Cryotherapy device and cryotherapy system

Abstract

The present application relates to a cryotherapy device and system. The system comprises: a human-machine interaction module, a cryotherapy device, and a cryogenic catheter. The human-machine interaction module is electrically connected to the cryotherapy device. The cryogenic catheter is mechanically connected to the cryotherapy device by means of a cold source joint. A throttling module is arranged in the cryotherapy device, or a throttling module is arranged in the cryogenic catheter, or throttling modules are arranged in the cryotherapy device and the cryogenic catheter. N throttling mechanisms are arranged in the throttling module of the cryotherapy device, where N is greater than or equal to 1. M throttling mechanisms are arranged in the throttling module of the cryogenic catheter, where M is greater than 1. The cryotherapy device and the cryogenic catheter form an M+N-level cryotherapy system. The system achieves stable and accurate cryotherapy temperature control, thereby improving the therapeutic effect and surgical safety.

Description

Cryotherapy device and cryotherapy system Technical Field

[0001] The present application relates to the technical field of medical equipment, and in particular to a multi-stage throttling cryotherapy device and a cryotherapy system for cryotherapy. Background Art

[0002] In recent years, cryotherapy technology has made great progress in the treatment of human diseases. Low-temperature surgical instruments, such as cryotherapy equipment, can be used in different departments such as oncology, interventional medicine, orthopedics, general surgery, dermatology, thoracic surgery, otolaryngology, obstetrics and gynecology, urology, and neurology to perform low-temperature cryosurgical treatment on lesion tissues. For example, it can be used to treat certain forms of arrhythmias such as atrial fibrillation (AF), ablate tumors in cancer treatment, and be used for skin diseases, obstetric surgery, bronchial biopsy, etc. Cryotherapy technology has low trauma, few complications, and patients feel little pain during treatment. It is currently a relatively mature treatment method in clinical practice. In modern science and technology, when using cryotherapy technology to kill / extract abnormal tissue, the commonly used cooling principle is mainly the Joule-Thomson effect. Different types of cryotherapy instruments have been developed based on this principle. For example, the cryoablation method and system for treating atrial fibrillation (AF) disclosed in patent number CN 106687058 B utilizes temperature control of a heat treatment element of a medical device to maintain the temperature of the cryoablation fluid within a range of -20°C and -25°C for a period of time between 2 seconds and 40 seconds, thereby extending the melting period of the cryoablation procedure.

[0003] While this patent offers some improvements in treating atrial fibrillation by extending the fluid's thawing period compared to previous technologies, effective treatment of various diseases using this technology remains challenging in actual clinical practice. Analysis revealed that during each cryotherapy session, the refrigerant gas undergoes primary throttling within the cryo unit, specifically at the tip of the cryotube. This evaporation absorbs heat, removes tissue heat, lowers the temperature of the target treatment area, and destroys abnormal tissue, thus achieving the cryotherapy goal. However, the primary throttling employed in existing technologies suffers from the following four drawbacks.

[0004] 1. Inability to provide sufficiently low cryotherapy temperatures. It is known in the art that lower temperatures require shorter dwell / treatment times, and shorter dwell / treatment times are more patient-friendly. However, due to limitations on the refrigerant flow rate through the probe, the refrigerant's properties, and especially energy losses during the process, the lowest cryotherapy temperature achievable with existing technologies is essentially fixed. Providing sufficiently low treatment temperatures to enable cryotherapy to be applied to a wider range of lesions, as well as providing sufficiently low treatment temperatures to shorten treatment times and shorten the device's dwell / treatment time on the patient, present challenges with existing technologies.

[0005] Second, it cannot provide a sufficiently fast cooling rate. It is known in the art that the faster the cooling rate, the better the cryonics effect on target tissue. However, the cooling rate achievable with a single-stage throttling system is limited. To improve the cryonics effect, increasing the number of freezes and freezing time or lowering the freezing temperature is generally employed. However, increasing the number of freezes and freezing time correspondingly increases the risk of cryodamage to normal tissue. Lowering the freezing temperature is, in turn, limited by the theoretical limits of a single-stage throttling system.

[0006] Third, the excessively large diameter of cryo-catheters limits the permeability of catheter-based interventional treatments. Due to the varying anatomical structures of different blood vessels, respiratory tracts, and digestive tracts, different diameters of interventional catheters are suitable. The minimum diameter of some instrument channels, such as those in the bronchi and coronary arteries, is only approximately 1 mm, placing extremely stringent requirements on the diameter of interventional cryo-catheters. Using existing technology, it has proven difficult to simultaneously provide a small cryo-catheter with sufficient cooling capacity.

[0007] Fourth, the pressure at the end of the probe entering the body is too high, posing safety risks and technical limitations. Existing technology uses single-stage throttling to maintain a high pressure differential before and after throttling, which can produce lower freezing temperatures. However, the excessive refrigerant pressure entering the probe poses a significant safety risk. To address this issue, most foreign companies use high-pressure balloons. However, due to material and processing precision issues, high-pressure balloon technology is primarily monopolized by multinational corporations, which has temporarily limited breakthroughs in this field for domestic medical device companies.

[0008] Fifth, a single device cannot provide a wide range of cryotherapy temperatures. Existing technologies rarely achieve multifunctionality with a single device. This is because different temperatures are suitable for treating different lesions. For example, the cryotherapy temperature range for atrial fibrillation treatment is generally -40°C to -50°C, while the cryotherapy temperature range for tumor treatment is much lower, generally -40°C to -196°C. Existing technology generally uses the same cryotherapy device for the same lesion. The fundamental reason is that the system's cryotherapy temperature cannot be precisely adjusted. This phenomenon results in a significant waste of resources and creates unnecessary difficulties for medical staff to learn how to use it.

[0009] Based on the above-mentioned deficiencies in the prior art, the problem to be solved by this application is:

[0010] 1. How to achieve lower treatment temperatures, faster cooling rates, and a larger cryoprotection range to shorten treatment time and reduce surgical risks;

[0011] 2. How to provide a small-diameter cryocatheter with high cryoenergy output density within a unit diameter limit to achieve the treatment of lesions in special locations with stringent requirements for permeability?

[0012] 3. How to provide a solution that can reduce the problem of high refrigerant pressure before and after throttling in existing refrigeration units, and even be suitable for low-pressure balloons, thereby reducing surgical risks and breaking through technical barriers?

[0013] 4. How to provide a wide range of adjustable cryotherapy temperatures to enable cryotherapy of different lesions with the same device. Summary of the Invention

[0014] The purpose of this application is to address the shortcomings of the prior art that only has one level of throttling, and to provide a cryotherapy device and a cryotherapy system, which includes a cryotherapy device with an integrated multi-stage throttling mechanism and a freezing catheter with an integrated multi-stage throttling mechanism. The implementation scheme of this application to solve the problems of the prior art is to configure multiple throttling mechanisms in the cryotherapy system, and the number of throttling stages is several levels. In actual operation, by adjusting the coordination relationship between the throttling at each level, the cold output density is increased, the working temperature is reduced, and the cooling rate and freezing range are increased, thereby increasing the freezing depth of the lesion tissue, and on this basis, effective control of the size of the tissue freezing killing range and the freezing depth is achieved. In addition, the amount of refrigerant fluid required is minimized. This solution effectively reduces the diameter of the freezing catheter, reduces the internal pressure of the freezing catheter, avoids operational difficulties, high refrigerant pressure before and after throttling in the freezing unit, and poses safety risks, unstable treatment temperature and other problems.

[0015] In order to solve the problems existing in the prior art, on the one hand, the purpose of this application is achieved through the following technical solutions.

[0016] A cryotherapy device comprises: an air source module, the air source module is connected to a cold source joint through a pipeline, the cryotherapy device is connected to a freezing catheter through the cold source joint, the air source module delivers refrigerant to the distal end of the freezing catheter through the cold source joint, a throttling module is provided on the pipeline between the air source module and the cold source joint, one end of the throttling module is connected to the air source module, and the other end of the throttling module is connected to the freezing catheter through the cold source joint, and N throttling mechanisms are provided in the throttling module, where N is greater than or equal to 1.

[0017] The cryogenic fluid passes through N throttling mechanisms provided in the throttling module and completes the final throttling in the freezing catheter to form an N+1-stage throttling cryotherapy system. The ratio of the cooling capacity obtained by the multi-stage throttling of the cryotherapy system to the cooling capacity obtained by the traditional single-stage throttling conforms to the following formula:

[0018] in: is the cooling capacity ratio, f(P t0 , T t0 ) is the energy value of the fluid after completing single-stage throttling in the traditional single-stage throttling freezing pipe, f(Pt[n+1] , T t[n+1] ) is the energy value of the fluid after N+1 multi-stage throttling; f(P E , T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F , T F ) is the energy value of the fluid when it absorbs heat to saturation state through single-stage throttling expansion.

[0019] The purpose of this application can be further achieved through the following technical solutions:

[0020] In one embodiment of the cryotherapy device, the cryotherapy device is further provided with a control module and a human-computer interaction module, and the control module is electrically connected to the human-computer interaction module.

[0021] In one embodiment of the cryotherapy device, the cryotherapy device is further provided with an acquisition module, and the acquisition module is electrically connected to the control module and the human-computer interaction module respectively.

[0022] In one embodiment of the cryotherapeutic device, one or more bypass lines are provided within the throttling module, with the ends of the bypass lines respectively communicating with the inlet and outlet of the throttling mechanism. A solenoid valve and a check valve are provided on the bypass lines, allowing the throttling level of the cryotherapeutic device to be adjustable. Preferably, the solenoid valve is a three-wire, two-control electric ball valve of the same diameter as the connecting pipeline.

[0023] In one embodiment of the cryotherapy device, the throttling level of the cryotherapy device is determined by the fluid state (e.g., temperature, pressure, etc.) generated after each stage of multi-stage throttling and the total cooling capacity Q that can be generated after the multi-stage throttling. The maximum cooling capacity Q that can be generated by the fluid after the multi-stage throttling is t It can be expressed as follows:

[0024] Among them, △H is the enthalpy change of the fluid before and after each stage of throttling, f(P x , T x ), f(P tx , T tx ) are the energy values ​​of the fluid before and after the xth throttling respectively; T t and P t are the final fluid temperature and pressure after multi-stage throttling; T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, and v is the specific volume of the fluid:

[0025] Final fluid temperature after multi-stage throttling Tt It can be expressed as: t =Φ- 1( Qt ， P t )

[0026] When the total cooling capacity Q generated by multi-stage throttling is not less than Q t , the fluid temperature after multi-stage throttling does not exceed T t , the throttling levels selected by the system meet the requirements.

[0027] In one embodiment of the cryotherapy device, the throttling mechanism is at least one of a throttling valve, a capillary tube, a reducing tube, an orifice plate, and a nozzle.

[0028] In one embodiment of the cryotherapy device, the throttle valve is an electric proportional control valve with adjustable throttle opening.

[0029] In one embodiment of the cryotherapy device, one or more pre-cooling modules are arranged in the throttling module.

[0030] In one embodiment of the cryotherapy device, the pre-cooling module is connected to a cold supply module, and the pre-cooling temperature of the pre-cooling module is adjustable.

[0031] In one embodiment of the cryotherapy device, the pre-cooling module is a heat exchanger, and the heat exchanger includes at least one of a downstream heat exchanger, a countercurrent heat exchanger, a fin heat exchanger, a shell and tube heat exchanger, and an immersion heat exchanger.

[0032] In one embodiment of the cryotherapy device, the cold supply module includes at least one of a micro semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, and a phase change pre-cooling module.

[0033] In one embodiment of the cryotherapy device, the cold supply module is arranged inside the cryotherapy device, or the cold supply module is arranged outside the cryotherapy device.

[0034] In one embodiment of the cryotherapeutic device, the number of pre-cooling stages of the cryotherapeutic device is adjustable during the pre-cooling process. Preferably, the number of pre-cooling stages of the cryotherapeutic device is one more than the number of throttling stages.

[0035] In one embodiment of the cryotherapy device, the pre-cooling amount of the refrigerant supplied by the pre-cooling module must be less than the critical pre-cooling amount of the refrigerant phase change: Δu1 = q m [f(P1, T1)+f(P0, T0)]<Δu0

[0036] Among them, △u1 is the pre-cooling capacity of the refrigerant supplied by the first-level pre-cooling mechanism, △u0 is the critical pre-cooling capacity of the refrigerant phase change, q mis the fluid mass flow rate, f(P1, T1) and f(P0, T0) are the energy values ​​of the refrigerant before and after passing through the first-stage precooling mechanism.

[0037] In one embodiment of the cryotherapy device, the cooling capacity of the cooling capacity supply module of the cryotherapy device is:

[0038] Among them, w is the cooling capacity supplied to the module of each stage of pre-cooling mechanism, f is the thermal efficiency of each stage of pre-cooling mechanism, and △u is the pre-cooling capacity of the refrigerant supplied by each stage of pre-cooling mechanism.

[0039] In one embodiment of the cryotherapy device, the dryness of the refrigerant in the cryotherapy system before and after multi-stage throttling meets the following relationship: 0≤X(P tn , T tn )<X(P t0 , T t0 )

[0040] Where: X(P t0 , T t0 ) is the dryness of the refrigerant after throttling in the traditional single-stage throttling refrigeration pipe, X(P tn ,T tn ) is the refrigerant dryness of the refrigerant in a multi-stage throttling refrigeration pipe after throttling by the final throttling mechanism. Through the rational configuration of multi-stage throttling and pre-cooling mechanisms, the refrigerant dryness after throttling by the final throttling mechanism can be significantly reduced. The resulting liquid refrigerant entering the refrigeration unit absorbs significantly more heat through vaporization, thereby increasing the cooling capacity of the refrigeration pipe.

[0041] In one embodiment of the cryotherapeutic device, the cryotherapeutic device is provided with one or more pressure sensing elements and / or temperature sensing elements, each of which can be connected to the human-computer interaction module, the acquisition module, and the control module via electrical signals, thereby facilitating an operator to monitor and / or control the pressure and / or temperature within the treatment area. Preferably, the pressure sensing element and the temperature sensing element are integrated.

[0042] In one embodiment of the cryotherapeutic device, a pressure relief valve is provided in the cryotherapeutic device to prevent excessive pressure.

[0043] In one embodiment of the cryotherapy device, the gas source module is a gas cylinder, a reservoir or a small gas tank.

[0044] On the other hand, another object of the present application is achieved through the following technical solutions:

[0045] A cryotherapy system comprises: a cryotherapy device and a cryotherapy catheter, wherein the cryotherapy catheter is mechanically connected to the cryotherapy device via a cold source connector.

[0046] The cryotherapy device includes a gas source module, which is connected to the cold source connector via a pipeline, and the gas source module delivers refrigerant to the distal end of the freezing catheter through the cold source connector;

[0047] The freezing catheter includes a tube body and a freezing unit, the proximal end of the tube body is connected to the cold source joint, the distal end of the tube body is connected to the proximal end of the freezing unit, an air intake passage and an air return passage are provided in the tube body, the distal ends of the air intake passage and the air return passage are connected to the freezing unit, and the proximal end of the air intake passage is connected to the air source module through the cold source joint.

