5B As shown, the width (i.e., minimum width) of the obstruction within the radiation area is 5 cm, and the width of the slit is 0.1 cm. The second data acquisition module 220 can move the slit along the detector's channel direction, with each movement being 0.1 cm, to 50 positions (N=50) of the obstruction within the radiation area. It then acquires the second scan data corresponding to the attenuated rays passing through the 5 cm water phantom after passing through each of these 50 positions: scan data 2-1, scan data 2-2, scan data 2-3, scan data 2-4…scan data 2-50. Similarly, the second data acquisition module 220 can acquire the second scan data corresponding to the attenuated rays passing through the 10 cm, 15 cm, and 20 cm water phantoms, respectively.

[0095] In some embodiments, the shield can include N small slits arranged at intervals.

[0096] The number of small slits is increased, and the probability of scattered rays passing through the small slits is increased. Figure 6 is a schematic diagram of arranging N small slits on a shield according to some embodiments of the present specification. For example, as shown in Figure 6 , positions 1, 2 and 3 on the shield are respectively provided with small slits g1, g2 and g3, and the scattered rays (not shown) that cannot pass through the small slit g1 can pass through the small slit g2. Therefore, in some embodiments, in order to avoid scattered rays that can pass through the small slit, the interval between the N small slits can be determined based on the maximum scattering range of the scattered rays. In some embodiments, the second data acquisition module 220 can set the interval between the N small slits to be greater than the maximum scattering range. It can be understood that when the interval between the N small slits is greater than the maximum scattering range, even if the number of small slits is increased, the probability of scattered rays passing through the small slits can remain extremely low. Continuing with Figure 6 , the scattering range of the scattered rays that cannot pass through the small slit g1 must be less than the interval between positions 1 and 2, and therefore, the scattered rays must be reflected by the shielding area between positions 1 and 2 and cannot pass through the small slit g2.

[0097] In some embodiments, the relative positions between the N small slits and the non-shielded area can be fixed. As shown in Figure 6 , the small slit g1, the small slit g2 and the small slit g3 can be respectively fixedly arranged at positions 1, 2 and 3.

[0098] In some embodiments, the second data acquisition module 220 can arrange the shield in the radiation area. As shown in Figure 6 , the shield can be arranged entirely in the radiation area, and the width of the shield is the minimum width.

[0099] In some embodiments, the second data acquisition module 220 can cause the imaging device to scan each thickness scanning object to obtain scanning data corresponding to N positions. For example, continuing with Figure 6 , the second data acquisition module 220 can obtain the second scanning data corresponding to the attenuated rays passing through the 5cm water phantom after the radiation beam respectively passes through the small slit g1, the small slit g2 and the small slit g3: scanning data 2-1, scanning data 2-2 and scanning data 2-3. Similarly, the second data acquisition module 220 can respectively obtain the second scanning data corresponding to the attenuated rays passing through the 10cm water phantom, the 15cm water phantom and the 20cm water phantom.

[0100] As described above, the width of the shield can be greater than the minimum width, so that the non-shielded area can still shield the radiation beam from passing through the scanning object when the shield is moved along the channel direction. In some embodiments, when the scattering range is small, the spacing between the N small slits is relatively wide compared to the scattering range, resulting in a small number of small slits. The shield can be moved along the channel direction of the detector to obtain more scanning data corresponding to different positions. As shown in FIG. 7B, the width of the shield can be increased by d Figure 6 to the left. y After obtaining the scanning data at positions 1, 2 and 3, the shield is moved along the channel direction of the detector by a distance d y so that the small slit g1 and the small slit g2 are moved from positions 1 and 2 to positions 4 and 5, respectively, to obtain the scanning data at positions 4 and 5: scanning data 2-4 and scanning data 2-5.

[0101] In some embodiments, the scanning data at each position in the second scanning data can be represented by a matrix. In some embodiments, the dimension of the scanning data at each position in the second scanning data can be the same as the dimension of the detection element corresponding to the position. For detailed description of the detection element corresponding to each position, please refer to step 710 and its related description, which will not be repeated here. For example, as shown in FIG. 8B, the detection element corresponding to the current position of the small slit on the shield 1 is the detection element within the dashed line range of ab width on the detector, and the dimension of the detection element within the range is 20x320, so the dimension of the scanning data at the position in the second scanning data is 20x320. Figure 4B

[0102] Some embodiments of the present specification utilize multiple small slits to collect pure energy spectrum signals, and determine the spacing between the multiple small slits based on the scattering range. The efficiency of collecting pure energy spectrum signals can be improved while ensuring that the small slits collect pure energy spectrum signals, thereby improving the efficiency of the entire hardening correction.

[0103] Step 330: based on the first scanning data and the second scanning data, obtaining the non-spectral signal corresponding to each thickness of the scanning object. Specifically, step 330 can be performed by the non-spectral signal acquisition module 230.

