A Robotic Multi-Needle Puncture Trajectory Planning Method for Prostate Cancer

Abstract

This invention discloses a robotic multi-needle puncture trajectory planning method for prostate cancer. By acquiring two-dimensional ultrasound images and spatial positioning data of the prostate, the coordinates of three-dimensional feature points of obstacles such as blood vessels and the pubic bone are obtained. The tumor contour is extracted using a combination of manual delineation and an improved target detection algorithm to complete three-dimensional reconstruction of the prostate and tumor, as well as implicit function modeling of obstacles, constructing a personalized three-dimensional surgical environment. This method employs a progressive planning strategy, solving for a collision-free reachable workspace for each needle, optimizing the needle insertion trajectory with the shortest path and minimal trauma as objectives, and establishing a tissue deformation compensation model to correct target point offset. Simultaneously, the implanted puncture needles are used as dynamic obstacle iterative update constraints to achieve cyclical optimization of the multi-needle trajectory. Finally, a six-degree-of-freedom robotic arm equipped with a needle guide device completes precise positioning and puncture assistance, achieving orderly, collision-free multi-needle implantation. This invention effectively improves puncture positioning accuracy and surgical safety, reduces manual intervention, and provides an automated, high-precision trajectory planning solution for prostate particle implantation.

Description

Technical Field

[0001] This invention relates to the field of medical devices, belonging to the interdisciplinary field of medicine, mechanics, and automation, and specifically to a robotic multi-needle puncture trajectory planning method for prostate cancer. Background Technology

[0002] Currently, radioactive particle implantation is the most widely used and effective minimally invasive treatment for prostate cancer, offering advantages such as high targeting, minimal trauma, fewer complications, and rapid postoperative recovery. Clinically, multiple puncture needles are typically implanted, with particles evenly distributed to ensure dose coverage. Traditional surgery relies on manual manipulation under ultrasound, CT, or MRI image guidance, using a puncture template to determine the needle insertion point. This method heavily depends on the surgeon's experience and touch, making it difficult to plan multiple puncture paths in three-dimensional space. This can easily lead to problems such as needle path crossing, uneven particle distribution, and abnormal radiation dose, directly affecting treatment outcomes. Furthermore, the prostate's complex anatomy, with surrounding vital tissues like the pubis and blood vessels, makes precise obstacle avoidance difficult during manual puncture, easily damaging normal tissue and increasing the risk of bleeding, infection, and tumor metastasis. In addition, the force generated by inserting each needle can cause soft tissue deformation in the prostate, leading to target displacement. The implanted needles themselves become dynamic obstacles to subsequent punctures, and current methods cannot update the planning environment in real time for compensation and correction. Summary of the Invention

[0003] The main objective of this invention is to solve the problem of puncture tasks in complex environments, achieve collision-free and optimal trajectory planning for multi-needle puncture in prostate cancer, and thus provide a robotic multi-needle puncture trajectory planning method for prostate cancer.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] A method for planning the trajectory of multiple punctures in prostate particle implantation surgery, characterized by comprising the following:

[0006] (1) Data acquisition: Collect continuous 2D ultrasound images and synchronous spatial tracking data of the patient’s prostate area, and obtain the three-dimensional coordinates of scattered feature points on the surface of obstacles such as blood vessels and pubis in the surgical area.

[0007] (2) Three-dimensional surgical environment modeling: Select some 2D tomographic images to manually delineate the tumor boundary, and use an improved target detection algorithm to automatically identify the tumor region in the remaining tomographic images. After integrating the complete outline, construct a personalized three-dimensional model of the prostate and tumor using a three-dimensional reconstruction algorithm to determine the number of puncture needles and preset target points. Construct implicit functions based on obstacle feature points to complete the mathematical modeling of obstacles and form a unified three-dimensional surgical environment model.

[0008] (3) Progressive trajectory planning: According to the preset needle insertion order, calculate the collision-free reachable workspace (CFRW) for each needle, and select the optimal needle insertion trajectory and epidermal needle insertion point with the shortest path and the least trauma as the goal; establish a tissue deformation displacement compensation model to correct the target point offset, treat the implanted puncture needle as a dynamic obstacle, iteratively update the constraint conditions and cycle to complete the subsequent puncture needle trajectory planning.

[0009] (4) Puncture-assisted execution: The six-degree-of-freedom robotic arm is equipped with a special needle guide device and is precisely moved to the planned needle insertion position. Multiple needles are implanted in an orderly manner in conjunction with manual puncture.