[0048] A throttling module is provided in the cryotherapy device, or a throttling module is provided in the freezing catheter, or a throttling module is provided in both the cryotherapy device and the freezing catheter. The throttling module of the cryotherapy device has N throttling mechanisms built in, N is greater than or equal to 1, and the throttling module of the freezing catheter has M throttling mechanisms built in, M is greater than 1. The cryotherapy device and the freezing catheter form an M+N-level cryotherapy system.

[0049] After the cryogenic fluid is throttled by the M+N throttling mechanisms provided in the cryotherapy system, the ratio of the cooling capacity obtained in the multi-stage throttling refrigeration system to the cooling capacity obtained by the traditional single-stage throttling conforms to the following formula:

[0050] in: is the cooling capacity ratio, f(P t0 ,T t0 ) is the energy value of the fluid after completing single-stage throttling in the traditional single-stage throttling conduit, f(P t[m+n] ,T t[m+n] ) is the energy value of the fluid after M+N level throttling; f(P E ,T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the fluid when it absorbs heat to saturation in a single-stage throttling expansion in the freezing conduit.

[0051] The above-mentioned purpose of this application can be further achieved by the following technical solutions:

[0052] In one embodiment of the cryotherapy system, the throttling module of the cryotherapy device is arranged on the pipeline between the gas source module and the cold source connector.

[0053] In one embodiment of the cryotherapy system, the throttling module of the freezing catheter is arranged on the air inlet passage, one end of the throttling module is connected to the air source module through the cold source connector, and the other end of the throttling module is connected to the freezing unit to transport refrigerant to the distal end of the freezing catheter.

[0054] In one embodiment of the cryotherapy system, the throttling mechanism is at least one of a throttling valve, a capillary tube, a reducing tube, an orifice plate, and a nozzle.

[0055] In one embodiment of the cryotherapy system, the throttle valve is an electric proportional control valve with adjustable throttle opening.

[0056] In one embodiment of the cryotherapy system, the cryotherapy system is provided with a control module and a human-computer interaction module, and the control module and the human-computer interaction module are electrically connected.

[0057] In one embodiment of the cryotherapy system, the cryotherapy system is provided with a collection module. The throttling module of the cryotherapy device is electrically connected to the control module and the collection module, respectively. The throttling module of the cryotherapy catheter is electrically connected to the collection module and the control module within the cryotherapy device via a cold source connector. One or more bypass lines are provided within the throttling module, the two ends of which are respectively connected to the inlet and outlet of the throttling mechanism. A solenoid valve and a check valve are provided on the bypass line, so that the throttling level of the cryotherapy device can be adjusted. Preferably, the solenoid valve is a three-wire, two-control electric ball valve of the same diameter as the connecting pipeline.

[0058] In one embodiment of the cryotherapy system, the throttling level of the cryotherapy system is determined by the fluid state (e.g., temperature, pressure, etc.) generated after each stage of multi-stage throttling and the total cooling capacity Q that can be generated after the multi-stage throttling. The maximum cooling capacity Q that can be generated by the fluid after the multi-stage throttling is t It can be expressed as follows:

[0059] Among them, △H is the enthalpy change of the fluid before and after each stage of throttling, f(P x ,T x ), f(P tx ,T tx ) are the energy values ​​of the fluid before and after the xth throttling respectively; T t and P t are the final fluid temperature and pressure after multi-stage throttling; T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, v is the specific volume of the fluid;

[0060] Final fluid temperature after multi-stage throttling T t It can be expressed as: t =Φ -1 (Qt , Pt ) When the total cooling capacity Q generated by multi-stage throttling is not less than Q t , the fluid temperature after multi-stage throttling does not exceed T t , the throttling levels selected by the system meet the requirements.

[0061] In one embodiment of the cryotherapy system, the pre-cooling module is connected to a cold supply module, and the pre-cooling temperature of the pre-cooling module is adjustable.

[0062] In one embodiment of the cryotherapy system, the pre-cooling module is a heat exchanger, and the heat exchanger includes at least one of a co-current heat exchanger, a counter-current heat exchanger, a fin heat exchanger, a shell and tube heat exchanger, and an immersion heat exchanger.

[0063] In one embodiment of the cryotherapy system, the cold supply module includes at least one of a micro semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, and a phase change pre-cooling module.

[0064] In one embodiment of the cryotherapeutic system, the pre-cooling level of the cryotherapeutic system is adjustable during the pre-cooling process.

[0065] In one embodiment of the cryotherapy system, the pre-cooling amount of the refrigerant supplied by the pre-cooling module must be less than the critical pre-cooling amount of the refrigerant phase change: Δu1 = q m [f(P1, T1)+f(P0, T0)]<Δu0

[0066] Among them, △u1 is the pre-cooling capacity of the refrigerant supplied by the first-level pre-cooling mechanism, △u0 is the critical pre-cooling capacity of the refrigerant phase change, q m is the fluid mass flow rate, f(P1, T1) and f(P0, T0) are the energy values ​​of the refrigerant before and after passing through the first-stage precooling mechanism.

[0067] In one embodiment of the cryotherapy system, the cryotherapy device supplies a cooling capacity to the module:

[0068] Among them, w is the cooling capacity supplied to the module of each stage of pre-cooling mechanism, f is the thermal efficiency of each stage of pre-cooling mechanism, and △u is the pre-cooling capacity of the refrigerant supplied by each stage of pre-cooling mechanism.

[0069] In one embodiment of the cryotherapy system, the dryness of the refrigerant before and after the multi-stage throttling meets the following relationship: 0≤X(P tn , T tn)<X(P t0 , T t0 )

[0070] Where: X(P t0 , T t0 ) is the dryness of the refrigerant after throttling in the traditional single-stage throttling refrigeration pipe, X(P tn , T tn ) is the refrigerant dryness of the refrigerant in a multi-stage throttling refrigeration pipe after throttling by the final throttling mechanism. Through the rational configuration of multi-stage throttling and pre-cooling mechanisms, the refrigerant dryness after throttling by the final throttling mechanism can be significantly reduced. The resulting liquid refrigerant entering the refrigeration unit absorbs significantly more heat through vaporization, thereby increasing the cooling capacity of the refrigeration pipe.

[0071] In one embodiment of the cryotherapy system, one or more pressure sensing elements and / or temperature sensing elements are provided within the cryotherapy system. Each of the pressure sensing elements and temperature sensing elements can be connected to the human-computer interaction module, the acquisition module, and the control module via electrical signals, thereby facilitating an operator to monitor and / or control the pressure and / or temperature within the treatment area. Preferably, the pressure sensing element and the temperature sensing element are integrated.

[0072] In one embodiment of the cryotherapy system, the human-computer interaction module includes a computer or microprocessor configured to receive temperature, pressure, and flow rate information from the acquisition module, generate cooling capacity control commands based on the temperature, pressure, and flow rate information, and transmit the commands to automatic adjustment components within the cryotherapy device and cryocatheter to adjust the cryotherapy temperature. The automatic adjustment components may include valves, resistors, heaters, and the like.

[0073] In one embodiment of the cryotherapy system, a pressure relief valve is provided within the cryotherapy device to prevent excessive pressure.

[0074] In one embodiment of the cryotherapy system, the gas source module is a gas cylinder, a reservoir or a small gas tank.

[0075] In one embodiment of the cryotherapy system, a rewarming heating element is provided on the freezing unit.

[0076] In one embodiment of the cryotherapeutic system, the cryocatheter is one of a cryoprobe, a cryoablation catheter, or a cryoballoon.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] 1. Prior art methods achieve primary throttling by releasing refrigerant within the freezing unit. Evaporation absorbs heat, removing tissue heat, lowering the temperature of the target treatment area and destroying abnormal tissue, thereby achieving the therapeutic goal. Unlike prior art methods, the present embodiment utilizes multi-stage throttling. The system is equipped with one or more throttling mechanisms, with several throttling stages. The refrigerant gas passes through several throttling mechanisms in sequence, each of which causes the high-pressure cooling medium to undergo a pressure drop and a temperature drop, achieving a step-by-step reduction in temperature and pressure. This multi-stage throttling and pressure reduction process ultimately reaches the freezing unit, where the final throttling and pressure reduction are completed, allowing cryotherapy to be performed at a lower pressure, thereby achieving the therapeutic goal. This system can be combined into a split, integrated, or handheld cryotherapy system by selecting different throttling components or structural forms. The throttling mechanism of the present application can be installed within the cryotherapy device to form a multi-stage throttling cryotherapy device; it can also be installed separately or used in combination within the freezing catheter and cryotherapy device to form a multi-stage throttling cryotherapy system.

[0079] 2. The multi-stage throttling cryotherapy system described herein allows for selection of appropriate throttling levels and cryotherapy temperatures based on actual lesion treatment needs. The cryotherapy system also incorporates one or more pre-cooling modules to supplement the refrigerant's cooling capacity. This multi-stage throttling combined with pre-cooling increases the enthalpy difference between the refrigerant before and after the multi-stage throttling, further reducing the cryotherapy temperature. Even with a reduced cryotherapy unit diameter, the required cryotherapy temperature and cooling capacity can still be achieved, effectively meeting the needs of cryotherapy for lesions in confined areas. Furthermore, during treatment, by adjusting the coordination between the throttling levels, the cooling capacity of the refrigerant carrier and the cryotherapy unit temperature are controlled, thereby controlling the freezing depth of the lesion tissue and minimizing the amount of refrigerant fluid required. Furthermore, the use of multi-stage throttling reduces the refrigerant temperature and pressure after catheter throttling, accelerating the cooling rate. This system can be used with low-pressure cryoballoons, breaking the technological monopoly of high-pressure balloons abroad. This system can reduce the temperature fluctuation at the end of the catheter's cryounit, ensuring stable and accurate cryotherapy temperature control, improving treatment efficacy and surgical safety.

[0080] 3. The throttling mechanism of the present application can be set in either the cryotherapy device or the tube body of the cryotherapy catheter to form a multi-stage throttling module. During treatment, the throttling level of the cryotherapy system is adjustable, and all or part of the throttling mechanisms can be selectively activated according to the actual needs of lesion treatment. By adjusting the coordination relationship between the throttling mechanisms at each level, the cryotherapy temperature of the freezing unit can be controlled and the amount of refrigerant fluid required can be minimized. Compared with the existing technology, the technical solution of the present application can reduce the diameter of the freezing unit, reduce the refrigerant pressure and cryotherapy temperature in the tube body of the freezing catheter and its freezing unit.

[0081] 4. The present application configures several heating elements in the freezing unit of the freezing catheter, which can accelerate the rewarming rate and improve the efficiency of freezing injury. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] FIG1 is a schematic structural diagram of the first embodiment of the cryotherapy device in Example 1 of the present application.

[0083] FIG2 is a schematic structural diagram of the second embodiment of the cryotherapy device in Example 1 of the present application.

[0084] FIG3 is a schematic structural diagram of the third embodiment of the cryotherapy device in Example 1 of the present application.

[0085] FIG4 is a schematic structural diagram of an implementation method of the second embodiment of the cryotherapy device of the present application.

[0086] FIG5 is a schematic diagram showing the evolution of the refrigerant medium in the pressure-enthalpy diagram during the three-stage throttling process of the present application.

[0087] FIG6 is a schematic structural diagram of a cryotherapy system composed of a cryotherapy device with two-stage throttling and three-stage pre-cooling and a cryocatheter according to the present application.

[0088] FIG7 is a schematic diagram showing the evolution of the refrigerant medium in the pressure-enthalpy diagram during the throttling process of the cryotherapy system shown in FIG6 .

[0089] FIG8 is a theoretical model for calculating the temperature of the medium after throttling in the multi-stage throttling process of the present application.

[0090] Figures 9 to 13 are structural schematic diagrams of other embodiments of the multi-stage throttling cryotherapy device of the present application. The device and the ordinary cryocatheter (or cryoballoon) in the prior art constitute a multi-stage throttling cryotherapy system.

[0091] FIG14 is a schematic structural diagram of a two-stage throttling freezing catheter.

[0092] FIG15 is a schematic structural diagram of a three-stage throttling freezing catheter provided with a pre-cooling mechanism.

[0093] FIG16 is a schematic structural diagram of a cryotherapy system having a three-stage throttling cryocatheter.

[0094] FIG17 is a schematic diagram showing the evolution of the cryogenic medium in the pressure-enthalpy diagram during the throttling process of the cryotherapy system shown in FIG14 .

[0095] FIG18 is another structural schematic diagram of a three-stage throttling freezing catheter provided with a pre-cooling mechanism.

[0096] Figure 19 is a structural schematic diagram of the multi-stage throttling cryotherapy system of the present application in which multiple throttling mechanisms are set in the cryotherapy equipment and the cryocatheter.

[0097] FIG20 is a schematic diagram showing the evolution of the cryogenic medium in the pressure-enthalpy diagram during the throttling process of the cryotherapy system shown in FIG19 .

[0098] Figures 21 to 25 are structural schematic diagrams of other embodiments of the multi-stage throttling cryotherapy system of the present application. DETAILED DESCRIPTION

[0099] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0100] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0101] For the convenience of description, if the words "up", "down", "left" and "right" appear in this application, they only indicate that they are consistent with the up, down, left and right directions of the drawings themselves, and do not limit the structure. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting this application.

[0102] The multi-stage throttling mentioned in this application refers to the entire system undergoing two or more throttling processes. The "proximal end" mentioned in this application refers to the end close to the surgical operator, and the "distal end" mentioned in this application refers to the end away from the surgical operator.

[0103] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments, and cannot be used to limit the scope of the present application.

[0104] The present application absorbs heat through the evaporation of the refrigerant, takes away the heat from the tissue, rapidly reduces the temperature of the target treatment site, and destroys the abnormal cell tissue, thereby achieving the treatment purpose. Its basic treatment principle is consistent with the principle of the prior art. The focus of the present application is the use of multi-stage throttling, the system is equipped with a throttling mechanism, and the number of throttling stages is several levels. Unlike the prior art, the refrigerant gas of the present application passes through several throttling mechanisms in sequence to complete multi-stage throttling and pressure reduction, and finally reaches the freezing unit, and completes the last throttling in the freezing unit. The multi-stage throttling cryotherapy system of the present application includes a human-computer interaction module, a cryotherapy device, and a freezing catheter, which can be combined into a split, integrated or handheld cryotherapy system by selecting different models of components or structural forms. The throttling mechanism of the present application can be set entirely in the cryotherapy device, or entirely in the freezing catheter, or can be set separately in the freezing catheter and the cryotherapy device and used in combination to form a multi-stage throttling cryotherapy system. This application utilizes multiple pre-cooling modules within the multi-stage throttling process to further supplement the cryotherapy system's energy, enabling the cryotherapy unit to achieve optimal cooling output and therapeutic efficacy during cryotherapy. Compared to existing technologies, this application allows for the selection of appropriate throttling levels and cryotherapy temperatures based on the specific lesion treatment needs. This multi-stage throttling combined with pre-cooling increases the enthalpy difference between the refrigerant before and after vaporization within the cryotherapy unit. Given a given lesion's required cooling capacity, even with a reduced cryotherapy unit diameter, the desired temperature and cooling capacity can still be achieved. During the treatment procedure, by adjusting the coordination between the throttling levels and controlling the cooling capacity of the refrigerant carrier, the cryotherapy terminal temperature can be controlled, thereby controlling the freezing depth of the lesion tissue and minimizing the amount of refrigerant fluid required. This multi-stage throttling reduces the refrigerant temperature and pressure within the cryotherapy unit before and after throttling, accelerating the cooling rate. This allows for use with low-pressure balloons, reducing surgical risks and breaking through the technological monopoly of high-pressure balloons abroad.

