Built-in wireless temperature measuring device based on microwave ablation composite cable and use method of built-in wireless temperature measuring device

Abstract

The invention relates to the technical field of microwave ablation, in particular to a built-in wireless temperature measuring device based on a microwave ablation composite cable and a use method thereof, and the method comprises the following steps: S1, importing a preoperative medical image of a patient into a host system, and marking a tumor volume and a target ablation volume; s2, inserting a microwave ablation needle with a plurality of wireless temperature sensing nodes arranged along the axial direction into a target tissue, and enabling the sensor nodes to cover a tumor area; s3, starting microwave ablation and recording microwave power and a temperature measurement value {yi (t)} of each node in real time; according to the method, micro wireless temperature nodes with dense front ends and sparse rear ends are arranged in an ablation cable, anti-interference multi-access wireless communication is adopted, a prediction model based on simplified Pennes equation + normalized SAR template and assisted by online data assimilation, and closed-loop power control with a safety priority principle as a core are adopted, so that the ablation accuracy is improved; the thermal field space sampling density is remarkably improved while extra puncture wounds are reduced.

Description

Technical Field

[0001] This invention relates to the field of microwave ablation technology, specifically to a built-in wireless temperature measurement device based on microwave ablation composite cable and its usage method. Background Technology

[0002] Microwave ablation is a commonly used clinical method for local tumor ablation. It involves inputting microwave energy into the target tissue to raise the tissue temperature to the threshold of irreversible necrosis (such as 54°C or 60°C).

[0003] Current clinical temperature measurement relies mainly on single-point thermocouples or external wired temperature measuring needles, which have few sampling points, low spatial resolution, and require additional punctures, increasing trauma. Some existing multi-point or wired built-in temperature measurement solutions still have significant limitations in terms of microwave field interference, cable wiring, mechanical strength, and clinical operability (e.g., multiple punctures, complex wiring), making it difficult to achieve real-time, reliable prediction and automatic energy adjustment of the three-dimensional thermal field during surgery.

[0004] How to integrate multiple miniature temperature measurement nodes within a single ablation needle / coaxial cable to improve spatial sampling density without compromising antenna performance and mechanical integrity; how to achieve low-latency, interference-resistant wireless data transmission across multiple nodes in a strong microwave field environment; how to extend discrete multi-point temperature observations into reliable three-dimensional short-term temperature field predictions through physical models and online parameter calibration; and how to implement real-time closed-loop power control based on this prediction to ensure tumor coverage and safety boundaries while prioritizing the prevention of carbonization, needle tract burns, and maintaining a safe response in case of node disconnection / communication anomalies. Therefore, there is an urgent need for a built-in wireless temperature measurement device based on microwave ablation composite cables and its usage method. Summary of the Invention

[0005] The purpose of this invention is to provide a built-in wireless temperature measurement device based on microwave ablation composite cable and its usage method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The built-in wireless temperature measurement device based on microwave ablation composite cable and its usage method include the following steps:

[0008] S1: Import the patient's preoperative medical images into the host system and label the tumor volume and target ablation volume. ;

[0009] S2: Insert a microwave ablation needle with multiple wireless temperature sensing nodes arranged along the axial direction into the target tissue so that the sensor nodes cover the tumor area.

[0010] S3: Initiate microwave ablation and record microwave power in real time. and the temperature measurement values ​​of each node {y i(t)};

[0011] S4: The host system uses a simplified thermal field model based on the Pennes biological heat conduction equation, and employs a normalized SAR template to construct a microwave energy source term using real-time power scaling for numerical solution, thereby obtaining the predicted temperature field. and threshold volume ;

[0012] S5: The host system compares based on the closed-loop power control law. and And generate and issue power commands ;

[0013] S6: When the preset completion conditions are met or a security rule is triggered, execute the corresponding termination or security action.

[0014] As a further optimization of the present invention, in S4, the tissue parameters used include density ρ, specific heat c, thermal conductivity k, and perfusion rate. The perfusion rate Online parameter estimation based on least squares regularization or recursive filtering is performed, followed by online calibration to obtain the estimated values. .

[0015] As a further optimization of this invention, in S4, the discrete approximation of the energy source term and the semi-implicit difference scheme are used for time advancement to update the grid point temperature to obtain the discrete approximation. .

[0016] As a further optimization of the present invention, in S4, the sensor measurement is regarded as a sampling of the temperature field at the sensing point, including a measurement noise term and a parameter estimation form based on least squares regularization, based on the sensor measurement. Optimize the model parameters θ.

