Detector and imaging device

Abstract

A detector and an imaging device. The detector comprises: a plurality of pixels, wherein the plurality of pixels are arranged in a first direction and a second direction, and the size of the pixels in the first direction and the size of the pixels in the second direction satisfy a preset proportional relationship.

Description

Detectors and imaging devices

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202410913163.2, filed on July 8, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of imaging technology, and more specifically, to a detector and an imaging device. Background Technology

[0004] Isotropic resolution in CT (Computed Tomography) images refers to the fact that the resolution of an image is the same in all directions during a CT scan. Isotropic resolution means that the image will have the same clarity and detail regardless of the viewing angle. It plays a crucial role in improving clinical image quality and diagnostic conclusions.

[0005] However, due to various factors, the spatial resolution in the xy and z directions of the image may differ in related technologies. Summary of the Invention

[0006] This application provides a detector and an imaging device to improve the quality of images generated by the imaging device.

[0007] In a first aspect, this application provides a detector comprising a plurality of pixels arranged along a first direction and a second direction, wherein the dimensions of the pixels in the first direction and the dimensions in the second direction satisfy the following: b = (M-1) 2 M = L / D

[0008] Among them, dw xy dw represents the size of a pixel in the first direction. z This represents the pixel size in the second direction, L represents the distance from the focal point to the isocenter, D represents the distance from the focal point to the detector, and fw xy fw represents the focal length in the first direction. z SR represents the focal length in the second direction. xy SR represents the spatial resolution of the image in the first direction. z SR represents the spatial resolution of the image in the second direction. xy =c·SR z , c represents the ratio of the spatial resolution of the image in the first direction to the spatial resolution of the image in the second direction.

[0009] According to the detector of this application, by constructing a relationship function between the size of pixels in the detector and the spatial resolution of the image, the relationship between the spatial resolution of the image in different directions and the size of pixels can be obtained. This allows the size of pixels in the detector to be determined during the design phase, so that the spatial resolution of the generated image in different directions meets the preset relationship, thereby improving the quality of the image generated by the imaging device.

[0010] According to one embodiment of this application, SR xy Equal to the limiting spatial resolution of the image in the first direction, SR z It equals the limiting spatial resolution of the image in the second direction.

[0011] In this embodiment, the limiting spatial resolution of the image is equal to the spatial resolution of the image, so the spatial resolution can be determined by the limiting spatial resolution of the image.

[0012] According to one embodiment of this application, SR xy =MTF xy (# xy %), SR z =MTF z (# z %); MTF xy (# xy %) indicates that the ordinate of the MTF curve in the first direction is #. xy Spatial resolution at % MTF z (# z %) indicates that the ordinate of the MTF curve in the second direction is #. zy Spatial resolution at %

[0013] In this embodiment, the relationship between the spatial resolution of an image and the MTF curve can be determined by the relationship function between the limiting spatial resolution of the image and the MTF curve.

[0014] According to one embodiment of this application, the relationship function between the limiting spatial resolution of an image and the MTF curve is determined as follows:

[0015] On an imaging device with a known limit to spatial resolution, the phantom is scanned using the highest resolution to obtain image data;

[0016] Spectral analysis was performed on the image data to obtain the MTF curve;

[0017] By comparing and analyzing the known limiting spatial resolution with the plotted MTF curve, the relationship function between the limiting spatial resolution and the MTF curve is obtained.

[0018] In this embodiment, image data is obtained by scanning at the highest resolution on a molding device with a known limiting spatial resolution. Then, the obtained image data is analyzed by spectrum to obtain an MTF curve, from which the spatial resolution of the image can be determined. By comparing and analyzing the limiting spatial resolution and the MTF curve, the relationship function between the limiting spatial resolution and the MTF curve can be obtained.

[0019] According to one embodiment of this application, the ordinate of the MTF curve in the first direction is # xy % and the ordinate of the MTF curve in the second direction # zy The difference between the percentages is less than the preset value.

[0020] In this embodiment, by making the difference between the ordinate of the MTF curve in the first direction and the ordinate of the MTF curve in the second direction less than a preset value, the imaging quality of the image generated by the designed detector can be similar in the first and second directions, thereby improving the image generation quality.

