Design method of 3D printing implant guide plate and 3D printing implant guide plate

Abstract

The application discloses a design method of a 3D printing implant guide plate and the 3D printing implant guide plate. The design method comprises the following steps: 1) individual modeling of the implant guide plate based on CT / MRI image data of a patient, wherein the implant guide plate comprises a columnar implant and positioning support plates integrally arranged on both sides of the root of the columnar implant; 2) determination of a feasible solution space and generation of multiple groups of straight needle channel designs; 3) redesign of the straight needle channels that generate interference into arc-shaped needle channels; 4) dose optimization of the multiple groups of needle channel designs to select a group of needle channel designs with the optimal dose volume; and 5) 3D printing of the implant guide plate according to the shape parameters and the optimal group of needle channel designs. The application avoids the part of organs through the arc-shaped needle channel design, and the multiple groups of straight needle channels are reserved, so that the effective needle channel design in the front part is effectively avoided, and the main purpose of the arc-shaped needle channel is to reduce the area that cannot be avoided by the original straight needle channel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image processing, in particular to a design method of a 3D printed implantation guide plate based on gynecological tumor images and a 3D printed implantation guide plate. BACKGROUND

[0002] In the process of brachytherapy, the position of the radiation source needs to be kept relatively fixed, but the operation of patient transportation, CT scanning, connection of treatment pipeline, etc. is easy to cause the displacement of the applicator (hollow catheter) along the needle path, and then deviate from the preset radiation source track, affecting the treatment accuracy. The implantation guide plate needs to be fixed at a specific position before treatment, therefore, the structure design and needle path layout of the implantation guide plate are crucial to ensure the stability of the applicator, and the related research has clearly pointed out the technical points: such as Chino J et al. in The American Brachytherapy Society (ABS) consensus guidance for hybrid intracavitary interstitial brachytherapy for locally advanced cervical cancer (Brachytherapy, 2025, 24(4):463-78) emphasized that hybrid intracavitary interstitial brachytherapy needs to optimize the needle path design of the implantation guide plate to reduce the displacement of the applicator; Zhu X et al. in 3D-printed individual template brachytherapy for the treatment of intractable central pelvic recurrent cervical cancer: A single institution experience (Brachytherapy, 2024, 23(6):634-40) pointed out that the needle path adaptability of the individual guide plate directly affects the stability of the radiation source track; International Commission on Radiation Units and Measurements (ICRU) Report 89 (2013, 13(1-2)) also made clear requirements for the quality control of guide plate fixation and needle path design in brachytherapy.

[0003] In the prior art, Chinese patent CN112933428A discloses "a brachytherapy guide plate design method and a brachytherapy guide plate", which optimizes the radiation safety by eliminating the interference area (such as the vaginal wall, blood vessel area, part of the bladder wall and rectal wall) that cannot be avoided by the straight needle path, but still has the defects of insufficient applicator fixation stability and easy deviation of the radioactive source track, which cannot meet the precision requirements of brachytherapy.

[0004] Moreover, in actual treatment, it is also necessary to balance the protection of organs at risk, such as the bladder, rectum, etc., and to maintain the predetermined radiation dose to the tumor, and often conflicts that cannot be balanced and coordinated occur, which leads to damage to normal organs or incomplete elimination of tumors. SUMMARY

[0005] Therefore, the present application solves the problem of providing a design method for a 3D printed brachytherapy guide plate that can effectively balance the protection of organs at risk and the treatment effect based on image processing technology through computational simulation.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is:

[0007] A design method for a 3D printed brachytherapy guide plate, comprising the following steps,

[0008] 1) Individual modeling of the brachytherapy guide plate based on patient CT / MRI image data, the brachytherapy guide plate comprising a columnar implant and positioning support plates arranged on both sides of the root of the columnar implant;

[0009] 2) Determining the three-dimensional space needle path distribution and generating multiple sets of straight line needle path designs;

[0010] 3) Redesigning the straight line needle path that produces interference into an arc-shaped needle path, the arc-shaped needle path comprising at least one arc-shaped or curved needle path bending segment, and the needle path bending segment satisfying the minimum curvature radius limit to meet the applicator passability requirement;

[0011] 4) Selecting a set of needle path design with the optimal dose volume by dose optimization of multiple sets of needle path designs;

[0012] 5) 3D printing the brachytherapy guide plate according to the shape parameters and the set of needle path design with the optimal dose volume.

