Medical imaging equipment, collimator and processing method thereof

Abstract

The invention relates to medical imaging equipment, a collimator and a processing method of the collimator. As the two adjacent rows of collimation holes of the collimation body are arranged in a staggered manner, if a cross splicing method in the prior art is adopted, splicing seams are formed in the collimation holes, so that parts of the collimation holes are shielded by the splicing seams, or the splicing seams are formed between the two collimation holes, so that the thickness of a partition plate between the two collimation holes is increased; therefore, part of gamma photons capable of entering the collimation hole are blocked, the sensitivity of the part is reduced, and the uniformity of the collimator is influenced. According to the invention, the splicing edge of the collimator is designed, so that in the collimator formed by splicing, the splicing seam is located in the collimation hole, although the splicing seam is formed in the collimation hole, the equivalent aperture of the collimation hole at the splicing seam is not changed, namely the effective aperture is not changed, so that the counting of gamma photons entering the collimation holes is consistent, and the accuracy of the gamma photons entering the collimation holes is improved. Therefore, the uniformity of the collimator can be ensured, and the image quality is further ensured.

Description

Technical Field

[0001] This application relates to the field of medical imaging technology, and in particular to medical imaging equipment, collimators and their manufacturing methods. Background Technology

[0002] SPECT (Single Photon Emission Computed Tomography) is a nuclear medicine imaging technique used to generate three-dimensional images of the distribution of radioactive isotopes within the body. SPECT technology combines radioactively labeled tracers, a gamma camera, and computer image processing techniques to diagnose and monitor a variety of diseases.

[0003] In SPECT, the collimator's function is to ensure that each scintillator pixel receives gamma photons from its corresponding region while blocking gamma photons from outside the field of view from entering that scintillator pixel. The collimator's manufacturing accuracy has a significant impact on the system's imaging performance and directly determines the quality of the final image.

[0004] Manufacturing large-sized collimators in a single process is difficult, so they are generally manufactured in sections and then spliced ​​together. In related technologies, uneven seams between the collimators affect their uniformity, thus impacting image quality. Summary of the Invention

[0005] Therefore, it is necessary to provide a collimator processing method to address the problem of existing collimator processing methods affecting the uniformity of the collimator.

[0006] A method for manufacturing a collimator, the method comprising:

[0007] Multiple collimators are obtained, wherein the included angle between the first splicing edge and the second splicing edge of the collimator is an acute angle or an obtuse angle; wherein each collimator is provided with multiple rows of collimation holes, and adjacent rows of collimation holes are arranged alternately.

[0008] The collimators are divided into pairs, and the first splicing edges of two collimators in the same group are spliced ​​together to form a collimation module with a first splice.

[0009] The second splicing edges of two adjacent collimation modules are spliced ​​together to form a collimator with a second splice; wherein the first splice and the second splice are respectively located in the collimation holes at corresponding positions, and the equivalent aperture of the collimation hole in the splice area is equal to the aperture of the collimation hole in the non-sponge area.

[0010] In one embodiment, the step of obtaining multiple collimators includes: determining the cross-sectional area of ​​the collimating hole in the spliced ​​region based on the cross-sectional area of ​​the collimating hole in the non-splicing region.

[0011] In one embodiment, the side length of the aligning hole in the seam area is greater than the side length of the aligning hole in the non-seam area.

[0012] In one embodiment, the first seam and the second seam respectively divide the collimation hole at the corresponding position into two equal parts.

[0013] In one embodiment, at least a portion of the extension direction of the first seam intersects the depth direction along the depth direction of the collimating hole;

[0014] Along the depth direction of the collimating hole, at least a portion of the extension direction of the second joint intersects the depth direction of the hole.

[0015] In one embodiment, at least one of the first seam and the second seam is oblique along the depth direction of the collimating hole; or, at least one of the first seam and the second seam is stepped.

[0016] In one embodiment, the step of obtaining a plurality of collimators includes:

[0017] Establish a 3D model of the collimator;

[0018] Based on the 3D model of the collimator, the collimator is sintered into shape using selective laser sintering.

[0019] In one embodiment, the step of sintering the collimator into shape using selective laser sintering based on the 3D model of the collimator includes:

[0020] Depositing fusible powder onto a forming plate;

[0021] The laser beam's trajectory is controlled based on data from the 3D model to scan and melt fusible powder.

[0022] Adjust the intensity of the laser beam to sinter and solidify the fusible powder within a preset layer height range.

