A control method for limiting freeze overshoot of a cryoablation device

Abstract

The present application relates to a kind of control methods for limiting the freeze ablation equipment freeze overshoot, the control method is combined with temperature probe temperature and temperature drop rate to judge and control, compared with the traditional way relying on artificial experience, can more accurately grasp the working state of freezing unit, can effectively control the cooling overshoot, significantly improve the precision of temperature control, provide more stable and reliable temperature conditions for freeze ablation treatment, so as to improve the treatment effect.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and specifically to a control method for limiting overshoot in cryoablation equipment. Background Technology

[0002] Cryoablation therapy is a minimally invasive interventional treatment technique that uses extremely low temperatures to destroy (ablate) diseased tissue. During cryoablation therapy, the cryoablation device needs to precisely control the external temperature probe to quickly reach the set temperature and maintain it for a certain period of time in order to achieve effective ablation of the target tissue.

[0003] However, during ablation, the positions of the thermometer and ablation needle are not fixed, and the distance between the external thermometer and the cryoablation unit is unknown and has significant hysteresis, making overshoot highly likely during cooling. Currently, the common approach is to pause freezing prematurely based on manual experience to try to reduce overshoot, but this method has significant drawbacks. On the one hand, manual experience lacks precise quantitative standards, and differences in judgment among different operators lead to unstable control effects; on the other hand, this method cannot be dynamically adjusted in real time according to actual temperature changes, making it difficult to meet precise control requirements, thus affecting the efficacy and safety of cryoablation treatment. Summary of the Invention

[0004] The purpose of this invention is to provide a control method for limiting overshoot in cryoablation equipment, so as to solve the overshoot problem caused by the unknown distance between the external temperature probe and the freezing unit and the large hysteresis, and to achieve precise control of the temperature of the external temperature probe while achieving maximum power cooling.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for controlling overshoot in a cryoablation device includes the following steps:

[0007] S1. The ablation device is turned on with the set first freezing power to obtain the current temperature of the thermometer needle and the rate of temperature drop in real time.

[0008] S2. Compare the real-time temperature of the thermometer with the set temperature to determine whether it is close to the target value and whether the temperature drop rate meets the conditions. If the current temperature and the temperature drop rate meet the set conditions, the refrigeration unit stops working and allows the thermometer to cool down naturally.

[0009] S3. Based on the temperature of the thermometer and the rate of temperature drop monitored in real time during the natural cooling process, determine whether the refrigeration unit needs to be started and control the refrigeration power after the refrigeration unit is started, until the temperature of the thermometer reaches the target value.

[0010] S4. Once the temperature of the thermometer needle reaches the set target value, the second freezing power is used to control the temperature of the thermometer needle to ensure that the difference between the temperature of the thermometer needle and the set temperature is less than the set value, and this is maintained for a certain period of time to complete the cryoablation treatment process.

[0011] In one embodiment, in step S2, if the difference between the current temperature of the thermometer and the target value reaches a first set temperature and the cooling rate meets the set conditions, the refrigeration unit stops working and allows the thermometer to cool down naturally; if the cooling rate of the thermometer does not meet the set conditions, and the difference between the current temperature of the thermometer and the target value reaches a second set temperature, the refrigeration unit stops working and allows the thermometer to cool down naturally.

[0012] In one embodiment, in step S2, if the difference between the current temperature of the thermometer and the target value is less than 20°C and the cooling rate is greater than 50°C / min, the refrigeration unit stops working to allow the thermometer to cool down naturally.

[0013] In one embodiment, in step S2, if the cooling rate of the temperature sensor does not meet the set conditions, and the difference between the current temperature of the temperature sensor and the target value is less than 10°C, the refrigeration unit stops working, allowing the temperature sensor to cool down naturally.

[0014] In one embodiment, in step S3, if the temperature drop rate is <5℃ / min or the temperature of the thermometer needle does not reach the target value after the set time has elapsed, the refrigeration unit is restarted and cooled with a constant third refrigeration power until the temperature of the thermometer needle reaches the target value.

[0015] In one embodiment, the first refrigeration power is set as a, the second refrigeration power is set as b, and the third refrigeration power is set as c, wherein the relationship between the three is in accordance with the formula: a > c > b.

[0016] In one embodiment, the first freezing power is at least 80% of the maximum rated freezing power of the ablation device.

[0017] In one embodiment, in step S4, a PID algorithm is used to adjust the second freezing power so that the temperature of the thermometer needle fluctuates within 5°C above and below the set temperature.

[0018] In one embodiment, in step S3, when the difference between the temperature of the thermometer needle and the target value is less than 2.5°C, the process proceeds to step S4.

[0019] In one embodiment, in step S1, the temperature drop rate is calculated by the data processing module of the ablation device based on the temperature changes at adjacent time points.

