Constant temperature control and regulation system for target area of microwave thermotherapy of experimental animals

Abstract

The present application relates to the technical field of experimental animal hyperthermia, and discloses a microwave hyperthermia target area temperature constant control and regulation system for experimental animals. The signal response module of the system responds to a microwave hyperthermia control signal; the temperature data acquisition module acquires temperature data of multiple preset positions in the target area in real time; the initial state determination module determines the starting temperature of the target area based on the temperature data; the threshold comparison module compares the residual temperature difference corresponding to the starting temperature with a preset threshold; when the residual temperature difference is less than or equal to the preset threshold, the first control execution module controls the output power of the microwave emitter by using a first control strategy; when the residual temperature difference is greater than the preset threshold, the second control execution module divides the hyperthermia process into multiple time windows and applies different control strategies. The system can improve the temperature control precision and stability of the target area and meet the experimental requirements.

Description

Technical Field

[0001] This invention relates to the field of experimental animal hyperthermia technology, specifically to a system for constant temperature control and regulation of the target area in experimental animal microwave hyperthermia. Background Technology

[0002] In the field of biomedical research, tumor hyperthermia studies in laboratory animals are an important direction for revealing the medical value of hyperthermia. This research covers exploring tumor treatment mechanisms and evaluating the efficacy of combined hyperthermia and drug therapy. However, dedicated microwave hyperthermia devices suitable for this field are relatively scarce. Precise control of target area temperature is a key prerequisite for ensuring the reliability and reproducibility of experimental results. Current technology struggles to overcome this core requirement. Traditional laboratory animal microwave hyperthermia systems generally suffer from limitations such as insufficient temperature control precision and poor adaptability, failing to meet the stringent requirements for targeted temperature control in animal tumor hyperthermia research.

[0003] Traditional systems often employ a single power regulation mode, relying solely on temperature data from a single point in the target area for feedback control. This ignores the uneven temperature distribution within the animal's tissues, leading to overheating and tissue burns in some areas while other areas fail to reach the preset treatment temperature, ultimately affecting the accuracy of experimental data. Traditional systems also suffer from insufficient dynamic adjustment capabilities during hyperthermia. When the initial temperature of the animal's target area differs significantly from the preset target temperature, the system often operates at high power until the temperature approaches the target value before reducing power. This "one-size-fits-all" control method is prone to temperature overshoot and may cause additional damage to normal tissues in small animals due to prolonged high-power radiation. While some systems attempt to introduce segmented control, the time windows lack scientific basis, and the control strategies within each window are not integrated with the actual temperature changes in the target area, further hindering the accuracy of temperature control to meet experimental requirements.

[0004] As experimental animal models are increasingly used in medical research, the requirements for temperature control of microwave hyperthermia systems are constantly increasing. The aforementioned defects of traditional systems make it difficult for researchers to obtain stable and reproducible experimental data when conducting animal tumor hyperthermia experiments, which in turn affects the accurate judgment of the hyperthermia effect. Ultimately, this has led to a serious lag in the research and development and application of dedicated hyperthermia devices, becoming a major bottleneck restricting the advancement of research in this field. Developing a regulation system that can achieve precise and constant temperature control of animal target areas has become an urgent problem to be solved in the field of biomedical experimental equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a constant temperature control and regulation system for the target area of ​​microwave hyperthermia in experimental animals, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a system for constant temperature control and regulation of the target area in experimental animal microwave hyperthermia, the system comprising:

[0007] The signal response module is used to respond to the received microwave hyperthermia control signal;

[0008] The temperature data acquisition module is used to acquire temperature data at multiple preset locations within the target area of ​​the experimental animal in real time.

[0009] An initial state determination module is used to determine the initial temperature of the experimental animal target area based on the temperature data.

[0010] The threshold comparison module is used to compare the remaining temperature difference corresponding to the starting temperature with a preset threshold, wherein the preset threshold is the amount of temperature change corresponding to when the temperature of the experimental animal target area reaches the preset target temperature;

[0011] The first control execution module is used to control the output power of the microwave transmitter using a first control strategy if the remaining temperature difference is less than or equal to the preset threshold.

[0012] The second control execution module is used to control the output power of the microwave transmitter using a segmented control strategy if the remaining temperature difference is greater than the preset threshold. The segmented control strategy includes dividing the hyperthermia process into multiple time windows, with each time window applying a different control strategy.

[0013] Preferably, the segmented control strategy divides the thermotherapy process into a first segment, a second segment, a third segment, and a fourth segment, with each segment corresponding to a time window. The linear feature vector of each time window is obtained by analyzing the collinearity between temperature data at multiple preset locations, and the segment corresponding to the current time window is determined by combining the trend of real-time temperature data.

