Linear array detector, computed tomography apparatus, and projection imaging apparatus

Abstract

The present disclosure provides a linear array detector, a computer tomography device and a projection imaging device; wherein the linear array detector comprises a circuit board and a plurality of pixels arranged on the circuit board; the plurality of pixels are arranged into N columns along a first direction and M rows along a second direction, N>M≥2 and N and M are integers, the first direction and the second direction intersect; each pixel comprises a silicon photomultiplier and a scintillation crystal coupled with the silicon photomultiplier, the scintillation crystal being used for converting X-rays into scintillation light; in any two adjacent rows of pixels, at least part of the silicon photomultipliers are arranged in a staggered manner in the first direction. The linear array detector can further improve the spatial resolution without further reducing the physical size of the silicon photomultiplier.

Description

Technical Field

[0001] This disclosure relates to the field of X-ray detection technology, and in particular to a linear array detector, a computed tomography (CT) scanner, and a projection imaging device. Background Technology

[0002] For linear array detectors used in X-ray detection, the size of the silicon photomultiplier (SiPM) is the main factor affecting the spatial resolution of the linear array detector. For example, the pixel size of commercially available SiPMs is too large, making it difficult to meet the needs of computer tomography (CT) and projection imaging equipment for sub-millimeter resolution to distinguish tiny structures.

[0003] Therefore, how to further improve the spatial resolution of linear array detectors used for X-ray detection has become an urgent problem to be solved. Utility Model Content

[0004] In view of the above problems, this disclosure provides a linear array detector, a computed tomography scanning device, and a projection imaging device, which can further improve the spatial resolution of the X-ray linear array detector without further reducing the physical size of the silicon photomultiplier tube.

[0005] Firstly, the following technical solution is provided through an embodiment:

[0006] A linear array detector includes a circuit board and a plurality of pixels disposed on the circuit board; the plurality of pixels are arranged in N columns along a first direction and in M ​​rows along a second direction, where N>M≥2 and N and M are integers, and the first direction and the second direction intersect; each pixel includes a silicon photomultiplier tube and a scintillation crystal coupled to the silicon photomultiplier tube, the scintillation crystal being used to convert X-rays into scintillation light; in any two adjacent rows of pixels, at least some of the silicon photomultiplier tubes are staggered in the first direction.

[0007] In some embodiments, for any two adjacent rows of pixels, the j-th silicon photomultiplier tube in the i-th row of pixels is offset from the j-th silicon photomultiplier tube in the (i+1)-th row of pixels by the same distance in the first direction; 1≤i≤M-1, 1≤j≤N, and i and j are integers.

[0008] In some embodiments, the misalignment distance is equal to k1 / M times the pixel pitch of the silicon photomultiplier tube, and the pixel pitch is equal to the sum of the width of a single silicon photomultiplier tube in the first direction and the gap distance between two adjacent silicon photomultiplier tubes in the same row of pixels in the first direction, and the value of k1 ranges from 0.95 to 1.05.

[0009] In some embodiments, the width of each scintillation crystal in the first direction is equal to k2 / M times the pixel pitch, where k2 ranges from 0.8 to 1.0.

[0010] In some embodiments, for any two adjacent rows of pixels, the orthographic projection of all scintillation crystals in the (i+1)th row of pixels onto the reference plane has no intersection with the orthographic projection of all scintillation crystals in the ith row of pixels onto the reference plane; the reference plane is a plane extending along a first direction and perpendicular to the circuit board.

[0011] In some embodiments, the silicon photomultiplier tube includes an effective region and a peripheral region surrounding the effective region, and the orthographic projection of the scintillation crystal onto the silicon photomultiplier tube is located within the effective region.

[0012] In some embodiments, the width of each silicon photomultiplier tube in the first direction is less than 1.8 mm and the width in the second direction is less than 1.5 mm; in any row of pixels, the gap between two adjacent silicon photomultiplier tubes in the first direction is between 0.2 mm and 0.6 mm.

[0013] In some embodiments, the silicon photomultiplier tube is used to convert the scintillation light into an electrical signal; the circuit board includes a conversion circuit and a measurement circuit, the input terminal of the conversion circuit is connected to the silicon photomultiplier tube, and the output terminal is connected to the measurement circuit; the conversion circuit is used to convert the electrical signal into a pulse width signal and output it, and the measurement circuit is used to obtain photon energy information based on the pulse width signal.

