Evaluation method and system of spherical focused ultrasound system based on integrated ablation and monitoring functions

Abstract

The invention discloses an evaluation method and system of a spherical focused ultrasound system based on integrated ablation and monitoring functions, and belongs to the technical field of biomedical engineering ultrasound. The system comprises a spherical cavity standing wave focused ultrasonic transducer, a multi-mode real-time monitoring module and an evaluation model construction and optimization unit. The transducer module adopts a spherical cavity standing wave for focusing to generate a sub-wavelength-level focal region; the monitoring module synchronously collects the temperature, cavitation signals and morphological images at the focus in real time; the evaluation unit processes the multi-modal data and constructs a correlation model of the acoustic parameters and the ablation effect. According to the invention, integration of high-precision ultrasonic ablation and whole-process multi-parameter real-time monitoring is realized, a systematic and quantitative experiment evaluation platform is provided, the influence rule of different acoustic parameters on thermal ablation and cavitation ablation effects can be effectively researched, and a powerful data support and analysis tool is provided for optimizing an ultrasonic treatment strategy.

Description

Technical Field

[0001] This invention relates to the field of ultrasound medical diagnostic technology, and in particular to an evaluation method and system for a spherical focused ultrasound system based on integrated ablation and monitoring functions. Background Technology

[0002] High-intensity focused ultrasound (HIFU) is a novel non-invasive ablation technique. The thermal ablation effect of HIFU is currently the most thoroughly researched treatment mechanism. This technique precisely focuses high-intensity ultrasound waves from outside the body onto a specific area within the body, causing a rapid increase in local temperature to above 55°C, leading to coagulative necrosis of the target area. HIFU thermal ablation has been widely used in the clinical treatment of various diseases, including uterine fibroids, prostate cancer, liver tumors, and breast lesions. Based on the cavitation effect of HIFU, a non-thermal tissue ablation technique is histotripsy. Histotripsy utilizes short pulses of high-intensity, low-duty-cycle ultrasound waves to cause nonlinear oscillations of gaseous nuclei within the tissue under ultrasound irradiation, resulting in violent expansion and rupture of bubbles. This generates high sound pressure locally, thereby destroying cell structure without significant heat accumulation. This non-thermal mechanism shows significant advantages in tissue selectivity, ablation precision, and reduced damage to adjacent tissues. Currently, histotripsy technology has been successfully applied in various animal experiments, including research on the treatment of non-tumor tissues such as the brain, thyroid, liver, kidney, and prostate. In addition, this technology has been widely used in ablation studies of tumor models such as liver cancer, pancreatic cancer and bone cancer, and has shown good application prospects in areas such as softening aortic valve calcification deposits and thrombus removal.

[0003] Currently, the most mainstream HIFU (High-Intensity Focused Ultrasound) primarily uses concave spherical transducers for traveling wave field focusing. The physical characteristics of traveling wave field focusing result in a focusing size of approximately 10 wavelengths along the acoustic axis and approximately 1-2 wavelengths perpendicular to the acoustic axis. Its focal zone is often relatively long along the acoustic axis, leading to a "cigar-shaped" energy distribution and causing the ablation area to extend excessively along the acoustic axis. This can result in non-target thermal deposition and insufficiently precise ablation when ablating small or irregular lesions. To improve the focal zone size of HIFU, a spherical cavity transducer with openings at both ends is used for standing wave field focusing. The surface of the spherical cavity transducer serves as both the emitting and strongly reflecting surface of ultrasound waves. The acoustic field of the standing wave field focusing is composed of the superposition of sound waves radiated from the spherical surface and those reflected multiple times. When the focused sound wave at the center of the sphere and the sound waves from each reflection are in phase, a very high sound pressure can be generated at the center of the sphere. Previous studies have demonstrated that standing wave field focusing gain (PFG) exceeds three times, and the focal size of standing wave field focusing can reach the subwavelength level, which is beneficial for fine ablation. Research has also shown that standing wave field focusing exhibits smaller focus shift and focal beam distortion in non-homogeneous media. Standing wave field focusing has certain advantages in focusing accuracy compared to traveling wave field focusing.

[0004] Existing high-intensity focused ultrasound (HIFU) ablation techniques primarily employ concave spherical transducers for traveling wave focusing. This results in a long focal zone along the acoustic axis, resembling a "cigar," leading to insufficient focusing precision and potential damage to non-target tissues during delicate ablation. Furthermore, current systems lack effective real-time monitoring during treatment, relying heavily on pre- and post-treatment image comparisons. This fails to simultaneously capture dynamic changes in key physical parameters such as thermal field distribution and cavitation activity within the ablation area. Treatment processes are often open-loop controlled, with parameter settings dependent on experience and unable to dynamically adjust based on real-time tissue responses, resulting in low levels of intelligence. Additionally, treatment, imaging, and monitoring equipment are typically independent, leading to low system integration, cumbersome operation, and registration errors, all of which negatively impact experimental reliability and repeatability. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an evaluation method and system for a spherical focused ultrasound system based on integrated ablation and monitoring functions. The method utilizes multi-source data fusion for synchronous monitoring and adjustment of the focused ultrasound system.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions provided by this invention includes the following steps: Step S1: Set the acoustic parameters of the spherical focused ultrasound and place the experimental sample in the focal region of the spherical focused ultrasound. Step S2: Simultaneously start ultrasonic ablation and trigger the multimodal real-time monitoring module to collect data, including temperature data of the focal area, cavitation acoustic emission signal, and image data of the focal area; Step S3: Real-time processing of the acquired data, including: calculating the cumulative equivalent thermal dose (CEM43) based on the temperature data, calculating the inertial cavitation dose (ICD) based on the cavitation acoustic emission signal, and calculating the morphological parameters of the damaged area based on the image data, wherein the morphological parameters of the damaged area include those used to calculate the ablation efficiency. The ablation area; Step S4: Associate the acoustic parameters set in step S1 with the physical response parameters calculated in step S3. The physical response parameters include at least CEM43, ICD, and ablation efficiency. The correlation results are then stored in an evaluation database used to analyze the influence of acoustic parameters on ablation effects. Step S5: Based on the evaluation database, analyze the influence of different combinations of acoustic parameters on CEM43, ICD, η_EA and the final ablation effect.

