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

Abstract

The invention discloses a design method of a 3D printing implantation guide plate and the 3D printing implantation guide plate, the design method comprises the following steps: 1) individualized modeling is carried out on the implantation guide plate based on CT / MRI image data of a patient, and the implantation guide plate comprises a columnar implantation body and positioning support plates integrally constructed on two sides of the root of the columnar implantation body; 2) determining a feasible solution space and generating a plurality of groups of linear needle passage designs; 3) redesigning the linear needle passages generating interference into arc needle passages; 4) performing dose optimization on the multiple groups of needle passage designs, and selecting a group of needle passage designs with optimal dose volume; 5, the 3D printing implantation guide plate is designed according to the appearance parameters and the optimal group of needle passages.By means of the arc-shaped needle passageway design, the part of organs are avoided, multiple groups of linear needle passageways are reserved, the situation that effective needle passageway design is abandoned in the front portion is effectively avoided, and the main purpose of the arc-shaped needle passageway is to reduce the area which cannot be avoided by an original straight needle passageway.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, specifically to a design method and a 3D-printed implantation guide plate based on gynecological tumor images. Background Technology

[0002] During brachytherapy, the position of the radiation source needs to be kept relatively fixed. However, operations such as patient transport, CT scans, and connection of treatment tubing can easily cause the applicator (hollow catheter) to shift along the needle path, thus deviating from the preset radiation source trajectory and affecting the accuracy of treatment. Before treatment, the implantation guide plate needs to be fixed in a specific position. Therefore, the structural design and needle path layout of the implantation guide plate are crucial to ensuring the stability of the applicator. Relevant studies have clarified the key points of this technique: For example, Chino J et al. emphasized in "The American Brachytherapy Society (ABS) consensus guidance for hybrid intracavitary interstitial brachytherapy for locally advanced cervical cancer" (Brachytherapy, 2025, 24(4):463-78) that hybrid intracavitary interstitial brachytherapy requires optimizing the needle path design of the implantation guide plate to reduce applicator displacement; Zhu X et al. pointed out 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) that the needle path adaptability of the personalized guide plate directly affects the stability of the radiation source trajectory; International Commission on Radiation Units and Measurements (ICRU) Report 89 (2013, 13(1-2) also puts forward 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 design method for an implantation guide plate and an implantation guide plate". This technology optimizes radiation safety by eliminating unavoidable interference areas in the straight needle path (such as the vaginal wall, vascular area, part of the bladder wall and rectal wall), but it still has the defects of insufficient fixation stability of the applicator and easy deviation of the radiation source trajectory, which cannot meet the accuracy requirements of brachytherapy.

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

[0005] In view of this, the problem to be solved by the present invention is to provide a design method for 3D printed implantation guides that can effectively balance the protection of organs at risk and the therapeutic effect through computational simulation based on image processing technology.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A design method for a 3D-printed insertion guide plate includes the following steps: 1) Individualized modeling of the implantation guide plate is performed based on the patient's CT / MRI image data. The implantation guide plate includes a columnar implant and positioning support plates set on both sides of the root of the columnar implant. 2) Determine the three-dimensional spatial needle path distribution and generate multiple sets of straight needle path designs; 3) The straight needle path that causes interference is redesigned into an arc-shaped needle path. The arc-shaped needle path includes at least one arc-shaped or curved needle path bending section, and the needle path bending section meets the minimum radius of curvature limit to meet the applicator passability requirements. 4) Optimize the dosage of multiple needle path designs and select the needle path design with the optimal dosage and volume; 5) Design a 3D-printed insertion guide plate based on the optimal set of needle channels according to the shape parameters and dosage volume.

[0007] As one preferred embodiment, the outer surface of the columnar implant described in step 1) is constructed with a groove on the side corresponding to the organ at risk (referring to the side adjacent to normal organs such as the bladder and rectum) to provide a flexible protective element for positioning and radiation protection.