[0104] In some embodiments, for each thickness of the scanning object, the non-spectral signal acquisition module 230 can obtain the non-spectral signal at N positions based on the first scanning data and the second scanning data, and then obtain the non-spectral signal of the scanning object corresponding to the entire radiation region based on the non-spectral signal at the N positions.

[0105] For detailed description of obtaining the non-spectral signal corresponding to each thickness of the scanning object, please refer to Figure 7 and its detailed description, which will not be repeated here.

[0106] ​At step 340, for each thickness scanning object, the first scanning data is corrected based on the non-spectral signal to obtain corrected scanning data. Specifically, step 340 can be performed by the correction module 240.

[0107] The corrected scanning data can be scanning data without interference of the non-spectral signal. Corresponding to the first scanning data and the second scanning data, in some embodiments, the corrected scanning data can include, but is not limited to, any one of the spectral signal, the projection value and the projection image.

[0108] Similarly to the non-spectral signal and the first scanning data corresponding to each thickness scanning object, in some embodiments, the corrected scanning data can be represented by a matrix, and the dimension of the matrix can be the same as the dimension of the detection element.

[0109] In some embodiments, the correction module 240 can subtract the non-spectral signal from the first scanning data to obtain the corrected scanning data.

[0110] In some embodiments, the first scanning data can be the first energy signal. As described before, further, the correction module 240 can subtract the element at the corresponding position in the non-spectral signal from each element in the first energy signal, so as to obtain the corrected scanning data in the form of the spectral signal. For example, the first energy signal I 1 1 corresponding to the 5cm-thickness water phantom is subtracted by the non-spectral signal I 1 3 corresponding to the 5cm-thickness water phantom, to obtain the corrected scanning data in the form of the spectral signal I 1 4 corresponding to the 5cm-thickness water phantom.

[0111] In some embodiments, the correction module 240 can convert the corrected scanning data in the form of the spectral signal into forms such as the projection value and the projection image. The conversion between the forms of the corrected scanning data can be referred to the relevant description of step 310, which will not be described here again.

[0112] Similarly, the correction module 240 can obtain the corrected scanning data corresponding to the 10cm-thickness water phantom, the 15cm-thickness water phantom and the 20cm-thickness water phantom, for example, I 2 4, I 3 4 and I 4 4.

[0113] In some embodiments, the corrected scanning data can be a corrected scanning data curve (or function) with thickness as the independent variable. In some embodiments, the correction module 240 can fit to obtain the corrected scanning data curve (or function) based on the corrected scanning data corresponding to at least one thickness scanning object.

[0114] At step 350, the hardening correction coefficient corresponding to the imaging device is determined based on the modified scan data corresponding to each thickness scan object. Specifically, step 350 can be performed by the correction coefficient determination module 250.

[0115] The hardening correction coefficient can be data used to correct the hardening effect of the imaging device. In some embodiments, the hardening correction coefficient can represent the relationship between the reference scan data (i.e., theoretical data) and the corresponding modified scan data (i.e., measured data) of different thickness scan objects of the same material.

[0116] The reference scan data can be the calculated scan data based on the assumption that there is no interference such as scattered radiation and hardening effect. Similar to the modified scan data, in some embodiments, the reference scan data can include, but is not limited to, any one of the energy spectrum signal, the projection value, and the projection image.

[0117] In some embodiments, the correction coefficient determination module 250 can determine the reference scan data corresponding to different thickness scan objects. In some embodiments, the correction coefficient determination module 250 can obtain the reference CT value according to formula (2) based on the absorption coefficient of the material of the scan object.

[0118]

[0119] wherein CT r is the reference CT value, μ r is the absorption coefficient of the material of the scan object, μ w is the absorption coefficient of water, μ w = 1, and K is the graduation factor, K = 1000.

[0120] It can be understood that when there is no scattered radiation and hardening effect in the radiation beam, the attenuation of the radiation beam passing through the scan object of the uniform material in the ideal state is due to the absorption of the scan object material to the radiation beam, so the attenuation coefficient of the radiation beam should be equal to the absorption coefficient of the material of the scan object.

[0121] For example, the correction coefficient determination module 250 can calculate the reference CT value CT r = 0 of the water phantom based on the absorption coefficient of water.

[0122] In some embodiments, the correction coefficient determination module 250 can convert the reference CT value into the reference scan data in the form of the reference energy spectrum signal, the reference projection value, and the reference projection image based on the thickness of the scan object. The detailed description of obtaining the energy spectrum signal, the projection value, and the projection image based on the CT value can be referred to the related description of step 310, which will not be described here.

[0123] For example, the correction coefficient determination module 250 can obtain the reference scan data corresponding to the 5cm-thickness water phantom, such as the reference energy spectrum signal I 1 r Similarly, the correction coefficient determination module 250 can obtain the reference scan data corresponding to the 10cm-thickness water phantom, 15cm-thickness water phantom and 20cm-thickness water phantom, such as the reference energy spectrum signals I 2 r , I 3 r and I 4 r .