[0014] Preferably, the system further includes a feature analysis module, used to obtain a cumulative trend test matrix for each time window based on the cumulative trend test of the linear feature vector and the real-time temperature data sequence;

[0015] The difference coefficient generation module is used to obtain the stratified monitoring difference coefficient of each time window by analyzing the difference degree of the cumulative trend test matrix between each time window and its previous time window, and the similarity of the linear feature vector between each time window and its previous time window.

[0016] Preferably, the system further includes an error adjustment matrix generation module, which is used to obtain the error adjustment matrix for each time window by analyzing the difference between the temperature data of each preset location in each time window and the preset standard temperature, and combining the distribution ratio of the layered monitoring difference coefficients of each time window.

[0017] A power adjustment module is used to adjust the output power value of the microwave transmitter based on the error adjustment matrix.

[0018] Preferably, if the current time window is the first segment, a first control strategy is adopted to control the microwave output; the first control strategy includes controlling the initial value of the output power to be above the minimum effective power value, controlling the fluctuation of the output power to be within a preset fluctuation range, and controlling the output power to change linearly at a preset rate of change to achieve a preset power value.

[0019] Preferably, before applying the first control strategy, a compensation calculation module is further included to obtain the initial output power value, output gain coefficient, preset power function polynomial and dynamic compensation coefficient.

[0020] The compensation output module is used to determine the compensation power value based on the output gain coefficient, the preset power function polynomial, and the dynamic compensation coefficient.

[0021] The output determination module is used to determine the output power value of the first control strategy based on the sum of the initial output power value and the compensation power value.

[0022] Preferably, if the current time window is the second segment, a second control strategy is used to control the microwave output; the second control strategy includes using an adaptive control algorithm to control the output power change rate so that the temperature change rate reaches the target change rate, and using a feedforward compensation factor to control the temperature fluctuation amplitude.

[0023] Preferably, before applying the second control strategy, a change calculation module is also included to obtain the temperature change rate deviation, proportional parameter, integral parameter and feedforward compensation factor.

[0024] The first change module is used to determine the first power change based on the temperature change rate deviation at the current moment, the temperature change rate deviation at the previous moment, and the proportional parameter.

[0025] The second change module is used to determine the second power change based on the temperature change rate deviation and the integral parameter at the current moment;

[0026] The target change module is used to determine the target power change based on the sum of the first power change and the second power change.

[0027] The output duty cycle module is used to determine the output power value of the second control strategy based on the feedforward compensation factor and the target power change.

[0028] Preferably, if the current time window is the third segment, a third control strategy is used to control the microwave output; the third control strategy includes: if the temperature change rate reaches the target change rate and the fluctuation amplitude is within a preset range, the output power value of the previous moment is used to maintain a constant output; if the temperature change rate exceeds the target change rate and the fluctuation amplitude is within a preset range, a composite control algorithm is used to control the output power.

[0029] Preferably, if the current time window is the fourth segment, a fourth control strategy is used to control the microwave output; the fourth control strategy includes using an attenuation function to control the output power to continuously decrease until the temperature of the experimental animal target area reaches the preset target temperature.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This experimental animal microwave hyperthermia target area temperature constant control and regulation system effectively solves many problems in temperature control of traditional microwave hyperthermia systems through the collaborative work of multiple modules. The signal response module can quickly respond to microwave hyperthermia control signals, ensuring that the system quickly enters the working state after receiving control commands, reducing the delay between command transmission and execution, and ensuring the timeliness of subsequent temperature control. The temperature data acquisition module acquires temperature data from multiple preset locations within the target area in real time, breaking the limitation of traditional systems that rely on only a single temperature point for control. It can comprehensively reflect the internal temperature distribution of the target area, avoiding control errors caused by local temperature data deviations, making the system's monitoring of the target area temperature more comprehensive and accurate.

[0032] The initial state determination module determines the target area's initial temperature based on multi-location temperature data, providing a precise initial reference for subsequent temperature adjustment. This helps the system formulate a control scheme that better meets requirements based on the actual initial state, avoiding adjustment deviations caused by inaccurate initial temperature judgment. The threshold comparison module compares the remaining temperature difference corresponding to the initial temperature with a preset threshold, clearly defining different temperature adjustment scenarios. This provides a scientific basis for the system to select an appropriate control strategy, enabling the system to adopt the optimal adjustment method under different temperature differences, thus improving the flexibility and targeting of control.