[0007] Furthermore, in step S3, the calculation of the cumulative equivalent heat dose (CEM) 43 The formula is: ; Where T represents the average temperature over a time interval of ∆t = 0.5 seconds. The R value is 0.25 below 43℃ and 0.5 above 43℃.

[0008] Furthermore, in step S3, the formula for calculating the inertial cavitation dose (ICD) is: ; Where N is the total number of samples, and Fmax is the maximum frequency in the calculation.

[0009] Furthermore, in step S3, the morphological parameters of the damaged area include the ablation area; the method also includes calculating the ablation efficiency. The steps and calculation formula are as follows: ; Where P represents acoustic power, t is the equivalent exposure time, and S is the maximum ablation area.

[0010] Furthermore, in step S3, the processing of the cavitation acoustic emission signal includes obtaining a spectrum diagram and a time spectrum diagram using a short-time Fourier transform.

[0011] Furthermore, the processing of the cavitation acoustic emission signal also includes: using a comb filter based on fast Fourier transform to eliminate the HIFU fundamental frequency and its first nine harmonic components.

[0012] Furthermore, in step S2, the acquisition of the image data is performed intermittently during the ablation process or after the ablation is completed.

[0013] This invention provides an evaluation system based on a spherical focused ultrasound system with integrated ablation and monitoring functions, comprising: A spherical cavity standing wave focusing ultrasonic transducer is used to generate an ultrasonic focal point for focusing a standing wave field in the central region of a spherical cavity. The multimodal real-time monitoring module is synchronously triggered with the spherical cavity standing wave focusing ultrasonic transducer and is used to monitor the temperature data, cavitation acoustic emission signal and image data of the focal region in real time. The evaluation model construction and optimization unit is communicatively connected to the multimodal real-time monitoring module. It is used to receive and process the data from the multimodal real-time monitoring module, calculate the physical response parameters, and store the acoustic parameters in the evaluation database after associating them with the physical response parameters, so as to analyze the influence of different combinations of acoustic parameters on the ablation effect.

[0014] Furthermore, the spherical cavity standing wave focusing ultrasonic transducer includes a spherical cavity ultrasonic transducer with openings at both ends, a center frequency of 660kHz, an inner radius of 115mm, an aperture height of 115mm, and upper and lower opening diameters of 199mm.

[0015] Furthermore, the multimodal real-time monitoring module includes: The temperature monitoring unit includes a needle thermocouple placed in the focal region; The cavitation signal monitoring unit includes a passive cavitation detector that is positioned at the focal point via confocal alignment.

[0016] The beneficial effects of this invention are as follows: This invention provides an evaluation method and system for a spherical focused ultrasound system with integrated ablation and monitoring functions, belonging to the field of biomedical engineering ultrasound technology. This method integrates high-precision ultrasound ablation with real-time monitoring of multiple parameters throughout the process. It constructs an integrated ablation-monitoring system based on a spherical focused transducer, enabling simultaneous monitoring of multiple parameters such as temperature, cavitation signal, and damage morphology. This allows for effective research into the influence of different acoustic parameters on thermal ablation and cavitation ablation effects, providing powerful data support and analytical tools for optimizing ultrasound treatment strategies. Through real-time multimodal monitoring of the standing wave focused ultrasound ablation process, and based on the monitoring data, the system evaluates the impact of different acoustic parameters on treatment effects, providing data support for optimizing treatment strategies.

[0017] The method provided by this invention can be used to evaluate the effects of different ultrasonic parameters (such as acoustic energy, power, and pulse mode) on thermal dose, cavitation intensity, and final damage effect, and has the following advantages: High focusing accuracy: It adopts spherical standing wave focusing, and the focal size reaches the subwavelength level, which is suitable for fine ablation research.

[0018] Comprehensive and real-time monitoring: Simultaneously acquires multi-dimensional information such as heat, cavitation, and morphology to achieve panoramic visualization of the ablation process.

[0019] Evaluation Systems Science: Provides a standardized platform for systematically studying the impact of different acoustic parameters on ablation efficacy, and provides experimental evidence for optimizing clinical parameters.

[0020] High integration and easy operation: The integrated design of ablation and monitoring reduces registration errors and improves experimental repeatability and reliability.

[0021] The above and other objects, advantages, and features of the present invention will be more fully set forth and demonstrated through the following detailed description of specific embodiments in conjunction with the accompanying drawings. Those skilled in the art, upon referring to the following detailed description and the accompanying drawings, will be able to better understand and realize the above advantages of the present invention. Other objects, features, and advantages of the present invention will become clearer after being described in detail in the detailed description section in conjunction with the accompanying drawings. Attached Figure Description

[0022] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following drawings are provided for illustration.