[0008] As one preferred embodiment, an optimization trial is conducted prior to step 5), which includes: 41) Based on the optimal set of needle channel designs with shape parameters and dosage volume, a test specimen is 3D printed, and a flexible protective component is arranged in the groove. 42) Conduct radiation dose tests on the predetermined area of ​​the test specimen and the outer side of the flexible protective component; 43) If the radiation dose in the predetermined area is less than the designed radiation dose, increase the maximum dose limit of the area corresponding to the flexible protective component and update the optimal set of needle channel designs according to step 4). 44) Repeat steps 41)-43) until the dose in the predetermined radiation area is not less than the designed radiation dose.

[0009] As one preferred embodiment, step 42) involves applying a radiometric measuring film to a predetermined area and the outside of the flexible protective component to measure the radiation dose.

[0010] As one preferred embodiment, the flexible protective component is composed of two or more flexible radiation shielding layers stacked together.

[0011] As one preferred embodiment, the thickness of the flexible radiation shielding layer is 0.1-0.3 mm, the number of layers is 2-10, and an adhesive is applied between adjacent flexible radiation shielding layers.

[0012] As one preferred embodiment, raised textures or raised dots are formed on the inner wall of the needle path corresponding to the arc-shaped bending section.

[0013] A 3D-printed implantation guide plate obtained by a design method includes a columnar implant and a positioning support plate, wherein at least one needle channel in the columnar implant includes at least one arc-shaped or curved needle channel bending section.

[0014] The advantages and positive effects of this invention are: Compared to existing technologies, this invention does not directly abandon straight needle paths that interfere with normal organs. Instead, it avoids these organs by using an arc-shaped needle path design that includes curved or curved bends. The retention of multiple straight needle paths effectively avoids discarding effective needle path designs at the beginning. The main purpose of the arc-shaped needle path is to reduce areas that cannot be avoided by the original straight needle path, such as the vaginal wall, vascular areas, parts of the bladder wall, and rectal wall, thereby reducing side effects for patients during insertion, including but not limited to bleeding, pain, bladder wall damage, and rectal infection. Furthermore, introducing curved or curved bends into the arc-shaped needle path design enhances the spatial distribution of the final needle exit angle, improves the adaptability of the needle path design to tumors of different shapes, facilitates effective spatial coordination of multiple radiation points, and effectively improves treatment outcomes. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] Figure 1 This is a schematic diagram of the insertion guide plate of the present invention from a first-view perspective; Figure 2 yes Figure 1 The diagram shows another perspective of the structure. Figure 3 This is a schematic diagram of the cross-section of a columnar implant; Figure 4 The diagram shows an arc-shaped needle path, where parts A and B are schematic diagrams of straight needle paths in the prior art, and part C is a schematic diagram of the arc-shaped needle path of the present invention.

[0017] Figure label: 1. Columnar implant; 2. Positioning support plate; 10. Straight needle path; 11. Groove; 12. Flexible protective component; 13. Arc-shaped needle path; 21. Vulvar contour part; 22. Buttock contour part; 3. Applicator. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] First Embodiment A design method for a 3D-printed insertion guide plate includes the following steps: 1) Individualized modeling of the implantation guide based on the patient's CT / MRI image data, that is, designing the shape parameters of the implantation guide according to the preoperative images. The implantation guide includes a columnar implant 1 and a positioning support plate 2 integrally constructed or fixedly connected to both sides of the root of the columnar implant 1. 2) Determine the three-dimensional spatial needle path distribution and generate multiple sets of straight needle path designs. Generally, this step can be achieved by using dose optimization software to generate multiple sets of straight needle paths 10. 3) The straight needle path that causes interference is redesigned into an arc-shaped needle path 13. The arc-shaped needle path includes at least one arc-shaped (such as a circular arc) or curved needle path bending section. The bending section of the needle path meets the minimum radius of curvature limit to meet the applicator passability requirements. Generally, the minimum radius of curvature is ≥5mm. 4) Optimize the dosage of multiple needle path designs to select the needle path design with the optimal dosage-volume ratio; 5) Based on the optimal set of needle channels with shape parameters and dose-volume, a 3D-printed implantation guide plate is designed. The specific feasible solution space and straight needle channel design are based on dose optimization, analysis of needle channel spatial distribution, DVH (dose-volume histogram), etc., which are similar to the existing clinical brachytherapy planning system TPS (Treatment Planning System) technology, such as the commercial system Oncentra Brachy. It will not be elaborated here. This invention only describes the improvement part relative to the existing technology.