[0033] When the remaining temperature difference is less than or equal to a preset threshold, the first control execution module uses a first control strategy to control the output power of the microwave transmitter. At this time, the system can slowly bring the target area temperature closer to the preset target temperature through fine-tuning of the power, effectively avoiding temperature overshoot and ensuring that the target area temperature can stably reach the target value and remain constant. When the remaining temperature difference is greater than the preset threshold, the second control execution module adopts a segmented control strategy, dividing the hyperthermia process into multiple time windows and applying different control strategies. This method can adjust the power output according to the temperature change requirements at different stages. For example, when the temperature difference is large at the beginning of hyperthermia, a relatively high but stable power can be used to quickly increase the target area temperature. As the temperature gradually approaches the target value, the power adjustment amplitude is gradually reduced in subsequent time windows to achieve a smooth temperature transition. This shortens the time to reach the target value and avoids damage to experimental animal tissues caused by prolonged high power.

[0034] Through the close coordination of its modules, the entire system achieves precise control over the entire process, from temperature monitoring and status assessment to strategy execution. This effectively improves the accuracy of temperature stability in the target area of ​​experimental animals, reduces the impact of temperature fluctuations on experimental data, and enables researchers to obtain more stable and reliable experimental results. Furthermore, the system's control method is more flexible, adapting to the temperature control needs of different experimental animal models and target areas, thus broadening its applicability and providing better equipment support for various microwave hyperthermia-related experiments. This contributes to the further application and development of hyperthermia technology in the field of biomedical research. Attached Figure Description

[0035] Figure 1 This is a timing diagram of the experimental animal microwave hyperthermia target area constant temperature control and regulation system described in this invention;

[0036] Figure 2 A flowchart for determining the segments of a segmented control strategy;

[0037] Figure 3 The flowchart shows the error adjustment and power adjustment processes.

[0038] Figure 4 The flowchart shows the compensation calculation for the first control strategy. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1 This invention provides a system for constant temperature control and regulation of the target area in experimental animal microwave hyperthermia, the system comprising:

[0041] Precise and constant control of the target area temperature is achieved by real-time monitoring of the target area temperature and dynamic selection of control strategies based on the initial temperature state. The system includes a signal response module, a temperature data acquisition module, an initial state determination module, a threshold comparison module, a first control execution module, and a second control execution module. The signal response module receives external microwave hyperthermia control commands and initiates the system workflow. The temperature data acquisition module collects temperature data in real-time from multiple temperature sensors distributed within the experimental animal target area at each preset location. The initial state determination module calculates the average initial temperature of the target area based on the acquired temperature data. The threshold comparison module calculates the remaining temperature difference between the initial temperature and the preset target temperature and compares this difference with a preset threshold. If the remaining temperature difference is less than or equal to the preset threshold, the first control execution module uses a first control strategy to adjust the output power of the microwave transmitter; if the remaining temperature difference is greater than the preset threshold, the second control execution module uses a segmented control strategy, dividing the hyperthermia process into multiple time windows and applying different control strategies in different time windows to control the output power of the microwave transmitter.

[0042] Example 1: See Figure 2 In implementing the segmented control strategy, the system divides the hyperthermia process into four consecutive time windows, corresponding to the first, second, third, and fourth segments, respectively. The division of each time window depends on the dynamic changes in the temperature distribution characteristics of the target area. The system collects data in real time through multiple temperature sensors deployed within the target area of ​​the experimental animal. These sensors are arranged in a grid pattern inside and around the target area. For example, in a cylindrical target area with a diameter of 3 cm, nine temperature measurement points are set: one at the center, four in a middle ring, and four in an outer ring, with a sampling frequency of 10 times per second.

[0043] Once hyperthermia is initiated, the system first performs collinearity analysis on the temperature dataset collected within the initial 30 seconds. This analysis employs multiple linear regression to calculate the variance inflation factor among the data from each sensor. If the variance inflation factor of a group of sensor data exceeds a preset threshold (e.g., >5), it is determined that the group of sensors exhibits significant collinearity. The system then performs principal component analysis on the collinear sensor groups, extracting the first principal component as a linear feature vector representing the temperature distribution characteristics within that time window. This vector contains weighting coefficients for each sensor orientation, reflecting the spatial distribution pattern of the temperature field in the target area.

[0044] As hyperthermia progresses, the system generates a new time window every 10 seconds. Within each time window, the system repeats the collinearity analysis and principal component extraction processes described above to obtain the linear eigenvector of the current window. Simultaneously, the system calculates the trend of the average temperature change in the target area using a moving average method, recording the rate of temperature change (°C / min) and the fluctuation amplitude (°C). By comparing the Euclidean distance between the current linear eigenvector and four preset segmented feature templates, combined with the comparison of the real-time temperature change rate with a preset threshold (e.g., 0.5°C / min), the system dynamically determines the segment category to which the current time window belongs. For example, when the distance between the eigenvector and the first segment template is the smallest, and the temperature change rate is below 0.3°C / min, it is determined that the current segment is the first segment.