[0014] Secondly, based on the same inventive concept, the following technical solution is provided through an embodiment:

[0015] A computed tomography (CT) device includes a linear array detector as provided in the first aspect embodiment.

[0016] Thirdly, based on the same inventive concept, the following technical solution is provided through an embodiment:

[0017] A projection imaging device includes a linear array detector provided in the first aspect embodiment.

[0018] According to one of the technical solutions in the above embodiments, the following beneficial effects or advantages are achieved:

[0019] This disclosure provides a linear array detector. Multiple pixels are arranged on a circuit board, each pixel including a silicon photomultiplier tube (SiPM) and a coupled scintillation crystal. The scintillation crystal converts X-rays into scintillation light, and the SiPM converts the scintillation light into an electrical signal, thus achieving X-ray detection. At least some SiPMs in any two adjacent rows of pixels are staggered in the first direction. This allows for the arrangement of more SiPMs within the same space of the linear array detector, i.e., within the space of the first direction, without further reducing the physical size of the SiPMs. The staggered SiPMs between adjacent rows can cover the vertical gaps between them in the first direction, achieving higher-density photon detection, improving the positioning accuracy of X-ray converted photons, and thus improving the spatial resolution of the X-ray linear array detector. Simultaneously, the staggered arrangement of SiPMs can reduce optical crosstalk between adjacent SiPMs. By appropriately increasing the distance between adjacent SiPMs through staggered arrangement, the spatial resolution is improved while reducing the occurrence of optical crosstalk.

[0020] The above description is merely an overview of the technical solution disclosed herein. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this disclosure more apparent and understandable, specific embodiments of this disclosure are described below. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0022] Figure 1A A top view of a linear array detector staggered in a first direction, according to an embodiment of the present disclosure, is shown.

[0023] Figure 1B A top view of another linear array detector staggered in a first direction, provided according to an embodiment of the present disclosure, is shown.

[0024] Figure 1C A top view of another linear array detector staggered in a first direction, provided according to an embodiment of the present disclosure, is shown.

[0025] Figure 2A A schematic diagram of the pixel arrangement of a linear array detector in the related technology is shown;

[0026] Figure 2B A schematic diagram of the pixel arrangement of another linear array detector in the related technology is shown;

[0027] Figure 3 A schematic diagram of the frame of a linear array detector provided according to an embodiment of the present disclosure is shown;

[0028] Figure 4 A schematic diagram is shown showing a scintillation crystal coupled to the effective region of a silicon photomultiplier tube according to an embodiment of the present disclosure;

[0029] Figure 5A A top view of an existing silicon photomultiplier tube is shown;

[0030] Figure 5B It shows Figure 5A The left view;

[0031] Figure 6A A schematic diagram of a silicon photomultiplier array according to an embodiment of the present disclosure is shown;

[0032] Figure 6B A schematic diagram of a scintillation crystal array provided according to an embodiment of the present disclosure is shown.

[0033] Figure 6C A top view is shown of a 4×16 pixel array formed by a silicon photomultiplier tube coupled with a scintillation crystal according to an embodiment of the present disclosure;

[0034] Figure 6D It shows Figure 6C Front view of the pixel array;

[0035] Figure 6E It shows Figure 6C The main view of the pixel array;

[0036] Explanation of reference numerals in the attached figures:

[0037] 10. Circuit board; 11. Conversion circuit; 12. Measurement circuit; 20. Pixel; 21. Silicon photomultiplier tube; AA, effective area; ZA, peripheral area; 22. Scintillation crystal. Detailed Implementation

[0038] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0039] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0040] In the context of this disclosure, when a layer / element is referred to as being "above" another layer / element, the layer / element may be directly above the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "above" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0041] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0042] Typically, further reducing pixel size, i.e., further reducing the size of silicon photomultiplier tubes (SMTs), is an easy-to-think approach to improving the spatial or physical resolution of linear array detectors. However, limited by current semiconductor manufacturing processes, further reducing the size of SMTs not only incurs high costs but also results in a significant increase in dark noise. At present, obtaining smaller SMTs requires further miniaturization of the SMT production line, which would incur substantial modification costs.