[0023] A collimator is manufactured using the collimator manufacturing method described above.

[0024] A medical imaging device includes a detector and a collimator as described above.

[0025] The aforementioned collimator manufacturing method, due to the staggered arrangement of adjacent rows of collimating holes in the collimator, results in seams forming within the collimating holes if the existing cross-stitching method is used. This causes partial obstruction of the collimating holes, or seams forming between two collimating holes, increasing the thickness of the partition between them. Consequently, some gamma photons that could enter the collimating holes are blocked, leading to decreased sensitivity and affecting the uniformity of the collimator. This application, however, designs the stitching edges of the collimator so that the seams are located within the collimating holes. Although the seams are formed within the collimating holes, the equivalent aperture of the collimating holes at the stitching points remains unchanged, i.e., the effective aperture remains unchanged. Therefore, the gamma photon count entering each collimating hole is consistent, ensuring the uniformity of the collimator and thus guaranteeing image quality. Attached Figure Description

[0026] Figure 1 This is a top view of a collimator in the prior art.

[0027] Figure 2 This is a side view of the response of a collimator in the prior art to a uniform source.

[0028] Figure 3 This is a side view of the response of a collimator in the prior art to a uniform source.

[0029] Figure 4 This is a top view of a collimator provided in an embodiment of this application.

[0030] Figure 5 for Figure 4 The collimator shown is shown in a side view of its response to a uniform source.

[0031] Figure 6 for Figure 4 The collimator shown is a split top view.

[0032] Figure 7 for Figure 6 A schematic diagram of one of the collimators shown.

[0033] Figure 8A for Figure 6 A schematic diagram of the collimation hole in the non-seam region of the collimator shown.

[0034] Figure 8B for Figure 6 A schematic diagram of the alignment holes in the seam area of ​​the collimator shown.

[0035] Figure 9A for Figure 8A A schematic diagram of the collimation hole in the non-seam region of the collimator shown.

[0036] Figure 9B for Figure 8B A schematic diagram of the alignment holes in the seam area of ​​the collimator shown.

[0037] Figure 10 A side view of the seam in the collimator provided in the first embodiment.

[0038] Figure 11 A side view of the seam in the collimator provided for the second embodiment.

[0039] Figure 12 This is a schematic diagram of a collimator manufacturing method provided in an embodiment of this application.

[0040] Reference numerals: 100, collimator; 110, collimator body; 111, collimation aperture; 112, first splicing edge; 113, second splicing edge; 114, partition; 120, first seam; 130, second seam; 200, detector crystal; 300, uniform source; 400, projection. Detailed Implementation

[0041] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0042] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0043] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0044] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0045] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0046] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0047] SPECT is a mature imaging technology in the field of nuclear medicine and is widely used in clinical testing. For a SPECT system, the collimator is a key component, determining many performance indicators. In terms of morphology, collimators include: parallel aperture collimators, fan-shaped beam aperture collimators, tapered beam aperture collimators, and pinhole collimators. In terms of energy, there are low-energy, medium-energy, and high-energy collimators. The machining accuracy of the collimator has a significant impact on the system's imaging performance. Common dual-probe SPECT systems are generally equipped with parallel aperture collimators, typically approximately 500mm x 500mm in size. Manufacturing collimators of this size in a single operation is difficult; machining them in sections and then splicing them together is easier, but common splicing methods can easily cause changes in the aperture morphology at the splicing points.

[0048] For example Figure 1The collimator shown is composed of four small collimating bodies spliced ​​together, with a central crosshair forming the seam. The shape of the collimating hole 111 at the seam differs from other parts, as shown in the first row of collimating holes 111. The seam is formed within the collimating hole 111, and part of the collimating hole 111 is obscured by the seam. Figure 2 It can be seen that the uniform source 300 is above the partition 114, and the gap between the partitions 114 is the gap of the collimating aperture 111. Below the partition 114 is the detector crystal 200 and the projection 400 of the uniform source 300 onto the detector crystal 200. It can be seen that due to the obstruction of the seam, the gamma photon count entering the collimating aperture 111 decreases, and the uniformity of the collimator 100 decreases. In the second row of collimating apertures 111, the seam is formed between two collimating apertures 111, resulting in an increase in the thickness of the partition 114 between the two collimating apertures 111. Figure 3 As shown, the increased thickness of the partition 114 obstructs part of the gaps in the collimation holes on both sides of the partition 114, blocking some gamma photons that could enter the two adjacent collimation holes 111, resulting in a decrease in the uniformity of the collimator 100. Taking a hexagonal parallel-hole collimator as an example, according to the collimator sensitivity calculation formula:

