Offline navigation system for flexible afterloading source applicator in rectum cavity

Abstract

The invention discloses an off-line navigation system for a flexible afterloading source applicator in a rectum cavity, which comprises data processing equipment and a flexible afterloading source applicator for off-line navigation in the rectum cavity, the source applicator comprises a flexible source applicator main body, a space positioning identifier and a deformation sensing module, and an axial graduated scale and a circumferential reference identifier are arranged on the surface of a flexible shell of the source applicator; and four groups of U-shaped turn-back resistance wire type strain sensors are orthogonally embedded and fixed in the inner circumferential direction of the sensor. The physiological bending and unexpected torsion distortion of the source applicator are accurately decoupled and monitored through the tension and pressure differential signal and the neutral surface resistance change, and the accurate positioning of the source applicator is realized from a physical bottom layer through the physical criterion of a 3% steady-state early warning threshold. Patients only need to be subjected to single-time CT scanning filing during first treatment, and accurate registration can be achieved by means of internal and external feature cross validation of physical dimensions in subsequent treatment. Therefore, the waiting time of single treatment is greatly shortened, accumulated radiation toxic and side effects of patients are remarkably reduced, and the operation load of large-scale image equipment in hospitals is greatly released.

Description

Technical Field

[0001] This invention relates to the field of spatial positioning of medical devices, specifically to an offline navigation system for a flexible afterloading applicator in the rectum. Background Technology

[0002] Brachytherapy is a core method for local tumor control, and afterloading technology, as its main implementation method, relies heavily on the precise placement of the applicator within the target area for accurate dose distribution. However, due to the unique anatomical features of the rectum, it is extremely difficult to precisely and repeatedly fix existing flexible intraluminal afterloading applicators in the same ideal three-dimensional spatial position during actual multiple fractionated treatments.

[0003] Traditional clinical treatment relies heavily on the subjective experience of physicians. To verify the exact orientation of the applicator, frequent, repeated CT scans are typically required before each treatment session. This not only significantly increases the cumulative ionizing radiation exposure dose and waiting time per treatment for patients, but also greatly exacerbates the operational burden on medical resources and the suffering of patients during device placement. How to confirm the three-dimensional orientation of intracavitary devices without repeated imaging scans is a critical technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an offline navigation system for a flexible afterloading applicator in the rectum. By integrating a physical strain sensor array with a multi-dimensional coordinate space mapping matrix, the system can achieve physical-level precise confirmation of the applicator's three-dimensional spatial pose within the rectum without the need for external high-frequency imaging positioning, thereby improving the safety and clinical efficiency of radiotherapy dose distribution.

[0005] To achieve the above objectives, this invention proposes an offline navigation system for a flexible afterloading applicator in the rectum, comprising a data processing device and an offline navigation flexible afterloading applicator in the rectum. The system is configured to execute an offline positioning method based on multi-source coordinate mapping. The data processing device specifically includes: The image coordinate system construction module is used to acquire the anatomical structure of the target area based on a single medical image scan and to establish an image reference coordinate system. The physical coordinate system construction module is used to establish a physical coordinate system with the objective anatomical landmarks on the target body surface as reference points; The applicator coordinate system construction module is used to establish a local coordinate system of the applicator based on the spatial readings of the axial scale structure and circumferential reference mark of the applicator. The spatial registration and verification module is used to realize the three-dimensional spatial mapping and association of the image coordinate system, physical coordinate system and applicator coordinate system through rigid body registration algorithm; and in the subsequent offline image-guided treatment stage, by aligning the external markers of the physical coordinate system and applicator coordinate system and simultaneously analyzing the deformation electrical signal output by the deformation sensing module, the consistency of the internal shape of the applicator is verified, thereby achieving high-precision spatial positioning and verification of the applicator without the need for continuous image scanning assistance.