[0023] Figure 1 Flowchart of the evaluation method for a spherical focused ultrasound system with integrated ablation and monitoring functions; Figure 2 This serves as an experimental platform for transducer ablation and monitoring. Figure 3 For CEM 43 Change curve; Figure 4 This is a temperature change curve; Figure 5 The curve showing the change in ablation size with acoustic energy; Figure 6 For ablation efficiency η EA The curve of change of sound energy; Figure 7 The curve showing the variation of cavitation intensity ICD with acoustic energy; Figure 8 This is a frequency domain characteristic diagram of the cavitation signal from a spherical focusing transducer. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0025] Example 1 like Figure 1 As shown in this embodiment, the evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions is characterized by the following steps: Step S1: Set the acoustic parameters of the spherical focused ultrasound and place the experimental sample in the focal region of the spherical focused ultrasound. The experimental samples in this embodiment are isolated biological tissues or tissue phantoms; Step S2: Simultaneously start ultrasonic ablation and trigger the multimodal real-time monitoring module to collect data, including temperature data of the focal area, cavitation acoustic emission signal, and image data of the focal area; In this embodiment, the acquisition of image data is performed intermittently during the ablation process or after the ablation is completed.

[0026] In this embodiment, data acquisition is performed by a multimodal real-time monitoring module consisting of a temperature monitoring unit, a cavitation signal monitoring unit, and a damage morphology monitoring unit. Step S3: Real-time processing of the collected data, including: calculating the cumulative equivalent heat dose (CEM) based on the temperature data. 43 The inertial cavitation dose (ICD) is calculated based on the cavitation acoustic emission signal, and the morphological parameters of the damaged area are calculated based on the image data. The calculation of cumulative equivalent heat dose (CEM) described in this embodiment 43 The formula is: ; Where T represents the average temperature within a preset time interval, and in this embodiment, the preset time interval can be set to ∆t = 0.5 seconds; The R value is 0.25 below 43℃ and 0.5 above 43℃. Indicates the end time of the action; Indicates the length of the time interval; The formula for calculating the inertial cavitation dose (ICD) in this embodiment is as follows: ; Where N is the total number of samples, F max This represents the maximum frequency in the calculation; Indicates frequency; In this embodiment, the morphological parameters of the damaged area include the ablation area; the method also includes calculating the ablation efficiency. The steps and calculation formula are as follows: ; Where P represents sound power; t is the equivalent exposure time; S represents the maximum ablation area; In this embodiment, the processing of the cavitation acoustic emission signal includes using short-time Fourier transform to obtain a spectrum diagram and a time spectrum diagram.

[0027] The processing of the cavitation acoustic emission signal in this embodiment also includes: using a comb filter based on fast Fourier transform to eliminate the HIFU fundamental frequency and its first nine harmonic components.

[0028] Step S4: Associate the acoustic parameters set in step S1 with the physical response parameters calculated in step S3, and store the association results in the evaluation database; The example constructs a dataset linking acoustic parameters to multimodal physical responses (temperature, cavitation, damage morphology) through experiments and establishes a predictive model. This model can perform forward prediction of treatment effects based on parameters, and backward optimization by recommending optimal parameters based on treatment goals, thereby achieving intelligent pre-selection of treatment parameters, as detailed below: The acoustic parameters (sound power, duration, pulse mode) set in each experiment were used as input variables, and the CEM calculated in real time was used as input variables. 43 The unit uses curve characteristic values ​​(such as the time to reach the 240-minute threshold and the maximum heating rate), ICD curves (such as the mean and decay rate), and final damage morphology parameters (ablation size and ablation efficiency) as output responses to establish a "parameter-response" correlation dataset. Based on an experimental database, this unit employs fitting methods (such as multinomial regression and exponential fitting) to establish a predictive model from acoustic parameters to physical responses. The model can be used for: forward prediction: estimating temperature rise, cavitation intensity, and final damage size during treatment based on set acoustic parameters; and backward optimization: recommending the optimal combination of acoustic parameters based on expected treatment goals (such as maximum damage area, minimum thermal diffusion, and specific cavitation levels), achieving intelligent pre-selection and optimization of treatment parameters.

[0029] In this embodiment, three core quantitative indicators are used to evaluate the effect of ultrasound ablation, namely the multimodal quantitative evaluation index (CEM). 43 , ICD, η EA ), of which CEM 43 (Equivalent thermal damage dose) Real-time monitoring of thermal effect progress and risk; ICD (Inertial Cavitation Dose) Precisely quantifies the intensity of cavitation mechanical damage; η EA(Ablation efficiency) comprehensively evaluates treatment efficacy from the perspective of energy utilization. These three factors together constitute a multimodal, quantifiable treatment effect evaluation system, as detailed below: Cumulative thermal injury dose (CEM) 43 Based on real-time temperature data of the focal region, this index converts the thermal effects under different temperature-time histories into the cumulative effect time (minutes) at 43°C. 43 It is the gold standard for assessing the effect of thermal ablation, and its value is directly related to the degree of coagulative necrosis of tissue proteins. This is achieved by monitoring CEM (Continuous Emission Model). 43 The system can quantify the thermal deposition efficiency of ultrasonic energy and provide early warnings of overheating risks by displaying the real-time growth curve.

[0030] Inertial cavitation dose (ICD): Calculated based on the acquired cavitation acoustic emission signal spectrum, it is obtained by integrating and normalizing the broadband noise energy in a specific frequency band (filtering out the fundamental and harmonic frequencies). ICD is a key indicator for quantifying the intensity of transient cavitation activity, directly reflecting the mechanical destructive force generated by the violent collapse of bubbles. This indicator is used to assess the activity level of non-thermal ablation (such as tissue pulverization) and the cavitation enhancement effect accompanying thermal ablation.

[0031] Ablation efficiency (η) EA η is calculated based on the morphological image of the final damaged area and is defined as the ratio of the input acoustic energy (acoustic power P × action time t) to the maximum ablation area S produced, i.e., η EA = (P·t) / S. This index assesses treatment effectiveness from a macroscopic perspective of energy utilization efficiency; a lower η EA The value indicates that a unit of input energy produces a larger damage area, signifying higher ablation efficiency. It comprehensively reflects the synergistic effect of sound field focusing performance, tissue response characteristics, and thermal / cavitation mechanisms.