[0049] , ;

[0050] Where d is the aperture, t is the partition thickness, a is the aperture length, and μ is the pore length. C Let be the linear attenuation coefficient of the collimator material for gamma photons. It can be seen that if the seam is formed within the collimator aperture, the effective aperture diameter d decreases, obviously leading to a decrease in sensitivity; if the seam is formed between two collimator apertures, the partition thickness t increases, also leading to a decrease in sensitivity. Therefore, the existing collimator manufacturing method has the problem of affecting the uniformity of the collimator. Based on this, an embodiment of this application provides a collimator processing method that can solve the above problems. The collimator processing method provided by an embodiment of this application will be described in detail below with reference to the accompanying drawings.

[0051] See Figure 4 , Figure 6 , Figure 7 and Figure 12 As shown, a method for processing a collimator 100 provided in one embodiment of this application includes:

[0052] Step S100: Obtain multiple collimators 110 such that the included angle between the first splicing edge 112 and the second splicing edge 113 of the collimator 110 is an acute angle or an obtuse angle; wherein, each collimator 110 is provided with multiple rows of collimation holes 111, and adjacent rows of collimation holes 111 are arranged alternately.

[0053] The collimator 110 can be manufactured using 3D printing. The steps for 3D printing the collimator 110 include: Step S110, firstly, establishing a 3D model of the collimator 110. Specifically, the cross-sectional area of ​​the collimator hole at the splicing edge can be determined based on the cross-sectional area of ​​the collimator hole at the non-splicing edge, thereby determining the size of the collimator hole 111 at the splicing edge, and then using computer 3D modeling software to establish a 3D model of the collimator 110.

[0054] After establishing the 3D model of the collimator 110, the process further includes step S120, whereby the collimator 110 is sintered into shape using selective laser sintering (SLS) based on the 3D model. It is understood that selective laser sintering is typically performed in a helium-filled inert gas processing chamber. In this embodiment, specifically, a very thin layer of fusible powder is first deposited onto a forming plate, which can move vertically up and down; then, a computer controls the trajectory of a carbon dioxide laser beam according to the data from the 3D model to scan and melt the fusible powder; finally, the laser beam intensity is adjusted to sinter and solidify the fusible powder within a preset layer height range.

[0055] In this way, as the laser beam scans and moves along a given path, it sinters the powder in the area it passes through, thereby generating individual cross-sections of the collimator 110. In selective laser sintering, each layer is sintered on top of the previous layer, ensuring a strong bond between the current layer and the previous one. After the collimator 110 is sintered, unsintered powder can be removed using a brush or compressed air. The soluble powder materials used in selective laser sintering typically include nylon, wax, ABS, resin-coated sand (coated sand), polycarbonates, metals, and ceramics. In this embodiment, the sintering material used in selective laser sintering is a metal, such as tungsten.

[0056] Of course, in addition to using the 3D printing method described in the above embodiments to process the collimator 110, the collimator 110 can also be formed by injection molding.

[0057] After obtaining multiple collimators 110, the method further includes step S200, which divides the multiple collimators 110 into pairs, and splices the first splicing edges 112 of the two collimators 110 in the same group to form a collimation module with a first splice 120.

[0058] See Figure 4 , Figure 6 , Figure 7As shown, in this embodiment, there are four collimators 110. Each collimator 110 has a first splicing edge 112 and a second splicing edge 113 with acute or obtuse angles. By dividing the collimators 110 into pairs and splicing the first splicing edges 112 of two collimators 110 together, a complete collimation aperture 111 is formed at the first seam 120. That is, the first seam 120 is located within the collimation aperture 111, but the equivalent aperture of the collimation aperture 111 in the first seam 120 region is still equal to the aperture of the collimation aperture 111 in the non-splicing region, that is, the effective aperture remains unchanged. Therefore, the gamma photon count entering each collimation aperture 111 is consistent. The first splicing edges 112 of two collimators 110 in the same group can be connected by adhesive.