[0006] The aforementioned flexible postloading applicator for the rectal lumen comprises: Flexible applicator body: includes an integrally molded flexible polyurethane shell, the flexible shell being a cylinder with a ball head, and having multiple radiation source channels extending along its axial direction inside for accommodating radiation source guide tubes, as well as multiple sensor channels extending along its axial direction. Spatial positioning mark: set on the outer surface of the flexible shell, including an axial scale structure for indicating the insertion depth of the applicator, and a circumferential reference mark set on the end face of the tail of the flexible shell for indicating the spatial rotation angle of the applicator. Deformation sensing module: includes multiple sets of resistance wire strain sensors that are independently and precisely embedded in the sensor channel; the deformation electrical signal output by the deformation sensing module, the axial scale structure and the circumferential reference mark are configured to cooperate with each other to establish the three-dimensional spatial deformation and pose state of the applicator in the target cavity.

[0007] Furthermore, the present invention employs an orthogonal decoupled topology design for the deformation sensing module: the number of sensor channels is four, orthogonally spaced at 90-degree intervals along the circumferential cross-section of the flexible shell. The four resistance wire strain sensors, with the phase of the circumferential reference marker as the absolute zero point, are divided into a first and a second sensor located radially opposite each other within the "expected bending plane," and a third and a fourth sensor located radially opposite each other within the "non-bending neutral plane."

[0008] Furthermore, when the flexible shell bends unidirectionally to conform to the physiological curvature of the cavity, the first and second sensors generate differential resistance change signals in opposite directions due to tensile and compressive stresses. When the flexible shell undergoes uncontrolled axial torsional distortion deviating from the expected plane, the third and / or fourth sensors, which were originally in a steady state, will be subjected to shear force and generate relative resistance changes. When the absolute value of this rate of change exceeds the preset steady-state reference tolerance threshold, the system determines that an axial torsional offset has occurred and triggers a warning electrical signal indicating an abnormal posture. Preferably, the steady-state reference tolerance threshold is 3% of the initial nominal resistance.

[0009] Furthermore, each of the aforementioned resistance wire strain sensors includes a front fixing block, a rear fixing block, and a continuous resistance wire. The resistance wire is U-shaped at the front fixing block, with both ends stretched and anchored to the rear fixing block in parallel, and extends out from one side of the rear end of the housing to form a resistance measurement interface for connecting an external detection device. Both the front and rear fixing blocks are cylindrical and have two parallel through holes for the resistance wire to pass through.

[0010] This invention provides an offline intrarectal navigation system based on the aforementioned flexible applicator, comprising a data processing device and the flexible applicator. The system is configured to perform the following spatial registration and offline verification methods: In the initial image localization stage, an image coordinate system is established based on single medical image scan data; a physical coordinate system is established based on the treatment target; and a local coordinate system of the applicator is established based on the spatial readings of the external axial scale and circumferential reference mark of the applicator. Subsequently, the mapping correlation matrix of the three coordinate systems is solved by the rigid body registration algorithm, and the deformation resistance matrix output by the four sensors at this time is saved as reference data.

[0011] In the subsequent unguided, staged treatment phase, an external confirmation signal indicating that the external rigid body marker has completed physical alignment is received, and the real-time electrical signal output by the deformation sensing module is simultaneously analyzed by the data processing device. Thus, without the need for subsequent medical imaging verification, it is confirmed that the applicator has achieved high-precision target area spatial docking mapping that is completely consistent with the initial positioning.

[0012] The beneficial effects of this invention are as follows: This application utilizes a 90-degree orthogonal array layout to precisely decouple complex spatial distortions into expected physiological compliance bending and unexpected torsional distortions. Through the physical criterion of the expected bending surface tension-compression differential signal and the 3% steady-state warning threshold of the neutral surface, precise positioning of the applicator is achieved from a physical level. Patients only need a single CT scan for initial record-keeping during the first treatment; subsequent treatments rely on cross-verification of internal and external physical features for accurate registration. This not only significantly shortens the waiting time for a single treatment and substantially reduces the cumulative radiation toxicity side effects on patients, but also greatly reduces the operational load on large-scale imaging equipment in hospitals. Attached Figure Description

[0013] To more clearly describe the technical solutions in this invention patent, the accompanying drawings required in the description of the embodiments or prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this invention.

[0014] Figure 1 This is a cross-sectional view of a flexible postloading applicator for the rectum according to the present invention.

[0015] Figure 2 This is a top view of a flexible postloading applicator for the rectum according to the present invention.

[0016] Figure 3 This is a side view of a flexible postloading applicator for the rectal cavity according to the present invention.