[0124] Corresponding to the modified scan data, in some embodiments, the reference scan data can be represented by a matrix, and the dimension of the matrix can be the same as the dimension of the detection element.

[0125] Corresponding to the modified scan data curve (or function), in some embodiments, the reference scan data can be a reference scan data curve (or function) with thickness as the independent variable. In some embodiments, the correction coefficient determination module 250 can obtain the reference scan data curve (or function) based on the calculation formula of the reference scan data.

[0126] It can be understood that when the imaging device scans a scan object with non-uniform thickness (for example, the liver of patient A), since the thickness of the scan object is unknown, the reference scan data cannot be calculated based on the thickness of the scan object, and therefore, the corresponding reference scan data needs to be obtained based on the modified scan data according to the hardening correction coefficient.

[0127] Further, in some embodiments, the correction coefficient determination module 250 can fit the reference scan data and the modified scan data corresponding to each thickness scan object to determine the hardening correction coefficient corresponding to the imaging device.

[0128] In some embodiments, the hardening correction coefficient can be determined based on the fitted hardening correction function.

[0129] The hardening correction function can be a function that maps the modified scan data to the reference scan data. For example, the hardening correction function y = f(x) can map the modified scan data: x = I x to the reference scan data: I y In some embodiments, the correction coefficient determination module 250 can obtain the hardening correction function by a polynomial linear fitting method. Specifically, the correction coefficient determination module 250 can establish an n-order polynomial, and then obtain n coefficients corresponding to the n-order polynomial based on the reference scan data and the modified scan data corresponding to scan objects with different thicknesses.

[0130] For example, the correction coefficient determination module 250 can first establish a second order polynomial y=ax+bx 2 +c, and then based on the correction scan data x1=I 1 4 corresponding to the 5cm-thickness water phantom and the reference scan data y1=I 1 r , the correction scan data x2=I 2 4 corresponding to the 10cm-thickness water phantom and the reference scan data y2=I 2 r , the correction scan data x3=I 3 4 corresponding to the 15cm-thickness water phantom and the reference scan data y3=I 3 r , the correction scan data x4=I 4 4 corresponding to the 20cm-thickness water phantom and the reference scan data y4=I 4 r , and obtain the coefficients a, b and c, so as to obtain the hardening correction function.

[0131] In some embodiments, the value of n can be determined based on the fitting error corresponding to different polynomials. Specifically, the correction coefficient determination module 250 can establish a first order polynomial, a second order polynomial and a third order polynomial respectively, and based on the reference scan data and the correction scan data corresponding to the scanning objects with different thicknesses, solve different polynomial coefficients, and take the polynomial corresponding to the minimum error as the hardening correction function.

[0132] As described above, the correction scan data and the reference scan data can be curves (or functions) with thickness as the independent variable. In some embodiments, the correction coefficient determination module 250 can obtain the hardening correction function mapping the correction scan data curve (or function) to the reference scan data curve (or function) based on the same “thickness” independent variable by using formula transformation, and further obtain the hardening correction coefficient. For example, the correction coefficient determination module 250 can first fit the correction scan function x=f1(d) with the thickness of the scanning object as the independent variable based on the correction scan data, fit the reference scan function y=f2(d) with the thickness of the scanning object as the independent variable based on the reference scan data, and then obtain the hardening correction function y=F(x) based on the correction scan function x=f1(d) and the reference scan function y=f2(d), such as y=ax+bx 2 +c, so as to determine the hardening correction coefficients a, b and c.

[0133] As mentioned above, the modified scan data and the reference scan data can be represented by matrices, the dimensions of which can be the same as the dimensions of the detection elements, i.e. each detection element corresponds to an element in the modified scan data and an element in the reference scan data. For example, the coefficients a, b and c are also matrices with the same dimensions as the detection elements, each element in the 3 matrices contains 3 coefficients of the 3-term polynomial corresponding to each detection element. For another example, the coefficients a, b and c can form a matrix, each element in the matrix can correspond to a detection element i, containing 3 coefficients of the 3-term polynomial corresponding to the detection element i. i i i

[0134] In some embodiments, the hardening correction coefficients can be determined based on a trained hardening correction model.

[0135] The hardening correction model can be a model for obtaining the reference scan data based on the input modified scan data. In some embodiments, the hardening correction model can be a machine learning model.

[0136] In some embodiments, the hardening correction model can be trained based on a large number of training sample sets with labels. For example, the training sample sets with labels are input into an initial hardening correction model M1, the parameters of the initial hardening correction model M1 are updated through training until a preset condition is met, and a trained hardening correction model M2 is obtained.