[0105] The present application is described in detail below through some embodiments of a multi-stage throttling cryotherapy device and a multi-stage throttling cryotherapy system.

[0106] Example 1

[0107] Referring to FIG1 , a cryotherapeutic device includes a gas source module 201 and a throttling module 204. The gas source module 201 is connected to a cold source connector 301 via a pipeline. The cryotherapeutic device is connected to a cryotube via the cold source connector 301. The gas source module 201 delivers refrigerant to the distal end of the cryotube via the cold source connector 301. The throttling module 204 is disposed in the pipeline between the gas source module 201 and the cold source connector 301. One end of the throttling module 204 is connected to the gas source module 201, and the other end of the throttling module 204 is connected to the cryotube via the cold source connector 301. A throttling mechanism, namely a first throttling mechanism 208, is disposed within the throttling module 204. The first throttling mechanism 208 can be at least one of a throttle valve, a capillary tube, a reducer, an orifice plate, and a nozzle. The cryotherapy device is connected to an external device (such as a cryocatheter) via a cold source connector 301. The refrigerant in the gas source module 201 completes the first throttling through the throttling module 204, and then continues to be transported to the distal end of the cryocatheter through the cold source connector 301, completing the second throttling in the freezing unit of the cryocatheter. Therefore, the cryotherapy device can form a two-stage throttling cryotherapy system together with the cryocatheter.

[0108] The ratio of the cooling capacity obtained after the refrigeration fluid (refrigerant) passes through a throttling mechanism provided in the throttling module 204 and completes the last throttling in the refrigeration conduit to the cooling capacity obtained by using the traditional single-stage throttling conforms to the following formula:

[0109] in: is the cooling capacity ratio, f(P t0 , T t0 ) is the energy value of the fluid in the traditional freezing catheter after single-stage throttling, f(P t2 ,T t2 ) is the energy value of the fluid after secondary throttling; f(P E ,T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the fluid when it absorbs heat to saturation during single-stage throttling expansion in the freezing pipe.

[0110] Using a common structure in the prior art, the liquid refrigerant stored in the gas source module 201 is converted into a working fluid and transported via a pipeline to the cold source connector 301. The refrigerant is then transported via the cold source connector 301 to a cryotherapy area such as a cryocatheter, cryoprobe, or cryoablation catheter. Building on the prior art, the present application provides one or more throttling mechanisms on the pipelines of the cryotherapy device 2, enabling the cryotherapy device to achieve multi-stage throttling.

[0111] Referring to Figure 2, a second embodiment of the above-mentioned cryotherapy device, the cryotherapy device 2 is provided with a control module 202 and a human-computer interaction module 1, the control module 202 is electrically connected to the human-computer interaction module 1, and the human-computer interaction module 1 includes a computer or a microprocessor for generating a cooling control command and sending it to the control module 202 and the freezing catheter of the cryotherapy device 2, so as to control the valves, resistors, heaters and other automatic adjustment components provided in the cryotherapy device 2 to achieve the adjustment of the cryotherapy temperature of the target area.

[0112] In this embodiment, several flow meters and pressure relief elements are also provided within the cryotherapy device to control the flow rate and safe pressure relief within the pipeline within the throttling module 204 to prevent excessive refrigerant pressure. The flow meter and pressure relief element can be directly installed on the pipeline within the throttling module 204, or they can be installed at other locations within the delivery pipeline of the cryotherapy device 2. As shown in Figure 2, a flow meter 205 and a pressure relief valve 223 are provided within the throttling module 204. The flow meter 205 is provided on the side of the first throttling mechanism 208 close to the gas source 201, and the pressure relief valve 223 is provided on the side of the throttling mechanism 208 close to the cold source connector 301 to prevent excessive fluid pressure.

[0113] Referring to FIG3 , the third embodiment of the cryotherapeutic device described above, compared to the second embodiment, includes a data acquisition module 203. The data acquisition module 203 is electrically connected to the control module 202 and the human-computer interaction module 1 and includes several temperature and / or pressure sensing elements. The human-computer interaction module 1 is configured to receive temperature, pressure, and flow rate information from the data acquisition module, generate cooling capacity control commands based on these information, and transmit them to the control module 202 and cryotube of the cryotherapeutic device 2. This control controls the valves, resistors, heaters, and other automatic control components within the cryotherapeutic device 2 to achieve the desired cryotherapeutic temperature at the target site. The throttling module 204 includes a flowmeter 205, a temperature sensing element 207, a pressure sensing element 215, and a pressure relief valve 223. The temperature sensing elements 207 are positioned on either side of the first throttling mechanism 208 to monitor the refrigerant temperature before and after throttling. The flowmeter 205 is disposed on the side of the first throttle mechanism 208 near the gas source 201. The pressure sensing element 215 and the pressure relief valve 223 are disposed on the side of the throttle mechanism 208 near the cold source connector 301 to monitor the pressure within the pipeline, control the fluid pressure, and prevent excessive fluid pressure. The temperature sensing element can be a K-type thermocouple, a T-type thermocouple, or a patch temperature sensor. The pressure sensing element can be a pressure-type, piezoresistive, piezoelectric, capacitive, or electromagnetic pressure sensor.

[0114] Example 2

[0115] Referring to FIG4 , this embodiment has a substantially identical structure to the first embodiment, differing in that the throttling module 204 includes two throttling mechanisms, namely a first throttling mechanism 208 and a second throttling mechanism 212. These two throttling mechanisms are throttling valves and, therefore, may also be referred to as the first throttling valve and the second throttling valve. The temperature sensing element and the pressure sensing element are integrated temperature and pressure sensors. Therefore, the throttling module 204 includes a flow meter 205, multiple temperature and pressure sensors 209, and a pressure relief valve 223. The multiple temperature and pressure sensors 209 are respectively disposed on either side of the first throttling mechanism 208 and the second throttling mechanism 212 to monitor the temperature and pressure of the refrigerant before and after throttling. The flow meter 205 is disposed on the side of the first throttling mechanism 208 near the gas source 201, and the pressure relief valve 223 is disposed on the side of the second throttling mechanism 212 near the cold source connector 301. In one embodiment, the first and second throttle valves are preferably electrically operated proportional control valves with adjustable throttle openings. The throttle module 204 is disposed in the pipeline between the gas source module 201 and the cold source connector 301. In another embodiment, bypass lines are provided within the throttle module 204, corresponding to the pipelines for the first and second throttle valves. The inlet and outlet of the bypass lines are connected to the inlet and outlet of the first or second throttle valves, respectively. A solenoid valve 243 and a check valve 244 are provided on the bypass lines, allowing the cryotherapeutic device to adjust the throttling level. The solenoid valve 243 is preferably a three-wire, two-control electric ball valve of the same diameter as the connecting pipeline to reduce the local resistance of the fluid caused by the valve structure. In this embodiment, the cryotherapeutic device can be combined with a cryotube to form a three-stage throttling cryotherapeutic system.

[0116] The ratio of the cooling capacity obtained after the refrigerant fluid passes through the first throttling mechanism 208 and the second throttling mechanism 212 provided in the throttling module 204 and completes the last throttling in the refrigerant pipe to the cooling capacity obtained by using the traditional single-stage throttling conforms to the following formula:

[0117] in: is the cooling capacity ratio, f(P t0 , T t0 ) is the energy value of the fluid in the traditional freezing catheter after single-stage throttling, f(P t3 ,T t3 ) is the energy value of the fluid after three-stage throttling; f(P E ,T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the fluid when it absorbs heat to saturation during single-stage throttling expansion in the freezing pipe.

[0118] During use, the operator can control the opening and closing of the first throttle mechanism 208, the second throttle mechanism 212, and the solenoid valve 243 by operating the human-computer interaction module 1 to send an electrical signal to the throttling module 204, thereby adjusting the throttling level of the cryotherapeutic device to one or two levels during the treatment process. For example, closing the bypass solenoid valve 243 on the first throttle mechanism 208 and the second throttle mechanism 212, and opening the bypass solenoid valve 243 on the second throttle mechanism 212 and the first throttle mechanism 208, changes the cryotherapeutic device from a two-level throttling system to a one-level throttling system. When the cryotherapeutic device and the cryocatheter together form a cryotherapeutic system, a three-level throttling system can be adjusted to a two-level throttling system. Similarly, closing the first throttle mechanism 208 and the second throttle mechanism 212 and opening all the solenoid valves 243 can adjust the three-level throttling system of the cryotherapeutic device and the cryocatheter together to a one-level throttling system of the prior art.

[0119] Referring to FIG5 , when using a cryotherapy device of the prior art for cryoablation, under ideal conditions, it is assumed that the state of the refrigerant before entering the cryotube throttling is phase point 1 (P1, T1), where P and T represent the pressure and temperature of the refrigerant in this state, respectively. After completing the first level of throttling (i.e., the process from phase point 1 to phase point 6) in the freezing unit of the cryotube, the throttled refrigerant directly reaches phase point 6 (P t0 、T t0 ). The present application adopts multi-stage throttling. Theoretically, the refrigerant can enter the refrigeration unit at any pressure lower than phase point 1. As shown in FIG5 , in the first embodiment, the refrigerant at phase point 1 (P1, T1) undergoes primary throttling to phase point 2, and then enters the refrigeration unit. After the throttling of the refrigeration unit, the secondary throttling is completed. In the second embodiment, the refrigerant at phase point 1 ((P1, T1)) undergoes primary throttling to phase point 3, and then enters the refrigeration unit. After the throttling of the refrigeration unit, the secondary throttling is completed. In the third embodiment, the refrigerant at phase point 1 (P1, T1) undergoes primary throttling to phase point 2, secondary throttling to phase point 3, and finally enters the refrigeration unit. After the throttling of the refrigeration unit (i.e., the process from phase point 3 to phase point 4), the tertiary throttling is completed. After throttling, the refrigerant reaches phase point 4 (P t3 、T t3 ). Compared with the existing technology, the unit cooling capacity q2 of multi-stage throttling is q2>q1 compared with the unit cooling capacity q1 of single-stage throttling. The pressure P after multi-stage throttling is E Compared with the pressure P after single-stage throttling F Compared with P E <P FThe multi-stage throttling method of the present application can increase the cooling capacity of the freezing unit and reduce the refrigerant pressure before and after throttling in the freezing unit. Therefore, the cryotherapy equipment can be used in conjunction with a low-pressure cryoballoon to reduce surgical risks.

[0120] If the distance between the two stages of throttling is too small, the fluid flow may be disturbed, resulting in unstable phenomena such as eddies, fluctuations or oscillations. If the distance is too large, the pipeline may be too long, the flow resistance may be too large, resulting in serious energy loss and increasing the ineffective length of the conduit. This application determines the setting of each stage of throttling mechanism based on the fluid flow rate and the required pressure drop. According to the fluid properties and process requirements, the distance and position between adjacent throttling mechanisms are determined based on calculations and experimental verification to ensure that the fluid can smoothly transition between the two stages of throttling. By combining the Bernoulli equation and the continuity equation, the flow rate after throttling can be solved. The specific calculation process needs to be determined according to the actual operating status, including known parameters such as pressure, flow rate, cross-sectional area before throttling. It should be noted that the above calculations need to be derived under certain assumptions, such as incompressible, ideal fluid, etc. In actual applications, some correction factors need to be considered, such as the compressibility of the fluid, viscosity loss, friction, etc.

[0121] The throttling stages of the cryotherapy device are based on the formula for the fluid enthalpy change before and after each throttling stage to establish a theoretical model of multi-stage throttling. Taking any point P and T of the fluid in the cryotherapy device as independent variables, the enthalpy change of the specific enthalpy H=f(P,T) is:

[0122] According to the formula,

[0123] dH=Tds+vdp

[0124] It can be deduced that

[0125] According to Maxwell's relations:

[0126] And the formula,

[0127] The general expression for fluid enthalpy change is derived using the equation of state and specific heat:

[0128] Since the enthalpy of the fluid in the catheter changes to △H before and after throttling, the above expression can be used to deduce the values ​​of f(P1, T1) and f(P t1 ,T t1 ) Enthalpy change:

[0129] The number of throttling stages of the cryotherapy device is determined by the fluid state (e.g., temperature, pressure, etc.) generated after each stage of multi-stage throttling and the total cooling capacity Q that can be generated after the multi-stage throttling. The maximum cooling capacity Q that can be generated by the fluid after the multi-stage throttling is t It can be expressed as follows:

[0130] Among them, △H is the enthalpy change of the fluid before and after each stage of throttling, f(P x ,T x ), f(P tx ,T tx ) are the energy values ​​of the fluid before and after the xth throttling respectively; T t and P t are the final fluid temperature and pressure after multi-stage throttling; T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, and v is the specific volume of the fluid.

[0131] Final fluid temperature after multi-stage throttling T t It can be expressed as: t =Φ -1 (Q t ,P t )

[0132] When the total cooling capacity Q generated by multi-stage throttling is not less than Q t , the fluid temperature after multi-stage throttling does not exceed T t , the throttling levels selected by the system meet the requirements.

[0133] The number of throttling stages in the cryotherapy device was verified using a multi-stage throttling theoretical model combined with experimental testing. Calculations and experiments revealed that when multi-stage throttling is used, the distance between the center points of the throttling mechanisms at each stage is preferably 5-100 times the maximum diameter of the pipeline. This is correlated with the throttling mechanism's structure and installation location.

[0134] Example 3

[0135] Referring to FIG6 , a multi-stage throttling cryotherapy device 2 includes a gas source module 201, a control module 202, a collection module 203, and a throttling module 204. The control module 202 and the collection module 203 are each electrically connected to the human-computer interaction module 1 via communication lines. The throttling module 204 is also electrically connected to the control module 202 and the collection module 203 via communication lines. The throttling module 204 is disposed in the pipeline between the gas source module 201 and the cold source connector 301. This embodiment differs from the second embodiment in that, in addition to the two throttling mechanisms disposed within the throttling module 204, three pre-cooling modules are also disposed. Each pre-cooling module is disposed at the front end of the throttling mechanism, and adopts a pre-cooling-then-throttling operation mode. The cryotherapy device 2 is connected to the freezing catheter 3 via a cold source connector 301. The refrigerant output by the gas source module 201 passes through the throttling module 204 and reaches the cold source connector 301. It is then transported to the freezing catheter 3 connected to the cold source connector 301 through the cold source connector 301, and finally the refrigerant is transported to the freezing unit 304 at the far end of the freezing catheter 3. The cryotherapy device and the freezing catheter together constitute an implementation scheme of "three-stage pre-cooling + three-stage throttling".