[0020] The method for controlling cryoovershoot in cryoablation equipment provided by this invention has the following advantages over existing methods for controlling cryoovershoot:

[0021] 1. This invention combines the temperature of the thermometer needle and the rate of temperature drop for judgment and control. Compared with the traditional method that relies on human experience, it can more accurately grasp the working status of the cryoablation unit. It can effectively control the temperature overshoot to less than 10°C and the temperature fluctuation during the maintenance phase to less than 5°C, which significantly improves the accuracy of temperature control and provides more stable and reliable temperature conditions for cryoablation treatment, thereby improving the treatment effect.

[0022] 2. This control method achieves automated control, eliminating the need for frequent manual intervention by operators based on experience. It reduces the complexity and uncertainty of manual operation, improves the convenience and efficiency of operation, and also reduces the risk of operational errors caused by human factors.

[0023] 3. Because it can dynamically adjust in real time according to the actual temperature and rate of change of the temperature measuring needle, this control method can better adapt to the problems of unknown distance between the temperature measuring needle and the refrigeration unit and large hysteresis under different working conditions, and has stronger environmental adaptability and versatility. Attached Figure Description

[0024] Figure 1 The diagram illustrates the relationship between temperature, freezing rate, and time in the control method of the present invention, which includes three stages: rapid cooling, natural cooling, and PID temperature adjustment.

[0025] Figure 2 The diagram illustrates the relationship between temperature, freezing rate, and time in the control method of the present invention, which includes four stages: rapid cooling, natural cooling, forced cooling, and PID temperature control. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0027] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0028] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0029] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0030] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0031] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0032] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] This invention provides a control method for limiting overshoot in cryoablation equipment, which specifically includes the following steps:

[0035] S1. Turn on the freezing power of the ablation device at the set value and obtain the current temperature and temperature drop rate of the thermometer in real time. The current temperature of the thermometer can be obtained by collecting the temperature data of the thermometer in real time through the temperature sensor in the control system of the cryoablation device itself. At the same time, the temperature drop rate is calculated by the data processing module based on the temperature change of the thermometer at adjacent time points.

[0036] S2. Compare the real-time temperature of the thermometer with the set temperature to determine if it is close to the target value and if the temperature drop rate meets the conditions. If the difference between the current temperature of the thermometer and the target value reaches the first set temperature and the temperature drop rate meets the set conditions, the refrigeration unit stops working and allows the thermometer to cool down naturally. If the temperature drop rate of the thermometer does not meet the set conditions, and the difference between the current temperature of the thermometer and the target value reaches the second set temperature, the refrigeration unit stops working and allows the thermometer to cool down naturally.

[0037] S3. Based on the temperature of the thermometer and the rate of temperature drop monitored in real time during the natural cooling process, determine whether the refrigeration unit needs to be activated and control the refrigeration power after activation to allow the thermometer temperature to reach the set temperature again. If the rate of temperature drop is <5℃ / min or the temperature of the thermometer has not reached the target value after the set time has elapsed, restart the refrigeration unit and cool down at a constant refrigeration power until the temperature of the thermometer reaches the target value.

[0038] S4. Once the temperature of the thermometer needle reaches the vicinity of the set temperature again, the temperature continues to be monitored in real time. The PID algorithm is used to fine-tune the lower freezing power to ensure that the temperature fluctuates less than 5°C above and below the set temperature and is maintained for a certain period of time to complete the cryoablation treatment process.

[0039] The method for controlling cryoovershoot in cryoablation equipment provided by this invention has the following advantages over existing methods for controlling cryoovershoot:

[0040] 1. This invention combines the temperature of the thermometer needle and the rate of temperature drop for judgment and control. Compared with the traditional method that relies on human experience, it can more accurately grasp the working status of the cryoablation unit. It can effectively control the temperature overshoot to less than 10°C and the temperature fluctuation during the maintenance phase to less than 5°C, which significantly improves the accuracy of temperature control and provides more stable and reliable temperature conditions for cryoablation treatment, thereby improving the treatment effect.

[0041] 2. This control method achieves automated control, eliminating the need for frequent manual intervention by operators based on experience. It reduces the complexity and uncertainty of manual operation, improves the convenience and efficiency of operation, and also reduces the risk of operational errors caused by human factors.

[0042] 3. Because it can dynamically adjust in real time according to the actual temperature and rate of change of the temperature measuring needle, this control method can better adapt to the problems of unknown distance between the temperature measuring needle and the refrigeration unit and large hysteresis under different working conditions, and has stronger environmental adaptability and versatility.

[0043] Example:

[0044] In this embodiment, a surface-type (non-needle, flat-head) ablation device was used to conduct a tumor (melanoma model, on the body surface) treatment experiment in mice. The cryoinlet of the surface-type ablation device was inserted into atmospheric pressure liquid nitrogen, the ablation probe was attached to the tumor surface, and the temperature probe was inserted into the bottom of the tumor. The target temperature was set to -20°C and maintained for 5 minutes.