[0137] In some embodiments, the training sample sets can include modified scan data of different thicknesses. For example, the training sample sets can include: training sample 1

modified scan data I14 corresponding to a 5cm-thick water phantom

modified scan data I24 corresponding to a 10cm-thick water phantom

modified scan data I34 corresponding to a 15cm-thick water phantom

modified scan data I44 corresponding to a 20cm-thick water phantom

[0138] In some embodiments, the labels can include reference scan data corresponding to the thickness. For example, the labels corresponding to the training samples can include: label 1

reference scan data I1r corresponding to a 5cm-thick water phantom

reference scan data I2r corresponding to a 10cm-thick water phantom

reference scan data I3r corresponding to a 15cm-thick water phantom

reference scan data I4r corresponding to a 20cm-thick water phantom

[0139] In some embodiments, the hardening correction model can include, but is not limited to, one or more combinations of a feedforward neural network model, a deep neural network model, a convolutional neural network model, and the like.

[0140] ​​​Further, in some embodiments, the correction coefficient determination module 250 can take the parameters of the trained hardening correction model as the hardening correction coefficients.

[0141] Figure 7 is an exemplary flowchart of acquiring non-spectral signals corresponding to each thickness scanning object in the entire radiation region according to some embodiments of the present specification. Specifically, Figure 7 may be performed by the non-spectral signal acquisition module 230. As Figure 7 indicated, the flow 700 includes the following steps:

[0142] Step 710, acquiring scanning data corresponding to N positions from the first scanning data.

[0143] As described before, the detector can be composed of a plurality of detection elements, and different detection elements can receive attenuated rays of the radiation beam passing through the tomography of different positions of the scanning object and convert them into corresponding spectral signals (or scanning data) in the first energy signal (or first scanning data). Therefore, the first scanning data can include scanning data acquired by different detection elements corresponding to different positions.

[0144] In some embodiments, the non-spectral signal acquisition module 230 can determine the detection elements for acquiring scanning data corresponding to N positions based on the N positions. Specifically, for each position, the non-spectral signal acquisition module 230 can determine the irradiation range of the radiation beam passing through the corresponding position on the detector based on the intersection of the line connecting the radiation source and the small slit edge and the detector, so as to determine the detection elements for acquiring scanning data of the corresponding position. For example, as Figure 4A indicated, the non-spectral signal acquisition module 230 can determine the width range ab of the irradiation of the radiation beam passing through the small slit of the current position on the detector based on the lines l3 and l4 connecting the radiation source and the small slit edge on the blocker 1, as Figure 4B indicated, the non-spectral signal acquisition module 230 determines the detection elements in the corresponding dashed line range based on the width range ab.

[0145] In some embodiments, the non-spectral signal acquisition module 230 can acquire scanning data corresponding to each position based on the projection elements corresponding to each position. Continuing with Figure 4B as an example, the non-spectral signal acquisition module 230 can filter out the scanning data acquired by the detection elements in the ab range from the first scanning data acquired by all elements of the detector, as the scanning data corresponding to the current position of the small slit on the blocker 1.

[0146] In some embodiments, the scanning data under each position in the first scanning data can be represented by a matrix. In some embodiments, the dimension of the scanning data under each position in the first scanning data can be the same as that of the detection elements corresponding to the position. For example, asFigure 4B As shown, the detector element corresponding to the current position of the small gap of the shield 1 is within the dashed line range of the ab width on the detector, and the dimension of the detector element within the range is 20x320. Therefore, the dimension of the scanning data at the position in the first scanning data is 20x320.

[0147] Similarly, the non-spectral signal acquisition module 230 can acquire the scanning data corresponding to the 5 positions of the 5cm-thick water phantom from the first scanning data. For example, continuing with the example in the foregoing Figure 5A For example, the non-spectral signal acquisition module 230 can acquire the scanning data passing through the position 1, the position 2, the position 3, the position 4 and the position 5 in the first scanning data: the scanning data 1-1, the scanning data 1-2, the scanning data 1-3, the scanning data 1-4 and the scanning data 1-5.

[0148] Further, the non-spectral signal acquisition module 230 can acquire the scanning data corresponding to the 5 positions of the 10cm-thick water phantom from the first scanning data corresponding to the 10cm-thick water phantom, the scanning data corresponding to the 5 positions of the 15cm-thick water phantom from the first scanning data corresponding to the 15cm-thick water phantom, and the scanning data corresponding to the 5 positions of the 20cm-thick water phantom from the first scanning data corresponding to the 20cm-thick water phantom.

[0149] Corresponding to the first scanning data, in some embodiments, the scanning data in the first scanning data can include, but is not limited to, any one of the first energy signal, the first projection value and the first projection image.

[0150] Step 720, based on the scanning data at the N positions in the first scanning data and the scanning data at the N positions in the second scanning data, obtaining the non-spectral signal at the N positions.

[0151] The non-spectral signal at the N positions can be the signal generated by the scattering radiation and other interference at the N positions.