[0136] The throttling module 204 is provided with a flow meter 205, a first pre-cooling module 206, a first throttling mechanism 208, a second pre-cooling module 210, a second throttling mechanism 212, a third pre-cooling module 214 and a pressure relief valve 223 in sequence from the gas source module 201 to the freezing conduit 3. A temperature sensing element 207 is provided at the inlet and outlet of each of the first pre-cooling module 206, the first throttling mechanism 208, the second pre-cooling module 210, the second throttling mechanism 212 and the third pre-cooling module 214. A pressure sensing element 215 is provided at the outlet of the first throttling mechanism 208 and the second throttling mechanism 212. The first pre-cooling module 206, the second pre-cooling module 210 and the third pre-cooling module 214 can be a heat exchanger with two inlet and two outlet interfaces. The heat exchanger includes at least one of a downstream heat exchanger, a countercurrent heat exchanger, a fin heat exchanger, a shell and tube heat exchanger and an immersed heat exchanger. The pre-cooling module is connected to the cold supply module 231. The pre-cooling temperature of the pre-cooling module is adjustable, and the cold energy of the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214 is derived from the cold supply module 231. The cold supply module 231 includes at least one of a micro-semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, and a phase change pre-cooling module. The cold supply module 231 and the pre-cooling module respectively exchange heat using the countercurrent heat exchange method indicated by the arrow b→a. The cold supply module 231 can be located within the cryotherapy device 2, or can be located outside the cryotherapy device 2, or can be sourced from a hospital's medical refrigeration system. If the cold supply module 231 is located outside the cryotherapy device 2, a corresponding cold circulation supply interface must be provided on the cryotherapy device. The first pre-cooling module 206, the second pre-cooling module 210 and the third pre-cooling module 214 can share a cooling supply module according to different cooling supply requirements, or they can be provided with cooling supply modules separately. Common technical means can be used to achieve different modes of cooling supply, which will not be repeated here.

[0137] The inlet of the throttling module 204 of this embodiment is mechanically connected to the outlet of the pressure regulating valve provided at the outlet of the gas source 201 through a pipeline. The outlet of the throttling module 204 is mechanically connected to the handle of the freezing catheter 3 through a cold source connector 301 .

[0138] In this embodiment, the flow meter 205, the first precooling module 206, and the first throttling mechanism 208 are connected in series via piping to form a "first-stage precooling + first-stage throttling" mechanism. The second precooling module 210 and the second throttling mechanism 212 are connected in series via piping to form a "second-stage precooling + second-stage throttling" mechanism. The third precooling module 214 and the pressure relief valve 223 are connected in series via piping to form a "third-stage precooling mechanism." The freezing catheter 3 is mechanically connected to the cryotherapy device 2 via the cold source connector 301. The throttling effect of the freezing unit 304 itself constitutes the "third-stage throttling mechanism" of the multi-stage throttling cryotherapy device 2.

[0139] The temperature sensing element 207 and the pressure sensing element 215 can be installed in the series pipeline between the pre-cooling module and the inlet and outlet ports of the throttling mechanism according to the requirements of the system design. The temperature sensing element 207 is a temperature sensor, and the pressure sensing element 215 is a pressure sensor. In this embodiment, as shown in FIG6 , the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214 cooperate with the first throttling mechanism 208 and the second throttling mechanism 212 to form a multi-stage throttling cooling structure. By adjusting the cooling power of the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214 and adjusting the valve opening of the first throttling mechanism 208 and the second throttling mechanism 212, the refrigerant before throttling can always be in a saturated liquid state / gas-liquid mixed state, while the medium state after throttling by the throttling mechanism is in a non-solid phase region. As shown in FIG7 , the phase change diagram of the refrigerant in the multi-stage throttling in the cryotherapy device 2, the phase point position of the refrigerant before and after throttling is preferably located in the shaded area shown in FIG7 , and the phase point position of the refrigerant before and after throttling when entering the freezing catheter 3 is preferably located in the area to the right of the saturated liquid line in the shaded area shown in FIG7 .

[0140] During operation, referring to FIG6 , the acquisition module 203 collects data from the temperature sensors, pressure sensors, flowmeter 205 within the throttling module 204, and the temperature and pressure sensor 315 within the freezing unit, and uploads the obtained temperature, pressure, and flow information to the human-computer interaction module 1. The human-computer interaction module 1, via a microprocessor or controller using a PID or non-PID software algorithm, generates a cooling capacity control command based on this temperature, pressure, and flow information. The command is then sent to automatic adjustment components within the cryotherapy device 2, such as the flow control controller within the flowmeter 205, the throttle valve electric actuator within the first throttling mechanism 208 and the second throttling mechanism 212, the cooling capacity adjustment device within the cooling capacity supply module 231, and the heating power regulator of the heating module 316 within the freezing unit 304, to achieve precise control and adjustment of the target cryotherapy temperature and freezing-rewarming time.

[0141] Furthermore, by adjusting the cooling power of the cooling supply module 231 and the valve openings of the first throttle mechanism 208 and the second throttle mechanism 212, a wide range of cooling capacity and temperature requirements within the freezing unit 304 can be met. Depending on the refrigerant supplied, the temperature adjustment range can be from +80°C to -196°C. This temperature adjustment range allows the same cryotherapy device to be adapted for treating a variety of lesions. The refrigerant used in the cryotherapy device can be one of CO2, N20, Freon, nitrogen, or argon.

[0142] 6 and 7, assuming that the refrigerant is at phase point 2 (P1, T1) before throttling, P and T represent the pressure and temperature in this state respectively. The process of the refrigerant completing the multi-stage "pre-cooling + throttling" is as follows: the refrigerant is throttled from phase point 2 (P1, T1) through the first throttling mechanism 208 to phase point 3 (P t1 、T t1 ); then precooled by the second precooling module 210 to phase point 4 (P2, T2), and then throttled by the second throttling mechanism 212 to phase point 5 (P t2 、T t2 ); then precooled by the third precooling module 214 to phase 6 (P3, T3), and finally completed in the freezing unit 304 the last throttling (ie, the completion of the phase 6-phase 7 process), after throttling to phase 7 (P t3 、T t3 The throttled refrigerant in the freezing unit 304 exchanges heat with the tissue in the freezing unit 304, completing the process from phase 7 to phase 9. After absorbing heat, the energy value of the refrigerant increases and it continues to vaporize. At the same time, the refrigerant absorbs heat through evaporation, taking away the heat of the tissue, lowering the temperature of the target treatment site to form an ice ball, and the abnormal cell tissue is destroyed. The refrigerant throttles and expands to absorb heat to a saturated state and reaches phase 9 (P E 、T E After cryoablation is completed, the vaporized low-pressure refrigerant gas is discharged to the waste gas recovery system or a designated location through the exhaust port 307 of the cryotube 3. The heat absorbed by the refrigerant at the evaporation pressure is equal to the latent heat of evaporation of the refrigerant, which is the cooling capacity of the cryotube, as shown in the following formula: q2=f(P E , T E )-f(P3, T3)

[0143] Among them, q2 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 7-phase point 9 process), f(P3, T3) is the energy value of the refrigerant at phase point 6, and f(P E , T E ) is the energy value of the refrigerant when it expands and absorbs heat to saturation at phase point 9.

[0144] According to the embodiment of the present application, the pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure P3 of phase 6, and the pressure after throttling in the refrigeration unit is the pressure P of phase 7. t3 , the pressure difference before and after multi-stage throttling is ΔP2.

[0145] According to the laws of thermodynamics, there is no heat or work exchange between the refrigerant before and after throttling, so the energy value remains unchanged. Referring to Figure 7, the throttling process of the refrigerant should theoretically be an isenthalpic line perpendicular to the horizontal axis, and the initial phase point of the refrigerant before throttling is phase point 2 (P1, T1). According to the existing technology, if the refrigerant is only throttled in the refrigeration unit of the refrigeration pipe without multi-stage throttling and pre-cooling auxiliary links, then the refrigerant will be throttled and reduced in pressure directly from phase point 2 (P1, T1) to phase point 8 (P t0 、T t0 ), the refrigerant after throttling undergoes heat exchange in the freezing unit 304. After absorbing heat, the energy value of the refrigerant increases and it continuously vaporizes. The refrigerant absorbs heat through evaporation, takes away the heat of the tissue, and lowers the temperature of the target treatment site to form an ice ball, destroying the abnormal cell tissue. After throttling and expanding to absorb heat to a saturated state, the refrigerant reaches the phase point 10 (P F 、T F ), completing the process from phase point 8 to phase point 10.

[0146] Referring to FIG7 , the cryoablation treatment process of the prior art is a process of the first-order throttling phase point 2-8-10. Under the evaporation pressure, the heat absorption of the refrigerant is equal to the latent heat of evaporation of the refrigerant, which is equal to the cooling capacity of the cryotube. The cooling capacity of the cryotube of the prior art is shown as follows: q1=f(P F ,T F )-f(P t0 ,T t0 )

[0147] Among them, q1 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 8-10 process), f(P t0 , T t0 ) is the energy value of the refrigerant at phase point 8, f(P F , T F ) is the energy value of the refrigerant when it expands and absorbs heat to saturation at phase point 10.

[0148] The pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure P1 of phase 2, and the pressure after throttling in the refrigeration unit is the pressure P of phase 8. t0 , the pressure difference before and after throttling is ΔP1.

[0149] As mentioned above, the ratio of the cooling capacity obtained by the throttling expansion of the fluid after three-stage throttling to the cooling capacity obtained by the traditional single-stage throttling conforms to the following formula:

[0150] in, is the cooling capacity ratio, f(P t0 , T to ) is the energy value of the fluid after the first level of throttling using the existing technology, f(P t3 , T t3 ) is the energy value of the fluid after three-stage throttling; f(P E , T E ) is the energy value of the refrigerant's three-stage throttling expansion and heat absorption to saturation, f(P F , T F ) is the energy value of the refrigerant absorbed by the single-stage throttling expansion to the saturated state.

[0151] Compared with the prior art, the cryotherapy system provided by the embodiment of the present application has a significantly increased refrigeration capacity per unit refrigerant for cryotherapy. When the refrigerant enters the freezing unit 304, the pressure before throttling P3 is less than P1, and the pressure after throttling P t3 <P t0 , the pressure before and after the multi-stage throttling can be significantly reduced compared with the existing technology. According to thermodynamic calculations, under ideal conditions, by adopting the technical solution of the present application, under the same cooling demand, the diameter of the freezing catheter can be reduced compared with the existing technology. The reduction in the diameter of the freezing catheter can increase the application scope of cryotherapy technology in distal bronchial biopsy of the lungs, coronary artery dredging, etc. In addition, by adopting the technical solution of the present application, the pressure in the freezing unit is significantly reduced before and after throttling, which not only reduces the risk of surgery, but also makes the application of low-pressure balloons in the treatment of some lesions extremely feasible, breaking through the technical limitations of foreign countries on high-pressure balloon materials.

[0152] This application can establish a theoretical model of multi-stage throttling by monitoring the temperature and pressure of the refrigerant before and after throttling, and determine the appropriate throttling level for cryotherapy equipment based on the theoretical model. The specific implementation steps are as follows:

[0153] First, preset the freezing temperature T required for lesion treatment according to the purpose of the cryotherapy equipment. tn , Refrigeration unit allowable pre-throttling pressure P n , refrigeration unit design diameter D, calculate the fluid mass flow rate q m , the target phase point where the fluid is finally throttled in the conduit (P tn 、T tn );

[0154] Referring to Figure 8, in the second step, according to the initial phase point (P0, T0) and the target phase point (P tn 、T tn ) The number of pre-divided throttling stages is n (n>1);

[0155] The third step is to plan the phase point position before and after the fluid throttling. If a pre-cooling mechanism is required, the pre-throttling value phase point is planned at the phase point position after pre-cooling and before throttling. For example, if pre-cooling is performed before the first-stage throttling, the pre-throttling mechanism before the first-stage throttling is set according to the planned pre-throttling value phase point (P1, T1), and the cooling capacity Δu1 of the corresponding pre-cooling supply mechanism is calculated. The pre-cooling capacity of the refrigerant supplied by the pre-cooling module must be less than the critical pre-cooling capacity of the refrigerant phase change: Δu1 = q m [f(P1,T1)-f(P0,T0)]<Δu0

[0156] Among them, △u1 is the pre-cooling capacity of the refrigerant supplied by the first-level pre-cooling mechanism, △u0 is the critical pre-cooling capacity of the refrigerant phase change, q m is the fluid mass flow rate, f(P1, T1) and f(P0, T0) are the energy values ​​of the refrigerant before and after passing through the first-stage precooling mechanism;

[0157] According to the phase point before throttling (P1, T1), the phase point after throttling (P t1 、T t1 ), the enthalpy change of the fluid after the first stage of throttling can be expressed as follows:

[0158] Among them, △H is the enthalpy change of the fluid before and after throttling, (P1, T1), f(P t1 ,T t1 ) are the energy values ​​of the fluid before and after the first stage of throttling, T1, T t1 and P1, P t1 are the fluid temperature and pressure before and after the first stage of throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, and v is the specific volume of the fluid.

[0159] The fourth step is to calculate the cooling capacity Δu2 of the second stage precooling mechanism and the fluid pressure P after the second stage throttling according to the theoretical model of the first stage precooling and the first stage throttling. t2 , the fluid temperature after the second stage throttling T t2 , and so on, the enthalpy change of the fluid after the x-th stage throttling can be expressed as follows:

[0160] Among them, △H is the enthalpy change of the fluid before and after throttling, f(P x , T x ), f(P tx ,T tx ) are the energy values ​​of the fluid before and after the x-th stage throttling, T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, and v is the specific volume of the fluid.

[0161] The pre-cooling capacity of the refrigerant supplied by the x-th stage pre-cooling is: Δu x =q m [f(P x ,T x )-f(P t(x-1) ,T t(x-1) )]

[0162] The fluid phase point after all throttling of multi-stage throttling is completed is (P tn 、T tn ), the enthalpy change of the fluid after the last stage of throttling can be expressed as follows:

[0163] The pre-cooling capacity of the refrigerant supplied by the last stage of pre-cooling is: Δu n =q m [f(P n ,T n )-f(P t(n-1) ,T t(n-1) )]

[0164] Step 5: Analyze whether the precooling / throttling process reaches the critical pressure according to different throttling types, establish a safe and economical multi-stage throttling cryotherapy plan, and determine the final throttling and precooling stages, as well as the maximum precooling capacity of each stage;

[0165] The sixth step is to control and adjust the valve opening and inter-stage pre-cooling amount during the actual operation of the multi-stage throttling cryotherapy equipment through a microprocessor or controller using a PID or non-PID software algorithm, thereby controlling the actual phase point position of the refrigerant after each stage of throttling and pre-cooling to match the designed phase point position, thereby achieving precise control of the refrigerant temperature and pressure before and after each stage of throttling.