[0021] According to one embodiment of this application, the limiting spatial resolution of an image and the size of the pixels in the detector satisfy the following relationship function:

[0022] Where cutoff represents the limit spatial resolution, M represents the ratio of the distance D from the focal point to the isocenter to the distance L from the focal point to the detector, dw represents the size of the pixel in the detector, fw represents the focal point size, and represents the period width.

[0023] In this embodiment, by constructing a relationship function between the size of the pixels in the detector and the limit spatial resolution of the image, it can be known from the first relationship function that when the ratio M of the distance D from the focal point to the isocenter and the distance L from the intersection point to the detector, and the focal size fw are known, the correspondence between the size of the pixels in the detector and the limit spatial resolution of the image can be obtained, and thus the size of the pixels in the detector can be calculated from the limit spatial resolution of the image.

[0024] According to one embodiment of this application, the method further includes:

[0025] When the imaging device uses image reconstruction technology to optimize the spatial resolution of the image, weights are assigned to the size of the pixels in the detector to correct the relationship function between the limiting spatial resolution of the image and the size of the pixels in the detector.

[0026] In this embodiment, image reconstruction technology can be used to assign weights to the size of pixels in the detector. The size in the first direction and the size in the second direction are corrected according to the assigned weights. The corrected size is then substituted into the relationship function between the limit spatial resolution of the image and the size of pixels in the detector for further correction. The ratio of the size of the pixel in the first direction to the size in the second direction is calculated based on the corrected relationship function. By using image reconstruction technology and taking into account the impact on spatial resolution, the corrected spatial resolution obtained after the change of formula parameters can be obtained. The size ratio obtained based on the corrected spatial resolution is more accurate.

[0027] According to one embodiment of this application, assigning weights to the size of pixels in the detector when the imaging device uses image reconstruction technology to optimize the spatial resolution of the image includes:

[0028] Determine the number and type of image reconstruction techniques to be used;

[0029] The size of pixels in the detector is weighted according to the number and type of image reconstruction techniques used; the weight assigned to each type of image reconstruction technique is different.

[0030] In this embodiment, various image reconstruction techniques or combinations thereof can be used. When using image reconstruction techniques for correction, it is necessary to consider that different types of image reconstruction techniques assign different weights to the pixel size in the detector. The pixel size in the detector is weighted according to the number of different types of image reconstruction techniques used, and the pixel size ratio in the detector is then calculated based on the assigned weights. Assigning weights after confirming the number and types of image reconstruction techniques used can make the obtained results more accurate.

[0031] According to one embodiment of this application, c equals 1.

[0032] In this embodiment, c equals 1, which means that in the process of designing the detector, the goal is to install the designed detector in the imaging device so that the spatial resolution of the image generated by the imaging device is equal or similar in different directions, that is, to satisfy the image resolution in the same direction, thereby improving the quality of the image generated by the imaging device.

[0033] In a second aspect, this application provides an imaging device including a detector as described in the first aspect above.

[0034] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a flowchart illustrating the detector design provided in an embodiment of this application;

[0037] Figure 2 is a schematic diagram of the imaging device according to an embodiment of this application;

[0038] Figure 3 is a schematic diagram of the MTF curve of an embodiment of this application;

[0039] Figure 4 is a schematic diagram of the implementation process of the fly-focus technology in an embodiment of this application;

[0040] Figure 5 is a schematic diagram of the MTF curves of the embodiments of this application using image reconstruction technology and not using image reconstruction technology. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0042] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0043] CT images are medical images obtained through computed tomography (CT) scanning. A computer receives signals from detectors and uses complex algorithms to reconstruct the tomographic image. The spatial resolution of a CT image describes the smallest detail that can be displayed in the image and assesses the CT image's ability to distinguish objects. It is usually expressed as lp / cm or lp / mm. Image isotropicity refers to the fact that an image has the same or very similar resolution in all directions. This can mean that the resolution on the xy-plane and the resolution on the z-axis are the same or very similar. Isotropic imaging helps improve image quality, allowing doctors to observe and analyze lesions from multiple angles and reducing the uncertainty caused by resolution inhomogeneity. High-quality CT images are of great value for doctors in diagnosing diseases, developing treatment plans, and evaluating treatment effectiveness.