[0152] It can be understood that the scanning data corresponding to the N positions in the first scanning data and the scanning data at the N positions in the second scanning data correspond to the same radiation, the scanning object position and the detector element respectively. Therefore, in some embodiments, the dimension of the scanning data corresponding to each position in the first scanning data and the scanning data in the second scanning data is the same. For example, the scanning data in the first scanning data and the scanning data in the second scanning data corresponding to the current position of the small gap of the shield 1 in the foregoing Figure 4A

[0153] ​In some embodiments, the non-spectral signal acquisition module 230 can first convert the scan data corresponding to N positions in the first scan data and the scan data corresponding to N positions in the second scan data into the form of energy spectrum signals and pure energy spectrum signals, respectively. Then, it can subtract the corresponding pure energy spectrum signals corresponding to N positions in the second scan data from the energy spectrum signals corresponding to N positions in the first scan data to obtain the non-spectral signals corresponding to N positions.

[0154] For example, if the first scan data is a first energy signal and the second scan data is a second energy spectrum signal, then the scan data corresponding to N positions in the first scan data is directly in the form of an energy spectrum signal, and the scan data corresponding to N positions in the second scan data is directly in the form of a pure energy spectrum signal.

[0155] In another example, if the first scan data is a first projection value and the second scan data is a second projection value, then the scan data corresponding to N positions in the first scan data and the scan data corresponding to N positions in the second scan data are both in the form of projection values. The non-spectral signal acquisition module 230 can convert the scan data corresponding to N positions in the first scan data and the scan data corresponding to N positions in the second scan data into the form of energy spectrum signals and pure energy spectrum signals respectively based on formula (1).

[0156] For another example, if the first scan data is a first projected image and the second scan data is a second scan data, then the scan data corresponding to N positions in the first scan data and the scan data corresponding to N positions in the second scan data are both in the form of projected images. The non-spectral signal acquisition module 230 can first convert the pixel values ​​of the projected image into CT values, then convert the CT values ​​into attenuation coefficients, and then convert them into projection values ​​based on the thickness of the scanned object. Then, based on formula (1), the scan data corresponding to N positions in the first scan data and the scan data corresponding to N positions in the second scan data are respectively converted into spectral signals and pure spectral signals.

[0157] For a detailed description of the format conversion of the scanned data, please refer to step 310 and its related description, which will not be repeated here.

[0158] For example, with Figure 5A For example, the non-spectral signal acquisition module 230 can convert the scan data corresponding to 5 positions in the first scan data of a 5cm thick water model—scan data 1-1, scan data 1-2, scan data 1-3, scan data 1-4, and scan data 1-5—into spectral signals: I 1 1-1 I 1 1-2 I 1 1-3 I 11-4 and I 1 1-5 The scan data from five locations in the second scan of the 5cm thick water phantom—scan data 2-1, scan data 2-2, scan data 2-3, scan data 2-4, and scan data 2-5—were converted into pure energy spectrum signals: I 1 2-1 I 1 2-2 I 1 2-3 I 1 2-4 and I 1 2-5 Then, non-spectral signals were obtained at five locations corresponding to a 5cm thick water model: I 1 3-1 I 1 3-2 I 1 3-3 I 1 3-4 and I 1 3-5 .

[0159] For example, with Figure 5B For example, similarly, the non-spectral signal acquisition module 230 can acquire non-spectral signals at 50 locations corresponding to a 5cm thick water model: I 1 3-1 I 1 3-2 ,…..and I 1 3-50 .

[0160] In some embodiments, the non-spectral signal can be represented by a matrix. In some embodiments, the dimension of the non-spectral signal at each location can be the same as the dimension of the detector element corresponding to that location. Continuing with the example above, Figure 4A The dimension of the non-spectral signal corresponding to the current position of the small slit on the middle obstruction 1 can be 20×320.

[0161] Step 730: Based on the non-spectral signals at N locations, obtain the non-spectral signal corresponding to each thickness scan object in the entire radiation region.

[0162] The non-spectral signal corresponding to the scanned object within the entire radiation area can be a signal generated by interference such as scattered rays from the radiation beam passing through all parts of the scanned object. As described above, in some embodiments, the non-spectral signal at each location on the obstruction within the radiation area can correspond to a portion of the scanned object. For example, with... Figure 4AFor example, the non-spectral signal at the current position of the small slit in the obstruction 1 can correspond to the shadow portion of the water model. Similarly, the non-spectral signals at N positions can correspond to N parts of the scanned object. Therefore, in some embodiments, the non-spectral signal corresponding to the scanned object is the non-spectral signal at all positions on the obstruction.

[0163] In some embodiments, the dimension of the non-spectral signal corresponding to the scanned object can be the same as the dimension of the detection element on the detector. For example, as described above. Figure 4B If the dimension of the detection element is 1000×320, then the dimension of the non-spectral signal corresponding to the scanned object is 1000×320.