[0017] In the diagram: 1- Flexible polyurethane shell; 11- Circumferential reference mark; 12- Scale; 2- Resistance wire strain sensor; 21- Front end fixing block; 22- Resistance wire; 23- Tail end fixing block; 24- Resistance measurement interface; 3- Radiation source channel; 4- Sensor channel. Detailed Implementation

[0018] like Figures 1-3 As shown, this embodiment provides an intrarectal offline navigation flexible afterloading applicator, whose core physical entities mainly include an integrally molded flexible polyurethane shell 1, an embedded deformation sensing module, and multiple radiation source channels 3.

[0019] The flexible polyurethane shell 1 is made of medical-grade polymer flexible material, possessing excellent tissue compliance. Inside, eight radiation source channels 3 are formed along the central axis. These eight channels are evenly distributed circumferentially along the cross-section of the flexible polyurethane shell 1, used for precise placement of radiation source guide tubes during the afterloading radiotherapy execution phase.

[0020] To achieve external geometric representation of the applicator's spatial pose, the outer surface of the flexible polyurethane shell 1 is provided with high-contrast spatial positioning markers: one is an axial scale 12, with the anus, a natural anatomical landmark on the body surface, as the zero point, which visually indicates the axial depth reference value of the applicator when inserted into the target cavity; the other is a circumferential reference marker 11 located on the tail end face, used to accurately indicate the radial rotation angle of the applicator in a cylindrical coordinate system. The scale 12 and the circumferential reference marker 11 together constitute the external rigid body reference for establishing the local spatial pose of the applicator.

[0021] Inside the flexible polyurethane shell 1, four sensor channels 4 are orthogonally spaced at 90-degree intervals along its cross-section. The deformation sensing module includes four independently packaged resistance wire strain sensors 2, which are respectively embedded in the four sensor channels 4. Each set of resistance wire strain sensors 2 includes a continuous resistance wire 22, and a front fixing block 21 and a tail fixing block 23 respectively embedded at the beginning and end of the sensor channel 4. The resistance wire 22 is U-shaped at the front fixing block 21, and its two ends are tensioned in parallel within the sensor channel 4 and extend in the same direction to be anchored at the tail fixing block 23. Finally, it leads out to the outside of the tail end to form a resistance measurement interface 24 for connecting to a high-precision data acquisition device.

[0022] This system constructs an orthogonal topological array of four resistance wire strain sensors 2 with the phase of the circumferential reference marker 11 as the absolute zero position. The array is divided into: a first and a second sensor located radially opposite each other within the expected bending plane of the actuator; and a third and a fourth sensor located radially opposite each other within the non-bending neutral plane.

[0023] During the standard insertion procedure, the applicator will bend unidirectionally to conform to the curvature of the intestine. At this time, the first sensor, located on the convex side of the bend, experiences tensile stress on the substrate, resulting in a decrease in the cross-sectional area of ​​the resistance wire and an increase in its output resistance. Conversely, the second sensor, located on the concave side, experiences compressive stress, resulting in a decrease in resistance. The system processing equipment can quantitatively fit the bending parameters of the applicator in the expected plane by acquiring differential resistance signals from both sides of the neutral plane in opposite directions. In a purely bent state, the third and fourth sensors, located on the "non-bending neutral plane," do not experience significant axial tension or compression, and their resistance should remain stable. However, when the applicator deviates from the expected "axial torsional yaw" due to physiological peristalsis or blind placement, the third and fourth sensors will undergo significant deformation. The data processing logic embedded in this system is configured such that when the absolute value of the relative resistance change rate of the third and / or fourth sensors exceeds the preset steady-state reference tolerance, the underlying algorithm objectively determines that the applicator has undergone uncontrolled torsional displacement sufficient to disrupt the preset dose distribution, and immediately triggers an early warning representing an abnormal pose. In this embodiment, it is preferably set to 3% of the initial nominal resistance, which completely eliminates the medical risk of target area deviation from a physical dimension.