[0044] In a CT imaging system, the detector is a key component, responsible for receiving X-rays passing through the patient's body and converting them into electrical signals. These electrical signals are then used to reconstruct the image. The size of the pixels in the detector is directly related to the spatial resolution limit of the image; the detector's size design affects the image's resolution limit. Therefore, the detector's size is a critical parameter in its design, influencing the performance of the imaging equipment. The resolution of a CT image in the xy-plane is generally determined by the size of the pixels in the detector along the x-axis, and the resolution of a CT image in the z-axis is generally determined by the size of the pixels in the detector along the z-axis.

[0045] This application considers that if a relationship function between the size of pixels in the detector and the spatial resolution of the image can be constructed, and the size ratio of pixels in the detector in different directions can be calculated, the size of pixels in the detector can be determined during the design phase, so that the spatial resolution of the generated image in different directions meets the requirements, thereby improving the quality of the image generated by the imaging device.

[0046] The detector and imaging device provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0047] This application provides a detector including multiple pixels arranged along a first direction and a second direction, wherein the size of the pixels in the first direction and the size in the second direction satisfy the following: b = (M-1) 2 M = L / D

[0048] Among them, dw xy dw represents the size of a pixel in the first direction. z This represents the pixel size in the second direction, L represents the distance from the focal point to the isocenter, D represents the distance from the focal point to the detector, and fw xyfw represents the focal length in the first direction. z SR represents the focal length in the second direction. xy SR represents the spatial resolution of the image in the first direction. z SR represents the spatial resolution of the image in the second direction. xy =c·SR z , c represents the ratio of the spatial resolution of the image in the first direction to the spatial resolution of the image in the second direction.

[0049] In this embodiment, on the detector of the imaging device, a pixel refers to a photosensitive element on the sensor that can detect and convert incident light into an electrical signal. These photosensitive elements (pixels) are physically arranged in an array, with each element corresponding to a specific location on the generated image. In different imaging technologies, the pixels of the detector can take different forms; for example, in a digital camera, it might be a CCD (Charge-Coupled Device) or CMOS (Complementary Metal-Oxide-Semiconductor) sensor; in medical imaging, it might be an X-ray detector; and in an astronomical telescope, it might be a CCD camera, etc. Regardless of the form, the pixels on the detector are an indispensable part of the imaging process.

[0050] Since the arrangement of pixels in the detector affects the spatial resolution of the generated image, in this embodiment, the arrangement size of pixels in the detector in different directions can be designed according to the pre-defined spatial resolution requirements of the image in different directions. For example, if the requirement is to satisfy image resolution isotropicity, it means that the resolution of the generated image needs to be equal in different directions. Therefore, according to the above formula, c can be set to 1, so that the designed detector, when installed in the imaging device, generates images with equal or similar spatial resolution in different directions, thus satisfying image resolution isotropicity and improving the quality of the image generated by the imaging device. If it is necessary to make the resolution of the image in the first direction lower than that in the second direction, c can be set to 0.99, 0.95, etc. c can be set to any other arbitrary value as needed, and this embodiment does not limit this.

[0051] In this embodiment, since the internal structure and relative position of the detector and the radiation source generally do not change, the ratio M of the distance D from the focal point to the isocenter and the distance L from the focal point to the detector can be considered a fixed value. The parameter b is only related to M and can also be considered a fixed value. The focal size fw in the first direction... xy Focal size fw in the second direction zThese are inherently fixed physical characteristics, determined by the design and manufacturing of the X-ray source. Therefore, these two values ​​can also be considered fixed values. X-ray sources typically use X-ray tubes. According to the formula, the spatial resolution dw of the image in the first direction is... xy and the spatial resolution dw of the image in the second direction z The ratio varies with parameter a xy and a z It changes with the changes, and a xy and a z The spatial resolution SR of the image in the first direction is respectively determined by the image. xy And the spatial resolution of the image in the second direction SR z The determination is based on the pixel size dw in the detector, calculated according to the formula, in the first direction. xy and the size dw of the pixel in the detector in the second direction z By designing a detector according to a certain ratio, the spatial resolution of the generated image in different directions can meet different requirements, resulting in higher image quality.

[0052] According to the detector of this application, by constructing a relationship function between the size of pixels in the detector and the spatial resolution of the image, the relationship between the spatial resolution of the image in different directions and the size of pixels can be obtained. This allows the size of pixels in the detector to be determined during the design phase, so that the spatial resolution of the generated image in different directions meets the preset relationship, thereby improving the quality of the image generated by the imaging device.