[0164] In some embodiments, the non-spectral signal acquisition module 230 can acquire non-spectral signals at all locations on the obstruction within the radiation area based on non-spectral signals at N locations, thereby acquiring the non-spectral signal corresponding to each thickness scanning object. In some embodiments, the form of the non-spectral signal corresponding to each thickness scanning object may include, but is not limited to, function graphs, functional relationships, and matrices.

[0165] In some embodiments, the non-spectral signal acquisition module 230 can fit the non-spectral signals at all locations within the radiation region based on the non-spectral signals at N locations.

[0166] Specifically, the non-spectral signal acquisition module 230 can take the center position of the obstruction in the radiation area as the origin O, the channel direction as the X-axis, and the row direction as the Y-axis to acquire the coordinates of each point at one of the N positions. Each point can correspond to a detection element on the detector. Based on the coordinates of the points at the N positions and the intensity value of the non-spectral signal corresponding to each coordinate, the module can fit and obtain the non-spectral signal intensity surface corresponding to all points on the plane of the obstruction in the radiation area, i.e., a function graph. For example, the non-spectral signal acquisition module 230 can acquire the five non-spectral signals I corresponding to a 5cm thick water model. 1 3-1 I 1 3-2 I 1 3-3 I 1 3-4 and I 1 3-5 The corresponding 5×20×320=3200 points are used to fit a non-spectral signal intensity surface consisting of 50×20×320=32000 points.

[0167] In some embodiments, the non-spectral signal acquisition module 230 can acquire the position coordinates on the obstruction and the functional relationship between the non-spectral signal and the non-spectral signal based on the non-spectral signal intensity surface.

[0168] In some embodiments, the non-spectral signal obtaining module 230 can interpolate the non-spectral signals at the N positions, obtain the non-spectral signals at the positions to be interpolated, and thus obtain the non-spectral signals at all positions of the occlusion in the radiation region. For example, as described above, the width (i.e., the minimum width) of the occlusion in the radiation region is 5 cm, and the width of the small gap is 0.1 cm, so the occlusion in the radiation region can correspond to 50 positions, and the non-spectral signal obtaining module 230 can interpolate the non-spectral signals at N (e.g., 10) positions, obtain the non-spectral signals at the remaining 40 positions, and thus obtain the non-spectral signals at all positions of the occlusion corresponding to the 5 cm thick water phantom in the radiation region.

[0169] In some embodiments, the interpolation can include, but is not limited to, at least one of a nearest neighbor interpolation, a quadratic interpolation, a cubic interpolation, and other adaptive interpolation algorithms. In some embodiments, the non-spectral signal obtaining module 230 can select at least one position adjacent to the position to be interpolated from the N positions based on different interpolation algorithms.

[0170] For example, the non-spectral signal obtaining module 230 can select the non-spectral signal at the position adjacent to the position to be interpolated from the N positions based on the nearest neighbor interpolation algorithm. For example, in the example of Figure 6 For example, the position adjacent to the position to be interpolated P1 from the positions 1-5 is position 4, and the non-spectral signal at position 4 can be selected as the non-spectral signal at the position to be interpolated P1.

[0171] For another example, the non-spectral signal obtaining module 230 can select the leftmost and rightmost positions adjacent to the position to be interpolated from the N positions based on the quadratic interpolation algorithm, and further obtain the average of the non-spectral signals at the leftmost and rightmost positions as the non-spectral signal at the position to be detected. For example, in the example of Figure 6 For example, the leftmost and rightmost positions adjacent to the position to be interpolated P1 from the positions 1-5 are positions 4 and 2, respectively, and the average of the non-spectral signals at positions 2 and 4 can be selected as the non-spectral signal at the position to be interpolated P1.

[0172] As described above, the N positions of the occlusion in the radiation region can include all positions of the occlusion in the radiation region, and the non-spectral signals at the N positions can be the non-spectral signals at the positions of the occlusion in the radiation region.

[0173] For example, as described above, the N positions of the occlusion in the radiation region can include all positions of the occlusion in the radiation region, and the non-spectral signals at the N positions can be the non-spectral signals at the positions of the occlusion in the radiation region. Figure 5BAs shown, the 50 locations of the obstruction within the radiation area represent all locations of the obstruction within the radiation area. Therefore, the non-spectral signals at these 50 locations represent the non-spectral signals under the obstruction within the radiation area. For example, the non-spectral signals corresponding to a 5cm thick water phantom at 50 locations on the obstruction within the radiation area may include: I 1 3-1 I 1 3-2 ,…..and I 1 3-50 .

[0174] Some embodiments of this specification can directly move the slit to all positions of the shielding object within the radiation area, thereby eliminating the need for fitting or interpolation and directly obtaining the non-spectral signal corresponding to the scanned object. This improves the accuracy of the non-spectral signal corresponding to the scanned object, and thus improves the accuracy of hardening correction.