[0020] Compared to existing technologies, this invention does not directly abandon straight needle paths that interfere with normal organs. Instead, it avoids these organs by incorporating arc-shaped or curved needle path bends in the needle path design. The retention of multiple straight needle paths effectively avoids discarding effective needle path designs at the beginning. The main purpose of the arc-shaped needle path is to reduce areas that the original straight needle path could not avoid, such as the vaginal wall, vascular areas, parts of the bladder wall, and rectal wall, thereby reducing side effects for the patient during insertion, including but not limited to bleeding, pain, bladder wall damage, and rectal infection. Furthermore, introducing arc-shaped needle path bends into the needle path design enhances the spatial distribution of the final needle exit angle, improves the adaptability of the needle path design to tumors of different shapes, facilitates effective spatial coordination of multiple radiation points, and effectively improves treatment efficacy.

[0021] The applicator 3 used in the treatment is made of elastic medical polymer material, such as polytetrafluoroethylene or polyurethane. It is a tubular structure with one end closed. Its open end is located at the root of the columnar implant, which facilitates the insertion of the radiation source for radiotherapy. With the arc-shaped needle path design, as long as the bending angle is not less than the predetermined angle, the applicator can travel along the predetermined trajectory of the needle path. The straight needle path can be designed as an arc-shaped needle path, which can be achieved by manual replacement or with the help of software. This will not be elaborated here.

[0022] Furthermore, raised textures or protrusions are formed on the inner wall of the needle channel corresponding to the arc-shaped bending section, or raised textures or protrusions are provided at the exit of the needle channel. The protrusions are 0.1-0.3mm high and spirally distributed at intervals of 2-5mm. This feature can improve the feel when inserting the applicator and increase friction, which can effectively improve the positioning effect of the columnar implant on the applicator and avoid displacement caused by the operation of the radiation source.

[0023] In step 1), the outer surface of the cylindrical implant described herein has a groove 11 on the side corresponding to the organ at risk, which serves to locate and protect against radiation. This groove is positioned towards the anterior wall of the rectum or the posterior wall of the bladder. One or two grooves 11 can be provided depending on the situation. The depth of the groove is generally 2-10 mm, typically 2-5 mm. A flexible protective element 12 is fixed within the groove. The design of the groove and the application of the radiation-protective flexible protective element on the cylindrical implant can directionally enhance the protective strength in that direction. The closer to the needle tract, the stronger the shielding effect. A larger shielding range can be achieved using fewer flexible protective elements. Furthermore, the overall volume does not increase, which can reduce discomfort during treatment to some extent. The design position of the groove can be generated based on CT scan results and the actual location of the organs in different patients. That is, for patients with different body types and postures, the position, size, and shape of the groove can be appropriately adjusted according to the actual location of the organs.

[0024] Specifically, the thickness of the flexible radiation shielding component is 0.1-0.3 mm, typically 0.2-3 mm, with 2-10 layers, typically 2-5 layers. This means multiple layers are bonded together to form a single unit of a certain thickness, generally 2-5 mm. Adhesive is applied between adjacent flexible radiation shielding layers. Experiments show that compared to a single layer of the same thickness, using a multi-layer bonding method reduces the radiation equivalent of approximately 8 Gy by more than 30% when about 5 layers are stacked. Furthermore, when the number of layers reaches 10, the shielding strength exceeds 50%.

[0025] The flexible radiation-proof protective component can be made of diethyltriaminepentaacetic acid (DTPA), as detailed in CN113321877B. Furthermore, the flexible protective components used in the embodiments of this invention all employ the aforementioned product. Of course, any similar flexible radiation-proof material, as long as it has a very thin thickness and provides radiation protection, can achieve the technical requirements of this invention.

[0026] Generally, the flexible protective components are made by stacking different specifications to form a combination of thicknesses, and then cut according to the shape and design thickness of the groove, and then bonded to the groove with the bottom adhesive.