[0017] As a further optimization of the present invention, in S5, the completion determination is that Vablate(t;54℃)≥Vtarget and the duration is not less than the preset holding time Δt.

[0018] As a further optimization of the present invention, the closed-loop power control law takes safety priority as a prerequisite.

[0019] when or When this occurs, power reduction or output cessation will be triggered first.

[0020] If the above safety conditions are not triggered, power commands are generated and issued according to other branches of the closed-loop power control law.

[0021] As a further optimization of the present invention, when a sensor node is found to have missing observations or communication abnormalities for M consecutive time steps, the system switches to the conservative power Psafe control mode according to the abnormality handling strategy and prompts the operator.

[0022] As a further optimization of the present invention, in step S6, the host system also generates a temperature-time curve, a predicted maximum ablation range, and whether the ablation target has been reached after the treatment is completed. Obtain the postoperative report and save or export it.

[0023] As a further optimization of the present invention, it includes: a microwave ablation needle, wherein N miniature wireless temperature sensing nodes are non-equidistantly embedded inside the coaxial cable of the microwave ablation needle, and multiple miniature wireless temperature sensor nodes are arranged along the axial direction of the microwave ablation needle. The sensing nodes have built-in miniature antennas and use frequency division multiple access communication to send temperature data to the host system at carrier frequencies that are independent of each other and do not interfere with each other.

[0024] The host system includes a receiving module for receiving and demodulating temperature data from each node;

[0025] The modeling module includes a built-in thermal field model based on the Pennes biological heat conduction equation, used to apply the temperature data and real-time microwave power... The three-dimensional temperature field T(x, y, z,t) is calculated and predicted in real time using the preset tissue electrothermal parameters as input.

[0026] The control module is used to generate power control commands for the microwave generator output according to preset rules based on the predicted three-dimensional temperature field or directly based on the nodal temperature data. ;

[0027] A coaxial cable, installed at the end of the main system, is used to connect to the microwave ablation equipment via cable.

[0028] As a further optimization of the present invention, the spatial distribution of the miniature wireless temperature sensor nodes satisfies the following: starting from the tip of the ablation needle, the node spacing is D1 in the interval [0, L1], and the node spacing is D2 in the interval (L1, L2], and D1 < D2, where L1 ≤ 2cm and D1 ≤ 0.5cm.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] In this invention, by arranging miniature wireless temperature nodes with a dense front end and a sparse rear end within the ablation cable, employing anti-interference multiple access wireless communication, using a prediction model based on simplified Pennes equations and normalized SAR templates supplemented by online data assimilation, and closed-loop power control with safety as the core principle, it achieves the following: significantly increasing the sampling density of the thermal field space while reducing additional puncture trauma; maintaining low latency and reliable data transmission under microwave operating conditions; obtaining short-term three-dimensional temperature fields and key isothermal surfaces from a small number of measurement points, enabling intuitive visualization and judgment during the procedure; reducing the risk of overburning / carbonization and improving the first-time target achievement rate through prediction-driven automatic or semi-automatic power adjustment; switching to a conservative strategy to ensure clinical safety in case of communication or temperature measurement abnormalities; and generating traceable postoperative reports for quality control and follow-up. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 This is a schematic diagram showing the distribution of multiple wireless temperature sensing nodes in the built-in wireless temperature measurement device based on microwave ablation composite cable of the present invention.

[0033] In the diagram: 1. Microwave ablation needle; 2. Main unit system; 3. Coaxial cable. Detailed Implementation

[0034] Please see Figures 1-2 The present invention provides a technical solution: as a further implementation of this solution,

[0035] The built-in wireless temperature measurement device based on microwave ablation composite cable and its usage method include the following steps:

[0036] S1: Import the patient's preoperative medical images into the host system and label the tumor volume and target ablation volume. ;

[0037] S2: Insert a microwave ablation needle with multiple wireless temperature sensing nodes arranged along the axial direction into the target tissue so that the sensor nodes cover the tumor area.

[0038] S3: Initiate microwave ablation and record real-time microwave power. and the temperature measurement values ​​of each node {y i (t)};

[0039] S4: The host system uses a simplified thermal field model based on the Pennes biological heat conduction equation, and employs a normalized SAR template to construct a microwave energy source term using real-time power scaling for numerical solution, thereby obtaining the predicted temperature field. and threshold volume The simplified Pennes biological heat conduction equation used is expressed as:

[0040] (1)

[0041] In the formula, Tissue density, sourced from a tissue parameter library. The specific heat of the tissue is the preset value. The thermal conductivity of the tissue is a preset value. Blood density and specific heat are preset values. For local blood perfusion rate, Arterial blood temperature, which is the preset value. This serves as a template for normalized energy distribution.