[0175] In some embodiments, the non-spectral signal acquisition module 230 can directly stitch together the non-spectral signals at all locations on the obstruction within the radiation area to obtain the non-spectral signal corresponding to the scanned object. For example, it can obtain the non-spectral signals I corresponding to a 5cm thick water phantom at 50 locations on the obstruction within the radiation area. 1 3-1 I 1 3-2 ,…..and I 1 3-50 By splicing the images, the non-spectral signal I corresponding to a 5cm thick water model was obtained. 1 3 = [I 1 3-1 I 1 3-2 , ..., I 1 3-50 Similarly, the non-spectral signal acquisition module 230 can acquire the non-spectral signals corresponding to water models with a thickness of 10 cm, 15 cm, and 20 cm, respectively: I 2 3. I 3 3 and I 4 3.

[0176] Some embodiments of this specification utilize pure energy spectrum signals at N locations and corresponding projection data in the first projection data to obtain non-energy spectrum signals at N locations. Then, the non-energy spectrum signals at N locations are used to obtain the non-energy spectrum signal corresponding to the scanned object in the entire radiation area. By utilizing the relationship between non-energy spectrum signals, pure energy spectrum signals, and the first projection data, non-pure energy spectrum signals can be obtained without obtaining the scattering kernel, thus reducing computational complexity and improving computational efficiency.

[0177] The beneficial effects that the embodiments of the present specification can bring include but are not limited to: (1) the relationship of the non-spectrum signal, the pure spectrum signal and the first projection data is utilized to obtain the non-pure spectrum signal, without obtaining the scattered nucleus, the complexity of the calculation is reduced, and the calculation efficiency is improved; (2) a small gap is formed on the shield, so that the probability of the scattered ray penetrating through the small gap is extremely low, thereby realizing the acquisition of the pure spectrum signal by the small gap, and the small gap is formed on the shield, so that the probability of the scattered ray penetrating through the small gap is extremely low, thereby realizing the acquisition of the pure spectrum signal by the small gap; (3) the direction of the small gap is set to be parallel to the row direction of the detector in the imaging device, so as to ensure that the hardening effect of each row of detection elements on the detector can be corrected, and the accuracy of the hardening correction of the wider detector of the collimator is improved; (4) the setting mode of the plurality of small gaps can select the number of small gaps formed and the mode of moving the small gap according to different requirements of efficiency, accuracy and the like, and the application range of the hardening correction is improved. It should be noted that different embodiments can have different beneficial effects, and in different embodiments, the beneficial effects that can be produced can be any one or a combination of the above, or any other beneficial effects that can be obtained.

[0178] The above detailed description has described only a few implementations of the present specification and alternative examples of the present specification are equally possible. Although the above detailed description has described certain examples, many modifications, alternative constructions, combinations, sub-combinations, and equivalents can exist. While the above detailed description has described certain examples, it should be apparent that certain features, structures, or characteristics described above in connection with one example can be applied to other examples without departing from the spirit and scope of the specification. Thus, the benefits of the present specification are not limited to those explicitly described herein but include additional benefits made apparent to those skilled in the art in the context of the specification.

[0179] Also, the present specification has used specific terms in describing the embodiments of the present specification. As "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic in connection with at least one embodiment of the present specification. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" or "an alternative embodiment" mentioned in different places in the present specification does not necessarily refer to the same embodiment. In addition, some features, structures, or characteristics in one or more embodiments of the present specification can be properly combined.

[0180] Furthermore, the order of the processing elements and sequences described in this specification are not intended to be construed as a limitation, unless specifically stated, but are included to provide a complete description of one or more embodiments of the present specification. Regardless of the particular sequence of processing elements and sequences, however, the description herein of a process should be understood to include any and all combinations of one or more elements of a process independently selected from each sequence. For example, although the system components described above can be implemented by hardware devices, they can also be implemented by software solutions, such as installing the described system on an existing server or mobile device.

[0181] Similarly, it is to be noticed that the term "comprising", used in the description, is not intended to exclude other elements or steps. It is to be understood that the description and the examples are intended to be illustrative, but not limiting, of the scope of the present specification. Thus, the scope of the present specification should be given by the appended claims, along with their full scope of equivalents, and not by an restricting interpretation of the description or the examples.

[0182] Some embodiments use numerical designations to describe components, quantities of attributes. It is to be understood that such numerical designations used in the description of embodiments are, in some examples, modified by the adjectives "about", "approximately", or "generally". Unless otherwise stated, "about", "approximately", or "generally" indicates that the stated numerical value is allowed ±20% variation. Accordingly, in some embodiments, numerical parameters in the description and claims are approximations, and are intended to be construed in a liberal manner, based on the knowledge that individual embodiments can have different requirements. In some embodiments, numerical parameters are provided as approximations, and are not to be construed in a limiting sense. Although numerical ranges and parameters setting forth the broadest scope of the embodiments are approximations, in some embodiments, the numerical values set forth in the specific examples are reported as precisely as practicable. The application scope is not intended to be limited to numerical ranges and parameters set forth in the specification and embodiments described.