[0045] The first phase involves rapid cooling: The freezing power of the surface ablation device is initially set to maximum, at which point the freezing rate gradually increases, and the temperature of the thermometer needle continuously decreases. When the temperature difference between the thermometer needle and the target temperature is less than 20°C (in this embodiment, the thermometer needle temperature is <0°C), the temperature drop rate is monitored. If the temperature drop rate is greater than 50°C / min, freezing is stopped. If the temperature drop rate consistently fails to meet the target temperature, freezing is stopped when the temperature difference between the thermometer needle and the target temperature is less than 10°C (in this embodiment, the thermometer needle temperature is <-10°C).

[0046] The natural cooling phase then begins: total duration 45 seconds. If the temperature difference between the thermometer and the target temperature is less than 2.5℃ (in this embodiment, the thermometer temperature is < -17.5℃), the PID fine-tuning phase begins. If the temperature drop rate is < 5℃ / min or the 45-second period ends, the forced cooling phase begins.

[0047] During the forced cooling phase: the refrigeration unit is restarted and cooled at a constant power until the temperature difference between the thermometer and the target temperature is less than 2.5℃ (in this embodiment, the temperature of the thermometer is <-17.5℃).

[0048] Finally, the process enters the PID fine-tuning stage: the refrigeration power is adjusted by the temperature feedback from the thermometer and the PID algorithm to keep the external temperature near the set value for 5 minutes.

[0049] like Figure 1 and Figure 2 As shown, Figure 1 and Figure 2 The graphs showing the changes in probe temperature and freezing rate over time during tumor ablation in mice using the ablation device in this embodiment are illustrated. Figure 1 In the curve graph, the temperature of the thermometer needle reaches the target temperature range during the natural cooling phase. Figure 2In the curve graph, if the temperature of the thermometer does not reach the target temperature range during the natural cooling phase, a forced cooling phase is initiated to bring the temperature of the thermometer up to the target temperature range. Figure 1 and Figure 2 As can be seen, the overshoot during cryoablation can be effectively controlled to less than 10℃, and the temperature fluctuation during the maintenance phase can be controlled to less than 5℃. This proves that the control method can better control the overshoot, significantly improve the accuracy of temperature control, and provide more stable and reliable temperature conditions for cryoablation treatment, thereby improving the treatment effect.

[0050] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for controlling overshoot in a cryoablation device, characterized in that, Includes the following steps: S1. The ablation device is turned on with the set first freezing power to obtain the current temperature of the thermometer needle and the rate of temperature drop in real time. S2. Compare the real-time temperature of the thermometer with the set temperature to determine whether it is close to the target value and whether the temperature drop rate meets the conditions. If the current temperature and the temperature drop rate meet the set conditions, the refrigeration unit stops working and allows the thermometer to cool down naturally. S3. Based on the temperature of the thermometer and the rate of temperature drop monitored in real time during the natural cooling process, determine whether the refrigeration unit needs to be started and control the refrigeration power after the refrigeration unit is started, until the temperature of the thermometer reaches the target value. S4. When the temperature of the thermometer needle reaches the set target value, the second freezing power is used to control the temperature of the thermometer needle to ensure that the difference between the temperature of the thermometer needle and the set temperature is less than the set value, and maintain it for a certain period of time to complete the cryoablation treatment process. In step S2, if the difference between the current temperature of the thermometer and the target value reaches the first set temperature and the cooling rate meets the set conditions, the refrigeration unit stops working and allows the thermometer to cool down naturally; if the cooling rate of the thermometer does not meet the set conditions, and the difference between the current temperature of the thermometer and the target value reaches the second set temperature, the refrigeration unit stops working and allows the thermometer to cool down naturally. In step S3, if the temperature drop rate is less than 5℃ / min or the temperature of the thermometer needle does not reach the target value after the set time has elapsed, the refrigeration unit is restarted and the temperature is reduced with a constant third refrigeration power until the temperature of the thermometer needle reaches the target value. In step S4, the second freezing power is adjusted using a PID algorithm so that the temperature of the thermometer needle fluctuates within less than 5°C above and below the set temperature.

2. The control method as described in claim 1, characterized in that, In step S2, if the difference between the current temperature of the thermometer and the target value is less than 20°C and the cooling rate is greater than 50°C / min, the refrigeration unit stops working to allow the thermometer to cool down naturally.

3. The control method as described in claim 1, characterized in that, In step S2, if the cooling rate of the temperature sensor does not meet the set conditions, and the difference between the current temperature of the temperature sensor and the target value is less than 10°C, the refrigeration unit stops working and allows the temperature sensor to cool down naturally.

4. The control method as described in claim 1, characterized in that, Let the first freezing power be a, the second freezing power be b, and the third freezing power be c, where the relationship between the three is as follows: a > c > b.

5. The control method as described in claim 4, characterized in that, The first freezing power is at least 80% of the maximum rated freezing power of the ablation device.

6. The control method as described in claim 1, characterized in that, In step S3, when the difference between the temperature of the thermometer needle and the target value is less than 2.5℃, proceed to step S4.

7. The control method as described in claim 1, characterized in that, In step S1, the temperature drop rate is calculated by the data processing module of the ablation device based on the temperature changes at adjacent time points.

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