[0053] The detector of this application embodiment will be described below in conjunction with the design process of the detector described above.

[0054] As shown in Figure 1, the design process of the detector includes steps 110 and 120.

[0055] Step 110: Construct a first relationship function between the pixel size in the detector and the limiting spatial resolution of the image; and construct a second relationship function between the limiting spatial resolution of the image and the spatial resolution of the image.

[0056] In this embodiment, the detector can be used in an imaging device, such as a CT scanner, a digital radiography imaging device, or an optical coherence tomography (OCT) scanner. This embodiment does not limit the scope of the invention.

[0057] The spatial limit resolution of an image refers to the highest resolution theoretically achievable by an imaging system. It represents the smallest spatial detail the system can distinguish. Unlike spatial resolution, the spatial limit resolution is a theoretical value under ideal conditions. In reality, spatial resolution rarely reaches the theoretical limit resolution due to various factors such as noise, scattering, and artifacts. While distinct from spatial resolution, the spatial limit resolution is related to spatial resolution; it influences the image's spatial resolution. The image's spatial limit resolution is a theoretical value under ideal conditions and remains unchanged by practical limitations. For an imaging device, the spatial limit resolution of the generated image is usually known and is part of the device's specifications.

[0058] In this embodiment, a first relational function cutoff = g(dw) can be constructed based on the relationship between the pixel size in the detector and the limiting spatial resolution of the image, where cutoff represents the limiting spatial resolution and dw represents the pixel size in the detector. A second relational function SR = f(cutoff) can be constructed based on the relationship between the limiting spatial resolution and the spatial resolution of the image, where SR represents the spatial resolution. The relationship between the pixel size in the detector and the spatial resolution of the image can be established using the constructed relational function based on the readily obtainable limiting spatial resolution of the image.

[0059] Step 120: Based on the first relation function and the second relation function, calculate the ratio of the size of the pixel in the detector in the first direction to the size of the pixel in the second direction, provided that the spatial resolution of the image in the first direction and the spatial resolution of the image in the second direction satisfy a preset relationship.

[0060] The spatial resolution of an image in different directions can be the spatial resolution on the x-axis, y-axis, xy-plane, and z-axis. The first direction can be the xy-plane, and the second direction can be the z-axis. Alternatively, three directions can be set: the first direction can be the x-axis, the second direction can be the y-axis, and the third direction can be the z-axis. This embodiment does not limit the number or allocation of directions. For images acquired by a CT detector, the spatial resolution in the xy-plane can be the intra-slice resolution, and the spatial resolution along the z-axis can be the inter-slice resolution (or thickness resolution). Each slice is a tomographic image. Generally, multiple slices are reconstructed after a CT scan, and these slices are distributed along the z-axis. The direction of the z-axis can be the extension direction of the CT scanner cavity, as shown in Figure 2; the direction perpendicular to the paper is the z-axis direction.

[0061] In some embodiments, the xy-plane can be designated as the first direction, and the z-axis as the second direction. The first direction of the image and the first direction of the detector can be the same. For example, if the first direction is the xy-plane, then the spatial resolution of the image in the first direction is the spatial resolution of the image in the two-dimensional plane. The size of a pixel in the detector in the first direction is the length of the pixel on the x-axis, and the length of the pixel on the x-axis affects the spatial resolution of the image in the two-dimensional plane. To ensure the quality of the generated image, the spatial resolution of the image in the first and second directions can be designed to satisfy a preset relationship when designing the pixel size in the detector. Based on the first and second relationship functions, the relationship between the size of the pixels in the detector in the first and second directions can be obtained. Based on this size relationship, the detector can be better designed so that the spatial resolution of the generated image in different directions satisfies the preset relationship, thereby improving the quality of the image generated by the imaging device.

[0062] In some embodiments, the preset relationship is that the spatial resolution of the image in the first direction is the same as the spatial resolution of the image in the second direction, or the ratio of the spatial resolution of the image in the first direction to the spatial resolution of the image in the second direction is a preset ratio.