[0166] Based on the temperature and pressure changes during the multi-stage throttling process and the target cryotherapy temperature, this model can accurately predict the pressure and temperature of different refrigerants in different modes, thus avoiding the formation of solids during the throttling and pre-cooling processes, which could cause ice blockage and affect the normal operation of the multi-stage throttling cryotherapy device. The control principle of multi-stage throttling cryotherapy equipment is to quickly supply sufficient cooling capacity to the cryotherapy unit while meeting the required cryotherapy temperature without ice blockage, minimize the diameter of the cryotherapy unit, minimize the pressure drop across the throttling mechanism, reduce the pre-cooling capacity, reduce the number of throttling stages, and reduce the number of pre-cooling stages. The model also provides methods for calculating the pre-cooling capacity of each stage and selecting the number of multi-stage throttling stages.

[0167] The present invention can reduce the dryness of the output refrigerant through multi-stage throttling and improve the refrigeration capacity of the freezing pipe. The dryness of the refrigerant in the freezing pipe after traditional single-stage throttling and pre-cooling is X(P t0 ,Tt0 )for:

[0168] Where: f x (P t0 ,T t0 ) is the phase point of the traditional single-stage throttling cryotube (P t0 、T t0 ) Actual energy value of refrigerant, f f (P t0 ,T t0 ) is the energy value of saturated liquid refrigerant; f s (P t0 ,T t0 ) is the energy value of saturated gaseous refrigerant.

[0169] The dryness of the refrigerant in the freezing pipe after multi-stage throttling and pre-cooling is X(P tn ,T tn )for:

[0170] Where: f x (P tn ,T tn ) is the phase point (P t n 、T t n ) Actual energy value of refrigerant, f f (P tn ,T tn ) is the energy value of saturated liquid refrigerant; f s (P tn ,T tn ) is the energy value of saturated gaseous refrigerant.

[0171] Therefore, the dryness of the refrigerant in the freezing pipe before and after the multi-stage throttling meets the following relationship: 0≤X(P tn ,T tn )<X(P t0 ,T t0 )

[0172] Where: X(P t0 ,T t0 ) is the dryness of the refrigerant after throttling in the single-stage throttling refrigeration pipe, X(P tn ,T tn ) is the dryness of the refrigerant after throttling by the last stage throttling mechanism in the multi-stage throttling refrigeration pipe.

[0173] Since the dryness of the refrigerant after multi-stage throttling is significantly lower than that of the traditional single-stage throttling, the liquid content of the refrigerant after multi-stage throttling is significantly increased, and the cooling capacity of the freezing pipe will be significantly improved.

[0174] Example 4

[0175] This embodiment differs from the pre-cooling-first, throttling-second technical solution in Example 3. It utilizes a throttling-first, pre-cooling-second approach, and also incorporates a different number of pre-cooling modules. The cryotherapy device of this embodiment, combined with existing cryotherapy catheters, implements a "three-stage throttling + one-stage pre-cooling" solution. The refrigerant flow path within the device may include one or more valves and pipelines. Referring to FIG9 , a cryotherapy device 2 includes a gas source module 201, a control module 202, a collection module 203, and a throttling module 204. The throttling module 204 includes a flow meter 205, a first throttling mechanism 208, a second throttling mechanism 212, a pre-cooling module, and a pressure relief valve 223, which are connected in sequence. The inlets and outlets of the first throttling mechanism 208, the second throttling mechanism 212, and the pre-cooling module are each provided with a temperature sensing element 207. Pressure sensing elements 215 are provided at the outlets of the first throttling mechanism 208 and the second throttling mechanism 212. The structure of this embodiment is substantially identical to that of the second embodiment, except that a precooling module is disposed behind the second throttling mechanism 212, positioned between the pressure sensing element 215 and the temperature sensing element 207. This precooling module is positioned identically to the third precooling module 214 in the third embodiment and may be considered the third precooling module 214. As in the third embodiment, a cooling capacity supply module 231 is disposed on the precooling module, and the cooling capacity of the precooling module is derived from the cooling capacity supply module 231. Through the human-computer interaction module 1, the operator can selectively control the refrigerant to always be in a gas-liquid mixed state after throttling and precooling. By adjusting the cooling capacity of the cooling capacity supply module 231 and the valve openings of the first throttling mechanism 208 and the second throttling mechanism 212, the cryotherapy temperature of the freezing unit 304 of the cryotube 3 can be selectively controlled and adjusted to meet a wide range of cooling capacity and temperature requirements within the freezing unit 304.

[0176] Example 5

[0177] This embodiment has a structure essentially identical to that of the third embodiment, and the cryotherapeutic device also features a "three-stage precooling + two-stage throttling" configuration. The difference lies in the adjustable throttling level of the cryotherapeutic device in this embodiment. The refrigerant flow path in this embodiment includes multiple valves, a main line, and a bypass line. The main line is equipped with a throttling mechanism with adaptive (optionally PID control) valve opening adjustment, a variable cooling capacity supply module, a precooling module, an automatic pressure relief valve, and components such as pressure and temperature sensors. The bypass line is connected in parallel to the throttling mechanism, and a solenoid valve and a check valve are installed on the bypass line. The throttling mechanism is preferably an electric proportional control valve with adjustable throttling opening. Referring to Figure 10, the throttling module 204 is positioned between the gas source module 201 and the cooling source connector 301. The cryotherapeutic device 2 and the cryotube 3 together form a cryotherapeutic system with a maximum of "three-stage precooling + three-stage throttling" and adjustable precooling and throttling levels. The main flow line within the throttling module 204 is sequentially provided with a flow meter 205, a first precooling module 206, a first throttling mechanism 208, a second precooling module 210, a second throttling mechanism 212, a third precooling module 214, and a pressure relief valve 223. A temperature sensor 207 is provided at the outlet of each of the first precooling module 206, the first throttling mechanism 208, the second precooling module 210, the second throttling mechanism 212, and the third precooling module 214. A pressure sensing element 215 is provided at the outlet of each of the first throttling mechanism 208 and the second throttling mechanism 212. A bypass line is provided at the first throttling mechanism 208, with its two ends connected to the inlet and outlet of the first throttling mechanism 208, respectively. Another bypass line is provided at the second throttling mechanism 212, with its two ends connected to the inlet and outlet of the second throttling mechanism 212, respectively. A solenoid valve 243 and a check valve 244 are provided on each of the bypass lines. The solenoid valve 243 is preferably a three-wire two-control electric ball valve with the same diameter as the connecting pipeline to reduce the local resistance of the fluid caused by the valve structure.

[0178] By operating the human-computer interaction module 1 and sending an electrical signal to the throttling module 204, the user can control the opening and closing of the throttling mechanism and the pre-cooling module, respectively. Referring to FIG10 , by controlling the opening and closing of the first throttling mechanism 208, the second throttling mechanism 212, and the solenoid valve 243, the cryotherapeutic device's throttling level can be adjusted to two or one levels during the treatment process. Controlling the opening and closing of the pre-cooling module can adjust the cryotherapeutic device's pre-cooling level to three, two, one, or zero levels. For example, by closing the first throttling mechanism 208 and the solenoid valve 243 on the bypass line of the second throttling mechanism, opening the second throttling mechanism 212 and the solenoid valve 243 on the bypass line of the first throttling mechanism, and opening the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214, the cryotherapeutic system, consisting of the cryotherapeutic device 2 and the cryocatheter 3, can be adjusted to a "three-level pre-cooling + two-level throttling" cryotherapeutic system. By further closing the first pre-cooling module 206, the system can be adjusted to a "two-stage pre-cooling + two-stage throttling" cryotherapy system. Similarly, by closing the second throttling mechanism 212 and the solenoid valve 243 on the bypass line of the first throttling mechanism, opening the first throttling mechanism 208 and the solenoid valve 243 on the bypass line of the second throttling mechanism, and opening the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214, the cryotherapy system can also be adjusted to a "three-stage pre-cooling + two-stage throttling" mode. This embodiment has the advantage of being able to adjust the number of pre-cooling and throttling stages of the cryotherapy device to control the target cooling output and target freezing temperature, thereby expanding the freezing temperature range and being suitable for treating a variety of lesions.

[0179] Example 6

[0180] This embodiment is similar to the pre-cooling-first, throttling-later technical solution of Example 5, differing in the number of throttling mechanisms and pre-cooling modules. The cryotherapeutic device of this embodiment incorporates only a single, automatically adjustable throttling valve. Together with existing cryotherapy catheters, this embodiment implements a "two-stage throttling + two-stage pre-cooling" solution. The refrigerant flow path within the device may include one or more valves and pipelines. Referring to Figure 11, a cryotherapeutic device 2 comprises a gas source module 201, a control module 202, a collection module 203, and a throttling module 204. The throttling module 204 includes, in sequence, a flowmeter 205, a first pre-cooling module 206, a first throttling mechanism 208, a third pre-cooling module 214, and a pressure relief valve 223. The outlets of the first pre-cooling module 206, the first throttling mechanism 208, and the third pre-cooling module 214 are each equipped with a temperature sensing element 207, and the outlet of the first throttling mechanism 208 is equipped with a pressure sensing element 215. Similar to other embodiments, the pre-cooling module is provided with a cold supply module 231, which supplies the pre-cooling module with cold energy. The operator can select the cryotherapy temperature of the freezing unit 304 through the human-computer interaction module 1. The human-computer interaction module 1 automatically adjusts the opening of the first throttling mechanism 208 via the control module 202 based on the operator-selected temperature and adjusts the cooling power of the cold supply module 231 to ensure that the cryotherapy temperature of the freezing unit 304 meets the treatment requirements.

[0181] Example 7

[0182] This embodiment has a substantially identical structure to the third embodiment, with the cryotherapeutic device also featuring a "three-stage precooling + two-stage throttling" structure. The difference lies in the following: The first throttling mechanism 208 of this embodiment is a non-adjustable throttling mechanism, which can be a throttle valve, capillary tube, reducer, orifice plate, or nozzle, while the second throttling mechanism 212 is an automatically adjustable throttle valve. Referring to FIG. 12 , the cryotherapeutic device 2 and the cryocatheter 3 together form a cryotherapeutic system with a maximum of three precooling stages and three throttling stages, with adjustable precooling and throttling levels.

[0183] The operator can select the cryotherapy temperature for the refrigeration unit 304 through the human-computer interaction module 1. The human-computer interaction module 1 automatically adjusts the opening of the second throttling mechanism 212 based on the operator-selected temperature through the control module 202. Furthermore, the refrigeration power of the cold supply module 231 is adjusted to ensure that the cryotherapy temperature of the refrigeration unit 304 meets the treatment requirements. This embodiment has the advantage of being able to adjust the pre-cooling power and the opening of the throttle valve of the second throttling mechanism to control the target cooling output and target freezing temperature, thus expanding the freezing temperature range and providing flexible and diverse device applications.

[0184] Example 8

[0185] A cryotherapeutic system includes: a human-machine interaction module, a cryotherapeutic device, and a cryotherapy catheter, wherein the human-machine interaction module is electrically connected to the cryotherapeutic device, and the cryotherapy catheter is mechanically connected to the cryotherapeutic device via a cold source connector. The cryotherapeutic system can be constructed by the multi-stage throttling cryotherapeutic device described in the above embodiment and an existing cryotherapy catheter, or by the cryotherapeutic device and the multi-stage throttling cryotherapy catheter of the prior art, or by the multi-stage throttling cryotherapeutic device and the multi-stage throttling cryotherapy catheter together. The multi-stage throttling cryotherapeutic system can be combined into an integrated or handheld multi-stage throttling cryotherapeutic system by selecting different types of components or different structural forms of the human-machine interaction module 1, the cryotherapeutic device 2, and the cryotherapy catheter 3. For example, the gas source module 201 in the cryotherapeutic device 2 can be a built-in small gas tank, making it smaller in size and more convenient to operate than other example products.

[0186] Referring to Figure 13, the cryotherapy system is constructed by a multi-stage throttling cryotherapy device and a conventional cryotherapy catheter. The specific structure of the multi-stage throttling cryotherapy device is the same as that of the cryotherapy device described in Example 6 and will not be repeated here.

[0187] Embodiment 9

[0188] A cryotherapy system includes a human-computer interaction module, a cryotherapy device, and a cryotherapy catheter. The human-computer interaction module is electrically connected to the cryotherapy device, and the cryotherapy catheter is connected to the cryotherapy device via a cold source connector. The multi-stage throttling cryotherapy system is constructed using the cryotherapy device and the multi-stage throttling cryotherapy catheter of the prior art.

[0189] 14, the freezing catheter includes a tube body 302 and a freezing unit 304, the proximal end of the tube body 302 is connected to the cold source connector 301, the distal end of the tube body 302 is connected to the proximal end of the freezing unit 304, an air intake passage 330 and an air return passage 328 are provided in the tube body 302, the distal ends of the air intake passage 330 and the air return passage 328 are in communication with the freezing unit 304, the proximal end of the air intake passage 330 is in communication with the cold source connector 301, and the proximal end of the air return passage 328 is provided. An exhaust outlet 307 is provided, connected to an exhaust gas recovery system or to the atmosphere. The cryotube is mechanically connected to the cryotherapy device via a cold source connector 301. A throttling module 303 is provided within the air inlet passage 330. The throttling module 303 includes a primary throttling mechanism 319, which is positioned within the air inlet passage 330 near the cold source connector 301. The primary throttling mechanism 319 and the freezing unit 304 together form a secondary throttling cryotube. The secondary throttling cryotube, when used in conjunction with conventional cryotherapy devices, can form a secondary throttling cryotherapy system.

[0190] In one embodiment, referring to FIG. 14 , a rewarming element 316 is also provided on the freezing unit 304. One or more temperature and pressure sensing elements are provided within the freezing catheter. These temperature and pressure sensing elements are connected to the human-machine interface module and the cryotherapy device via electrical signals, allowing the operator to monitor and / or control the temperature and / or pressure within the treatment area. The temperature sensing element may be a K-type thermocouple, a T-type thermocouple, or a patch temperature sensor. The pressure sensing element may be a pressure, piezoresistive, piezoelectric, capacitive, or electromagnetic pressure sensor. The temperature and pressure sensing elements may be integrated into a temperature and pressure sensor 327 and a temperature and pressure sensing element 315. The temperature and pressure sensor 327 is positioned distally to the primary throttling mechanism 319, while the temperature and pressure sensing element 315 is positioned within the freezing unit 304 to monitor the temperature and pressure within the pipeline and freezing unit, control the fluid pressure, and prevent excessive fluid pressure. The temperature and pressure sensor 327 is an integrated combination of the temperature and pressure sensors to enable simultaneous measurement of temperature and pressure.

[0191] In practical applications, the cryo-catheter is one of a cryoprobe, a cryoablation catheter or a cryo-balloon. The outer layer of the tube body 302 of the cryo-catheter is made of a heat-insulating material such as plastic or rubber.

[0192] During cryotherapy, the air inlet passage 330 serves as the refrigerant supply lumen for cryotherapy and is connected to the cryotherapy device via the cold source connector 301. The refrigerant can be one of CO2, N2O, Freon, nitrogen, or argon. The refrigerant originates from the gas source module of conventional cryotherapy devices. The refrigerant, delivered from the cryotherapy device to the cold source connector 301, then enters the cryotube through the inlet of the cold source connector 301. It then flows axially along the lumen of the air inlet passage 330, sequentially passing through the primary throttling mechanism 319, forming the first stage of throttling. It then flows through the gas nozzle 317 within the freezing unit 304, forming the second stage of throttling. The refrigerant gas expands within the expansion chamber of the freezing unit 304, absorbing heat until it reaches saturation, completing the cryotherapy process on the target tissue. The evaporated refrigerant enters the return air passage 328 through the return air port 324 within the freezing unit 304, reaching the exhaust outlet 307 and being discharged to the exhaust gas recovery system. At this point, the refrigerant completes a complete cryotherapy process through "secondary throttling" in the freezing catheter.