[0032] Step S5: Based on the evaluation database, analyze the influence of different combinations of acoustic parameters on the physical response and the final ablation effect. In this embodiment, the evaluation database and the influence patterns are used to guide the optimization of experimental parameters for spherical focused ultrasound ablation. This embodiment is based on a specific physical experimental platform and obtains real physical data through a specific multimodal monitoring module to construct an evaluation database for guiding the optimization of experimental parameters.

[0033] This embodiment experimentally constructs a correlation database between acoustic parameters (power, time, etc.) and physical responses (temperature rise, cavitation, damage). Based on this database, trend analysis is performed and a prediction model is trained to achieve positive prediction of parameter prediction effects and reverse optimization by recommending optimal parameters according to the target.

[0034] This plan uses three core quantitative indicators: CEM 43Assess thermal damage, quantify cavitation intensity using ICD, η EA Measuring energy efficiency. These three elements constitute a multimodal assessment system that comprehensively and objectively quantifies the therapeutic effect of ultrasound ablation.

[0035] The evaluation database constructed in this embodiment links acoustic parameter combinations with physical response data. The database is used for trend analysis to reveal patterns and serves as a training data source to build a predictive model from parameters to response.

[0036] The acoustic parameter combination includes: acoustic power, duration of action, acoustic energy, number of pulse cycles, pulse width, etc.

[0037] The trend analysis: By statistically analyzing multiple sets of experimental data in the database, the system can plot curves such as "damage size versus acoustic energy" (…). Figure 5 ), "η EA curve of change with sound power Figure 6 The relationship diagrams (such as those for acoustic parameters and physical response) visually reveal the influence of acoustic parameters on physical response, and are used to guide parameter optimization.

[0038] The model training basis: This database is the source of training data for constructing the evaluation models such as the multinomial regression. The system can learn the complex mapping relationship from acoustic parameters to physical response, and realize intelligent prediction of treatment response under new parameter combinations.

[0039] The therapeutic or ablation effects in this embodiment are analyzed using physical, morphological, and efficacy indicators. The physical indicators include: degree of thermal damage: expressed as cumulative equivalent thermal dose (CEM). 43 This indicates a particular focus on whether it has reached the threshold for coagulative necrosis (such as CEM). 43 ≥ 240 min); Cavitation activity intensity: expressed as inertial cavitation dose (ICD), reflecting the strength of the mechanical destructive effect; Real-time dynamic evolution: the dynamic changes in energy deposition and cavitation activity during treatment are displayed through temperature curves and ICD time-series curves; Among them, the morphological indicators include: Damage size: ablation area, size of the damage in each axis, visually representing the ablation range; Damage shape: contour roundness, aspect ratio, assessing the accuracy and regularity of ablation; Among them, the efficacy indicator: ablation efficiency η EA η EA = (P·t) / S, which evaluates the treatment effect from the perspective of energy utilization. The lower the value, the higher the energy efficiency.

[0040] This embodiment provides a spherical focused ultrasound system integrating ablation and monitoring functions, characterized in that it includes a spherical cavity standing wave focused ultrasound transducer, a multimodal real-time monitoring module, and an evaluation model construction and optimization unit; The spherical cavity standing wave focusing ultrasonic transducer is used to generate an ultrasonic focus for focusing a standing wave field in the central region of the spherical cavity. In this embodiment, the spherical cavity standing wave focusing ultrasonic transducer includes a spherical cavity with openings at both ends, a piezoelectric transducer unit disposed on the inner wall of the cavity, and a driving circuit; the driving circuit is used to drive the piezoelectric transducer unit to vibrate, forming an ultrasonic focal point for focusing the standing wave field in the central region of the spherical cavity.

[0041] The spherical focusing ultrasonic transducer described in this embodiment adopts a spherical cavity design with openings at both ends. The inner surface has an array of 64 concave piezoelectric ceramic elements, which are electrically connected in parallel. The center frequency of the piezoelectric ceramic elements is designed to be 660kHz, and the emitting surface also acts as an ultrasonic wave reflector, causing multiple reflections within the spherical cavity. The cavity is filled with degassed deionized water as the acoustic coupling medium to reduce energy loss during sound wave propagation. The transducer is entirely waterproof and sealed, and the interface is connected to the external drive circuit via a coaxial cable, ensuring long-term stable operation in liquid environments.

[0042] The core of the driving circuit described in this embodiment is a high-frequency signal generator and a power amplifier, capable of generating sinusoidal signals with a frequency range of 10kHz to 2MHz, and an output peak power exceeding 1000W. It supports both continuous wave (CW) and pulsed wave (PW) operating modes. All driving parameters (acoustic power, pulse width, duty cycle, total duration, etc.) can be set and adjusted in real time through a customizable MATLAB control interface, enabling flexible switching of treatment modes. The driving circuit has a synchronous trigger interface, allowing for second-level synchronization with multimodal monitoring modules (temperature, cavitation, imaging), ensuring the timing consistency between data acquisition and ultrasound emission. The circuit incorporates overcurrent, overtemperature, and impedance detection protection functions, automatically cutting off the output when an abnormality is detected to ensure system safety.

[0043] The multimodal real-time monitoring module is triggered synchronously with the spherical cavity standing wave focusing ultrasonic transducer and is used to monitor the temperature data, cavitation acoustic emission signal and image data of the focal region in real time. The multimodal real-time monitoring module described in this embodiment includes a temperature monitoring unit, a cavitation signal monitoring unit, and a damage morphology monitoring unit. A temperature monitoring unit is used to monitor the temperature change of the focal region in real time; it includes a needle thermocouple placed in the focal region. A cavitation signal monitoring unit is used to collect acoustic emission signals generated in the focal region in real time; including a passive cavitation detector set at the focal point by confocal alignment. The damage morphology monitoring unit is used to acquire an image of the focal region.