[0043] Another approach to improving the spatial resolution of linear array detectors is to apply optical multiplexing technology. However, using optical sharing or optical beam splitters can lead to signal crosstalk, which requires complex algorithms for correction.

[0044] Based on the above analysis, in a first aspect, in an optional embodiment, please refer to... Figure 1A A linear array detector is provided, including a circuit board 10 and a plurality of pixels 20 disposed on the circuit board 10; the plurality of pixels 20 are arranged in N columns along a first direction and in M ​​rows along a second direction, where N>M≥2 and N and M are integers, and the first direction and the second direction intersect; each pixel 20 includes a silicon photomultiplier tube 21 and a scintillation crystal 22 coupled to the silicon photomultiplier tube 21, the scintillation crystal 22 being used to convert X-rays into scintillation light; in any two adjacent rows of pixels 20, at least some of the silicon photomultiplier tubes 21 are staggered in the first direction.

[0045] Specifically, the embodiments disclosed herein provide a linear array detector for X-ray detection. Linear array detectors differ from flat panel detectors, which are typically composed of multiple large detector modules and can cover a large detection area. Linear array detectors, on the other hand, are linear arrays formed by multiple small detector units arranged in a one-dimensional linear direction, and are suitable for line-by-line scanning (line X-ray) detection methods.

[0046] The circuit board 10 of the linear array detector has an M×N pixel array. Each pixel 20 includes a silicon photomultiplier tube 21 (hereinafter referred to as SiPM) and a coupled scintillation crystal 22. Therefore, the number of SiPMs and scintillation crystals 22 are equal and correspond one-to-one, and they are both arranged in an M×N array. The scintillation crystal 22 is a crystal that can convert the kinetic energy of high-energy particles such as X-rays into light energy and emit a flash when bombarded by high-energy particles. Commonly used scintillation crystals 22 in X-ray detection include lutetium yttrium oxyorthosilicate (LYSO), gadolinium silicate (Gd2SiO5, GSO), and lutetium silicate (LSO). Unless otherwise specified, this embodiment uses LYSO crystal as an example for description. The scintillation crystal 22 is coupled to the SiPM by optical adhesive bonding or the like. The SiPM is connected to the circuit board 10 by electrical connection.

[0047] After the scintillation crystal 22 converts external X-rays into scintillation light, the SiPM coupled to it converts the scintillation light into an electrical signal. This electrical signal can then be transmitted via circuit board 10 to the back-end electronics system for information detection. Circuit board 10 can be a printed circuit board (PCB) or other types of circuit substrates. It should be noted that SiPM is different from Single Photon Avalanche Diode (SPAD). Although both belong to single-photon detection devices, the difference is that SiPM is a SPAD array formed by parallel connection of multiple SPAD micro-units. Therefore, SiPM has a higher dynamic range.

[0048] Although the M×N SiPMs in this embodiment are arranged in an array, for any two adjacent rows of pixels 20, at least some of the SiPMs are staggered in the first direction, that is, some or all of the SiPMs in the upper and lower rows are staggered by a certain distance from each other. Figure 1A The diagram illustrates a staggered arrangement of a 2×4 pixel array. The first direction can be considered the row direction, with each row of pixels 20 comprising 4 SiPMs. All SiPMs in the same row of pixels 20 are aligned or substantially aligned along their top and bottom edges in the row direction. The second direction can be considered the column direction, with each column comprising 2 SiPMs. However, the 2 SiPMs in each column of pixels 20 are staggered and misaligned in the column direction. Overall, the second row of pixels 20 is positioned relative to the first row of pixels 20, towards... Figure 1A The arrows in the first direction are staggered by a certain distance. The stagger distance can be referenced as follows: Figure 1A The d shown eff It is understood that, in some other embodiments, the second row of pixels 20 is oriented relative to the first row of pixels 20 towards... Figure 1A The arrows corresponding to the first direction in the middle are arranged in the opposite direction and offset by a certain distance, such as... Figure 1B As shown, this staggered arrangement scheme is similar to... Figure 1A The staggered arrangement scheme is equivalent.