[0059] In step S300, the second splicing edges 113 of two adjacent collimation modules are spliced ​​together to form a collimator 100 with a second seam 130. The second splicing edges 113 of the collimation modules can be connected using adhesive. See also... Figure 4 , Figure 6 , Figure 7 As shown, the second seam 130 is also located within the collimation aperture 111. Since the equivalent aperture of the collimation aperture 111 in the second seam 130 region is equal to the aperture of the collimation aperture 111 in the non-seam region, i.e., the effective aperture remains unchanged, the gamma photon count entering each collimation aperture 111 is consistent. Furthermore, as can be seen from the aforementioned empirical formula, the first seam 120 and the second seam 130 are not formed between the two collimation apertures 111. Therefore, the thickness t of the partition 114 remains unchanged, and since the equivalent aperture d remains unchanged, the sensitivity of the collimation aperture 111 in the seam region remains unchanged. This ensures the uniformity of the collimator 100, thereby guaranteeing image quality.

[0060] In one embodiment, the cross-sectional area of ​​the collimation aperture 111 in the seam region is equal to the cross-sectional area of ​​the collimation aperture 111 in the non-seam region. Since the cross-sectional area of ​​each collimation aperture 111 is the same, the gamma photon count entering each collimation aperture 111 is consistent, thus ensuring the uniformity of the collimator 100.

[0061] like Figure 8A and Figure 8B As shown, in one embodiment, the side length of the collimation hole 111 in the seam area is greater than the side length of the collimation hole 111 in the non-seam area. Understandably, taking a regular hexagonal hole as an example, this side length is the side length of the hexagon. By processing the collimation hole 111 at the seam edge, the half-hole is elongated, thereby making its equivalent aperture equal to the aperture of the non-seam area, thus ensuring that the sensitivity of the collimation hole 111 in the seam area remains unchanged and ensuring the uniformity of the collimator 100.

[0062] When the collimating hole 111 is not a circular hole, the area of ​​a circular hole can be equivalently derived from the area of ​​the collimating hole 111 (non-circular hole), and the diameter of this circular hole is the equivalent aperture. For example... Figure 9A and Figure 9B As shown, taking the collimation hole 111 as an example of a regular hexagonal hole, with a side length of S, then... Figure 9A The area of ​​the triangle shown is:

[0063]

[0064] In order to keep the areas equal, Figure 9A The area of ​​the triangle shown is Figure 9B The rectangles shown have equal areas, thus allowing us to... Figure 9B The area of ​​the rectangle shown (i.e. Figure 9A (area of ​​the triangle shown) and Figure 9B Given the length of the rectangle shown, calculate the width x of the rectangle:

[0065]

[0066] The dimensions of the elongation treatment for the collimation hole in the splicing area can be determined based on the width x of the rectangle.

[0067] In one embodiment, the first seam 120 and the second seam 130 respectively divide the collimation holes 111 at corresponding positions into two equal parts. That is, the collimation holes 111 on each collimator 110 located in the splicing edge region are half-holes. By setting the collimation holes 111 in the splicing edge region as half-holes, it is more convenient to process multiple collimators 110. In other embodiments, the division may not be two equal parts. For example, the collimation holes 111 at the splicing edge of one collimator 110 may account for one-third, and the collimation holes 111 at the splicing edge of another collimator 110 may account for two-thirds, etc.

[0068] like Figure 10 As shown, in one embodiment, at least a portion of the extension direction of the first seam 120 intersects the depth direction along the depth direction of the collimating aperture 111; at least a portion of the extension direction of the second seam 130 intersects the depth direction along the depth direction of the collimating aperture 111. That is, the thickness of the partitions 114 at the splicing edges is inconsistent vertically, so the thicker partition 114 can block the thinner partition 114, thereby preventing gamma photons from entering the crystal through the gaps at the first seam 120 or the second seam 130, reducing the possibility of affecting image quality.

[0069] Specifically, such as Figure 10As shown, along the depth direction of the aligning hole 111, at least one of the first seam 120 and the second seam 130 is oblique. For example, in this embodiment, both the first seam 120 and the second seam 130 are oblique. In other embodiments, such as... Figure 11 As shown, along the depth direction of the collimation hole 111, at least one of the first seam 120 and the second seam 130 can also be stepped. For example, in this embodiment, both the first seam 120 and the second seam 130 are stepped. This arrangement blocks gamma photons and prevents them from entering the crystal through the gaps at the first seam 120 or the second seam 130, thereby reducing the possibility of gamma photons affecting image quality.