[0044] The data acquisition of each unit is synchronously triggered with the ultrasonic emission of the transducer module.

[0045] The temperature monitoring unit in this embodiment is used to monitor the temperature changes in the focal region in real time. Specifically, it includes a needle thermocouple (diameter ≤ 1 mm) placed in the focal region, with its tip positioned approximately 1 mm outside the focal point to reduce acoustic field disturbances and artifacts. The thermocouple acquires temperature signals at a sampling rate of ≥ 2 Hz via a data acquisition card (TP700-16Q) and transmits them to a computer for real-time display and subsequent processing. The temperature data is smoothed by Savitzky-Golay filtering and used to calculate the cumulative equivalent heat dose (CEM) in real time. 43 ).

[0046] The cavitation signal monitoring unit in this embodiment is used to acquire cavitation acoustic emission signals generated in the focal region in real time. It includes a passive cavitation detector (PCD) positioned at the focal point using confocal alignment, with a center frequency of 15MHz (e.g., Olympus V319). The PCD signal is amplified by a broadband preamplifier and acquired by a high-speed digital oscilloscope (e.g., PicoScope5444D) at a sampling rate of ≥50MHz, then transmitted to a computer for time-frequency analysis. Signal processing includes: obtaining a time-frequency spectrum using a short-time Fourier transform (STFT, Hanning window, window length 1024 points, 90% overlap); eliminating the HIFU fundamental frequency and its first nine harmonics using an FFT-based comb filter; and calculating the inertial cavitation dose (ICD) by integrating the power spectral density within a set frequency band.

[0047] The damage morphology monitoring unit in this embodiment is used to acquire images of the focal region and extract morphological parameters of the damaged region. Specifically, it includes: an image acquisition device using a digital camera (Canon 850D) to capture images immediately after ablation; importing the acquired images into image processing software (such as ImageJ) to automatically delineate the damage boundaries and calculate the ablation area and equivalent size; furthermore, the system can calculate the ablation efficiency η based on the ablation area and the input acoustic energy. EA .

[0048] The evaluation model construction and optimization unit is communicatively connected to the multimodal real-time monitoring module. It is used to synchronously receive and process multimodal monitoring data, extract feature parameters, and construct an evaluation model between acoustic parameters and ablation effect based on historical experimental data. This model is used to quantitatively evaluate the treatment effect or optimize acoustic parameters. In this embodiment, the physical response parameters are calculated by receiving and processing data from the multimodal real-time monitoring module. The acoustic parameters are then associated with the physical response parameters and stored in the evaluation database to analyze the influence of different combinations of acoustic parameters on the ablation effect.

[0049] The specific construction process of the evaluation model in this embodiment is as follows: Model construction process: The evaluation model is constructed using a multinomial regression modeling method, specifically including the following steps: Data preparation: Extract historical experimental data from the evaluation database, including input variables (acoustic parameters such as sound power P, duration t, and pulse duty cycle D) and output responses (physical response parameters, CEM). 43 Threshold time T, ICD value, lesion area S, ablation efficiency η EA ); Feature construction: Construct polynomial feature terms based on acoustic parameters, such as building feature vectors including P, t, P*t, etc., to capture the nonlinear interaction between parameters; Model training: A polynomial regression model is fitted using the least squares method, with the general form as follows: Where y is the output response (such as S or η) EA ), x i For the input features, β i Here are the regression coefficients, and ε is the error term. Model validation: The dataset is divided into training and test sets proportionally, and the coefficient of determination R is used. 2 The goodness of fit and prediction accuracy of the model are evaluated using the root mean square error (RMSE). The evaluation model's structure and function: The evaluation model is a parametric prediction and optimization framework based on multinomial regression, and its structure includes: Input layer: Receives acoustic parameters or target treatment effect indicators set by the user; Feature transformation layer: converts the input parameters into a multinomial feature vector; Regression prediction layer: Calls the trained multinomial regression model and outputs the CEM. 43 ICD, damaged area, η EA Predicted values ​​for, etc. Optimize the decision layer: given an objective function (such as maximizing η) EA Based on the model, the recommended combination of acoustic parameters is derived. Output layer: Provides prediction curves, a list of recommended parameters, and confidence intervals.

[0050] The evaluation model construction and optimization unit described in this embodiment is configured to execute the above method steps S1-S5.

[0051] The spherical cavity standing wave focusing ultrasonic transducer described in this embodiment includes a spherical cavity ultrasonic transducer with openings at both ends, a center frequency of 660kHz, an inner radius of 115mm, an aperture height of 115mm, and upper and lower opening diameters of 199mm.

[0052] The center frequency of the passive cavitation detector described in this embodiment is 15MHz.

[0053] The method provided in this embodiment is to convert raw multimodal data into a quantitative evaluation index (CEM). 43 ICD This involves a systematic analysis process, starting with the "parameter-effect" correlation model. The resulting model can then be used to guide the optimal selection of acoustic parameters.

[0054] The specific steps of the evaluation method in this embodiment are as follows: Experimental preparation and system calibration: Prepare the experimental sample (phantom / ex vivo tissue) and place the sample in the focal region. Calibrate the position and zero point of each monitoring sensor.

[0055] Setting initial acoustic parameters: Set the treatment plan in the control software, including ultrasound frequency, power, working mode (continuous wave / pulse wave), pulse parameters (pulse width, duty cycle), total action time, etc.

[0056] Simultaneous ablation and monitoring: Treatment initiated. The system synchronously triggers the emission of therapeutic ultrasound and begins acquiring temperature signals, cavitation acoustic emission signals, and morphological images (such as timed scans).

[0057] Real-time processing of multimodal data: After filtering the temperature data, CEM is calculated in real time. 43 value.