[0013] As one of the preferred schemes, the outer surface of the columnar implant in step 1) is provided with a groove for positioning a flexible radiation protection member on the side corresponding to the organ at risk (i.e. the side adjacent to the normal organs such as the bladder and rectum).

[0014] As one of the preferred schemes, a test optimization step is included before step 5), which includes,

[0015] 41) according to the optimal set of needle path design of the external shape parameters and dose volume, 3D printing a test product, and arranging a flexible protective element in the groove;

[0016] 42) performing a radiation dose test on the predetermined area of the test product and the outside of the flexible protective element;

[0017] 43) if the radiation dose of the predetermined area is less than the designed radiation dose, increasing the maximum dose limit of the corresponding area of the flexible protective element and re-updating the optimal set of needle path design according to step 4);

[0018] 44) repeating steps 41) to 43) until the dose of the predetermined radiation area is not less than the designed radiation dose.

[0019] As one of the preferred schemes, the radiation dose measurement in step 42) is performed by pasting radioactive measurement films on the predetermined area and the outside of the flexible protective element.

[0020] As one of the preferred schemes, the flexible protective element is composed of two or more layers of flexible radiation protection layers.

[0021] As one of the preferred schemes, the thickness of the flexible radiation protection layer is 0.1-0.3 mm, the number of layers is 2-10, and the adjacent flexible radiation protection layers are coated with adhesive.

[0022] As one of the preferred schemes, the inner wall of the needle path corresponding to the arc-shaped bending section is formed with convex patterns or convex points.

[0023] A 3D printed implant guide obtained by the design method, comprising a columnar implant and a positioning support plate, at least one needle path in the columnar implant comprises at least one arc-shaped or curved needle path bending section.

[0024] The present application has the advantages and positive effects that:

[0025] Compared with the prior art, the present application does not directly discard the straight needle path which interferes with the normal organs, but avoids the part of the organs through the arc-shaped needle path design containing the arc-shaped or curved needle path bending section, and retains multiple straight needle paths, which effectively avoids discarding effective needle path design in the front part. The main purpose of the arc-shaped needle path is to reduce the area that cannot be avoided by the original straight needle path, such as the vaginal wall, the blood vessel area, part of the bladder wall and the rectal wall, so as to reduce the side effects of the patient during the implantation process, including but not limited to bleeding, pain, bladder wall damage, rectal infection, etc. Among them, the arc-shaped or curved needle path bending section is introduced into the arc-shaped needle path design, which enhances the spatial distribution of the final needle angle, improves the adaptability of the needle path design to different shapes of tumors, facilitates the effective cooperation of multiple radiation points in space, and effectively improves the treatment effect. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and are intended to provide a further understanding of the application, and are made a part of the description. Embodiments of the application will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0027] Figure 1 is a structural schematic diagram of the implant guide of the present application in a first perspective view;

[0028] Figure 2 is Figure 1 is another perspective structural schematic diagram shown in the figure;

[0029] Figure 3 is a schematic diagram of a columnar implant cross section;

[0030] Figure 4 is a schematic diagram of an arc-shaped needle path, wherein the marked A part and the marked B part are schematic diagrams of straight needle paths in the prior art, and the marked C part is a schematic diagram of an arc-shaped needle path of the present application.

[0031] Reference signs:

[0032] 1, columnar implant; 2, positioning support plate; 10, straight needle path; 11, groove; 12, flexible protective piece; 13, arc-shaped needle path; 21, external genitalia profiling part; 22, buttocks profiling part; 3, applicator. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0034] First embodiment

[0035] A design method of a 3D-printed implant guide, comprising the following steps,

[0036] 1) individualized modeling of the implant guide based on patient CT / MRI image data, i.e. designing the shape parameters of the implant guide according to preoperative images, wherein the implant guide comprises a columnar implant 1 and a positioning support plate 2 integrally constructed or fixedly connected on both sides of the root of the columnar implant 1;

[0037] 2) determining three-dimensional space needle path distribution and generating multiple groups of straight needle path designs, which can generally be realized by dose optimization software to generate multiple groups of straight needle paths 10;

[0038] 3) the straight needle path that causes interference is redesigned as an arc needle path 13, which at least includes an arc (such as a circular arc) or a curved needle path bending section; the needle path bending section satisfies the minimum curvature radius limit to meet the applicator passability requirement, and the minimum curvature radius is generally greater than or equal to 5 mm;