[0063] In this embodiment, the preset relationship can be that the spatial resolution of the image in the first direction is the same as the spatial resolution of the image in the second direction. That is, according to the above formula, c is set to 1. In this case, the size of the pixels in the detector can be determined during the design. Installing a detector of this size in the imaging device can make the spatial resolution of the generated image equal or similar in different directions, that is, satisfy the image resolution in the same direction, thereby improving the quality of the image generated by the imaging device.

[0064] By setting the preset relationship to the ratio of the spatial resolution of the image in the first direction to the spatial resolution of the image in the second direction, different size ratios of detectors can be set to meet different scenario requirements, depending on the actual situation. For example, in some scenarios, the spatial resolution of the image in the first direction needs to be 70%, 80%, 90% of the spatial resolution of the image in the second direction, or other values. That is, c can be set to 0.99, 0.95, 0.9, 0.8, etc., or set to any other arbitrary ratio as needed, to determine the size of the pixels in the detector.

[0065] According to the detector of this application, a first relationship function is constructed between the size of pixels in the detector and the limiting spatial resolution of the image. Based on the first and second relationship functions, the ratio of the detector's size in the first direction to its size in the second direction is calculated, provided that the spatial resolution of the image in the first direction and the spatial resolution of the image in the second direction satisfy a preset relationship. This embodiment of the application, by constructing a relationship function between the size of pixels in the detector, the limiting spatial resolution of the image, and the image's spatial resolution, obtains the relationship between the spatial resolution of the image in different directions and the size of pixels in the detector. This allows the size of pixels in the detector to be determined during the design phase, ensuring that the spatial resolution of the generated image in different directions satisfies the preset relationship, thereby improving the quality of the image generated by the imaging device.

[0066] In some embodiments, according to the formula M = L / D

[0067] Construct the first relationship function between the pixel size in the detector and the limiting spatial resolution of the image;

[0068] Where cutoff represents the limit spatial resolution, M represents the ratio of the distance D from the focal point to the isocenter to the distance L from the focal point to the detector, dw represents the size of the pixel in the detector, fw represents the focal point size, and cw represents the period width.

[0069] In this embodiment, as shown in Figure 2, the X-ray source represents the location of the focal point, and the rotation center represents the location of the isocenter. Since the internal structure and relative position of the detector and the X-ray source generally do not change, the distance D from the focal point to the isocenter and the distance L from the focal point to the detector can be considered as fixed values. Therefore, the ratio M of D to L can also be considered as a fixed value. The focal size fw itself is a fixed physical characteristic, determined by the design and manufacturing of the detector, and can also be considered as a fixed value. According to the formula, the limiting spatial resolution cutoff is mainly affected by the pixel size dw in the detector. At this time, by constructing a function relating the pixel size in the detector to the limiting spatial resolution of the image based on this formula, the limiting spatial resolution cutoff and the pixel size dw in the detector can be linked to obtain the relationship between them.

[0070] In some embodiments, the second relational function is the limit spatial resolution of the image, which is equal to the spatial resolution of the image.

[0071] In this embodiment, the limiting spatial resolution of the image can be considered equal to the spatial resolution of the image, i.e., SR = f(cutoff) = cutoff. Therefore, the spatial resolution SR of the image in the first direction can be derived. xy Equal to the image's limiting spatial resolution cutoff in the first direction xyThe spatial resolution of the image in the second direction is SR z Equal to the image's limiting spatial resolution cutoff in the second direction z .

[0072] In this embodiment, under ideal conditions, the limiting spatial resolution of the image can be considered to be equal to the spatial resolution of the image. When the imaging device is less affected by the actual situation, the second relationship function can be constructed relatively simply to obtain the relationship between the limiting spatial resolution and the spatial resolution.

[0073] In some embodiments, constructing a second relationship function between the limiting spatial resolution of an image and the spatial resolution of the image may include:

[0074] On an imaging device with a known limit to spatial resolution, the phantom is scanned using the highest resolution to obtain image data;

[0075] Spectral analysis of the image data yields the MTF curve;

[0076] By comparing and analyzing the known limiting spatial resolution with the plotted MTF curve, a third relationship function between the limiting spatial resolution and the MTF curve is obtained;

[0077] The second relation function is determined based on the third relation function.