[0024] The embodiments should not be considered as limitations on the present invention, but any improvements made based on the spirit of the present invention should be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An offline navigation system for a flexible afterloading applicator in the rectum, characterized in that, This includes data processing equipment and an intrarectal offline navigation flexible afterloading applicator. The data processing equipment specifically includes: The image coordinate system construction module is used to acquire the anatomical structure of the target area based on a single medical image scan and to establish an image reference coordinate system. The physical coordinate system construction module is used to establish a physical coordinate system with the objective anatomical landmarks on the target body surface as reference points; The applicator coordinate system construction module is used to establish a local coordinate system of the applicator based on the spatial readings of the axial scale structure and circumferential reference mark of the applicator. The spatial registration and verification module is used to realize the three-dimensional spatial mapping and association of the image coordinate system, physical coordinate system and applicator coordinate system through rigid body registration algorithm; and in the subsequent offline image-guided treatment stage, by aligning the external markers of the physical coordinate system and applicator coordinate system and simultaneously analyzing the deformation electrical signal output by the deformation sensing module to verify the consistency of the internal shape of the applicator, thereby achieving high-precision spatial positioning and verification of the applicator without the need for continuous image scanning assistance. The intrarectal flexible afterloading applicator includes a flexible applicator body, a deformation sensing module, and a spatial positioning marker; The flexible applicator body includes an integrally formed flexible shell, through which multiple radiation source channels and multiple sensor channels extending along its axial direction are provided. The radiation source channels are used to accommodate radiation source guide tubes. The deformation sensing module includes multiple resistance wire strain sensors that are independently disposed in the sensor channel. The deformation sensing module is configured to output a deformation electrical signal that characterizes the axial bending or circumferential torsion of the flexible shell under stress. A spatial positioning mark is provided on the outer surface of the flexible shell, including an axial scale structure for indicating the insertion depth of the applicator, and a circumferential reference mark provided at the tail end of the flexible shell for indicating the rotation angle of the applicator. The deformation electrical signal output by the deformation sensing module, the axial scale structure, and the circumferential reference mark are configured to cooperate with each other to establish the three-dimensional spatial deformation and pose state of the applicator in the target cavity.

2. The offline navigation system for a flexible afterloading applicator in the rectum according to claim 1, characterized in that: The number of radiation source channels of the flexible post-loading source device in the rectal cavity is eight, which are evenly distributed along the circumferential cross-section of the flexible shell; the number of sensor channels is four, which are orthogonally spaced at ninety degrees along the circumferential cross-section of the flexible shell, and each sensor channel is fixed with a resistance wire strain sensor.

3. The offline navigation system for a flexible afterloading applicator in the rectum according to claim 1, characterized in that: The four resistance wire strain sensors of the flexible post-loaded applicator in the rectum are divided into a first sensor and a second sensor located on the expected bending plane of the applicator, and a third sensor and a fourth sensor located on the non-bending plane, with the phase of the circumferential reference mark as the reference reference. The first sensor and the second sensor are arranged radially opposite each other, and the third sensor and the fourth sensor are arranged radially opposite each other. The first and second sensors are configured to generate differential resistance change signals in opposite directions due to tensile stress and compressive stress respectively when the flexible shell undergoes unidirectional bending deformation in accordance with the physiological curvature of the target cavity. The third and fourth sensors are configured such that when the flexible shell undergoes the expected unidirectional bending deformation, the change in its resistance remains within a preset steady-state reference tolerance range.

4. The offline navigation system for a flexible afterloading applicator in the rectum according to claim 1, characterized in that: The third and fourth sensors of the flexible post-loaded applicator in the rectal lumen are also configured to monitor unexpected torsional distortion of the flexible shell; when the relative resistance change rate output by the third and / or fourth sensors exceeds a preset threshold, it is used to determine that the applicator has undergone axial torsional displacement from the expected plane and trigger an early warning electrical signal indicating abnormal posture.

5. The offline navigation system for a flexible afterloading applicator in the rectum according to claim 1, characterized in that: Each sensor channel of the intrarectal flexible postloading applicator is fixed with a front end fixing block and a tail end fixing block at its front and rear ends, respectively; the resistance wire strain sensor includes a continuous resistance wire, which is folded back in a U-shape at the front end fixing block, with its two ends stretched in parallel and extending to the tail end fixing block, and leading out on the outside of the tail end fixing block to form a resistance measurement interface for connecting an external detection device.

6. The flexible postloading device for the rectal lumen according to claim 5, characterized in that: The preset threshold for determining an unexpected torsional offset is 3% of the sensor's initial reference resistance.

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