[0058] The cavitation signal is subjected to STFT and comb filtering, and the ICD value is calculated in real time.

[0059] The acquired images are processed in real time or near real time to extract the contours of the damaged areas.

[0060] Data correlation analysis and feature storage: Using the current combination of acoustic parameters as an index, and comparing it with the real-time calculated CEM 43 Curve, ICD timeline curve, final damage area / volume, calculated Equal feature values ​​are correlated and stored in the evaluation database.

[0061] Evaluation of model construction / invocation and effect evaluation: For new experiments, the system can predict the expected temperature rise curve, cavitation intensity, and damage morphology by matching with historical databases or by using trained models based on current parameters.

[0062] For completed experiments, the system can compare and analyze the various physical responses and final effect indicators corresponding to different parameter groups, and intuitively display the influence of parameters on the effect in the form of charts and other formats (e.g., displaying...). (Curve showing the change in sound power).

[0063] Parameter optimization suggestions (optional): Based on the evaluation model and preset treatment goals (such as maximizing damage efficiency and minimizing thermal diffusion), the system can recommend better combinations of acoustic parameters for subsequent experimental verification.

[0064] Example 2 like Figure 2 As shown, Figure 2 As a transducer ablation and monitoring experimental platform, the evaluation system based on a spherical focused ultrasound system with integrated ablation and monitoring functions provided in this embodiment mainly includes the following three core modules: a spherical cavity standing wave focused ultrasound transducer, a multimodal real-time monitoring module, and an evaluation model construction and optimization unit. These modules constitute a spherical focused ultrasound experimental platform integrating ablation, monitoring, and evaluation, enabling real-time multimodal monitoring of the standing wave focused ultrasound ablation process and evaluation of systematic parameter effects. The specific work of each module is explained in detail below: I. Spherical Cavity Standing Wave Focusing Ultrasonic Transducer Transducer Structure and Driving Method: The experimental study used a spherical cavity ultrasonic transducer with a center frequency of 660kHz, an inner radius of 115mm, an aperture height of 115mm, and upper and lower opening diameters of 199mm. Both types of focused ultrasonic transducers were used in deaerated deionized water (conductivity less than 10µS / cm, dissolved oxygen content less than 1.5ppm, temperature 20℃) and were driven by an ultrasonic drive unit consisting of a signal generator, a power amplifier, and an impedance matching box.

[0065] II. Multimodal Real-time Monitoring Module 1. Temperature Monitoring Unit: To measure the heat distribution during HIFU ablation, two 1mm diameter needle thermocouples were placed at the focal center and 5mm from the focal point, respectively, to measure the temperature rise. The tip of the thermocouple at the focal point was positioned 1mm outside the HIFU focal point to reduce the influence of thermocouple artifacts. Temperature changes were monitored in real-time using a data acquisition unit at a 2Hz sampling rate, and the data was then transmitted to a computer for processing and analysis using MATLAB software. To quantify the heat dose during ultrasound exposure, the cumulative equivalent minutes (CEM) at 43℃ were calculated. 43 This allows for a unified assessment of thermal damage under different treatment conditions. Data processing uses a sliding window (5 points) with a Savitzky-Golay filter in Origin to perform binomial fitting on the data in each window to smooth the raw data and reduce high-frequency noise. The formula for calculating the cumulative equivalent thermal dose CEM43 is as follows: ; Where T represents the average temperature within the time interval ∆t = 0.5 seconds, and R is 0.25 for below 43℃ and 0.5 for above 43℃.

[0066] 2. Cavitation Signal Monitoring Unit: To investigate the cavitation characteristics during tissue lesion treatment, a passive cavitation detector (PCD) was used to acquire acoustic emission signals at the focal point of a spherical transducer via confocal alignment. A 15MHz PCD transducer (V319, Evident) was used in the standing wave field, and a digital oscilloscope (PicoScope5444D, Pico Technology) was used to acquire signals at a sampling rate of 50MHz and transmit them to the computer. The raw signals were presented in the time domain, and MATLAB was used to perform short-time Fourier transform (STFT) to obtain the spectrum and time spectrum to observe the dynamic changes of the signal (Hannai window length set to 1024 points, 90% overlap between adjacent segments, 4096 Fourier points). To quantitatively evaluate the broadband noise intensity in the cavitation signal, inertial cavitation dose (ICD) was used as a characteristic parameter in this study. A comb filter based on Fast Fourier Transform (FFT) is used to eliminate the HIFU fundamental frequency and its first nine harmonics, as well as the 50kHz bandwidth eliminating the first seven harmonics and the 20kHz bandwidth eliminating harmonics above the seventh harmonic. Then, the power spectral density is integrated within the set frequency band to obtain the inertial cavitation intensity during each ultrasonic pulse. The formula for calculating the inertial cavitation dose (ICD) is as follows: ; Where N is the total number of samples, F max This represents the maximum frequency in the calculation.

[0067] 3. Damage Morphology Monitoring Unit: To compare the ablation morphology of different acoustic parameters in thermal ablation and cavitation ablation, ImageJ software is used to delineate the damage boundary and quantify the size and area of ​​the ablation. To quantify the ablation efficiency of different acoustic parameters.

[0068] ; Where P represents acoustic power, t is the equivalent exposure time, and S is the maximum ablation area.

[0069] lower The value indicates that a larger damage area can be obtained at the same energy.

[0070] III. Evaluation Model Construction and Optimization Unit This unit's function is to simultaneously collect, process, and fuse data from various monitoring channels, and establish a systematic evaluation model of "acoustic parameters-physical response-treatment effect." By quantitatively analyzing the physical characteristics and biological effects of the ablation process under different combinations of acoustic parameters, this unit provides a scientific basis for optimizing ablation strategies.