[0045] In the cumulative trend test phase, the system performs Mann-Kendall trend analysis on the temperature data series for each time window. This analysis uses a 10-second unit and calculates the S-statistic for 100 temperature sampling points (10 seconds × 10 Hz) within the window. After standardization, a Z-value sequence is obtained, forming a 10 × 10 cumulative trend test matrix. Each element in the matrix represents the significance level of temperature change within the corresponding time period; positive values ​​indicate an upward trend, and negative values ​​indicate a downward trend.

[0046] The difference coefficient generation process involves comparisons across time windows. The system calculates the Frobenius norm ratio of the cumulative trend test matrix of the current time window to that of the previous time window matrix, using this ratio as the matrix difference index. Simultaneously, it calculates the cosine similarity between the current linear eigenvector and the previous eigenvector. Substituting the matrix difference (0-1 range) and vector similarity (0-1 range) into a weighted calculation formula, with the matrix difference weight set to 0.6 and the vector similarity weight set to 0.4, the final output is a stratified monitoring difference coefficient within the 0-1 range. A coefficient exceeding 0.7 indicates a significant change in the temperature field, requiring adjustment of the control strategy. In specific implementation, when the initial temperature of the experimental animal target area is 36.5℃ and the target temperature is 42.0℃, the system detects a remaining temperature difference of 5.5℃, which exceeds the preset threshold of 3.0℃, thus activating segmented control. Feature analysis of the first 30 seconds of the time window showed that the correlation coefficient between the temperature of the center point and the middle layer sensors reached 0.92, the variance inflation factor was 6.8, and the extracted linear feature vector was [0.35, 0.30, 0.20, 0.15] (corresponding to center and middle layer sensors 1-4). The temperature change rate was 0.2℃ / min, which was determined to be the first segment. The cumulative trend test matrix showed that the Z value was in the range of 2.1-2.3 for the first 20 seconds, and dropped to 1.8 in the next 10 seconds. Compared with the initial state, the matrix difference was 0.25, the feature vector similarity was 0.95, and the layered monitoring difference coefficient was 0.37, which did not reach the adjustment threshold.

[0047] Entering the second time window (30-60 seconds), the eigenvector evolved to [0.33, 0.31, 0.21, 0.15], and the temperature change rate increased to 0.8℃ / min. The cumulative trend matrix showed that the Z-value remained above 2.5. Compared with the previous window, the matrix difference was 0.62 (norm ratio increased from 1.85 to 3.01), the eigenvector similarity was 0.98, and the stratified monitoring difference coefficient was 0.74, triggering fine-tuning of control parameters. The entire process was implemented through real-time data stream processing, with the analysis time for each time window controlled within 50ms, ensuring timely response to control commands.

[0048] Example 2: See Figure 3 After the system determines that the current time window belongs to the first segment, the error adjustment matrix generation module begins to work. This module first acquires real-time temperature data from nine preset temperature measurement points within the target area. These points are numbered according to their spatial location: the center point is marked P1, the four points in the middle ring are marked P2 to P5, and the four points in the outer ring are marked P6 to P9. The preset standard temperature is dynamically set according to the hyperthermia stage, with the initial target temperature set at 38.0 degrees Celsius during the heating stage. The system calculates the difference between the measured temperature and the standard temperature at each measurement point, forming a temperature deviation data set. For example, when the measured temperature at the center point P1 is 37.2 degrees Celsius, its temperature deviation is -0.8 degrees Celsius; when the measured temperature at the middle point P2 is 37.5 degrees Celsius, its temperature deviation is -0.5 degrees Celsius, and the deviation values ​​for the remaining points are calculated using the same method.

[0049] The distribution ratio of the stratified monitoring difference coefficients is obtained based on the coefficient sequence of historical time windows. Assuming that we are currently in the third time window (corresponding to the 60 to 90 second period), the system retrieves the stratified monitoring difference coefficients of the previous three time windows: the coefficient for the first time window (0 to 30 seconds) is 0.37, the coefficient for the second time window (30 to 60 seconds) is 0.74, and the coefficient for the third time window (60 to 90 seconds) is 0.68. When calculating the distribution ratio, each coefficient value is divided by the sum of the coefficients, and the weight ratios of the three time windows are obtained as 20.7%, 41.3%, and 38.0%, respectively.

[0050] The error adjustment matrix is ​​generated through multi-dimensional data processing. The system first establishes a temperature deviation vector containing the temperature deviation values ​​of nine measurement points. Simultaneously, a spatial weighting scheme is constructed: the center point P1 is assigned 40% weight, the four middle points P2 to P5 are each assigned 7.5% weight (totaling 30%), and the four outer points P6 to P9 are each assigned 7.5% weight (totaling 30%). The temperature deviation vector and distribution ratio matrix are combined and calculated, and then correspondingly processed with the spatial weighting scheme to ultimately form the error adjustment matrix. Each element of this matrix reflects the impact of a specific historical time window on the temperature compensation of the corresponding measurement point.