[0039] 4) dose optimization is performed on multiple groups of needle path designs to select a group of needle path designs with optimal dose volume;

[0040] 5) according to the shape parameters and the group of needle path designs with optimal dose volume, a 3D printing implant guide plate is printed, and the specific feasible solution space and the straight needle path design are based on dose optimization, analysis of needle path spatial distribution, DVH (dose volume histogram), and the like, which is similar to the existing clinical existing brachytherapy planning system TPS (Treatment Planning System) technology, such as the commercial system Oncentra Brachy, which will not be described here. Only the improved part of the present application compared with the prior art is described.

[0041] Compared with the prior art, the present application does not directly discard the straight needle path that causes interference with normal organs, but avoids the part of the organ through the needle path design containing the arc or curved needle path bending section, and retains multiple groups of straight needle paths, which effectively avoids discarding effective needle path designs in the front part. The main purpose of the arc needle path is to reduce the area that cannot be avoided by the original straight needle path, such as the vaginal wall, the blood vessel area, part of the bladder wall and the rectal wall, so as to reduce the side effects of the patient during the implantation process, including but not limited to bleeding, pain, bladder wall damage, rectal infection, etc. Among them, the arc needle path bending section is introduced into the needle path design, which enhances the final needle angle spatial distribution and improves the adaptability of the needle path design to different shapes of tumors, facilitates the effective cooperation of multiple radiation points in space, and effectively improves the treatment effect.

[0042] The applicator 3 used in treatment is made of a medical polymer material with elasticity, such as polytetrafluoroethylene or polyurethane, which is a tubular structure with a closed end, and the open end is located at the root of the columnar implant, which is convenient for the insertion of the radioactive source for radiotherapy operation. Through the arc needle path design, as long as the designed bending angle is not less than the predetermined bending angle, the applicator can travel along the predetermined trajectory of the needle path. The straight needle path is designed as an arc needle path, which can be replaced manually or assisted by software. Here, it will not be described here.

[0043] Further, a convex pattern or convex point is formed on the inner wall of the needle channel corresponding to the arc-shaped bending section, or a convex pattern or convex point is arranged at the outlet of the needle channel, the convex point has a height of 0.1-0.3 mm and is distributed in a spiral shape with a spacing of 2-5 mm. The arrangement can increase the hand feeling when the applicator is inserted, increase the friction, effectively improve the positioning effect of the columnar implant on the applicator, and avoid displacement caused by the radioactive source.

[0044] In step 1), a groove 11 for positioning a flexible radiation-proof protective member is formed on the outer surface of the columnar implant on the side corresponding to the endangered organ, the groove is arranged towards the rectal anterior wall direction or the bladder posterior wall direction. One or two grooves 11 can be arranged according to different conditions, the depth of the groove is generally 2-10 mm, and is generally 2-5 mm. A flexible radiation-proof protective member 12 is fixed in the groove. The design of the flexible radiation-proof protective member on the columnar implant through the groove can directionally enhance the protection strength in this direction, and the closer to the needle channel, the stronger the shielding effect, and less flexible radiation-proof protective member is used to achieve a larger shielding range. Moreover, the overall volume does not increase, and the discomfort during treatment can be reduced to a certain extent. Moreover, the design position of the groove can be generated according to the actual position of the organ of different patients according to the CT scan result, that is, for patients with different body types and postures, the position of the groove and the size and shape of the groove can be appropriately adjusted according to the actual position of the organ.

[0045] Specifically, the thickness of the flexible radiation-proof protective member is 0.1-0.3 mm, and the thickness is generally 0.2-3 mm. The number of superimposed layers is 2-10, and the number of layers is generally 2-5. That is, a plurality of layers of materials are combined into a whole with a certain thickness through multi-layer bonding. The overall thickness is generally 2-5 mm, and the adjacent flexible radiation-proof layers are coated with adhesive. Experiments show that, compared with a single layer of flexible radiation-proof layer with the same thickness, when the number of superimposed layers is about 5, the radiation equivalent of about 8 Gy is reduced by more than 30%, and when the number of layers reaches 10, the shielding strength is more than 50%.

[0046] The flexible radiation-proof protective member can be made of diethylenetriamine pentaacetic acid material, and specific reference can be made to CN113321877B. In the embodiments of the present application, the flexible protective member is made of the above product. Of course, as long as the flexible radiation-proof material has a very thin thickness and has a radiation-proof effect, it can also achieve the technology of the present application.