[0078] The MTF (Modulation Transfer Function) curve describes the ability of an imaging system to respond to different spatial frequencies in the field of imaging technology, that is, the level of detail that the system can clearly resolve. The MTF curve can reflect the relationship between the MTF value and spatial resolution. When the MTF value drops to a threshold, the corresponding spatial resolution can be considered as the spatial limit resolution. This threshold can be 20%, 10%, 5%, 3%, 2%, etc., and can be changed according to actual needs. This application does not limit this.

[0079] In this embodiment, by scanning an SSP (Slice Sensitivity Profile) phantom or a QA (Quality Assurance) phantom with the highest resolution on an imaging device with a known limit spatial resolution, high-resolution image data can be obtained when the device operates at its maximum recognition capability. The image data obtained in this case is closer to the image data under the limit resolution. Spectral analysis of the obtained image data yields the MTF curve, as shown in Figure 3. Comparing the limit spatial resolution and the MTF curve, a third relational function cutoff = MTF(#%) is obtained. Here, MTF(#%) represents the value of the abscissa when the ordinate of the MTF curve is #%, and this abscissa value represents the spatial resolution. Therefore, the third relational function represents the spatial resolution when the limit spatial resolution is equal to the spatial resolution when the ordinate of the MTF curve is #%. Thus, the relationship between the limit spatial resolution and the spatial resolution of the image can be obtained through the third relational function and the MTF curve. The relationship between the limit spatial resolution and the sub-spatial resolution can be determined, i.e., the second relational function cutoff = MTF(#%) = SR can be determined. Where #% can be 20%, 10%, 5%, 3%, 2%, etc. Compared to the ideal second relation function, this method, through scanning and comparative analysis, takes into account the actual situation, resulting in a more accurate second relation function.

[0080] Specifically, in this embodiment, spectral analysis of the image data can be performed to obtain the MTF curve in the first direction. xy MTF curve in the second direction z And the limiting spatial resolution in the first direction and the MTF curve MTF xy Comparative analysis yields the limiting spatial resolution and MTF curve in the first direction. xy The relationship between the upper MTF value and the limiting spatial resolution in the second direction and the MTF curve. z Comparative analysis yields the limiting spatial resolution and MTF curve in the second direction. z The relationship between the MTF values ​​is used to determine the relationship between the limiting spatial resolution in the first direction and the spatial resolution in the first direction, as well as the relationship between the limiting spatial resolution in the second direction and the spatial resolution in the second direction.

[0081] In this embodiment, image data is obtained by scanning at the highest resolution on a molding device with a known limiting spatial resolution. Then, the obtained image data is analyzed by spectrum to obtain an MTF curve, from which the spatial resolution of the image can be determined. By comparing and analyzing the limiting spatial resolution and the MTF curve, a third relationship function between the limiting spatial resolution and the MTF curve can be obtained. Based on the obtained third relationship function, a second relationship function can be determined. The second relationship function determined in this way can determine the spatial resolution of the image based on its limiting spatial resolution.

[0082] In some embodiments, SR xy =MTF xy (# xy %), SR z =MTF z (# z %); where MTF xy (# xy %) indicates that the ordinate of the MTF curve in the first direction is #. xy Spatial resolution at % MTF z (# z %) indicates that the ordinate of the MTF curve in the second direction is #. zy Spatial resolution at %

[0083] In this embodiment, combined with SR xy =c·SR z Then, by simultaneously establishing the second functional relationship cutoff = MTF(#%) = SR, we can obtain cutoff xy =MTF xy (# xy %) = SR xy =c·cutoff z =c·MTF z (# z %) = c·SR z Then, by combining the first relational function, we can obtain the calculation formula for the ratio of the size of the pixel in the first direction to the size of the pixel in the second direction in the detector.

[0084] In some embodiments, the ordinate of the MTF curve in the first direction is # xy % and the ordinate of the MTF curve in the second direction # zy The difference between the percentages is less than the preset value.

[0085] Since there are many points where the abscissas of the MTF curves in the first and second directions are equal, if the abscissas of the two curves are equal but the ordinates differ too much, it indicates a significant difference in the image resolution and imaging quality between the first and second directions. This will lead to an inaccurate size ratio of the detector in the first and second directions, making it difficult to meet the isotropic requirements of image resolution. Therefore, while ensuring that the abscissas of the two curves are equal, the ordinate of the MTF curve in the first direction should be made as close to # as possible. xy The ordinate of the MTF curve in the second direction is # zy The small difference between the percentages results in a more accurate determination of the detector's size ratio in the first and second directions. The preset values ​​can be 1%, 2%, 5%, etc., and can be set by those skilled in the art based on the actual conditions of the MTF curves in the first and second directions. This application does not limit this setting.