[0049] It should be noted that the first direction and the second direction are relative directions, and their orientation can be adjusted according to actual needs without affecting the staggered arrangement of the SiPM provided in this embodiment. For example, Figure 1C It shows the relationship with Figure 1A Equivalent derangement method, Figure 1C Compared to Figure 1AIf we swap the first and second directions, and consider the second direction as the row direction and the first direction as the column direction, then the 8 SiPMs are arranged in a 4×2 array. Each row contains 2 SiPMs, staggered by a certain distance in the second direction; each column contains 4 SiPMs, and the SiPMs in each column are aligned or nearly aligned in the first direction. Overall, adjacent columns of SiPMs are staggered by a certain distance in the first direction. If we consider the first direction as the row direction and the second direction as the column direction, the 8 SiPMs are still arranged in a 2×4 array. Each row contains 4 SiPMs, and each column contains 2 SiPMs. Overall, adjacent rows of SiPMs are staggered by a certain distance in the first direction. Therefore, Figure 1C and Figure 1A This is a substantially equivalent SiPM misalignment arrangement scheme.

[0050] To better illustrate the difference between staggered and normal layouts, please refer to [link / reference]. Figure 2A The provided pixel arrangement of a linear array detector is a single row of 1×N pixels 20, that is, N silicon photomultiplier tubes 21 are arranged in a row. Since there is only one row, there is no misalignment. Figure 2B Another pixel arrangement for a linear array detector is provided, which is a 2×N pixel array, that is, it includes two rows of pixels 20, each row of pixels 20 includes N silicon photomultiplier tubes 21, and the two rows of pixels 20 are completely aligned in the first direction, that is, the row direction, and there is no misalignment.

[0051] The advantage of staggered SiPM arrangement is that, within the same space of the linear array detector, especially along the linear extension direction of the detector, the photon detection density can be increased without reducing the size of the SiPM. Figure 1A Taking the provided linear array detector as an example, for two adjacent rows of pixels 20, in the first direction, that is, the linear arrangement direction of the linear array detector, the staggered arrangement can fill the blank area in the linear arrangement direction. Since the SiPM and scintillation crystal 22 of the adjacent rows are staggered and cover the gap between them in the first direction, it is equivalent to arranging more SiPM in the same area in the first direction, realizing higher density photon detection and effectively improving the spatial resolution of the linear array detector.

[0052] On the other hand, staggered arrangement can also reduce optical crosstalk between SiPMs. This is because, under the premise of unchanged SiPM size, if the arrangement density is increased by reducing the gap between SiPMs to improve spatial resolution, the scintillation light or visible light generated by the scintillation crystal 22 when capturing X-rays will crosstalk to the adjacent SiPMs because the adjacent SiPMs are too close together, causing distortion in the photon measurement of adjacent SiPMs. This problem exists in the field of X-ray detection, but not in fields such as laser ranging. Staggered arrangement can solve this problem well. By increasing the gap between adjacent SiPMs, the occurrence of optical crosstalk can be effectively reduced.

[0053] The electrical signal obtained by SiPM can be sent to back-end electronics processing via circuit board 10, or it can be processed on circuit board 10 to obtain photon energy information. In some embodiments, please refer to... Figure 3 The provided X-ray linear array detector can integrate a conversion circuit 11 and a measurement circuit 12 on a circuit board 10. The input of the conversion circuit 11 is connected to a silicon photomultiplier tube 21, and the output is connected to the measurement circuit 12. The conversion circuit 11 is used to convert electrical signals into pulse width signals and output them. The measurement circuit 12 is used to obtain photon energy information based on the pulse width signals.

[0054] In some embodiments, the conversion circuit 11 includes a charge-to-time conversion sub-circuit equal to the number of SiPMs, with one charge-to-time conversion sub-circuit connected to one SiPM; the number of measurement circuits 12 can also be equal to the number of SiPMs, with one measurement circuit 12 connected to one charge-to-time conversion sub-circuit. This enables independent readout of multi-channel electrical signals, which is beneficial for improving measurement accuracy. The corresponding signal processing flow is as follows:

[0055] 1) The scintillation crystal 22 receives the incident X-rays and converts them into scintillation light;

[0056] 2) The silicon photomultiplier tube 21 captures the scintillation light generated by the scintillation crystal 22 and generates multiple charges to convert the scintillation light into an electrical signal;

[0057] 3) The charge-to-time conversion sub-circuit converts the electrical signal into a pulse width signal, which contains X-ray photon energy information;

[0058] 4) The measurement circuit 12 performs time-to-digital conversion on the pulse width signal to obtain photon energy information.