[0047] Generally, the flexible protective member is combined in different specifications and thicknesses, and finally cut according to the shape and design thickness of the groove, and then adhered to the groove through the bottom adhesive.

[0048] Further, a pre-test optimization step before step 5) is included, which comprises,

[0049] 41) A test product is designed by 3D printing according to the external shape parameters and the optimal set of needle channels, and a flexible protective element is arranged in the groove;

[0050] 42) A radiation dose test is performed on the predetermined area of the test product and the outside of the flexible protective element;

[0051] 43) If the radiation dose of the predetermined area is less than the designed radiation dose and the radiation dose outside the flexible protective element is less than the radiation safety value (i.e. the maximum radiation dose that will not cause radiation damage to the corresponding normal organs), the maximum dose limit of the corresponding area of the flexible protective element is increased and the update of the optimal set of needle channel designs according to step 4) is performed again;

[0052] 44) Steps 41) to 43) are repeated until the radiation dose of the predetermined area is not less than the designed radiation dose and the radiation dose outside the flexible protective element is not greater than the radiation safety value.

[0053] In step 42), the radiation dose is measured by attaching radioactive measurement films to the predetermined area and the outside of the flexible protective element. The principle is that different intensities can form film development through X-ray exposure, and the total amount of X-rays can be calculated by the degree of development or shadow.

[0054] In actual treatment, the current general situation is that most patients do interstitial brachytherapy mainly because of the high rectal wall dose. In order to avoid excessive normal organ damage, it is easy to cause dose "cold area" in the tumor area, i.e. underdose, which may cause local tumor control rate to decrease, and ultimately lead to treatment failure or tumor recurrence. The present application measures the actual radiation dose outside the flexible protective element by setting the flexible protective element, which effectively calibrates the radiation scheme designed by computer based on image processing, effectively protects organs or tissues such as rectal wall, reduces rectal damage caused by excessive treatment, and improves local tumor control rate. In some cases, the conflict between treatment effect and normal organ protection can be balanced by matching a thicker flexible radiation protection layer to enhance the protection of organs at risk, and then appropriately increasing the maximum dose limit in the dose volume calculation.

[0055] Meanwhile, the present application also discloses a 3D printed interstitial guide plate prepared by the above design method, which comprises a columnar interstitial body and a positioning support plate, and at least one needle channel in the columnar interstitial body comprises at least one arc-shaped needle channel or a curved needle channel.

[0056] The implanting guide plate is integrally formed by polylactic acid (PLA) and copolymer 3D printing, and the overall weight is also lighter under the condition of ensuring the connection strength. The implanting guide plate comprises a columnar implant 1, positioning support plates 2 integrally constructed on both sides of the root of the columnar implant 1, the positioning support plates 2 comprise an external genitalia profiling part 21 and an anus profiling part 22, and the columnar implant 1 and the positioning support plates 2 are integrally formed by polylactic acid 3D printing, and the overall weight is also lighter under the condition of ensuring the connection strength.

[0057] The external genitalia profiling part 21 and the anus profiling part 22 can respectively provide protection and support for the external genitalia and the buttocks near the anus, so that the device can be clamped between the legs, and the contact surface is fitted with the external genitalia and the buttocks near the anus, so that the positioning support plates 2 are not easy to shake, thereby avoiding the problem of shaking of the columnar implant 1 in the body, and ensuring that the whole process is accurate and orderly. The shape of the positioning support plate is also based on the shape parameters obtained by different human body structures, and is formed by 3D printing, which has better personal adaptability. The external genitalia profiling part 21 is a ridge-shaped structure with high middle and inclined wings sinking downward, thereby fitting the contour of the external genitalia. The anus profiling part 22 is a petal-shaped structure and is uplifted away from the columnar implant 1, thereby fitting the contour of the buttocks near the anus. The cross-sectional area of the external genitalia profiling part 21 and the anus profiling part 22 increases away from the columnar implant 1, thereby fitting the contour structure of the lower body.

[0058] The direction, size, depth and the like of the groove 11 can be set according to the CT scanning results, image processing and the distribution position of other organs such as rectum, bladder and the like in the image, and the tolerance of each organ to radiation, so as to avoid the problem that the protection level is weakened due to the uniform distribution around, and to realize the key protection in the key direction.