[0042] S5: The host system compares based on the closed-loop power control law. and And generate and issue power commands ;

[0043] S6: When the preset completion conditions are met or the safety rules are triggered, the corresponding termination or safety measures are executed, realizing an integrated process from preoperative planning and real-time temperature measurement at multiple points within the line to short-term three-dimensional prediction and closed-loop power adjustment based on physical models, thereby improving the accuracy and real-time safety of ablation.

[0044] In S4, the tissue parameters used include density ρ, specific heat c, thermal conductivity k, and perfusion rate. The perfusion rate Online parameter estimation based on least squares regularization or recursive filtering is performed, followed by online calibration to obtain the estimated values. ;

[0045] The mathematical expression for parameter estimation is:

[0046] (2)

[0047] In the formula, The model parameter vector to be estimated (regional perfusion rate) ), For the parameter estimation results, For the sensing point ,time The model predicts the temperature (given by the numerical solution of equation (1)). For the i-th sensor at time... The observed temperature, The regularization coefficient is . With parameters as prior knowledge and preset values, online parameter calibration can compensate for individual tissue differences, improve the accuracy of thermal field prediction, and enhance the reliability of control decisions.

[0048] In S4, a discrete approximation of the energy source term and a semi-implicit difference scheme are used for time advancement to update the grid point temperature and obtain a discrete approximation. ,

[0049] The semi-implicit discrete update formula is:

[0050] (3)

[0051] In the formula, , For grid points At discrete temperatures at time steps n and n+1, For time step, For spatial heat conduction discrete operators, For grid points The normalized SAR value at the location is numerically realized using a semi-implicit / discrete approximation, which ensures both computational stability and meets real-time requirements, facilitating rapid intraoperative response and prediction updates.

[0052] In S4, sensor measurements are considered as sampling of the temperature field at the sensing point, including measurement noise terms and parameter estimation forms based on least squares regularization, based on sensor measurements. Optimize the model parameters θ, and the observation model is expressed as:

[0053] (4)

[0054] In the formula, For the i-th sensor at time The observed temperature, This represents the actual temperature at the sensing point in the model. For measuring noise;

[0055] The model parameter θ is optimized by using the least squares regularization form shown in Equation (2), which combines observation noise with regularization estimation to make the model more robust, reduce the impact of abnormal measurements on prediction and improve overall robustness.

[0056] In S5, the completion determination is as follows: (t;54℃)≥ And maintain a holding time of not less than a preset holding time Δt. The completion judgment is based on the volume judgment of the isothermal threshold. The isothermal surface and the threshold volume are defined as follows:

[0057] (5)

[0058] Among them commonly used =54℃ is used as the effective ablation threshold;

[0059] In the formula, For temperature isothermal surface, To satisfy T≥ The volume is approximately equal to 1. This is an indicator function that takes the value 1 when the condition is met. For unit volume, the completion judgment based on isothermal volume provides a quantifiable and repeatable treatment termination criterion, which helps to improve surgical consistency and efficacy controllability;

[0060] Closed-loop power control law prioritizes safety.

[0061] when or When this occurs, power reduction or output cessation will be triggered first.

[0062] If the above safety conditions are not triggered, power commands are generated and issued according to other branches of the closed-loop power control law. The closed-loop power control law adopts a safety-first branch logic, which can be represented in an illustrative segmented form:

[0063] (6)

[0064] in, = - ;

[0065] In the formula, For the issued power command, The minimum / maximum power allowed by the device. This represents the current actual output power. To reduce the step length, Let i be the temperature rise rate of the i-th node. The threshold for the rate of temperature rise. The carbonization threshold, The proportional gain for volume error. For volume error, Limit the value to [ The range of trimming functions and the safety-first control strategy can be quickly intervened when carbonization or abnormal temperature rise rate occurs, significantly reducing the risk of complications and ensuring patient safety;

[0066] When a sensor node fails to observe or experiences communication anomalies for M consecutive time steps, the system switches to the conservative power Psafe control mode according to the anomaly handling strategy and alerts the operator. This is illustrated as follows:

[0067] (7)

[0068] In the formula, M is the threshold for the number of consecutive invalid sampling steps. With a preset conservative power value, anomaly detection and automatic backoff logic ensure that a conservative safety strategy is maintained even in the event of observation loss or communication failure, thereby reducing risk and improving system reliability.