[0193] In one embodiment, the throttling module 303 is positioned within the tube body 302 near the cold source connector 301. Of course, the throttling module 303 may include one or more throttling mechanisms to achieve two-stage or multi-stage throttling. Theoretically, a greater number of throttling stages results in a better final effect for achieving the present application. However, since increasing the number of throttling stages increases the complexity of the cryotube processing steps, an appropriate number of throttling stages can be selected based on the actual application scenario.

[0194] Example 10

[0195] The structure of this embodiment is substantially the same as that of the ninth embodiment, except that, as shown in FIG15 , the throttling module 303 includes two throttling mechanisms, namely, a primary throttling mechanism 319 and a secondary throttling mechanism 321. The primary throttling mechanism 319 and the secondary throttling mechanism 321 are both disposed at the proximal end of the air inlet passage 330. Together with the refrigeration unit 304, the primary throttling mechanism 319 and the secondary throttling mechanism 321 form a three-stage throttling structure. Three pre-cooling mechanisms are also disposed within the throttling module 303, namely, a primary pre-cooling mechanism 318, a secondary pre-cooling mechanism 320, and a tertiary pre-cooling mechanism 322. These three pre-cooling mechanisms are respectively connected to a cooling capacity supply module 325. In this embodiment, the number of the precooling mechanisms is one more than the number of the throttling mechanisms. Therefore, the first-level throttling mechanism 319, the second-level throttling mechanism 321, the freezing unit 304, the first-level precooling mechanism 318, the second-level precooling mechanism 320, and the third-level precooling mechanism 322 together constitute a three-level throttling + three-level precooling freezing conduit.

[0196] The first-stage pre-cooling mechanism 318, the second-stage pre-cooling mechanism 320 and the third-stage pre-cooling mechanism 322 are a countercurrent heat exchanger, the main component of which is a high-conductivity heat transfer body, which can be used independently or in combination with each other. This countercurrent heat exchanger can be a wire, a belt or other longitudinal body that extends in the axial direction and can be constructed into a short sleeve or a ring. This longitudinal heat transfer body can also follow a spiral structure or be arranged to extend in the axial direction of the freezing tube. The first-stage pre-cooling mechanism 318, the second-stage pre-cooling mechanism 320 and the third-stage pre-cooling mechanism 322 are fixed on the outer surface of the tube wall 323 of the air inlet passage 330, and their energy is transmitted through the surface heat transfer body close to the tube wall 323. The energy penetrates the wall thickness of the tube wall 323 and is transmitted to the refrigerant fluid in the form of heat conduction, thereby cooling the refrigerant fluid. The heat exchange between the refrigerant fluid and the heat transfer body of the pre-cooling mechanism is countercurrent heat exchange. The heat transfer body of the pre-cooling mechanism and the tube wall 323 of the air inlet passage 330 are made of heat-conducting materials, such as copper, silver, aluminum or steel, preferably stainless steel or carbon fiber. The cooling capacity of the first-stage pre-cooling mechanism 318, the second-stage pre-cooling mechanism 320 and the third-stage pre-cooling mechanism 322 is supplied by a cooling capacity supply module 325. The cooling capacity supply module 325 can be set in the tube body 302 of the freezing catheter, and the preferred setting point is one end close to the cold source connector 301. The cooling capacity supply module 325 includes at least one of a micro-semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module and a phase change pre-cooling module.

[0197] The primary throttling mechanism 319 and the secondary throttling mechanism 321 can be at least one of a throttle valve, a capillary tube, a reducing tube, an orifice plate, and a nozzle. The freezing unit 304 is designed as an expansion chamber structure, providing space for the refrigerant to expand and evaporate, and throttling to generate a low temperature to freeze human tissue. A gas nozzle 317 at the distal end of the air inlet passage 330 is disposed within the freezing unit 304. A temperature and pressure sensing element 315 is also disposed within the freezing unit 304. A rewarming heating element 316 is disposed outside the freezing unit 304 to accelerate the rewarming rate and shorten the surgical procedure. The freezing unit 304 can be either a cryoprobe or a balloon. The cryocatheter also includes at least one return air passage 328, with an exhaust outlet 307 disposed proximal to the return air passage 328. A temperature and pressure sensor 327 is disposed within the tube body 302 of the cryocatheter. The temperature and pressure sensor 327 is located on the air inlet line 330 and is used to measure the temperature and pressure of the refrigerant within the air inlet line 330.

[0198] Referring to Figure 16 , a three-stage throttling + three-stage pre-cooling cryotube is used in conjunction with a cryotherapeutic device to form a three-stage throttling + three-stage pre-cooling cryotherapy system. During cryotherapy, the air inlet passage 330 serves as the cryotherapeutic refrigerant supply lumen, connecting to the cryotherapeutic device 2 via a cold source connector 301. The refrigerant can be one of CO2, N20, Freon, nitrogen, or argon. The refrigerant originates from the gas source module 201 in the cryotherapy device 2 and is transported from the gas source module 201 to the cold source connector 301 via the gas processing module 235. The refrigerant then enters the cryotube 3 at the inlet of the cold source connector 301. The refrigerant flows along the axial direction of the lumen of the air inlet passage 330, sequentially passing through the first-stage pre-cooling mechanism 318 and the first-stage throttling mechanism 319 within the throttling module 303, forming a "first-stage pre-cooling + first-stage throttling" process. The refrigerant then flows through the second-stage pre-cooling mechanism 320 and the second-stage throttling mechanism 321, forming a "second-stage pre-cooling + second-stage throttling" process. The refrigerant then flows through the third-stage pre-cooling mechanism 322, forming a "third-stage pre-cooling" process. Finally, the refrigerant flows through the gas nozzle 317 within the freezing unit 304 and is released within the freezing unit 304, forming a "third-stage throttling" process. The refrigerant gas throttles and expands within the expansion chamber of the freezing unit 304, absorbing heat until it reaches saturation, completing the cryotherapy process for the target tissue. The evaporated refrigerant passes through return port 324, enters return air passage 328, and reaches exhaust outlet 307, where it is discharged to the exhaust gas recovery system. At this point, the refrigerant passes through the cryotherapy device and undergoes a three-stage pre-cooling and three-stage throttling process within the cryotube, completing a complete cryotherapy process.

[0199] This "three-stage precooling + three-stage throttling" cryotherapy system can regulate the power of the cooling supply module 325 through a PID or non-PID software algorithm to control the cooling power of the primary precooling mechanism 318, the secondary precooling mechanism 320, and the tertiary precooling mechanism 322, respectively. This ensures that the refrigerant before and after throttling by the primary throttling mechanism 319 and the secondary throttling mechanism 321 is always in a saturated liquid state / gas-liquid mixed state, and the throttled refrigerant is always in the non-solid phase. Referring to FIG17 , a phase transition diagram of the refrigerant during multi-stage throttling within the cryotube 3 is shown. The phase points of the refrigerant before and after throttling preferably fall within the shaded area shown in FIG17 .

[0200] As shown in Figure 16, the acquisition module 203 collects temperature, pressure, and other data via the temperature and pressure sensor 327 and the temperature and pressure sensing element 315, and uploads the data to the human-computer interaction module 1. The microprocessor or controller in the human-computer interaction module 1 generates cooling control commands based on the temperature and pressure information collected by the acquisition module 203 using a PID or non-PID software algorithm. These commands are sent to the control module 202 of the cryotherapy device 2 and the electric actuators of automatic adjustment components such as valves, resistors, or heaters within the cryotube 3. These commands regulate the cooling power of the cooling supply module 325 and the heating power of the rewarming heating element 316 within the freezing unit 304. By adjusting the power of the cooling supply module 325, a wide range of cooling capacity and temperature requirements within the freezing unit 304 can be met, achieving regulation and control of the cryotherapy temperature of the target area. Furthermore, depending on the refrigerant supplied, the temperature adjustment range can range from +80°C to -196°C. This wide temperature adjustment range enables the same cryotherapy system to accommodate a variety of lesions. By adjusting the heating power of the rewarming heating element 316, the freezing rewarming time can be adjusted and accurately controlled.

[0201] Referring to Figure 17, it is assumed that the refrigerant is at phase point 2 (P1, T1), where P and T represent the pressure and temperature at that phase point, respectively. The refrigerant completes the multi-stage "pre-cooling + throttling" (phase points 2-3-4-5-6-7-9) process in the freezing pipe 3 as follows: the refrigerant is throttled from phase point 2 (P1, T1) through the first-stage throttling mechanism 319 to phase point 3 (P t1 、T t1 ); then pre-cooled by the secondary pre-cooling mechanism 320 to phase point 4 (P2, T2), and then throttled by the secondary throttling mechanism 321 to phase point 5 (P t2 、T t2 ), then pre-cooled by the three-stage pre-cooling mechanism 322 to phase point 6 (P3, T3), and then throttled by the gas nozzle 317 in the refrigeration unit 304 to phase point 7 (P t3 、T t3 ), the throttled refrigerant gas in the freezing unit 304 exchanges heat with the tissue. In the process of phase points 7-9, after absorbing heat, the energy value of the refrigerant increases and it continues to vaporize. At the same time, the refrigerant absorbs heat through evaporation, taking away the heat of the tissue, lowering the temperature of the target treatment site and destroying abnormal cell tissue. After throttling and expanding and absorbing heat to a saturated state, the refrigerant reaches phase point 9 (P E 、T E The vaporized low-pressure refrigerant gas is discharged to the exhaust system or a designated location through the exhaust port 307 of the freezing pipe 3. The heat absorbed by the refrigerant at the evaporation pressure is equal to the latent heat of evaporation of the refrigerant, which is the cooling capacity of the freezing pipe. As shown in the following formula: q2=f(P E ,T E)-f(P3,T3) Where, q2 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 7-phase point 9 process), f(P3,T3) is the energy value of the refrigerant at phase point 6, f(P E ,T E ) is the energy value of the refrigerant throttling expansion and heat absorption to saturation state.

[0202] According to the embodiment of the present application, the pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure P3 of phase 6, and the pressure after throttling in the refrigeration unit is the pressure P of phase 7. t3 , the pressure difference before and after multi-stage throttling is ΔP2.

[0203] According to the laws of thermodynamics, there is no exchange of heat or work between the refrigerant and the throttling, so the energy value remains unchanged. Referring to Figure 17, the throttling process of the refrigerant should theoretically be an isenthalpic line perpendicular to the horizontal axis. According to the prior art, the refrigerant is only throttled in the freezing unit, that is, the refrigerant is directly throttled and depressurized from phase point 2 to phase point 8. The entire throttling process is carried out in the freezing unit 304, without multi-stage throttling and pre-cooling auxiliary links. The process of the first-stage throttling of the refrigerant in the freezing catheter is a straight line from phase point 2 to phase point 8. The throttled refrigerant undergoes heat exchange in the freezing unit 304, and the process is from phase point 8 to phase point 10. After absorbing heat, the energy value of the refrigerant increases and it continues to vaporize. The refrigerant absorbs heat through evaporation, takes away tissue heat, reduces the temperature of the target treatment site, and destroys abnormal cell tissue. The refrigerant reaches phase point 10 (P F 、T F ).

[0204] Referring to FIG17, according to the prior art, the process of using a single-stage throttling from phase point 2-8-10 is adopted. At the evaporation pressure, the heat absorbed by the refrigerant is equal to the latent heat of evaporation of the refrigerant, which is equal to the cooling capacity of the freezing pipe: q1=f(P F ,T F )-f(P t0 ,T t0 )

[0205] Among them, q1 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 8-10 process), f(P t0 ,T t0 ) is the energy value of the refrigerant at phase point 8, f(P F ,T F ) is the energy value of the refrigerant when it absorbs heat to saturation state in single-stage throttling expansion at phase point 10.

[0206] The pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure P1 of phase 2, and the pressure after throttling in the refrigeration unit is the pressure P of phase 8. t0 , the pressure difference before and after throttling is ΔP1.

[0207] As described above, with the solution of the present application, the ratio of the cooling capacity obtained by the fluid after three-stage throttling and expansion to the cooling capacity obtained by single-stage throttling conforms to the following formula:

[0208] in, is the cooling capacity ratio, f(P t0 ,T to ) is the energy value of the fluid after the first level of throttling using the existing technology, f(P t3 ,T t3 ) is the energy value of the fluid after three-stage throttling; f(P E ,T E ) is the energy value of the refrigerant multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the refrigerant absorbed by the single-stage throttling expansion to the saturated state.

[0209] The refrigeration capacity of the unit refrigerant provided by the cryotherapy system for cryotherapy is significantly increased compared with the prior art; when the refrigerant enters the freezing unit 304, the pressure before throttling P3 is less than P1, and the pressure after throttling P t3 <P t0 , the pressure before and after the multi-stage throttling can be significantly reduced compared with the existing technology. According to thermodynamic calculations, under ideal conditions, by adopting the technical solution of the present application, under the same cooling demand, the diameter of the freezing catheter can be reduced compared with the existing technology. The reduction in the diameter of the freezing catheter can increase the application scope of cryotherapy technology in distal bronchial biopsy of the lungs, coronary artery dredging, etc. In addition, by adopting the technical solution of the present application, the pressure in the freezing unit is significantly reduced before and after throttling, which not only reduces the risk of surgery, but also makes the application of low-pressure balloons in the treatment of some lesions extremely feasible, breaking through the technical limitations of foreign countries on high-pressure balloon materials.

[0210] In this embodiment, the throttling levels of the cryotherapy system were verified using a multi-stage throttling theoretical model combined with experimental testing. The multi-stage throttling theoretical model is calculated based on the temperature, pressure, and fluid enthalpy changes before and after each throttling stage. Through layer-by-layer iteration, the governing equations for multi-stage throttling were established. The specific calculation method is consistent with the throttling level calculation method for cryotherapy equipment described above. The temperature after throttling was calculated using the established pre-cooling and pre-throttling temperature reduction calculation methods. Based on the different throttling types, the throttling levels and maximum pre-cooling capacity were analyzed to establish a safe and effective multi-stage throttling cryotherapy system solution. Based on the temperature and pressure changes during the multi-stage throttling process, as well as the minimum cryotherapy temperature, the refrigerant pressure and temperature under different modes can be accurately predicted, avoiding the formation of solid refrigerant during throttling and pre-cooling, which could cause ice blockage and affect the normal operation of the multi-stage throttling cryotherapy system. The control principle of the multi-stage throttling cryotherapy system is to supply sufficient cooling capacity to the freezing unit as quickly as possible, while meeting the temperature required for cryotherapy without ice blockage, minimizing the diameter of the freezing unit, minimizing the pressure drop before and after the throttling mechanism, reducing the pre-cooling capacity, the number of throttling stages, and the number of pre-cooling stages. The calculation method of the pre-cooling capacity of each stage and the selection method of the multi-stage throttling stages are also given.