[0059] Therefore, the linear array detector provided in this embodiment, by staggering at least some of the silicon photomultiplier tubes 21 in any two adjacent rows of pixels 20 in the first direction, achieves the arrangement of more SiPMs in the same space of the linear array detector, that is, in the space of the first direction, without further reducing the size of the SiPMs. The staggered SiPMs between adjacent rows can cover the vertical gaps between each other in the first direction, achieving higher density photon detection, improving the positioning accuracy of X-ray converted photons, and thus improving the spatial resolution of the X-ray linear array detector. At the same time, the staggered arrangement of SiPMs can also reduce optical crosstalk between adjacent SiPMs. By staggering the arrangement, the distance between adjacent SiPMs can be appropriately increased, thereby improving the spatial resolution while reducing the occurrence of optical crosstalk.

[0060] The size of the pixel array composed of multiple SiPMs can be determined according to actual needs. In some embodiments, the value of M ranges from 2 to 5, that is, the pixel array can include 2 to 5 rows of SiPMs. The value of N can be adjusted according to needs, for example, it can be 2 times, 4 times, 6 times, 8 times or 10 times M, etc. The embodiments disclosed herein do not limit it.

[0061] The size, arrangement, and misalignment distance of SiPMs are closely related to the improvement in spatial resolution. For example, using smaller SiPMs can achieve a pixel array with a higher density; therefore, in some embodiments, the width of each silicon photomultiplier tube 21 is less than 1.8 mm in the first direction and less than 1.5 mm in the second direction. Furthermore, for two adjacent rows of pixels 20, a misaligned arrangement of some SiPMs results in a slightly lower spatial resolution compared to a misaligned arrangement of all SiPMs, but still higher. Figure 2B The alignment arrangement is shown. Unless otherwise specified, the embodiments and accompanying drawings of this disclosure are illustrated using a staggered arrangement of all SiPMs as an example.

[0062] In some embodiments, the gap between two adjacent silicon photomultiplier tubes 21 in the first direction is between 0.2 mm and 0.6 mm. The gap should not be too small or too large; too small a gap will cause optical crosstalk between two adjacent SiPMs, while too large a gap will hinder the improvement of spatial resolution. 0.2 mm to 0.6 mm is a better gap distance to match the current size of the silicon photomultiplier tubes 21. Similarly, in some embodiments, the gap between two adjacent rows of silicon photomultiplier tubes 21 in the second direction is between 0.1 mm and 0.4 mm to reduce optical crosstalk between adjacent rows of pixels 20.

[0063] In some embodiments, for any two adjacent rows of pixels 20, the j-th silicon photomultiplier tube 21 in the i-th row of pixels 20 is offset from the j-th silicon photomultiplier tube 21 in the (i+1)-th row of pixels 20 by the same distance in the first direction; 1≤i≤M-1, 1≤j≤N, and i and j are integers. This ensures that the offset distance between any row of SiPMs and their nearest neighbor SiPMs in the linear extension direction of the linear array detector is equal, thereby making the SiPM distribution density more uniform in the linear extension direction and further increasing the spatial resolution improvement factor of the linear array detector. In some embodiments, one way to achieve equal offset distances is to make the width of each silicon photomultiplier tube 21 equal in the first direction; for any row of pixels 20, the gap distance between two adjacent silicon photomultiplier tubes 21 is equal in the first direction.

[0064] The misalignment distance can be correlated with the width and gap distance of the silicon photomultiplier tube 21 to accommodate design requirements using SiPMs of different sizes. In some embodiments, the misalignment distance is equal to k1 / M times the pixel pitch of the silicon photomultiplier tube 21, where the pixel pitch is equal to the sum of the width of a single silicon photomultiplier tube 21 in the first direction and the gap distance between two adjacent silicon photomultiplier tubes 21 in the same row of pixels 20 in the first direction, and k1 ranges from 0.95 to 1.05. This creates a continuously covered, gapless sampling area, which can better improve the spatial resolution of the linear array detector.