[0059] Meanwhile, for the position of the lower half of the columnar implant, especially for the vaginal entrance part, a flexible radiation protection layer can be selected to cover the outer periphery, which covers the flexible protection layer in the groove, thereby improving the positioning effect.

[0060] In treatment, the 3D printed columnar implant 1 is placed in the vagina, the positioning support plate 2 is clamped between the legs, the contact surface is attached to the perianal near the buttocks, so that the device is not easy to shake; then the source applicator (hollow pipe) is inserted into the tumor through the needle channel designed in the columnar implant, then accurately positioned under the image guidance, and then the radioactive source is delivered into the source applicator 3 for irradiation through the afterloading technology. The covering area formed by the flexible protective part 12 on the columnar implant 1 shields the rays emitted by the radioactive source, avoids the rays emitted by the radioactive source from penetrating out to damage the normal organ tissues (such as rectum and bladder area), that is, the preset angle irradiation is formed; for the part outside the covering area, the rays emitted by the radioactive source can penetrate through the part and then be emitted into the tumor, and through the cooperation of the space radiation of multiple radioactive sources, the patient is accurately treated. In the whole process, as shown in Figure 4 , the arc-shaped needle design (as shown in the case of mark C part) Figure 4 can effectively avoid the direct damage of the straight needle (as shown in the case of mark A part and mark B part) Figure 4 to the vaginal wall or the bladder rectal wall, and significantly reduces the serious side effects (pain, bleeding, etc.) related to implantation.

[0061] The above describes the embodiments of the present application in detail, but the content described is only the preferred embodiments of the present application, and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made within the scope of the present application should still belong to the scope covered by the present application.

Claims

1. A method for designing a 3D-printed implant guide, characterized in that, The method comprises the following steps: 1) individual modeling of the implant guide based on CT / MRI image data of the patient, the implant guide comprising a columnar implant (1) and a positioning support plate (2) arranged on both sides of the root of the columnar implant (1); the outer surface of the columnar implant is provided with a groove for positioning a flexible radiation protection member on the side corresponding to the organ at risk; the positioning support plate (2) comprises a vulva profiling portion (21) and a buttock profiling portion (22), which respectively provide protection and support positioning for the buttocks near the vulva and anus; 2) determining the three-dimensional spatial needle channel distribution and generating a plurality of groups of straight needle channel arrangements; 3) redesigning the interfering straight needle channel into an arc-shaped needle channel, the arc-shaped needle channel comprising at least one arc-shaped or curved needle channel bending segment, wherein the needle channel bending segment satisfies the minimum curvature radius limit to meet the applicator passability requirement; 4) performing dose optimization on the plurality of needle channel designs to select a group of needle channel designs with the optimal dose volume; 5) 3D printing the implant guide according to the shape parameters and the group of needle channel designs with the optimal dose volume; The method further comprises the following test optimization steps: 41) 3D printing a test product according to the shape parameters and the group of needle channel designs with the optimal dose volume, and arranging a flexible radiation protection member in the groove; the flexible radiation protection member is composed of two or more layers of flexible radiation protection layers; 42) performing radiation dose test on the predetermined area of the test product and the outer side of the flexible radiation protection member; 43) if the radiation dose of the predetermined area is less than the designed radiation dose, increasing the maximum dose limit of the corresponding area of the flexible radiation protection member and updating the group of needle channel designs with the optimal dose according to step 4); 44) repeating steps 41) to 43) until the dose of the predetermined radiation area is not less than the designed radiation dose.

2. The method of designing a 3D-printed implant guide according to claim 1, wherein, In step 42), the radiation dose is measured by pasting radioactive measurement films on the predetermined area and the outer side of the flexible radiation protection member.

3. The method of designing a 3D-printed implant guide according to claim 1, wherein, The thickness of the flexible radiation protection layer is 0.1-0.3 mm, the number of layers is 2-10, and adhesive is coated between adjacent flexible radiation protection layers.

4. The method of designing a 3D-printed implant guide according to claim 1, wherein, Ridges or protrusions are formed on the inner wall of the needle channel corresponding to the needle channel bending segment.

5. A 3D printed implant guide obtained by the design method of any one of claims 1-4, comprising a columnar implant and a positioning support plate, wherein the needle channel in the columnar implant at least partially comprises an arc-shaped or curved needle channel bending segment.

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