[0051] The power adjustment module applies an error adjustment matrix to the multi-channel control of the microwave transmitter. The transmitter is configured with three independent power output channels: Channel A specifically adjusts the central region (corresponding to point P1), Channel B adjusts the middle region (corresponding to points P2 to P5), and Channel C adjusts the outer region (corresponding to points P6 to P9). The compensation values ​​for each channel are obtained through matrix operations: the compensation value for Channel A is the sum of the elements in the first row of the matrix, the compensation value for Channel B is the average of the sums of the elements in the second to fifth rows of the matrix, and the compensation value for Channel C is the average of the sums of the elements in the sixth to ninth rows of the matrix. These compensation values ​​are converted into voltage control signals, with a voltage range of 0 to 5 volts corresponding to a power adjustment range of 0 to 200 watts, and each volt of voltage adjustment equivalent to 40 watts of power.

[0052] The first control strategy is initiated after power adjustment. The system sets a minimum effective power threshold of 180 watts and an initial power value of 200 watts, which is higher than the minimum effective threshold. Output power fluctuations are limited to within ±5% of the set value, achieved through a real-time power feedback mechanism: the actual output power value is collected every 0.1 seconds, and when the actual power deviates from the set value by more than 10 watts, the adjustment mechanism is triggered to complete correction within 0.05 seconds. The linear power change process has an adjustment cycle of 10 seconds, with a preset change rate of 10 watts per minute. For example, if the initial output is 200 watts, it adjusts to 201.7 watts after 10 seconds, 203.3 watts after 20 seconds, until the preset target power of 230 watts is reached. This change rate is calculated based on the physical characteristics of the target tissue, primarily referencing a specific heat capacity of approximately 3.6 kJ / kg / degree Celsius and a density of approximately 1.05 g / cm³.

[0053] Example 3: See Figure 4 Before applying the first control strategy, the compensation calculation module initiates the initialization process. The system acquires the initial output power value, which is calculated based on the difference between the initial temperature of the target area and the target temperature. For example, when the initial temperature is 36.5℃ and the first-stage target temperature is 38.0℃, the initial power requirement is calculated to be 200W according to the temperature-power conversion model. The output gain coefficient is determined through the system calibration program. During calibration, a standard thermal model is used, a series of test powers are applied, and the temperature rise curve is recorded. The gain coefficient is obtained by least squares fitting and is 0.85. The preset power function polynomial adopts the cubic term form: ;

[0054] in: Indicates the basic compensation power. This represents the average temperature of the target area collected in real time. , , The coefficients are polynomials, taking values ​​of 0.002, -0.15, and 3.2 respectively. These coefficients were obtained through regression analysis of historical thermotherapy data. The dynamic compensation coefficient is adjusted based on the absolute value of the temperature change rate, and the calculation formula is as follows: ,in This is the scaling factor (taken as 0.8). This represents the rate of temperature change over the last 10 seconds.

[0055] The compensation output module performs multi-level calculations. First, it substitutes the real-time temperature value into the power function polynomial. For example, when the average temperature of the target area reaches 37.2℃, it calculates... Then multiply this value by the output gain coefficient: Finally, a dynamic compensation term is added. If a temperature change rate of 0.5℃ / min is detected, then... Compensation power value The output determination module adds the initial output power value of 200W to the compensation power value of 36.355W to obtain the final output power value of 236.355W for the first control strategy. This value is rounded to 236W and then output to the microwave transmitter.

[0056] When the system determines that it has entered the second segment, the second control strategy is implemented. This strategy employs a model reference adaptive control structure, with the system having a built-in reference model describing the ideal temperature response curve. The time constant The time interval is 240 seconds. The adaptive mechanism adjusts the controller parameters in real time by comparing the deviation between the actual rate of temperature change and the output rate of change of the reference model. The feedforward compensation factor is calculated based on the disturbance model identified by the system, mainly compensating for ambient temperature fluctuations and blood flow heat dissipation effects, with an update cycle of 30 seconds.

[0057] In the specific implementation process, the experimental animal target area temperature transitioned from 37.5℃ to 39.0℃, entering the second segment. The change calculation module obtained the deviation of the current temperature change rate: the deviation between the actual change rate of 0.8℃ / min and the target change rate of 1.0℃ / min was -0.2℃ / min. The proportional parameter was set to 0.6, the integral parameter was set to 0.3, and the feedforward compensation factor was calculated to be 0.05 based on the ambient temperature fluctuation (±0.3℃). The first change module calculated the power change: (Assume the deviation at the previous moment was -0.15℃ / min). The second change module calculates the integral term: (Integral time constant: 2 minutes). Target power change. The output duty cycle module adds the feedforward compensation factor of 0.05 to the target change of -0.15 to obtain the final power adjustment value of -0.10, which adjusts the current power output from 250W to 249.9W.