[0027] Further, the pre-trial optimization step in step 5) includes, 41) Based on the external parameters and the optimal set of needle paths design, a prototype is 3D printed, and a flexible protective component is arranged in the groove. 42) Conduct radiation dose tests on the predetermined area of ​​the test specimen and the outer side of the flexible protective component; 43) If the radiation dose in the predetermined area is less than the designed radiation dose and the radiation dose on the outside of the flexible protective component is less than the radiation safety value (i.e., the maximum radiation dose that will not cause radiation damage to the corresponding normal organs), then increase the maximum dose limit of the area corresponding to the flexible protective component and update the optimal set of needle path designs according to step 4). 44) Repeat steps 41)-43) until the dose in the predetermined radiation area is not less than the design radiation dose and the radiation dose on the outside of the flexible protective component is not greater than the radiation safety value.

[0028] In step 42), radiation dose measurement is performed by attaching a radiometric measuring film to a predetermined area and the outside of the flexible protective component. The principle is that different intensities of radiation exposure create development on the film, and the degree of development or shadowing is used to calculate the total radiation dose.

[0029] In actual treatment, the common situation is that most patients undergoing brachytherapy are exposed to high doses to the rectal wall. To avoid damage to normal organs caused by overdose, a dose "cold zone" (underdose) often appears in the tumor area, potentially leading to a decrease in local tumor control rate, ultimately resulting in treatment failure or tumor recurrence. This invention addresses this by incorporating a flexible protective element and measuring the actual radiation dose on the outer side of the flexible protection. This effectively calibrates the computer-designed radiation scheme based on image processing, effectively protecting organs or tissues such as the rectal wall. It reduces rectal damage caused by overtreatment and improves local tumor control rate. Furthermore, in some cases, a thicker flexible radiation shielding layer can be designed to enhance protection of organs at risk, while appropriately increasing the maximum dose limit in dose-volume calculations to balance the conflict between treatment effectiveness and protection of normal organs.

[0030] The present invention also discloses a 3D printed implantation guide plate made by the above design method, which includes a columnar implant and a positioning support plate, wherein at least one needle channel in the columnar implant includes at least one arc-shaped needle channel or a curved needle channel.

[0031] The implantation guide plate is integrally molded using polylactic acid (PLA) and copolymers through 3D printing, achieving a lightweight overall structure while ensuring connection strength. The implantation guide plate includes a columnar implant body 1 and positioning support plates 2 integrally constructed on both sides of the root of the columnar implant body 1. The positioning support plates 2 include a vulvar contour portion 21 and a buttock contour portion 22. The columnar implant body 1 and the positioning support plates 2 are integrally molded using polylactic acid emulsion 3D printing, achieving a lightweight overall structure while ensuring connection strength.

[0032] The vulvar contour part 21 and the buttock contour part 22 provide protection and support for the vulva and the buttocks near the anus, respectively. This allows the device to be held between the legs, with the contact surfaces conforming to the vulva and the buttocks near the anus, preventing the positioning support plate 2 from wobbling and thus avoiding the problem of the columnar implant 1 moving inside the body, ensuring the entire process is precise and orderly. The shape of the positioning support plate is also based on the external parameters obtained from different specific human anatomy, and is 3D printed using 3D modeling, providing better personal adaptability. The vulvar contour part 21 has a roof-like structure with a high center and sloping, downward-sloping wings, conforming to the contour of the vulva. The buttock contour part 22 has a petal-like structure that rises away from the columnar implant 1, conforming to the contour of the buttocks near the anus. The cross-sectional area of ​​the vulvar contour part 21 and the buttock contour part 22 increases continuously away from the columnar implant 1, conforming to the contour of the lower body.

[0033] The direction, size, and depth of the groove 11 can be specifically set based on the CT scan results, image processing, and in conjunction with the distribution of other organs in the image, such as the rectum and bladder, as well as the radiation tolerance of each organ. This avoids the problem of weakened protection level caused by uniform circumferential distribution and achieves key protection in key directions.