[0010] Further design of the scheme: determine the order of needle insertion, preset the target area of ​​each needle according to the tumor distribution and clinical needs, and fix the target point coordinates as the trajectory planning benchmark; perform unified mathematical modeling for inherent obstacles such as blood vessels and pubis in the surgical environment, as well as dynamic obstacles formed by subsequently inserted needles, to clarify the three-dimensional obstacle avoidance range; construct a global unified coordinate system, simplify a single needle into a ball joint single joint model centered on the target point, and retain only two rotational degrees of freedom around the Y-axis and Z-axis to reduce computational complexity.

[0011] The actual target area location of the tip of the (j-1)th puncture needle is:

[0012]

[0013] Further design of the scheme: The three-dimensional collision-free reachable workspace (CFRW) is decomposed into multiple two-dimensional planes along the Z-axis. The one-dimensional boundary curves are solved plane by plane and then combined to form a three-dimensional CFRW. In the multi-obstacle scenario, the intersection of the CFRWs corresponding to each obstacle is taken as the final safe planning space. A set of nonlinear equations including needle insertion angle constraints, needle length constraints, and safety distance constraints is established to transform clinical constraints into calculable mathematical parameters and solve for a complete set of feasible trajectories for a single needle.

[0014] The kinematic constraint equations for needle j in coordinate system Σ are:

[0015]

[0016] The collision-free equation between needle j and the obstacle:

[0017]

[0018] Further design of the scheme: With the optimization objective of "shortest distance between the needle insertion point and the target point and minimal tissue trauma", the discrete mesh method is used to iteratively search for the optimal needle insertion point on the perineal epidermal surface. The ray method is used to determine whether the candidate trajectory is within the CFRW. After meeting the convergence accuracy and step size accuracy, the optimal needle insertion trajectory is determined. A prostate tissue deformation displacement compensation model is established to calculate the target point offset caused by the puncture force, and the actual coordinates of the target area are corrected in real time to eliminate the influence of deformation on the positioning accuracy. The inserted puncture needles are marked as new obstacles, and the planning environment and constraints of the next needle are updated. The obstacle modeling, CFRW solution, optimal trajectory selection, and deformation compensation steps are executed iteratively until all puncture needles have completed trajectory planning.

[0019] Mathematical model for finding the optimal needle entry point:

[0020]

[0021] Further design of the procedure: complete the coordinate registration of the preoperative 3D model with the actual intraoperative position, convert the planned trajectory into robot executable instructions, and complete the precise puncture and implantation with the assistance of a six-degree-of-freedom robotic arm; after the operation, verify the particle distribution, dose coverage and needle insertion accuracy through imaging to complete the surgical effect evaluation.

[0022] The beneficial effects of this invention are:

[0023] By organically combining coordinate system one, needle kinematics simplification, multi-obstacle CFRW intersection solution, dynamic obstacle update, target displacement compensation and discrete mesh optimization search, the robot solves technical problems such as multi-needle intersection, tissue collision, deformation drift and complex planning, enabling it to stably complete highly complex and highly accurate prostate multi-needle puncture surgery tasks. Attached Figure Description

[0024] Figure 1 Flowchart for multi-needle insertion trajectory planning.

[0025] Figure 2 Needle puncture trajectory planning.

[0026] Figure 3 A schematic diagram of the prostate biopsy procedure environment. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0028] First, comprehensive data collection related to the surgery is conducted to provide the initial basis for subsequent modeling and planning. Specifically, this includes: acquiring continuous 2D ultrasound images of the patient's prostate area and simultaneously recording corresponding spatial tracking data to ensure the 2D images correspond to the actual spatial location; concurrently, for key obstacles such as blood vessels and the pubic bone within the surgical area, the 3D coordinates of multiple dispersed feature points on their surfaces are collected to accurately characterize the spatial morphology and distribution of these obstacles, providing complete and reliable data support for subsequent mathematical modeling of these obstacles and avoiding modeling errors due to missing data.

[0029] After data acquisition, precise modeling is performed based on the acquired 2D images and obstacle feature points. First, several clear 2D tomographic images are selected, and the tumor boundary is manually and precisely delineated by the doctor to ensure the accuracy of the initial outline. The remaining tomographic images are then automatically identified using an improved target detection algorithm, reducing manual operation and improving modeling efficiency. Based on the complete tumor outline, a personalized 3D solid model of the patient's prostate and tumor is constructed using a 3D reconstruction algorithm. Then, the number of puncture needles and the preset target point locations are determined according to the tumor volume and lesion distribution. For obstacles such as blood vessels and the pubic bone, implicit functions are constructed based on the acquired scattered feature points to complete the mathematical description of the obstacles, forming a unified 3D surgical environment model and laying the geometric foundation for subsequent trajectory planning.