[0058] The entire control process is implemented in an embedded system, with a compensation calculation cycle of 100ms and a power output resolution of 0.1W. Temperature sampling employs an anti-interference design, eliminating random fluctuations through median filtering and moving average processing. The system maintains a historical power output queue, recording the output values ​​for the most recent 60 seconds for trend analysis. When the temperature change rate exceeds the tolerance range for three consecutive cycles, a parameter self-tuning program is triggered to recalibrate the proportional and integral parameters. The feedforward compensation factor is dynamically updated based on real-time environmental monitoring data; the ambient temperature sensor collects data every 10 seconds, and blood flow effect compensation is estimated based on pulse oximetry signals. After receiving the power command, the microwave transmitter controls the RF power amplifier through PWM modulation, maintaining output stability within ±0.5%.

[0059] Example 4: In the second control strategy implementation phase, the system executes a power adjustment process with a control cycle of 200 milliseconds. The change calculation module obtains real-time data streams from the temperature monitoring unit, and the temperature change rate deviation is obtained by calculating the difference between the current actual change rate and the preset target change rate (e.g., 1.2℃ / min). The proportional parameter is set to 0.45, which is determined through a system step response test: a 10% power step is applied to the thermal phantom, and the proportional gain corresponding to a temperature overshoot of 15% is recorded. The integral parameter is set to 0.18, tuned according to the time required for the system to eliminate steady-state error. The feedforward compensation factor is initialized to 0.12, which is dynamically updated based on the correlation analysis between the ambient temperature sensor readings and the thermal diffusivity of the target area.

[0060] The first change module employs a differential calculation mechanism. The system caches the temperature change rate deviation data for the two most recent cycles. For example, a deviation value of -0.25℃ / minute is recorded at timestamp 10:05:00.200, and -0.18℃ / minute is recorded at 10:05:00.400. The difference between the current deviation and the previous deviation is taken: -0.18 - (-0.25) = +0.07, multiplied by the scaling parameter 0.45 to obtain the first power change amount +0.0315. This calculation process is executed every 200 milliseconds, and the result is temporarily stored in a circular buffer.

[0061] The second variable module performs integration. The system maintains an integral accumulator, reading the current temperature change rate deviation (e.g., -0.18℃ / minute) each time, multiplying it by the integration parameter 0.18 and the integration time constant 0.2 minutes (i.e., the number of minutes corresponding to 200 milliseconds), to obtain a single integral value of -0.18 × 0.18 × 0.2 ≈ -0.00648. This value is accumulated into the integrator, while the integration limit range is set to ±5W to prevent integration saturation.

[0062] The target power change module performs vector superposition, extracting the latest first power change (+0.0315) from the buffer and reading the current cumulative value (-0.82) from the integrator. The two are added together to obtain the target power change of -0.7885. This value is transmitted to the output duty cycle module and then superimposed with a feedforward compensation factor (e.g., 0.12): the final adjustment is -0.7885 + 0.12 = -0.6685. The microwave transmitter receives this instruction and adjusts the current output power from 215.3W to 214.6W (rounded to 0.1W resolution).

[0063] When the system enters the third segment, the third control strategy is activated. The control unit continuously monitors two key parameters: the rate of temperature change (calculated via a 10-second sliding window) and the fluctuation amplitude (calculated via standard deviation). If the rate of change is detected to be within the range of 1.15-1.25℃ / minute for three consecutive cycles (target value 1.2℃ / minute), and the standard deviation of the fluctuation amplitude is less than 0.15℃, the system switches to constant power mode. For example, if the power output value is recorded as 228.7W at timestamp 10:07:30, this power will be maintained unchanged in subsequent cycles until the parameter exceeds the threshold.

[0064] If the detected temperature change rate exceeds 1.3℃ / minute but the fluctuation amplitude is still less than 0.15℃, the composite control algorithm is activated. This algorithm includes a dual-mode control structure: a fuzzy controller receives the temperature change rate deviation and the deviation change rate as input, and outputs the PID parameter adjustment; the PID controller calculates the power correction value based on the adjusted parameters. The fuzzy rule base is set to 49 rules; for example, when the deviation is "negatively large" and the deviation change rate is "positively small," the output is "increase proportional gain by 20%." The PID calculation uses an incremental algorithm, outputting a power fine-tuning instruction every 200 milliseconds (see Table 1).