[0211] Example 11

[0212] Referring to Figure 18 , this embodiment is a variation of the cryotube of Example 10. Unlike Figure 15 , this embodiment allows the cold supply module to be placed within the cryotherapy device, reducing the volume of the cryotube and simplifying its manufacturing. The cold supply module can be installed within the cryotherapy device as an independent refrigeration system, such as a micro-semiconductor refrigeration module. Theoretically, the cold supply module could also be a separate piping system branching off from the cryotherapy device's air source, utilizing the Joule-Thompson effect to generate a cooling source. The cold supply module could also utilize piping or thermoelectric elements within the cryotube to supply cold to the refrigerant within the air inlet passage 330. This implementation is a common method for cold supply and will not be further described here. The cold supply module includes at least one of a micro-semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, and a phase change pre-cooling module. The cooling energy from the cooling supply module is input through the pre-cooling cold source supply port C of the cold source connector 301, and is sequentially supplied along the cold source supply lumen 331 to the primary pre-cooling mechanism 318, the secondary pre-cooling mechanism 320, and the tertiary pre-cooling mechanism 322. The cooling energy is then output through the pre-cooling cold source outlet D and returned to the cryotherapy device. This embodiment further increases the cooling capacity of the refrigerant and prolongs its melting time.

[0213] The working process of the cryotherapy catheter of this embodiment is as follows: the refrigerant enters the air inlet passage 330 through the refrigerant inlet A, is first cooled by the first-stage pre-cooling mechanism 318, and then passes through the first-stage throttling mechanism 319 to complete the "first-stage pre-cooling + first-stage throttling"; then passes through the second-stage pre-cooling mechanism 320 to cool, and then passes through the second-stage throttling mechanism 321 to complete the "second-stage pre-cooling + second-stage throttling"; then passes through the third-stage pre-cooling module 322 to complete the "third-stage pre-cooling" and finally reaches the freezing unit 304 to complete the "third-stage throttling". The refrigerant absorbs heat through evaporation and completes the freezing of the tissue. The evaporated low-pressure refrigerant gas passes through the return air passage 328 and reaches the exhaust outlet B for discharge, completing a cryotherapy process.

[0214] In an alternative embodiment, as shown in FIG18 , a cold storage chamber 332 is provided within the lumen 302 of the freezing conduit. The cold storage chamber 332 is sleeved onto the outside of the pre-cooling mechanism and contains an antifreeze cold storage liquid. The antifreeze cold storage liquid may be ethylene glycol, glycerol, diethylene glycol, silicate, etc., and the freezing point temperature may be set within a range of -10°C to -50°C. Before or during program operation, the antifreeze cold storage liquid within the cold storage chamber 332 can accumulate cold energy to supply the first-stage pre-cooling mechanism 318, the second-stage pre-cooling mechanism 320, and the third-stage pre-cooling mechanism 322, continuously cooling the refrigerant within the air intake passage 330. The tube wall 323 of the air intake passage 330 is made of a heat-conducting material, such as copper, silver, aluminum, or steel, particularly stainless steel or carbon fiber.

[0215] In this embodiment, the first-stage throttling mechanism 319 and the second-stage throttling mechanism 321 are preferably orifice plates and nozzles. If the distance between the two stages of throttling is too small, the fluid flow may be disturbed, resulting in unstable phenomena such as eddy currents, fluctuations or oscillations. If the distance is too large, the pipeline may be too long, the flow resistance may be too large, resulting in energy waste and excessive volume. This application determines the setting of each stage of throttling mechanism in the freezing catheter based on the fluid flow rate and the required pressure drop. According to the fluid properties and process requirements, the distance and position between adjacent throttling mechanisms are determined based on calculations and experimental verification to ensure that the fluid can smoothly transition between the two stages of throttling. By solving the Bernoulli equation and the continuity equation simultaneously, the flow rate after throttling can be solved. The specific calculation process needs to be determined according to the actual operating state, including known parameters such as pressure, flow rate, cross-sectional area before throttling. It should be noted that the above calculation needs to be derived under certain assumptions, such as incompressible, ideal fluid, etc. In actual applications, some correction factors such as the compressibility of the fluid, viscosity loss, friction, etc. need to be considered. After calculation and experiments, it is found that when the freezing pipe adopts multi-stage throttling, the distance between the center points of the two-stage throttling mechanism should be between 5 and 100 times the maximum diameter of the pipeline, which is related to the structural form and installation position of the throttling mechanism adopted.

[0216] Example 12

[0217] 19 , the multi-stage throttling cryotherapy system of this embodiment is composed of the “three-stage pre-cooling + three-stage throttling” cryotherapy equipment and the “three-stage pre-cooling + three-stage throttling” cryocatheter described in the previous embodiment. The cryotherapy system generally adopts the “six-stage pre-cooling + six-stage throttling” implementation scheme of pre-cooling first and then throttling.

[0218] The flow meter 205, the first pre-cooling module 206, and the first throttling mechanism 208 provided in the throttling module 204 of the cryotherapy device 2 are connected in series through pipelines to form a "first stage pre-cooling + first stage throttling" of the multi-stage throttling cryotherapy system; the second pre-cooling module 210 and the second throttling mechanism 212 in the throttling module 204 are connected in series through pipelines to form a "second stage pre-cooling + second stage throttling"; the third pre-cooling module 214, the third throttling mechanism 216 and the pressure relief valve 2 in the throttling module 204 are connected in series through pipelines to form a "second stage pre-cooling + second stage throttling"; 23 are connected in series via pipes, forming a "third-stage precooling + third-stage throttling" system. The first-stage precooling mechanism 318 and the first-stage throttling mechanism 319 within the throttling module 303 of the cryotube 3 form a "fourth-stage precooling + fourth-stage throttling" system. The second-stage precooling mechanism 320 and the second-stage throttling mechanism 321 form a "fifth-stage precooling + fifth-stage throttling" system. The third-stage precooling mechanism 322 forms a "sixth-stage precooling" system. The gas nozzle 317 within the freezing unit 304 forms the "sixth-stage throttling" system of the cryotherapy system. The refrigerant gas undergoes throttling expansion within the expansion chamber of the freezing unit 304, absorbing heat until it reaches saturation, completing the cryotherapy process on the target tissue. The evaporated refrigerant enters the return gas passage 328 through the return gas port 324, reaches the exhaust gas outlet 307, and is discharged to the exhaust gas recovery system. This completes a complete cryotherapy process through the "sixth-stage precooling + six-stage throttling" system. The outlets of the first pre-cooling module 206, the first throttle mechanism 208, the second pre-cooling module 210, the second throttle mechanism 212, the third pre-cooling module 214, and the third throttle mechanism 216 are each provided with a temperature sensing element 207. The outlets of the first throttle mechanism 208, the second throttle mechanism 212, and the third throttle mechanism 216 are each provided with a pressure sensing element 215. The temperature sensing element and pressure sensing element provided within the freezing catheter 3 are an integrated temperature and pressure sensor 327 and a temperature and pressure sensing element 315. The temperature and pressure sensor 327 is provided at the distal end of the secondary throttle mechanism 321, and the temperature and pressure sensing element 315 is provided within the freezing unit 304 to monitor the temperature and pressure within the pipeline and freezing unit, controlling the fluid pressure to prevent excessive fluid pressure.

[0219] Referring to FIG19 , in this embodiment, a multi-stage throttling cooling structure is formed by the first pre-cooling module 206, the second pre-cooling module 210, the third pre-cooling module 214, the first pre-cooling mechanism 318, the second pre-cooling mechanism 320, the third pre-cooling mechanism 322, the first throttling mechanism 208, the second throttling mechanism 212, the third throttling mechanism 216, the first throttling mechanism 319, and the second throttling mechanism 321. By adjusting the cooling power of the pre-cooling modules and pre-cooling mechanisms and adjusting the opening of the throttling mechanisms, the refrigerant before throttling is always in a saturated liquid state / gas-liquid mixed state, and the medium state after throttling is in the non-solid phase region. Referring to FIG20 , a phase change diagram of the refrigerant during multi-stage throttling within the cryotherapy system is shown. The phase point of the refrigerant before and after throttling within the cryotherapy device 2 is preferably located in the shaded area A, and the phase point of the refrigerant before and after throttling within the cryotube 3 is preferably located in the shaded area B.

[0220] Referring to Figure 20, considering the system's longitudinal resistance and local resistance, the fluid pressure will be relatively reduced before and after pre-cooling. Assuming that the refrigerant of the cryotherapy device is initially at phase point 2 (P1, T1), P and T represent the pressure and temperature at this state point, respectively. The refrigerant completes the multi-stage "pre-cooling + throttling" process in the cryotherapy device 2 and the cryotube 3 in sequence as follows: the refrigerant is throttled from phase point 2 (P1, T1) through the first throttling mechanism 208 to phase point 3 (P t1 、T t1 ); then precooled by the second precooling module 210 to phase point 4 (P2, T2,), and then throttled by the second throttling mechanism 212 to phase point 5 (P t2 、T t2 ); then precooled by the third precooling module 210 to phase point 6 (P3, T3), and then throttled by the third throttling mechanism 214 to phase point 7 (P t3 、T t3 ); The refrigerant then enters the freezing conduit 3 through the cold source connector 301, is pre-cooled by the primary pre-cooling mechanism 318 to the phase point 4 (P4, T4), and then throttled by the primary throttling mechanism 319 to the phase point 9 (P t4 、T t4 ); then pre-cooled by the secondary pre-cooling mechanism 320 to the phase point 10 (P5, T5), and then throttled by the secondary throttling mechanism 321 to the phase point 11 (P t5 、T t5 ); then pre-cooled by the three-stage pre-cooling mechanism 322 to the phase point 12 (P6, T6), and then throttled by the gas nozzle 317 within the freezing unit 304 to the phase point 13 (P t6 、T t6), the refrigerant gas after throttling in the freezing unit 304 exchanges heat with the tissue in the freezing unit 304, and the process phases 13-15, after absorbing heat, the energy value of the refrigerant increases, and it continues to vaporize. At the same time, the refrigerant absorbs heat through evaporation, takes away the heat of the tissue, reduces the temperature of the target treatment site, and destroys the abnormal cell tissue. After throttling and expanding and absorbing heat to a saturated state, the refrigerant reaches phase 15 (P E 、T E The vaporized low-pressure refrigerant gas is discharged to the exhaust system / designated location through the exhaust outlet 307 of the freezing pipe 3. The heat absorbed by the refrigerant at the evaporation pressure is equal to the latent heat of evaporation of the refrigerant, which is equal to the cooling capacity of the freezing pipe. As shown in the following formula: q2=f(P E ,T E )-f(P6,T6)

[0221] Among them, q2 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 13-phase point 15 process), f(P6,T6) is the energy value of the refrigerant at phase point 12, and f(P E ,T E ) is the energy value of the refrigerant when it expands and absorbs heat to saturation at phase point 15.

[0222] According to the embodiment of the present application, the pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure P6 of the phase 12, and the pressure after the throttling of the refrigeration unit is the pressure P of the phase 13. t6 , the pressure difference before and after multi-stage throttling is ΔP2.

[0223] According to the laws of thermodynamics, there is no heat or work exchange between the refrigerant before and after throttling, so the energy value remains unchanged. As shown in Figure 20, the throttling process of the refrigerant should theoretically be an isenthalpic line perpendicular to the horizontal axis. According to the existing technology, the refrigerant is only throttled in the refrigeration unit, that is, the refrigerant is directly throttled and depressurized from phase point 2 to phase point 14 (P t0 、T t0 ), the entire throttling process is carried out in the refrigeration unit 304, without multi-stage throttling and pre-cooling auxiliary links. In Figure 20, the process of the refrigerant in the refrigeration pipe is from phase point 2 to phase point 14 (P t0 、T t0 ) line. The throttled refrigerant undergoes heat exchange in the freezing unit 304, and the process is from phase point 14 to phase point 16. After absorbing heat, the refrigerant energy value increases and continuously vaporizes. The refrigerant absorbs heat through evaporation, takes away tissue heat, reduces the temperature of the target treatment site, and destroys abnormal cell tissue. After throttling and expanding to absorb heat to a saturated state, the refrigerant reaches phase point 16 (P F 、T F ).

[0224] Referring to FIG20, according to the prior art, the process of using the first-stage throttling phase point 2-14-16, the heat absorption of the refrigerant at the evaporation pressure is equal to the latent heat of evaporation of the refrigerant, which is equal to the cooling capacity of the freezing pipe: q1=f(P F ,T F )-f(P t0 ,T t0 )

[0225] Among them, q1 is the cooling capacity released by the unit refrigerant in the freezing pipe (phase point 2-phase point 14 process), f(P t0 ,T t0 ) is the energy value of the refrigerant at phase point 14, f(P F ,T F ) is the energy value of the refrigerant when it expands and absorbs heat to saturation at phase point 16.

[0226] The pressure of the refrigerant entering the refrigeration unit of the refrigeration pipe is the pressure of phase 2 P1, and the pressure after throttling in the refrigeration unit is the pressure of phase 14 P t0 , the pressure difference before and after throttling is ΔP1.

[0227] As mentioned above, the cooling capacity obtained by the fluid after six-stage throttling expansion is compared with the cooling capacity obtained by single-stage throttling in accordance with the following formula:

[0228] in, is the cooling capacity ratio, f(P t0 ,T to ) is the energy value of the fluid after the first level of throttling using the existing technology, f(P t6 ,T t6 ) is the energy value of the fluid after six-stage throttling; f(P E ,T E ) is the energy value of the refrigerant multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the refrigerant absorbed by the single-stage throttling expansion to the saturated state.

[0229] The refrigeration capacity of the unit refrigerant provided by the cryotherapy system for cryotherapy is significantly increased compared with the prior art; when the refrigerant enters the freezing unit 304, the pressure before throttling P6 is less than P1, and the pressure after throttling P t6 <P t0, the pressure before and after the multi-stage throttling can be significantly reduced compared with the existing technology. According to thermodynamic calculations, under ideal conditions, by adopting the technical solution of the present application, under the same cooling demand, the diameter of the freezing catheter can be reduced compared with the existing technology. The reduction in the diameter of the freezing catheter can increase the application scope of cryotherapy technology in distal bronchial biopsy of the lungs, coronary artery dredging, etc. In addition, by adopting the technical solution of the present application, the pressure in the freezing unit is significantly reduced before and after throttling, which not only reduces the risk of surgery, but also makes the application of low-pressure balloons in the treatment of some lesions extremely feasible, breaking through the technical limitations of foreign countries on high-pressure balloon materials.

[0230] Example 13

[0231] The structure of this embodiment is basically the same as that of the twelfth embodiment, except that the throttling levels of the multi-stage throttling cryotherapy system of this embodiment are adjustable.