[0086] In some embodiments, the method further includes:

[0087] When the imaging device uses image reconstruction technology to optimize the spatial resolution of the image, weights are assigned to the size of the pixels in the detector to correct the relationship function between the limit spatial resolution of the image and the size of the pixels in the detector.

[0088] During the imaging process, images are affected by various real-world conditions such as noise, blur, and undersampling, leading to a decrease in image quality. Image reconstruction techniques are a series of methods used to improve image quality, including flying focal spot (FFS), using a special grid to occlude the detector, and deblurring. As shown in Figure 4, Flying Focal Spot (FFS) increases sampling density by rapidly shifting the focal point between two different locations, thereby improving resolution; using a special grid to occlude the detector reduces its size in a specific direction, thus improving image resolution; deblurring removes blurred portions of the image through the reverse process, thereby improving image resolution. This application does not limit the image reconstruction techniques used.

[0089] When image reconstruction techniques are used, the relevant parameters in the formula will be affected and changed. At this time, it is necessary to assign weights to the affected parameters according to the image reconstruction techniques used, so as to obtain the corrected parameters.

[0090] In this embodiment, if the imaging device uses image reconstruction technology to optimize the spatial resolution of the image, then the size of the pixels in the detector is weighted according to the technology used, the first relation function is corrected according to the corrected size of the pixels in the detector, and the first relation function is recalculated according to the corrected first relation function. The ratio of the size of the detector in the first direction to the size in the second direction obtained by this method is more accurate.

[0091] In some embodiments, when the imaging device uses image reconstruction techniques to optimize the spatial resolution of the image, assigning weights to the size of pixels in the detector to modify the first relational function may include:

[0092] Determine the number and type of image reconstruction techniques to be used;

[0093] The size of pixels in the detector is weighted according to the number and type of image reconstruction techniques used; the weight assigned to each type of image reconstruction technique is different.

[0094] The image reconstruction techniques used in the embodiments of this application can be a combination of multiple image reconstruction techniques. The image reconstruction techniques used in this application can be a single technique or a combination of multiple different techniques. This application does not impose any restrictions on this.

[0095] As shown in Figure 4, if a flying focus technique is used in the first or second direction, doubling the sampling interval, then the pixel size dw in the detector of the first relational function should be corrected by weights: dw′=cof1·dw

[0096] Where dw′ represents the pixel size in the corrected detector, and cof1 represents the weight value assigned based on the fly-focus technique. cof1 can be any value between 0 and 1, and can be determined according to the specific circumstances of the fly-focus technique used. For example, if two focal points are used, the value of cof1 can be 0.5.

[0097] In some embodiments, if other techniques are employed besides the fly-focus technique, such as occluding the detector with a special grid to reduce the detector size to A% of its original size in the first or second direction, then the pixel size dw in the detector in the first relation function should be corrected by weights: dw″ = cof1·cof2·dw

[0098] Where dw″ represents the pixel size in the corrected detector, and cof2 represents the weight value assigned based on the special grid technique. cof2 can be any value between 0 and 1, and can be determined according to the specific occlusion area. For example, if 40% is occluded in the second direction and 60% remains, then the value of cof2 can be 0.6.

[0099] Of course, for some image reconstruction methods, it may be impossible to obtain the specific influence weights through theoretical analysis or formula derivation. In such cases, the weight values ​​can be determined by adding algorithms to other models, collecting data, and fitting the MTF curve after the influence of the corresponding method. Taking Figure 5 as an example, assuming SR xy and SR z All directions have an MTF of 10% and a spatial resolution of 24 lp / cm. The second direction without image reconstruction has an MTF of 24 lp / cm, while the second direction with image reconstruction has an MTF of 26 lp / cm. Weight values ​​are then calculated based on the impact of image reconstruction on spatial resolution.