[0070] Furthermore, one embodiment of this application also provides a collimator 100, which is manufactured using the collimator 100 manufacturing method described above. Figure 4 As shown, the collimator 100 is composed of multiple collimating bodies 110 spliced ​​together. Each collimating body 110 has multiple rows of collimating holes 111, with adjacent rows of collimating holes 111 arranged alternately. The seams on the collimator 100 can be zigzag-shaped, with each seam located within a collimating hole 111. The effective aperture of the collimating hole 111 in the seam area is equal to the aperture of the collimating hole 111 in the non-seam area, meaning the effective aperture remains unchanged. Therefore, the gamma photon count entering each collimating hole 111 is consistent, and the sensitivity of the collimating holes 111 in the seam area and the non-seam area is consistent, thus ensuring the uniformity of the collimator 100 and consequently guaranteeing image quality.

[0071] Furthermore, one embodiment of this application also provides a medical imaging device (not shown), including a detector and a collimator 100 as described above. The collimator can be located between the object to be scanned and the detector, so that effective rays from the object to be scanned can pass through the collimation aperture and irradiate the detector. By controlling the gamma photon count entering each collimation aperture to be consistent through the collimator, image uniformity is ensured, thereby ensuring image quality.

[0072] In a specific application scenario, medical imaging equipment can be SPECT (Single Photon Emission Computed Tomography). A radioactive tracer is introduced into the body of the subject to be scanned, for example, through injection, oral administration, or inhalation. After the radioactive tracer reaches the tomographic location to be imaged, it emits gamma photons from the tomographic location due to radioactive decay. The gamma photons emitted by the radioactive tracer are detected by a detector (e.g., a gamma camera). With the help of computer algorithms, the data detected by the detector is reconstructed into a three-dimensional image, showing the metabolic activity of the examined organ or tissue, and realizing the clinical imaging interpretation of nuclear medicine.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for processing a collimator, characterized in that, The collimator manufacturing method includes: Multiple collimators (110) are obtained, wherein the included angle between the first splicing edge (112) and the second splicing edge (113) of the collimator (110) is an acute angle or an obtuse angle; wherein each collimator (110) is provided with multiple rows of collimation holes (111), and adjacent rows of collimation holes (111) are arranged alternately; The collimators (110) are divided into pairs, and the first splicing edges (112) of the two collimators (110) in the same group are spliced ​​together to form a collimation module with a first splice (120); The second splicing edges (113) of two adjacent collimation modules are spliced ​​together to form a collimator with a second splice (130); wherein the first splice (120) and the second splice (130) are respectively located in the collimation hole (111) at the corresponding position, and the equivalent aperture of the collimation hole (111) in the splice area is equal to the aperture of the collimation hole (111) in the non-sponge area.

2. The method for processing the collimator according to claim 1, characterized in that, The step of obtaining multiple collimators (110) includes: determining the cross-sectional area of ​​the collimator (111) in the joint area based on the cross-sectional area of ​​the collimator (111) in the non-joint area.

3. The method for processing the collimator according to claim 1, characterized in that, The side length of the collimation hole (111) in the seam area is greater than the side length of the collimation hole (111) in the non-seam area.

4. The method for processing the collimator according to claim 1, characterized in that, The first seam (120) and the second seam (130) respectively divide the collimation hole (111) at the corresponding position into two equal parts.

5. The method for processing the collimator according to claim 1, characterized in that, Along the depth direction of the aligning hole (111), at least a portion of the extension direction of the first joint (120) intersects the depth direction; Along the depth direction of the collimating hole (111), at least part of the extension direction of the second joint (130) intersects the depth direction.

6. The method for processing the collimator according to claim 5, characterized in that, Along the depth direction of the collimating hole (111), at least one of the first joint (120) and the second joint (130) is oblique; or, at least one of the first joint (120) and the second joint (130) is stepped.

7. The method for processing the collimator according to claim 1, characterized in that, The step of obtaining multiple collimators (110) includes: Establish a 3D model of the collimator (110); Based on the 3D model of the collimator (110), the collimator (110) is sintered using selective laser sintering.

8. The method for processing the collimator according to claim 7, characterized in that, The steps of sintering the collimator (110) into shape using selective laser sintering based on the 3D model of the collimator (110) include: Depositing fusible powder onto a forming plate; The laser beam's trajectory is controlled based on data from the 3D model to scan and melt fusible powder. Adjust the intensity of the laser beam to sinter and solidify the fusible powder within a preset layer height range.

9. A collimator, characterized in that, It is manufactured using the collimator manufacturing method described in any one of claims 1 to 8.

10. A medical imaging device, characterized in that, It includes a detector and a collimator as described in claim 9.

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