[0071] 1. The relationship between acoustic parameters and physical response The system synchronously collects experimental data through multi-channel real-time monitoring (such as temperature, cavitation signal, and lesion morphology). Based on this data, a correlation is established between acoustic parameters (such as acoustic power, action time, and pulse mode) and physical responses (such as temperature rise rate, cavitation intensity, lesion morphology, and ablation efficiency). Changes in acoustic parameters directly affect the distribution of ultrasound energy and tissue response, thereby influencing the treatment outcome.

[0072] Temperature: Changes in the rate of temperature rise and peak temperature will reflect the degree of thermal damage, thus affecting CEM. 43 The calculation of (cumulative equivalent minutes) has become a key parameter for evaluating thermal effects.

[0073] Cavitation intensity: The intensity of the ultrasonic cavitation effect is quantitatively assessed by calculating the inertial cavitation dose (ICD). The cavitation effect directly affects the efficiency of tissue ablation, and is especially crucial in non-thermal tissue ablation processes.

[0074] Damage morphology: The area and size of the damaged region are quantified through image analysis, serving as a physical indicator for assessing ablation precision and treatment efficacy. Ablation efficiency: using η EA To quantify the ablation efficiency of different acoustic parameters and evaluate the ablation effect of different acoustic parameters.

[0075] 2. Construct an evaluation database Using the collected experimental data, an evaluation database covering acoustic parameters, physical response, and treatment effects was established through multi-dimensional data mining techniques. The core function of this database is to provide quantitative data under different treatment conditions. Acoustic parameter optimization: The effects of different combinations of frequencies, power and pulse modes on temperature, cavitation intensity and damage morphology are evaluated by comparing them.

[0076] Treatment outcome prediction: Based on the relationship between actual treatment outcomes (such as ablation area and lesion ablation efficiency) and acoustic parameters, a predictive model is provided to provide data support for the design of personalized treatment plans.

[0077] This evaluation model goes beyond single acoustic parameters and physical responses, using multimodal data fusion to further enhance the precision and effectiveness of treatment. By integrating data such as temperature, cavitation, and lesion morphology, the system can comprehensively assess treatment efficacy from multiple dimensions.

[0078] Example 3 This embodiment uses isolated bovine liver tissue as a sample to evaluate the cavitation ablation effect of this method, and further elaborates on this method with specific illustrations and implementation process.

[0079] Operation process: The excised bovine liver sample was fixed on a three-dimensional moving platform, with its target area positioned at the preset focal point of the spherical transducer. Ultrasonic parameters were set in the control software: center frequency 660kHz, pulse mode (pulse width 8ms, pulse repetition frequency 10Hz), acoustic power 840W, and planned total duration 80 seconds (i.e., 80 pulses). The tip of a needle thermocouple was placed near the focal point, and a 15MHz PCD probe was confocally aligned through the side hole of the spherical shell. A high-frequency ultrasound imaging probe was placed on the side of the water tank's focal plane for intermittent scanning.

[0080] After clicking "Start," the system simultaneously transmits therapeutic ultrasound and initiates data acquisition from all monitoring devices. The software interface displays the focal temperature curve, the time-spectrum graph of the cavitation signal, and intermittently updated ultrasound images in real time. After treatment, the system automatically processes the data: generating a temperature curve and calculating the CEM. 43 The cavitation signal is subjected to STFT and filtering, and the ICD value corresponding to each pulse is calculated to form an ICD time-series curve. The final acquired ultrasound image (or photograph taken after tissue dissection) is thresholded to calculate the area and equivalent diameter of the damaged area, and the ablation efficiency under these parameters is further calculated. .

[0081] Subsequently, the evaluation unit compared the parameters (power 840W, 80 pulses) and results (final damage area S, average ICD) of this experiment. The data is automatically stored in the database. Researchers can retrieve the database and compare it with previous experiments using other parameters (such as different power levels and pulse numbers). For example, by comparing the lesion area growth curves and ICD decay curves under different pulse numbers, the dominant stage of cavitation effect in the ablation process and its efficiency changes can be clearly analyzed, thus providing a direct basis for determining the optimal treatment dose.

[0082] In this embodiment, a spherical transducer was used to establish a correlation between acoustic parameters (such as treatment time, power, pulse mode, etc.) and physical responses (such as temperature rise rate, cavitation intensity, damage morphology, ablation efficiency, etc.) in a BSA gel model and ex vivo bovine liver tissue. This enabled the evaluation of the therapeutic effect of the spherical focused ultrasound transducer under different acoustic energies.

[0083] BSA gel model, acoustic parameters: continuous wave, acoustic power 350w, action time 1-10s; Experimental Results: The system simultaneously recorded the temperature change curves and CEM43 curves at the focal point under different acoustic energies. The critical value for CEM43 was selected as 240 minutes in this study. The thermal ablation threshold was reached after 0.5 seconds of HIFU treatment. The focal heat dose showed a step increase in the mid-term (after 6 seconds of HIFU treatment). This discontinuous cumulative change suggests that transient cavitation activity or a brief enhancement of energy deposition may have occurred in the focal region, resulting in a sudden acceleration of the local heating rate.

[0084] Figure 3 Temperature change curve, Figure 4 For CEM 43 A curve used to show the temperature rise at the focal point over time under specific acoustic parameters (such as continuous wave, 350W), and the cumulative equivalent heat dose (CEM) calculated from this temperature curve. 43 The curve showing the increase over time is used to illustrate the system's temperature monitoring and heat dose assessment capabilities.

[0085] Figure 5 The curve shows the change in ablation size with acoustic energy. Figure 6 For ablation efficiency η EA Curve showing the change in sound energy. Figure 7 The curves showing the cavitation intensity ICD versus acoustic energy illustrate the "ablation size" and "ablation efficiency η". EA The figure shows the curve of "cavitation intensity ICD" as a function of "acoustic energy". This figure is used to quantitatively display the cavitation ablation effect evaluated by the system under different acoustic energies (corresponding to different acoustic parameters, such as pulse wave, 840W, and different action time), including the trend of damage size, the change of ablation efficiency, and the evolution of cavitation signal intensity.