[0034] Meanwhile, for the lower part of the columnar implant, especially the vaginal opening, a flexible radiation-proof layer can be designed to cover the periphery, which shields the flexible protective layer in the groove and improves its positioning effect.

[0035] During treatment, a 3D-printed cylindrical implant 1 is inserted into the vagina, and a positioning support plate 2 is clamped between the legs, with the contact surface conforming to the vulva and the buttocks near the anus, making the device less prone to shaking. Then, the applicator (hollow tube) is inserted near the tumor through a needle channel designed inside the cylindrical implant. Under image guidance, it is precisely positioned, and then the radiation source is delivered to the applicator 3 for irradiation using afterloading technology. A flexible protective component 12 forms a covering area on the cylindrical implant 1, shielding the radiation emitted from the radiation source and preventing it from penetrating and damaging normal organs and tissues (such as the rectum and bladder), thus forming a preset angle of irradiation. For the portion outside the covered area, the radiation emitted from the radiation source can pass through and be emitted into the tumor, allowing for precise treatment of the lesion through the spatial radiation from multiple radiation sources. Throughout the process, such as... Figure 4 As shown, the arc-shaped needle design ( Figure 4 The situation shown in section C can effectively avoid straight stitches ( Figure 4(As shown in parts A and B) directly damages the vaginal wall or bladder and rectal wall, significantly reducing serious side effects (pain, bleeding, etc.) associated with implantation.

[0036] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A design method for 3D printed insertion guide plates, characterized in that, Includes the following steps, 1) The implantation guide is modeled individually based on the patient's CT / MRI image data. The implantation guide includes a columnar implant (1) and a positioning support plate (2) set on both sides of the root of the columnar implant (1). 2) Determine the three-dimensional spatial needle path distribution and generate multiple sets of straight needle path designs; 3) The straight needle path that causes interference is redesigned into an arc-shaped needle path. The arc-shaped needle path includes at least one arc-shaped or curved needle path bending section, and the needle path bending section meets the minimum radius of curvature limit to meet the applicator passability requirements. 4) Optimize the dosage of multiple needle path designs and select the needle path design with the optimal dosage and volume; 5) Design a 3D-printed insertion guide plate based on the optimal set of needle channels according to the shape parameters and dosage volume.

2. The design method of the 3D printed insertion guide plate as described in claim 1, characterized in that, The outer surface of the columnar implant described in step 1) has a groove on the side corresponding to the organ at risk, which is used to position a flexible protective element for radiation protection.

3. The design method of the 3D printed insertion guide plate as described in claim 2, characterized in that, The experiment optimization step is included before step 5), which includes: 41) Design a set of needle channels with optimal shape parameters and dosage volume, 3D print a prototype, and arrange flexible protective parts in the grooves; 42) Conduct radiation dose tests on the predetermined area of ​​the test specimen and the outer side of the flexible protective component; 43) If the radiation dose in the predetermined area is less than the designed radiation dose, increase the maximum dose limit of the area corresponding to the flexible protective component and update the optimal set of needle channel designs according to step 4). 44) Repeat steps 41)-43) until the dose in the predetermined radiation area is not less than the designed radiation dose.

4. The design method of the 3D printed insertion guide plate as described in claim 3, characterized in that, In step 42), radiation dose measurement is performed by attaching a radioactive measuring film to a predetermined area and the outside of the flexible protective component.

5. The design method of the 3D printed insertion guide plate as described in claim 3, characterized in that, The flexible protective component is composed of two or more flexible radiation shielding layers stacked together.

6. The design method of the 3D printed insertion guide plate according to claim 5, characterized in that, The thickness of the flexible radiation shielding layer is 0.1-0.3 mm, the number of layers is 2-10, and an adhesive is applied between adjacent flexible radiation shielding layers.

7. The design method for the 3D printed insertion guide plate according to claim 1, characterized in that, Raised lines or raised dots are formed on the inner wall of the needle path corresponding to the bent section of the needle path.

8. A 3D printed implantation guide plate obtained by any one of the design methods of claims 1-7, comprising a columnar implant and a positioning support plate, wherein at least one needle channel in the columnar implant includes an arc-shaped or curved needle channel bending section.

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