[0069] S6 also includes the generation by the host system after treatment, which includes temperature-time curves, predicted maximum ablation range, and whether the ablation target has been reached. The automatically generated postoperative reports can be saved or exported, providing structured and traceable data support for clinical records, quality control, and efficacy follow-up.

[0070] Includes: microwave ablation needle 1, inside the coaxial cable of microwave ablation needle 1, N miniature wireless temperature sensing nodes are embedded non-equidistantly along its axis. Multiple miniature wireless temperature sensor nodes are arranged along the axis of microwave ablation needle 1. The sensing nodes have built-in miniature antennas and use frequency division multiple access communication to send temperature data to the host system at independent and non-interfering carrier frequencies.

[0071] Host system 2 includes a receiving module for receiving and demodulating temperature data from each node;

[0072] The modeling module includes a built-in thermal field model based on the Pennes biological heat conduction equation, used to generate thermal field models from temperature data and real-time microwave power. The three-dimensional temperature field T(x, y, z, t) is calculated and predicted in real time using the preset tissue electrothermal parameters as input.

[0073] The control module is used to generate power control commands for the microwave generator output according to preset rules, based on the predicted three-dimensional temperature field or directly from the nodal temperature data. ;

[0074] Coaxial cable 3 is installed at the end of the host system 2 and is used to connect to the microwave ablation equipment via cable. This device modularly integrates sensing, communication, modeling and control, which facilitates system integration in engineering implementation and can provide real-time prediction and closed-loop control capabilities during the operation.

[0075] The spatial distribution of the miniature wireless temperature sensor nodes satisfies the following: starting from the tip of the ablation needle, the node spacing is D1 in the interval [0, L1] and D2 in the interval (L1, L2], and D1 < D2, where L1 ≤ 2cm and D1 ≤ 0.5cm. The non-equidistant node layout design with dense front end and sparse rear end better captures the thermal dynamics of the high temperature gradient region at the needle tip, thereby improving the estimation accuracy of the isothermal surface and the ablation boundary.

[0076] The specific procedure is as follows: Preoperative image import and planning: Operation: Import the patient's CT / MRI into the host computer, delineate the tumor boundary and set the target ablation volume. (Including safety boundaries); Effects: Establishes individualized targets and geometric computational domains, providing a benchmark for subsequent thermal field prediction and control; Reference indicators: Image import / annotation latency < 2 min; Target volume files can be exported as DICOM / JSON;

[0077] Needle placement and sensor positioning: Procedure: Percutaneously insert an ablation needle with a multi-node wireless temperature sensor along the axial direction, confirming that the sensor covers the tumor area (intraoperative imaging / ultrasound localization); Results: Obtain a linear, multi-point, and realistic temperature sampling channel, reducing additional puncture trauma and increasing the sampling density of the thermal field space; Reference indicators: Number of sensor nodes N≥4; Positioning error < 5 mm (compared to preoperative planning).

[0078] Initiating Ablation and Real-time Acquisition: Operation: Turn on microwave output; the host continuously receives the temperature y at each node. i (t) and real-time power Time synchronization and verification are performed; Results: High time-frequency resolution temperature measurement sequences are obtained, providing experimental constraints for data assimilation and short-term prediction. Reference indicators: Sensor sampling period 50–200 ms; overall data reporting delay < 200 ms; Bit error rate (BER) controllable < 10⁻ under microwave operation. 4 ;

[0079] Modeling + Data Assimilation → Temperature Field Prediction: Operation: The host computer uses the simplified Pennes equation and pre-stored SAR template as described in the manual (source terms are...). Scaling), using semi-implicit difference or dimensionality reduction for fast solution; simultaneously using least squares / recursive filtering methods to calibrate key parameters online (such as... Effect: Extends discrete one-dimensional temperature measurement to three-dimensional short-term temperature field prediction, outputting key isothermal surfaces and threshold volumes. Significantly improves the visualization and predictability of ablation boundaries; Reference indicators / targets: prediction update cycle 0.5–2s; short-term (5–10s) temperature prediction error < ±2–3 ℃ (experimental / simulation target); calibrated volume prediction error <10–20% (in vitro / animal validation target);

[0080] Closed-loop power control decision-making and command issuance: Operation: The control module performs proportional / PI control based on safety priority logic (prioritizing carbonization threshold and temperature rise rate) combined with volume error, generating and issuing commands. Effects: Real-time adjustment of energy input to accelerate ablation of unmet targets or suppress overheated areas, reducing the risk of overburning / carbonization and organ damage, while improving the consistency of achieving target volume; Reference indicators: Power adjustment response time (from issuance to generator effect) <1s; Overburning rate reduced by ≥30% due to closed-loop control (compared to open-loop control); Improved treatment completion rate (first target achieved);