[0065] The mathematical expression of the above pattern is as follows:

[0066] d eff =k1×D pixel / M=k1×(d pixel +d gap ) / M (1)

[0067] In the above formula:

[0068] d eff The misalignment distance is equivalent to the effective pixel spacing after misalignment.

[0069] D pixel The pixel spacing between two adjacent silicon photomultiplier tubes 21 in a row of pixels 20;

[0070] d pixel The width of a single SiPM (pixel 20) in the first direction, such as Figure 1A or Figure 1B As shown;

[0071] d gap The distance between two adjacent SiPMs in the same row of 20 pixels, such as Figure 1A or Figure 1B As shown;

[0072] k1 is a correction coefficient to accommodate different needs; under normal circumstances, k1 is usually set to 1.

[0073] Taking an M×N pixel array and k1=1 as an example, after applying the above misalignment distance, the misalignment offset of pixel 20 in the i-th row relative to the first row is Δx. i for:

[0074] Δx i =[(i-1) / M]×(d pixel +d gap (2)

[0075] The value of i ranges from 2 to M.

[0076] Correspondingly, the spatial resolution improvement factor R is:

[0077] R = d pixel / d eff (3)

[0078] Further research shows that the size and position of the scintillation crystal 22 also affect the further improvement of spatial resolution, so it is necessary to constrain it.

[0079] On one hand, in some embodiments, for any two adjacent rows of pixels 20, the orthographic projections of all scintillation crystals 22 in the (i+1)th row of pixels 20 onto the reference plane do not intersect with the orthographic projections of all scintillation crystals 22 in the ith row of pixels 20 onto the reference plane; the reference plane is a plane extending along the first direction and perpendicular to the circuit board 10. The reference plane can be selected according to the actual situation; for example, it can be a wall of the housing in the X-ray array detector, which is perpendicular to the circuit board 10, and the intersection line of the wall and the plane where the circuit board 10 is located is parallel to the first direction, or parallel to any row of pixels 20. No intersection of orthographic projections means that the projected patterns of scintillation crystals 22 in adjacent rows do not overlap in the first direction, thus increasing the arrangement density of scintillation crystals 22 in the first direction, which can increase the photon detection density for a one-dimensional linear array detector. A better approach is to ensure that the orthographic projections of all rows of scintillation crystals 22 onto the reference plane do not intersect; in other words, when the observation direction is the same as the second direction, all scintillation crystals 22 in the array can be seen on the observation side. This allows for higher density photon detection, which further improves spatial resolution.

[0080] On the other hand, in some embodiments, please refer to Figure 4The silicon photomultiplier tube 21 includes an effective region AA and a peripheral region ZA surrounding the effective region AA. The orthographic projection of the scintillation crystal 22 onto the silicon photomultiplier tube 21 is located within the effective region AA. The orthographic projection being located within the effective region AA ensures that the width of the scintillation crystal 22 in the first direction does not exceed the width of the effective region AA of the SiPM in the first direction, i.e., it is narrower than the width of the SiPM in the first direction. This increases the arrangement density of the scintillation crystals 22 in the first direction while maintaining the spacing between adjacent scintillation crystals 22 in a row of pixels 20, thereby increasing the photon detection density while reducing optical crosstalk.

[0081] In some embodiments, the width of each scintillation crystal 22 in the first direction is equal to k² / M times the pixel pitch, where k² ranges from 0.8 to 1.0. This quantitative relationship regarding the width of the scintillation crystal 22 takes into account both assembly errors and imaging requirements, and can further improve the spatial resolution of the linear array detector.

[0082] The mathematical expression for the aforementioned width is as follows:

[0083] w cry =k2×(d pixel +d gap ) / M (4)

[0084] In the above formula, k2 is equivalent to the safety factor, which is used to reserve assembly tolerances and improve the yield of finished products.

[0085] The width of the scintillation crystal 22 in the second direction can be designed according to actual needs, as long as it does not exceed the width of the SiPM effective region AA in the second direction. The height of the scintillation crystal 22 is designed according to the X-ray detection requirements, and this disclosure does not limit it.