[0183] Each patent, patent application, publication, and other material cited in this specification is incorporated herein by reference in its entirety for the teachings relevant to the sentence and / or paragraph in which the reference is presented. Document histories, to the extent not inconsistent with this specification, are excluded to the extent that they are inconsistent or contradictory with the content of this specification, to the extent that they limit the broadest scope of the claims of this specification, and to the extent that they are added to this specification after the date of this specification. It is specifically noted that, to the extent that the description, definitions, and / or terminology used in the materials attached to this specification differ from the description, definitions, and / or terminology used in this specification, the description, definitions, and / or terminology used in this specification control.

[0184] Finally, it should be understood that the embodiments described herein are only given by way of example and that other modifications can occur to persons skilled in the art. Therefore, the scope of the present description is not intended to be limited to the embodiments described herein but is only limited by the claims that follow.

Claims

1. A hardening correction method, comprising: First scan data is obtained by scanning each of at least one scanned object of different thicknesses using an imaging device; A slit-shaped shield is placed in the radiation area of ​​the imaging device, and second scan data of each thickness of the scanned object is obtained based on the scanning of the imaging device; the shield is placed between the radiation source and the scanned object. Based on the first scan data and the second scan data, obtain the non-spectral signal corresponding to each thickness scan object; For each thickness scanned object, the first scan data is corrected based on the non-energy spectrum signal to obtain corrected scan data; Based on the corrected scan data corresponding to each thickness scan object, a hardening correction coefficient corresponding to the imaging device is determined. The hardening correction coefficient is used to correct the hardening effect of at least one detection element on the detector of the imaging device.

2. The method as described in claim 1, characterized in that, The second scan data is obtained by irradiating the scanned object of each thickness after the radiation beam of the imaging device passes through the slit.

3. The method as described in claim 2, characterized in that, When the obstruction is placed in the radiation area, the slit is parallel to the array direction of the detector in the imaging device.

4. The method as described in claim 3, characterized in that, The step of obtaining the second scan data for each thickness scan object includes: For each of the thickness scanned objects The slit is moved along the channel direction of the detector of the imaging device to N positions along the channel direction, where N is an integer greater than 1; and When the slit is in each of the N positions, the imaging device scans the object of each thickness to obtain the scan data corresponding to each position, and the second scan data includes the scan data at the N positions.

5. The method as described in claim 3, characterized in that, The obstruction includes N spaced-apart slits, and acquiring the second scan data for each thickness scan object includes: The shield is positioned within the radiation area; and The imaging device scans each thickness of the object to obtain scan data corresponding to N positions, and the second scan data includes the scan data at the N positions.

6. The method as described in claim 4 or 5, wherein obtaining the non-spectral signal corresponding to each thickness scanning object based on the first scan data and the second scan data includes: Obtain the scan data corresponding to the N positions from the first scan data; Based on the scan data at the N positions in the first scan data and the scan data at the N positions in the second scan data, the non-energy spectrum signal at the N positions is obtained; Based on the non-spectral signals at the N locations, the non-spectral signal corresponding to each thickness scanning object in the entire radiation area is obtained.

7. The method as described in claim 1, characterized in that, For each thickness scanned object, the first scan data is corrected based on the non-energy-spectral signal to obtain corrected scan data, including: The corrected scan data is obtained by subtracting the non-spectral signal from the first scan data.

8. The method of claim 1, wherein determining the hardening correction coefficient corresponding to the imaging device based on the corrected scan data corresponding to each thickness scan object includes: Determine the reference scan data corresponding to each thickness scan object; as well as The hardening correction coefficient corresponding to the imaging device is determined by fitting the reference scan data and the corresponding corrected scan data for each thickness scan object.

9. A hardening correction system, characterized in that, The system includes: The first data acquisition module is used to acquire first scan data by scanning each thickness of at least one scanned object of different thicknesses using an imaging device. The second data acquisition module is used to set a slit-shaped shield in the radiation area of ​​the imaging device, and to acquire second scan data of each thickness scanned object based on the scanning of each thickness scanned object by the imaging device; the shield is placed between the radiation source and the scanned object; The non-spectral signal acquisition module is used to acquire the non-spectral signal corresponding to each thickness scanning object based on the first scan data and the second scan data; The correction module is used to correct the first scan data for each thickness scan object based on the non-energy spectrum signal, and obtain the corrected scan data; The correction coefficient determination module is used to determine the hardening correction coefficient corresponding to the imaging device based on the corrected scan data corresponding to each thickness scan object. The hardening correction coefficient is used to correct the hardening effect of at least one detection element on the detector of the imaging device.

10. A computer-readable storage medium storing computer instructions, wherein when a computer reads the computer instructions in the storage medium, the computer executes the hardening correction method as described in any one of claims 1 to 8.

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