[0081] Complete assessment / safety procedures / postoperative report: Procedure: When (t;54℃)≥ And when the temperature remains ≥Δt, or when a safety rule is triggered, the system will stop or issue a warning; postoperative temperature-time curves, predicted ablation range, and judgment reports will be generated and archived; effects: automatic / semi-automatic termination conditions will be implemented, providing traceable treatment records and quality control data to facilitate clinical decision-making and follow-up; reference indicators: postoperative reports include: temperature curves, maximum predicted ablation volume, and whether the target has been met; PDF / JSON export time <30s.

[0082] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A method for using a built-in wireless temperature measurement based on a microwave ablation composite cable, characterized in that, The method comprises the following steps: S1 : import preoperative medical images of the patient into the host system and label the tumor volume and target ablation volume ; S2: inserting a microwave ablation needle with multiple wireless temperature sensor nodes arranged along the axial direction into the target tissue, so that the sensor nodes cover the tumor area; S3: Start microwave ablation and record microwave power in real time and the temperature measurements {y i (t)}; S4: The host system constructs the microwave energy source term by numerical solution based on the simplified thermal field model of Pennes bio-heat conduction equation and normalized SAR template according to real-time power scaling to obtain the predicted temperature field and threshold volume ; S5: the host system compares according to the closed-loop power control law and generates a power command to be issued ; S6: performing corresponding end or safety treatment when the preset completion condition or safety rule is met.

2. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. In S4, the used tissue parameters include density p, specific heat c, thermal conductivity k and perfusion rate where perfusion rate Online calibration is performed to obtain the estimates based on online parameter estimation by least square regularization or recursive filtering .

3. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. In S4, the grid point temperature is updated to obtain a discrete approximation by using a discrete approximation of the energy source term and a semi-implicit difference scheme for time advancement .

4. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. In S4, the sensor measurements are considered as samples of the temperature field at the sensor points, with measurement noise terms and a parameter estimation form based on least squares regularization, based on the sensor measurements Optimize the model parameters θ.

5. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. In S5, the completion criterion used is Vablate(t; 54℃) ≥ Vtarget and maintained for no less than a preset holding time Δt.

6. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. The closed-loop power control law takes safety priority as a prerequisite; When or preferentially triggers power reduction or stops output; When the above safety condition is not triggered, the power command is generated and issued according to other branches of the closed-loop power control law.

7. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. When the sensor node observation is missing or the communication is abnormal for M consecutive time steps, the system switches to the conservative power Psafe control mode according to the abnormal handling strategy, and prompts the operator.

8. The method of claim 1, wherein the microwave ablation composite cable is used for wireless temperature measurement. In S6, a post-treatment report is also generated by the host system including the temperature-time curve, the predicted maximum ablation zone and whether the target temperature was reached or not after the end of the treatment and saved or exported. ​ 9. The microwave ablation composite cable-based, internal wireless temperature sensing device of any of claims 1-8, wherein: It comprises: A microwave ablation needle (1) with N miniature wireless temperature sensor nodes arranged along the axial direction of the coaxial cable inside the microwave ablation needle (1) embedded in a non-equidistant manner, multiple miniature wireless temperature sensor nodes arranged along the axial direction of the microwave ablation needle (1), the sensor nodes are built-in miniature antennas, and use frequency division multiple access communication mode to send temperature data to the host system at carrier frequencies independent of each other and without interference; A host system (2) comprising a receiving module for receiving and demodulating the temperature data of each node; The modeling module is built-in with a heat field model based on the Pennes bio-heat conduction equation, for real-time calculation and prediction of a three-dimensional temperature field T(x, y, z, t) with the temperature data, real-time microwave power , and preset tissue electro-thermal parameters as inputs; a control module for generating power control instructions for the microwave generator output according to the predicted three-dimensional temperature field or directly from node temperature data, according to preset rules ; A coaxial cable (3) installed at the tail end of the host system (2) for connecting with the microwave ablation device through the cable.

10. The microwave ablation composite cable-based, wireless, internal temperature measurement device of claim 9, wherein: The spatial distribution of the miniature wireless temperature sensor nodes satisfies: taking the tip of the ablation needle as the starting point, the node spacing is D1 in the interval [0, L1], the node spacing is D2 in the interval (L1, L2], and D1 < D2, wherein L1 ≤ 2cm, D1 ≤ 0.5cm.

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