[0030] Based on a 3D surgical environment model, a progressive needle-by-needle trajectory planning process is implemented. First, for the first puncture needle, its collision-free reachable working space (CFRW) is calculated using obstacle constraints. Within this safe space, the optimal needle insertion trajectory and corresponding epidermal insertion point are selected with the goal of "shortest path and minimal trauma." Second, the stress deformation pattern of the prostate tissue during needle insertion is analyzed, a deformation displacement compensation model is established, and the target point offset caused by deformation is corrected, updating the actual target point position. Third, the first puncture needle, now inserted, is treated as a new dynamic obstacle. Combined with existing fixed obstacles, the CFRW of the second puncture needle is recalculated, and the optimal insertion trajectory and insertion point of the second needle are solved using the same optimization criteria. Subsequent puncture needles are planned iteratively according to this logic, ensuring that the trajectory of each needle meets the requirements of collision-free and high precision.

[0031] A six-degree-of-freedom robotic arm performs the puncture-assisted procedure. A dedicated needle guide device is mounted at the end of the robotic arm, driving the guide to move quickly and precisely to the planned insertion position. Once at the designated position, the doctor can manually insert the puncture needle along the guide to the tumor target site; after puncture, the puncture needle is removed. This positioning, puncture, and avoidance process is repeated sequentially to complete the implantation of all puncture needles, ensuring safety, stability, and controllability throughout the entire procedure.

[0032] The implementation process of multi-needle trajectory planning consists of the following steps:

[0033] (1) Clarify the order of needle insertion to lay the foundation for subsequent trajectory planning.

[0034] (2) Determine the target location where each puncture needle needs to be inserted and clarify the puncture guidance direction.

[0035] (3) Provide a detailed description and model of various obstacles in the surgical environment, and clarify the trajectory avoidance range.

[0036] (4) Calculate the collision-free reachable working space (CFRW) of the current puncture needle according to the preset needle insertion sequence.

[0037] (5) Within a collision-free accessible workspace, select and determine the optimal needle trajectory.

[0038] (6) Analyze the possible prostate tissue deformation during the puncture process and understand the pattern of target location changes.

[0039] (7) Update the obstacle information and target location information corresponding to the next puncture needle according to the current planning and insertion status of the puncture needle.

[0040] (8) Repeat steps 3 to 7 above until all the puncture needles that need to be used have completed the trajectory planning.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for planning the trajectory of multiple punctures in prostate particle implantation surgery, characterized in that, Includes the following: (1) Data acquisition: Collect continuous 2D ultrasound images and synchronous spatial tracking data of the patient's prostate area, and obtain the three-dimensional coordinates of scattered feature points on the surface of obstacles such as blood vessels and pubis in the surgical area; (2) Three-dimensional surgical environment modeling: Select some 2D tomographic images and manually delineate the tumor boundary. The remaining tomographic images are automatically identified by an improved target detection algorithm. After integrating the complete outline, a three-dimensional reconstruction algorithm is used to construct a personalized three-dimensional model of the prostate and tumor to determine the number of puncture needles and preset target points. Implicit functions are constructed based on obstacle feature points to complete the mathematical modeling of obstacles and form a unified three-dimensional surgical environment model; (3) Progressive trajectory planning: According to the preset needle insertion sequence, calculate the collision-free reachable workspace (CFRW) for each needle, and select the optimal needle insertion trajectory and epidermal needle insertion point with the goal of shortest path and minimal trauma; A tissue deformation displacement compensation model was established to correct the target point offset. The implanted puncture needle was used as a dynamic obstacle. The constraints were iteratively updated and the subsequent puncture needle trajectory planning was completed in a loop. (4) Puncture-assisted execution: The six-degree-of-freedom robotic arm is equipped with a special needle guide device and is precisely moved to the planned needle insertion position. Multiple needles are implanted in an orderly manner in conjunction with manual puncture.

2. The method for planning the trajectory of multiple punctures in a prostate particle implantation surgery according to claim 1, characterized in that: The specific steps are as follows: The implementation process of multi-needle trajectory planning consists of the following steps: (1) Clarify the order of needle insertion to lay the foundation for subsequent trajectory planning; (2) Determine the target location where each puncture needle needs to be inserted and clarify the puncture guidance direction; (3) Provide a detailed description and model of various obstacles in the surgical environment, and clarify the trajectory avoidance range; (4) Calculate the collision-free reachable working space (CFRW) of the current puncture needle according to the preset needle insertion sequence. (5) Within a collision-free accessible workspace, select and determine the optimal needle insertion trajectory; (6) Analyze the possible prostate tissue deformation during the puncture process and understand the pattern of target location changes; (7) Update the obstacle information and target location information corresponding to the next puncture needle according to the current planning and insertion status of the puncture needle; (8) Repeat steps 3 to 7 above until all the puncture needles that need to be used have completed the trajectory planning.

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