[0065] Table 1: Record of Execution Parameters for the Second Control Strategy

[0066]

[0067] In the embedded system implementation, power control commands are transmitted to the microwave generator via the CAN bus. The generator internally employs pulse width modulation (PWM) technology to convert the power setpoint into a duty cycle signal. The drive circuit is based on IGBT devices, with a switching frequency set to 20kHz, and the power output error is controlled within ±0.5W. The temperature monitoring unit uses a fiber optic temperature sensor with 8 channels for synchronous acquisition at a sampling rate of 50Hz; data transmission is achieved through an isolated SPI interface. The environmental compensation unit integrates temperature, humidity, and air pressure sensors, updating the feedforward compensation factor parameter table every 5 seconds. When the composite algorithm in the third control strategy runs, the system resource allocator automatically prioritizes the control thread, ensuring strict and timely execution within a 200-millisecond cycle.

[0068] Example 5: When the system determines that the current time window has entered the fourth segment, the fourth control strategy is implemented. This strategy is activated within approximately 1.0°C before the target temperature in the experimental animal reaches the preset target temperature. For example, if the target temperature is 42.0°C, the strategy switch is triggered when the temperature rises to 41.0°C. The system uses an exponential decay function to control the microwave transmitter output power. The initial decay rate is set to decrease by 15% of the rated power per minute. This rate is dynamically adjusted based on the thermal relaxation time constant of the target tissue. The thermal relaxation time constant is obtained by analyzing the temperature curve during the heating phase, and the time required for the temperature to drop to 63% of the peak value is taken as a reference value.

[0069] The microwave transmitter power output is controlled by time-discrete mechanisms, with an adjustment cycle of 5 seconds. At the beginning of each cycle, the system reads the current average temperature of the target area and calculates the remaining difference between this temperature and the preset target temperature. When the difference is greater than 0.3℃, the attenuation function adopts a fast attenuation mode, with a power reduction of 8% of the previous cycle's power value; when the difference is between 0.1-0.3℃, it switches to a slow attenuation mode, reducing the reduction to 3%; when the difference is less than 0.1℃, it enters a fine-tuning mode, adjusting the reduction to 1%. This graded attenuation mechanism is implemented through a state machine, and the state switching thresholds are stored in the system configuration register.

[0070] The system monitors the temperature distribution uniformity at nine temperature measurement points in the target area in real time. It calculates the standard deviation of the temperature at each point, and automatically adjusts the attenuation function parameters when the standard deviation exceeds 0.2℃: increasing the attenuation rate in high-temperature areas and decreasing it in low-temperature areas. For example, when the temperature at the center point P1 is 41.5℃ while the temperature at the edge point P9 is 41.2℃, the system increases the power attenuation rate in the center area to 10% and decreases it to 5% in the edge area. This spatially differentiated control is achieved through the multi-channel independent output of the microwave transmitter, with each channel equipped with an independent attenuation function generator.

[0071] During the power reduction process, the system sets a minimum power protection threshold of 30W. When the calculated target power is lower than this threshold, the output power remains at 30W. Simultaneously, a temperature stability monitoring program is initiated: if the target area temperature fluctuation is less than 0.1℃ for three consecutive cycles, the temperature is considered to have reached a stable state. At this point, the system automatically cuts off the microwave output but maintains the temperature sampling function. If subsequent monitoring reveals a temperature drop exceeding 0.2℃, the power output is reactivated, and the attenuation parameters are recalculated based on the difference between the current and target temperatures. In practice, when the experimental animal target area temperature rises to 41.0℃, the system enters the fourth segment. The initial power output is 180W, and the target temperature is 42.0℃. In the first cycle (0-5 seconds), the remaining difference is detected at 1.0℃, and a rapid attenuation mode is used, reducing the power to 165.6W (180×0.92). After the temperature rises to 41.1℃, in the second cycle (5-10 seconds), the remaining difference is 0.9℃, and the power drops to 152.3W. When the temperature reaches 41.5℃, with a remaining difference of 0.5℃, the system switches to slow decay mode. In the thirtieth cycle (150-155 seconds), the power drops to 45.2W. At this point, a temperature distribution standard deviation of 0.25℃ is detected, triggering spatial adjustment: the power decay rate of the center channel increases to 7%, while that of the edge channels decreases to 2%. In the fortieth cycle (200-205 seconds), the temperature reaches 41.9℃, with a remaining difference of 0.1℃, entering fine-tuning mode, with power decreasing by 1% per cycle. In the fiftieth cycle (250-255 seconds), the temperature stabilizes within the range of 42.0±0.05℃, and the system cuts off power output and enters monitoring mode. The entire cooling process lasts 4 minutes. Power control commands are transmitted via a high-speed serial bus with a command delay of less than 5 milliseconds, and the temperature sampling cycle is synchronized at 20 times per second. The system maintains a power decay history record, storing the output values ​​of the most recent 100 cycles for abnormal state diagnosis. When the ambient temperature fluctuates beyond ±1℃, a compensation factor is automatically injected to adjust the slope of the decay curve.