[0086] To illustrate the above scheme more intuitively, the following embodiments will use a linear array detector of a SiPM array with M=4 and N=16 as an example. The silicon photomultiplier tube 21 used is as follows: Figure 5A and Figure 5B As shown, Figure 5A This is a top view of the silicon photomultiplier tube 21, showing its width d in the first direction. pixel The width l in the second direction is 1.80 mm, and the width l in the second direction is 1.50 mm. Figure 5B for Figure 5A The left view shows a SiPM with a height or thickness h of 0.65 mm, making it one of the smallest existing SiPMs. A schematic diagram of the silicon photomultiplier tube array 21 can be found in [reference needed]. Figure 6A Adjacent rows are offset by the same distance d eff The crystals are misaligned. The scintillation crystal 22 uses LYSO crystals, cut into thin strips through sub-millimeter processing, and arranged along the first direction, i.e., the row direction of the array, forming a staggered arrangement. Figure 6B The scintillation crystal array 22 shown is coupled 1:1 with the silicon photomultiplier tube 21 to obtain a 4×16 pixel array. A top view of this pixel array is shown below. Figure 6C As shown, the front view is as follows Figure 6D As shown, the main view is as follows Figure 6E As shown.

[0087] Based on the width d of SiPM in the first direction pixel =1.80mm and the gap distance d between two adjacent SiPMs in the same row of 20 pixels. gap =0.20mm and k1=1, the misalignment distance d of SiPM can be calculated using Equation 1. eff :

[0088] d eff = (1.80 + 0.20) / 4 = 0.50 mm.

[0089] According to Equation 2, the offset of each row of SiPM relative to the first row of SiPM, starting from the second row, can be calculated:

[0090] Line 2: Δx2=[(2-1) / 4]×(1.80+0.20)=0.50mm;

[0091] Line 3: Δx3=[(3-1) / 4]×(1.80+0.20)=1.00mm;

[0092] Line 4: Δx4=[(4-1) / 4]×(1.80+0.20)=1.50mm.

[0093] The width of the scintillation crystal 22 in the first direction can be determined according to equation 4), where k2 is 0.9.

[0094] w cry =0.9×(1.80+0.20) / 4=0.45mm, the width of the scintillation crystal is 0.45mm.

[0095] The width l of the scintillation crystal 22 in the second direction cry The size of the effective region AA of SiPM can be similar, for example, it can be processed to about 1.0mm. The height of the scintillation crystal 22 is designed according to actual needs, for example, it can be processed to about 2mm.

[0096] from Figure 6D As can be seen, the staggered arrangement of the four rows of pixels 20 ensures that all the scintillation crystals 22 do not overlap in the vertical space extending along the first direction, which can significantly improve the spatial resolution of the linear array detector.

[0097] The equivalent pixel spacing and misalignment distance d of the linear array detector after misalignmenteff The same, i.e., 0.50mm, thus achieving sub-millimeter level spatial resolution. According to Equation 3, the effective resolution improvement rate after misalignment is 3.6 times compared to the normal arrangement.

[0098] Therefore, the linear array detector provided in the above embodiments has the following characteristics:

[0099] 1) Currently, due to process limitations, the size of the pixel 20 (SiPM) cannot be significantly reduced, resulting in a large pixel pitch and the inability to further improve the spatial resolution. This disclosure overcomes the limitation of the physical pixel size of SiPM by optimizing the coupling between the multi-row staggered arrangement and the size of the scintillation crystal 22, and significantly improves the spatial resolution of the linear array detector.

[0100] 2) While maintaining the existing SiPM process level, the linear array detector achieves sub-millimeter spatial resolution through geometric structure and arrangement innovation. Compared with the solution of reducing the SiPM package size by modifying the nanoscale SiPM process, the cost of the staggered layout solution is significantly reduced.

[0101] 3) The linear array detector provided in this disclosure can directly replace the traditional linear array detector without modifying the existing electronic system, and has good application advantages.