[0086] This embodiment compares the cavitation ablation effects under different acoustic energies, focusing on evaluating the differences in cavitation ablation size, ablation efficiency, and cavitation intensity. The size variation trend of cavitation damage is mainly lateral expansion. The η of SWF EA The curve shows an overall upward trend. The cavitation intensity exhibits a high value in the initial stage, decays rapidly as the acoustic energy increases, and tends to stabilize after about the 50th cycle.

[0087] like Figure 8 As shown, Figure 8 This is a frequency domain characteristic diagram of the cavitation signal from a spherical focusing transducer, used to illustrate the energy distribution characteristics of the cavitation acoustic emission signal generated in the focal region during spherical focusing ultrasound.

[0088] This experiment clearly demonstrates the evaluation capability of this method. By changing the key acoustic parameter of acoustic energy, the system simultaneously monitored the thermal response (temperature profile), cavitation response (ICD value), and final morphological response (damage size, etc.). The system addresses the systematic differences in thermal and cavitation dynamics. This system achieves real-time multimodal monitoring: successfully capturing the temporal evolution of thermal and cavitation dynamics under different parameters. The system also completes a systematic evaluation of parameter effects: through quantitative indicators (CEM). 43 ICD This method objectively compares the differences in therapeutic effects of different acoustic parameters (different acoustic energies). It can be used in in vitro tissue experiments, phantom studies, and animal experiments, providing a high-performance experimental platform for optimizing HIFU treatment parameters and assessing therapeutic effects using a spherical focused ultrasound transducer. The system's modular design facilitates the expansion to other monitoring methods, such as ultrasound elastography and photoacoustic imaging.

[0089] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. An evaluation method for a spherical focused ultrasound system integrating ablation and monitoring functions, characterized in that, Includes the following steps: Step S1: Set the acoustic parameters of the spherical focused ultrasound and place the experimental sample in the focal region of the spherical focused ultrasound. Step S2: Simultaneously start ultrasonic ablation and trigger the multimodal real-time monitoring module to collect data, including temperature data of the focal area, cavitation acoustic emission signal, and image data of the focal area; Step S3: Real-time processing of the acquired data, including: calculating the cumulative equivalent thermal dose (CEM43) based on the temperature data, calculating the inertial cavitation dose (ICD) based on the cavitation acoustic emission signal, and calculating the morphological parameters of the damaged area based on the image data, wherein the morphological parameters of the damaged area include those used to calculate the ablation efficiency. The ablation area; Step S4: Associate the acoustic parameters set in step S1 with the physical response parameters calculated in step S3. The physical response parameters include at least CEM43, ICD, and ablation efficiency. The correlation results are then stored in an evaluation database used to analyze the influence of acoustic parameters on ablation effects. Step S5: Based on the evaluation database, analyze the influence of different combinations of acoustic parameters on CEM43, ICD, η_EA and the final ablation effect.

2. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, In step S3, the formula for calculating the cumulative equivalent heat dose CEM43 is as follows: ； Where T represents the average temperature within the time interval ∆t = 0.5 seconds, and R is 0.25 for below 43℃ and 0.5 for above 43℃.

3. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, In step S3, the formula for calculating the inertial cavitation dose (ICD) is: ； Where N is the total number of samples, and Fmax is the maximum frequency in the calculation.

4. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, In step S3, the morphological parameters of the damaged area include the ablation area; the method further includes calculating the ablation efficiency. The steps and calculation formula are as follows: ； Where P represents acoustic power, t is the equivalent exposure time, and S is the maximum ablation area.

5. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, In step S3, the processing of the cavitation acoustic emission signal includes obtaining a spectrum diagram and a time spectrum diagram using short-time Fourier transform.

6. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, The processing of the cavitation acoustic emission signal also includes: using a comb filter based on fast Fourier transform to eliminate the HIFU fundamental frequency and its first nine harmonic components.

7. The evaluation method for a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 1, characterized in that, In step S2, the acquisition of image data is performed intermittently during the ablation process or after the ablation is completed.

8. An evaluation system based on a spherical focused ultrasound system integrating ablation and monitoring functions, characterized in that, include: A spherical cavity standing wave focusing ultrasonic transducer is used to generate an ultrasonic focus for focusing a standing wave field in the central region of a spherical cavity. The multimodal real-time monitoring module is synchronously triggered with the spherical cavity standing wave focusing ultrasonic transducer and is used to monitor the temperature data, cavitation acoustic emission signal and image data of the focal region in real time. The evaluation model construction and optimization unit is communicatively connected to the multimodal real-time monitoring module. It is used to receive and process the data from the multimodal real-time monitoring module, calculate the physical response parameters, and store the acoustic parameters in the evaluation database after associating them with the physical response parameters, so as to analyze the influence of different combinations of acoustic parameters on the ablation effect.

9. The evaluation system of the spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 8, characterized in that, The spherical cavity standing wave focusing ultrasonic transducer includes a spherical cavity ultrasonic transducer with openings at both ends, a center frequency of 660kHz, an inner radius of 115mm, an aperture height of 115mm, and upper and lower opening diameters of 199mm.

10. The evaluation system of a spherical focused ultrasound system based on integrated ablation and monitoring functions as described in claim 8, characterized in that, The multimodal real-time monitoring module includes: The temperature monitoring unit includes a needle thermocouple placed in the focal region; A cavitation signal monitoring unit includes a passive cavitation detector that is positioned at the focal point via confocal alignment. The damage morphology monitoring unit is used to acquire an image of the focal region.

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