[0072] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for constant temperature control and regulation of the target area in experimental animal microwave hyperthermia, characterized in that, include: The signal response module is used to respond to the received microwave hyperthermia control signal; The temperature data acquisition module is used to acquire temperature data at multiple preset locations within the target area of ​​the experimental animal in real time. An initial state determination module is used to determine the initial temperature of the experimental animal target area based on the temperature data. The threshold comparison module is used to compare the remaining temperature difference corresponding to the starting temperature with a preset threshold, wherein the preset threshold is the amount of temperature change corresponding to when the temperature of the experimental animal target area reaches the preset target temperature; The first control execution module is used to control the output power of the microwave transmitter using a first control strategy if the remaining temperature difference is less than or equal to the preset threshold. The second control execution module is used to control the output power of the microwave transmitter using a segmented control strategy if the remaining temperature difference is greater than the preset threshold. The segmented control strategy includes dividing the hyperthermia process into multiple time windows, with each time window applying a different control strategy.

2. The experimental animal microwave hyperthermia target area temperature constant control and regulation system as described in claim 1, characterized in that, The segmented control strategy divides the thermotherapy process into a first segment, a second segment, a third segment, and a fourth segment, with each segment corresponding to a time window. By analyzing the collinearity between temperature data at multiple preset locations, the linear feature vector of each time window is obtained, and combined with the changing trend of real-time temperature data, the segment corresponding to the current time window is determined.

3. The experimental animal microwave hyperthermia target area temperature constant control and regulation system as described in claim 2, characterized in that, It also includes a feature analysis module, which is used to obtain the cumulative trend test matrix for each time window based on the cumulative trend test of the linear feature vector and the real-time temperature data sequence. The difference coefficient generation module is used to obtain the stratified monitoring difference coefficient of each time window by analyzing the difference degree of the cumulative trend test matrix between each time window and its previous time window, and the similarity of the linear feature vector between each time window and its previous time window.

4. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 3, characterized in that, It also includes an error adjustment matrix generation module, which is used to obtain the error adjustment matrix for each time window by analyzing the difference between the temperature data of each preset location in each time window and the preset standard temperature, and combining the distribution ratio of the layered monitoring difference coefficient of each time window. A power adjustment module is used to adjust the output power value of the microwave transmitter based on the error adjustment matrix.

5. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 2, characterized in that, If the current time window is the first segment, then the microwave output is controlled by the first control strategy. The first control strategy includes controlling the initial value of the output power to be above the minimum effective power value, controlling the fluctuation of the output power to be within a preset fluctuation range, and controlling the output power to change linearly at a preset rate of change to achieve the preset power value.

6. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 5, characterized in that, Before applying the first control strategy, a compensation calculation module is also included to obtain the initial output power value, output gain coefficient, preset power function polynomial and dynamic compensation coefficient. The compensation output module is used to determine the compensation power value based on the output gain coefficient, the preset power function polynomial, and the dynamic compensation coefficient. The output determination module is used to determine the output power value of the first control strategy based on the sum of the initial output power value and the compensation power value.

7. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 2, characterized in that, If the current time window is the second segment, then the second control strategy is used to control the microwave output; the second control strategy includes using an adaptive control algorithm to control the output power change rate so that the temperature change rate reaches the target change rate, and using a feedforward compensation factor to control the temperature fluctuation amplitude.

8. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 7, characterized in that, Before applying the second control strategy, a change calculation module is also included to obtain the temperature change rate deviation, proportional parameter, integral parameter and feedforward compensation factor. The first change module is used to determine the first power change based on the temperature change rate deviation at the current moment, the temperature change rate deviation at the previous moment, and the proportional parameter. The second change module is used to determine the second power change based on the temperature change rate deviation and the integral parameter at the current moment; The target change module is used to determine the target power change based on the sum of the first power change and the second power change. The output duty cycle module is used to determine the output power value of the second control strategy based on the feedforward compensation factor and the target power change.

9. The experimental animal microwave hyperthermia target area temperature constant control and regulation system as described in claim 2, characterized in that, If the current time window is the third segment, then the third control strategy is used to control the microwave output. The third control strategy includes: if the temperature change rate reaches the target change rate and the fluctuation amplitude is within the preset range, then the output power value of the previous moment is used to maintain a constant output; if the temperature change rate exceeds the target change rate and the fluctuation amplitude is within the preset range, then a composite control algorithm is used to control the output power.

10. The experimental animal microwave hyperthermia target area constant temperature control and regulation system as described in claim 2, characterized in that, If the current time window is the fourth segment, then the fourth control strategy is used to control the microwave output; the fourth control strategy includes using an attenuation function to control the output power to continuously decrease until the temperature of the experimental animal target area reaches the preset target temperature.

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