[0100] In this embodiment, if the imaging device uses image reconstruction techniques to optimize the spatial resolution of the image, it is necessary to determine the number and type of image reconstruction techniques used, and to comprehensively consider the number and type of image reconstruction techniques used to assign different weights to the size of pixels in the detector, so as to obtain more accurate results.

[0101] This application also provides an imaging device, which includes the detector described above.

[0102] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0103] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0104] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A detector, characterized in that, It includes multiple pixels, which are arranged along a first direction and a second direction, wherein the dimensions of the pixels in the first direction and the dimensions in the second direction satisfy the following: b = (M-1) 2 M = L / D Among them, dw xy dw represents the size of a pixel in the first direction. z This represents the pixel size in the second direction, L represents the distance from the focal point to the isocenter, D represents the distance from the focal point to the detector, and fw xy fw represents the focal length in the first direction. z SR represents the focal length in the second direction. xy SR represents the spatial resolution of the image in the first direction. z SR represents the spatial resolution of the image in the second direction. xy =c·SR z , c represents the ratio of the spatial resolution of the image in the first direction to the spatial resolution of the image in the second direction.

2. The detector according to claim 1, wherein, SR xy Equal to the limiting spatial resolution of the image in the first direction, SR z It equals the limiting spatial resolution of the image in the second direction.

3. The detector according to claim 1 or 2, wherein, SR xy =MTF xy (# xy %), SR z =MTF z (# z %); MTF xy (# xy %) indicates that the ordinate of the MTF curve in the first direction is #. xy Spatial resolution at % MTF z (# z %) indicates that the ordinate of the MTF curve in the second direction is #. zy Spatial resolution at % 4. The detector according to claim 3, wherein, The relationship between the limiting spatial resolution of an image and the MTF curve is determined as follows: On an imaging device with a known limit to spatial resolution, the phantom is scanned using the highest resolution to obtain image data; Spectral analysis was performed on the image data to obtain the MTF curve; By comparing and analyzing the known limiting spatial resolution with the plotted MTF curve, the relationship function between the limiting spatial resolution and the MTF curve is obtained.

5. The detector according to claim 3 or 4, wherein, The ordinate of the MTF curve in the first direction is # xy % and the ordinate of the MTF curve in the second direction # zy The difference between the percentages is less than the preset value.

6. The detector according to any one of claims 2-5, wherein, The limiting spatial resolution of an image and the size of a pixel in the detector satisfy the following function: Where cutoff represents the limit spatial resolution, M represents the ratio of the distance D from the focal point to the isocenter to the distance L from the focal point to the detector, dw represents the size of the pixel in the detector, fw represents the focal point size, and cw represents the period width.

7. The detector according to claim 6, wherein, Also includes: When the imaging device uses image reconstruction technology to optimize the spatial resolution of the image, weights are assigned to the size of the pixels in the detector to correct the relationship function between the limiting spatial resolution of the image and the size of the pixels in the detector.

8. The detector according to claim 7, wherein, When the imaging device uses image reconstruction technology to optimize the spatial resolution of the image, assigning weights to the size of pixels in the detector includes: Determine the number and type of image reconstruction techniques to be used; The size of pixels in the detector is weighted according to the number and type of image reconstruction techniques used; the weight assigned to each type of image reconstruction technique is different.

9. The detector according to claim 7 or 8, wherein, According to the formula: dw′=cof1·dw Assign weights to the size of the pixels in the detector; Where dw represents the size of a pixel in the detector, dw′ represents the size of a pixel in the corrected detector, and cof1 represents the weight value assigned based on the first category of image reconstruction technology; the first category of image reconstruction technology is the fly-focus technique; cof1 is determined according to the number of focal points used by the fly-focus technique.

10. The detector according to claim 7 or 8, wherein, According to the formula: dw″=cof1·cof2·dw Assign weights to the size of the pixels in the detector; Wherein, dw represents the size of a pixel in the detector, dw″ represents the size of a pixel in the corrected detector, cof1 represents the weight value assigned based on the first category of image reconstruction techniques, and cof2 represents the weight value assigned based on the second category of image reconstruction techniques; the second category of image reconstruction techniques is the technique of occluding the detector through a grid; cof2 is determined according to the area of ​​the detector occluded by the grid.

11. The detector according to any one of claims 1-10, wherein, c equals 1.

12. An imaging device, characterized in that, Includes the detector as described in any one of claims 1-11.

Images