[0102] Based on the same inventive concept, in a second aspect, in some optional embodiments, a computed tomography (CT) device is provided, including the linear array detectors provided in the first aspect embodiment. The computed tomography device can be a medical CT system or an industrial CT system; one optional application is to use multiple linear array detectors to form a detector array for the CT system.

[0103] Based on the same inventive concept, in a third aspect, in some optional embodiments, a projection imaging device is provided, including the linear array detector provided in the first aspect embodiment. An X-ray projection imaging device is a device that uses X-rays to penetrate objects and generate images, primarily used in medical and industrial fields. It irradiates an object with X-rays and then uses the information from the X-rays penetrating the object to form an image on a detector. Examples include industrial X-ray inspection equipment, security inspection equipment, and bone densitometers. One optional application is to use a linear array detector as the detector in industrial X-ray inspection equipment, security inspection equipment, and bone densitometers.

[0104] Thanks to the linear array detector provided in this disclosure, spatial resolution can be improved without further reducing the physical size of the SiPM. Therefore, CT equipment and projection imaging equipment using the linear array detector provided in this disclosure can have higher resolution while controlling costs.

[0105] Although preferred embodiments of the present disclosure have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this disclosure.

[0106] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, this disclosure is also intended to include such modifications and variations.

Claims

1. A linear array detector, characterized by, It includes a circuit board and a plurality of pixels disposed on the circuit board; the plurality of pixels are arranged in N columns along a first direction and in M ​​rows along a second direction, where N>M≥2 and N and M are integers, and the first direction and the second direction intersect. Each pixel includes a silicon photomultiplier tube and a scintillation crystal coupled to the silicon photomultiplier tube, the scintillation crystal being used to convert X-rays into scintillation light; in any two adjacent rows of pixels, at least some of the silicon photomultiplier tubes are staggered in the first direction.

2. The linear array detector of claim 1, wherein, For any two adjacent rows of pixels, the j-th silicon photomultiplier tube in the i-th row of pixels is offset from the j-th silicon photomultiplier tube in the (i+1)-th row of pixels by the same distance in the first direction; 1≤i≤M-1, 1≤j≤N, and i and j are integers.

3. The linear array detector of claim 2, wherein, The misalignment distance is equal to k1 / M times the pixel pitch of the silicon photomultiplier tube. The pixel pitch is equal to the sum of the width of a single silicon photomultiplier tube in the first direction and the gap distance between two adjacent silicon photomultiplier tubes in the same row of pixels in the first direction. The value of k1 ranges from 0.95 to 1.

05.

4. The linear array detector of claim 3, wherein, The width of each of the scintillation crystals in the first direction is equal to k2 / M times the pixel pitch, where k2 ranges from 0.8 to 1.

0.

5. The linear array detector of claim 2, wherein, For any two adjacent rows of pixels, the orthographic projection of all scintillation crystals in the (i+1)th row of pixels onto the reference plane has no intersection with the orthographic projection of all scintillation crystals in the ith row of pixels onto the reference plane. The reference plane is a plane that extends along a first direction and is perpendicular to the circuit board.

6. The linear array detector of claim 1, wherein, The silicon photomultiplier tube includes an effective region and a peripheral region surrounding the effective region, and the orthogonal projection of the scintillation crystal onto the silicon photomultiplier tube is located within the effective region.

7. The linear array detector of claim 1, wherein, Each of the silicon photomultiplier tubes has a width of less than 1.8 mm in the first direction and a width of less than 1.5 mm in the second direction; in any row of pixels, the gap between two adjacent silicon photomultiplier tubes in the first direction is between 0.2 mm and 0.6 mm.

8. The linear array detector of claim 1, wherein, The silicon photomultiplier tube is used to convert the scintillation light into an electrical signal; the circuit board includes a conversion circuit and a measurement circuit, the input terminal of the conversion circuit is connected to the silicon photomultiplier tube, and the output terminal is connected to the measurement circuit; the conversion circuit is used to convert the electrical signal into a pulse width signal and output it, and the measurement circuit is used to obtain photon energy information based on the pulse width signal.

9. A computed tomography apparatus, characterized by Includes the linear array detector as described in any one of claims 1 to 8.

10. A projection imaging apparatus, characterized by comprising: Includes the linear array detector as described in any one of claims 1 to 8.

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