[0232] 21 , the cryotherapy system includes a human-computer interaction module 1, a cryotherapy device 2, and a cryocatheter 3. The cryotherapy device 2 includes a gas source module 201, a control module 202, a collection module 203, and a throttling module 204. The refrigerant flow path within the throttling module 204 of the cryotherapy device 2 includes multiple valves, a main line, and a bypass line. The main line within the throttling module 204 is sequentially provided with a flow meter 205, a first precooling module 206, a first throttling mechanism 208, a second precooling module 210, a second throttling mechanism 212, a third precooling module 214, a third throttling mechanism 216, and a pressure relief valve 223. A bypass line is provided at each of the first throttle mechanism 208 and the second throttle mechanism 212. The two ends of the bypass line are connected to the air inlet and air outlet of the first throttle mechanism 208 and the second throttle mechanism 212, respectively. A solenoid valve 243 and a check valve 244 are provided on the bypass lines of the first throttle mechanism 208 and the second throttle mechanism 212, respectively. The solenoid valve 243 is preferably a three-wire, two-control electric ball valve of the same diameter as the connecting pipeline to reduce the local resistance of the fluid caused by the valve structure.

[0233] The throttling mechanism provided on the main line is preferably an electrically operated proportional control valve with adjustable throttling opening. The precooling module provided on the main line is connected to the variable cooling capacity cold supply module, and the pressure relief valve 223 is an electrically operated pressure relief valve. Referring to FIG21 , the throttling module 204 is provided between the gas source module 201 and the cold source connector 301. The cryotherapy catheter 3, which has a three-stage precooling and three-stage throttling structure, is connected to the cryotherapy device 2 via the cold source connector 301. The cryotherapy device 2 and the cryotherapy catheter 3 together constitute a cryotherapy system with a maximum of six stages of precooling and six stages of throttling, with adjustable precooling and throttling levels.

[0234] By operating the human-computer interaction module 1 and sending an electrical signal to the throttling module 204, the user can control the opening and closing of the throttling mechanism and the pre-cooling module, respectively. Referring to FIG21 , by controlling the opening and closing of the first throttling mechanism 208, the second throttling mechanism 212, and the solenoid valve 243, the cryotherapeutic device's throttling level can be adjusted to five or four levels during the treatment process. Controlling the opening and closing of the pre-cooling module can adjust the cryotherapeutic device's pre-cooling level to six, five, four, or three levels. For example, by closing the solenoid valve 243 on the bypass line of the first throttling mechanism 208 and the second throttling mechanism 212, opening the solenoid valve 243 on the bypass line of the second throttling mechanism 212 and the first throttling mechanism 208, and opening the first pre-cooling module 206, the second pre-cooling module 210, and the third pre-cooling module 214, the cryotherapeutic system, consisting of the cryotherapeutic device 2 and the cryocatheter 3, can be adjusted to a "six-level pre-cooling + five-level throttling" cryotherapeutic system. By further closing the first precooling module 206, the system can be adjusted to a "five-stage precooling + five-stage throttling" cryotherapy system. Similarly, by closing the solenoid valve 243 on the bypass line of the second throttling mechanism 212 and the first throttling mechanism 208, opening the solenoid valve 243 on the bypass line of the first throttling mechanism 208 and the second throttling mechanism 212, and opening the first precooling module 206, the second precooling module 210, and the third precooling module 214, the cryotherapy system can also be adjusted to a "six-stage precooling + five-stage throttling" mode. Similarly, by controlling the opening and closing of the throttling mechanism and precooling modules, the number of precooling and throttling stages can be randomly adjusted. The advantage of this embodiment is that the number of precooling and throttling stages can be adjusted to control the target cooling output and target freezing temperature, thereby extending the freezing range of the cryotherapy system.

[0235] Example 14

[0236] Referring to Figure 22, a multi-stage throttling cryotherapeutic system with controllable cryotherapeutic temperature is shown. This embodiment differs from other embodiments in that the cryotherapeutic device 2 utilizes a two-stage throttling + one-stage precooling structure, while the cryotube 3 utilizes a three-stage throttling + three-stage precooling structure. Furthermore, in the cryotherapy device 2, the precooling module is located at the outlet of the second throttling module 212. Through the human-computer interaction module 1, the refrigerant can be selectively controlled to maintain a gas-liquid mixed state after throttling and precooling. Refrigeration power, and therefore the cryotherapy temperature of the cryotube 304, can be adjusted by selectively controlling the openings of the first throttling mechanism 208, the second throttling mechanism 212, the first throttling mechanism 319, and the second throttling mechanism 321, as well as selectively controlling the closing of the third precooling module 214, the first throttling mechanism 328, the second throttling mechanism 320, and the third throttling mechanism 322. This embodiment can also be considered a form of regulation of Example 13.

[0237] Example 15

[0238] Referring to Figure 23 , this embodiment differs from other embodiments in that the cryotherapy device 2 employs a no-precooling + three-stage throttling structure, while the cryotube 3 employs a three-stage throttling structure, resulting in a cryotherapy system with no precooling and six-stage throttling. Three bypass lines are provided within the throttling module 204 of the cryotherapy device 2: one at the first throttling mechanism 208, one at the second throttling mechanism 212, and one at the third throttling mechanism 216. The two ends of the bypass lines are connected to the air inlet and outlet of the first throttling mechanism 208, the second throttling mechanism 212, and the third throttling mechanism 216, respectively. A solenoid valve 243 and a check valve 244 are provided on the bypass lines, respectively. The solenoid valve is preferably a three-wire, two-control electric ball valve of the same diameter as the connecting pipeline.

[0239] The human-computer interaction module 1 can selectively control the opening and closing of the throttling mechanism and the solenoid valve to adjust the throttling level and thus control the cryotherapy temperature. This is suitable for low-pressure balloons and surgeries requiring relatively low cryotherapy temperature accuracy.

[0240] Example 16

[0241] Referring to Figure 24 , this embodiment differs from other embodiments in that a precooling module is provided within the cryotherapy device 1, and a throttling module 303 with two throttling mechanisms is provided within the cryotube 3, forming a "one-stage precooling + three-stage throttling" cryotherapy system. Separating the precooling module from the throttling module in this embodiment simplifies the cryotube manufacturing process.

[0242] Example 17

[0243] Referring to Figure 25 , this embodiment differs from other embodiments in that a throttling module with three throttling mechanisms is installed within the cryotherapy device 2, and a precooling mechanism is installed within the cryotube 3, forming a "first-stage precooling + third-stage throttling" cryotherapy system. Through the human-computer interaction module 1, the refrigerant can be selectively controlled to maintain a gas-liquid mixed state after throttling and precooling. The cooling power, and thus the cryotherapy temperature of the freezing unit 304, can be adjusted by designing the structures of the first throttling mechanism 208, the second throttling mechanism 212, and the third throttling mechanism 216, as well as selectively controlling the deactivation of the first precooling mechanism 318. In this embodiment, the cooling supply module 325, which provides cooling to the precooling mechanism, optionally contains an antifreeze cold storage liquid within the cold source supply lumen 331. This antifreeze cold storage liquid can be selected from ethylene glycol, glycerol, diethylene glycol, silicate, etc., with a freezing point setting range of -10°C to -50°C. The antifreeze cold storage liquid can delay the refrigerant's melting time, enhancing the freezing effect and shortening the total duration of the cryotherapy procedure.

[0244] Theoretically, this application can be formed by connecting any type of multi-stage throttling cryotherapy device 2 with any type of cryotube 3 to form a multi-stage throttling cryotherapy system; it can also be formed by connecting any type of cryotherapy device 2 with any type of multi-stage throttling cryotube 3 to form a multi-stage throttling cryotherapy system; it is also possible to choose a structure in which both the cryotherapy device 2 and the cryotube 3 have multi-stage throttling. These multi-stage throttling cryotherapy systems can be assembled into split, integrated, or handheld structures by selecting different types of components or structural forms. Multi-stage throttling cryotherapy systems composed of these different permutations and combinations also fall within the scope of protection of this application.

[0245] The foregoing is merely an exemplary embodiment of the present application and is not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A cryotherapy device, comprising a gas source module, the gas source module being connected to a cold source connector via a pipeline, the cryotherapy device being connected to a cryotube via the cold source connector, the gas source module delivering refrigerant to a distal end of the cryotube via the cold source connector, characterized in that: A throttling module is provided on the pipeline between the gas source module and the cold source joint. One end of the throttling module is connected to the gas source module, and the other end of the throttling module is connected to the freezing conduit through the cold source joint. N throttling mechanisms are provided in the throttling module, where N is greater than or equal to 1. The cryogenic fluid passes through the N throttling mechanisms provided in the throttling module and completes the final throttling in the freezing catheter to form an N+1-stage throttling cryotherapy system. The ratio of the cooling capacity obtained by the multi-stage throttling of the cryotherapy system to the cooling capacity obtained by the traditional single-stage throttling conforms to the following formula: in: is the cooling capacity ratio, f(P t0 ,T t0 ) is the energy value of the fluid after the single-stage throttling of the freezing conduit, f(P t[n+1] ,T t[n+1] ) is the energy value of the fluid after N+1 multi-stage throttling; f(P E ,T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F ,T F ) is the energy value of the fluid when it absorbs heat to saturation state through single-stage throttling expansion.

2. The cryotherapy device according to claim 1, characterized in that The cryotherapy device is also provided with a control module and a human-computer interaction module, and the control module is electrically connected to the human-computer interaction module.

3. The cryotherapy device according to claim 2, characterized in that The cryotherapy device is also provided with an acquisition module, which is electrically connected to the control module and the human-computer interaction module.

4. The cryotherapy device according to claim 1 or 3, characterized in that One or more bypass lines are provided in the throttling module, and the two ends of the bypass line are respectively connected to the inlet and outlet of the throttling mechanism. A solenoid valve and a check valve are provided on the bypass line, so that the throttling level of the cryotherapy device can be adjusted.

5. The cryotherapy device according to claim 1, characterized in that The throttling level of the cryotherapy device is determined by the fluid state generated after each level of multi-stage throttling and the total cooling capacity Q that can be generated after the multi-stage throttling. The maximum cooling capacity Q that can be generated by the fluid after the multi-stage throttling is t It can be expressed as follows: Among them, △H is the enthalpy change of the fluid before and after each stage of throttling, f(P x , T x ), f(P tx , T tx ) are the energy values ​​of the fluid before and after the xth throttling respectively; T t and P t are the final fluid temperature and pressure after multi-stage throttling; T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, v is the specific volume of the fluid; Final fluid temperature after multi-stage throttling T t It can be expressed as: T t =Φ -1 (Q t ,P t ) When the total cooling capacity Q generated by multi-stage throttling is not less than Q t , the fluid temperature after multi-stage throttling does not exceed T t , the throttling levels selected by the system meet the requirements.

6. The cryotherapy device according to claim 1, characterized in that The throttling mechanism is at least one of a throttle valve, a capillary tube, a reducing tube, an orifice plate, and a nozzle.

7. The cryotherapy device according to claim 1, characterized in that One or more pre-cooling modules are arranged in the throttling module.

8. The cryotherapy device according to claim 7, characterized in that The pre-cooling module is connected to the cold supply module, and the pre-cooling temperature of the pre-cooling module is adjustable.

9. The cryotherapy device according to claim 8, characterized in that The pre-cooling module is a heat exchanger, and the heat exchanger includes at least one of a downstream heat exchanger, a countercurrent heat exchanger, a fin heat exchanger, a shell and tube heat exchanger, and an immersion heat exchanger.

10. The cryotherapy device according to claim 9, characterized in that The cold supply module includes at least one of a micro semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, and a phase change pre-cooling module.

11. The cryotherapy device according to claim 7, characterized in that The pre-cooling level of the cryotherapy device is adjustable during the pre-cooling process.

12. The cryotherapy device according to claim 7, characterized in that The dryness of the refrigerant in the cryotherapy system before and after multi-stage throttling meets the following relationship: 0≤X(P tn ,T tn )<X(P t0 ,T t0 ) Where: X(P t0 , T t0 ) is the dryness of the refrigerant after throttling in the single-stage throttling refrigeration pipe, X(P tn , T tn ) is the refrigerant dryness in the multi-stage throttling refrigeration pipe after the refrigerant is throttled by the last stage throttling mechanism.

13. A cryotherapy system comprising: Cryotherapy equipment, cryotherapy catheter, the cryotherapy catheter is mechanically connected to the cryotherapy equipment via a cold source connector, The cryotherapy device includes an air source module, the air source module is connected to the cold source connector via a pipeline, and the air source module delivers refrigerant to the distal end of the freezing catheter through the cold source connector; The freezing catheter comprises a tube body and a freezing unit, wherein the proximal end of the tube body is connected to the cold source joint, and the distal end of the tube body is connected to the proximal end of the freezing unit. An air intake passage and an air return passage are provided in the tube body, and the distal ends of the air intake passage and the air return passage are connected to the freezing unit, and the proximal end of the air intake passage is connected to the air source module via the cold source joint. It is characterized in that a throttling module is provided in the cryotherapy device, or a throttling module is provided in the freezing catheter, or a throttling module is provided in both the cryotherapy device and the freezing catheter, the throttling module of the cryotherapy device is equipped with N throttling mechanisms, N is greater than or equal to 1, the throttling module of the freezing catheter is equipped with M throttling mechanisms, M is greater than 1, and the cryotherapy device and the freezing catheter constitute an M+N-level cryotherapy system. After the cryogenic fluid is throttled by the M+N throttling mechanisms provided in the cryotherapy system, the ratio of the cooling capacity obtained in the multi-stage throttling cryotherapy system to the cooling capacity obtained by using the traditional single-stage throttling satisfies: in: is the cooling capacity ratio, f(P t0 , T t0 ) is the energy value of the fluid after completing single-stage throttling in the traditional single-stage throttling freezing pipe, f(P t[m+n] ,T t[m+n] ) is the energy value of the fluid after M+N level throttling; f(P E ,T E ) is the energy value of the fluid multi-stage throttling expansion to absorb heat to saturation state, f(P F , T F ) is the energy value of the fluid when it absorbs heat to saturation in a single-stage throttling expansion in the freezing conduit.

14. The cryotherapy system according to claim 13, wherein: The throttling module of the cryotherapy device is arranged on the pipeline between the gas source module and the cold source connector.

15. The cryotherapy system according to claim 13, wherein: The throttling module of the freezing pipe is arranged on the air inlet passage, one end of the throttling module is connected to the air source module through the cold source joint, and the other end of the throttling module is connected to the freezing unit to transport refrigerant to the far end of the freezing pipe.

16. The cryotherapy system according to claim 13, wherein: The throttling mechanism is at least one of a throttle valve, a capillary tube, a reducing tube, an orifice plate, and a nozzle.

17. The cryotherapy system according to claim 13, wherein: The cryotherapy device is also provided with a control module, an acquisition module, and a human-computer interaction module. The control module and the human-computer interaction module are electrically connected, and the acquisition module is electrically connected to the control module.

18. The cryotherapy system according to claim 17, wherein: One or more bypass pipelines are provided in the throttling module. Both ends of the bypass pipeline are respectively communicated with the inlet and outlet of the throttling mechanism. A solenoid valve and a check valve are provided on the bypass pipeline.

19. The cryotherapy system according to claim 13 or 17, characterized in that The throttling level of the cryotherapy system is determined by the fluid state generated after each level of throttling and the total cooling capacity Q that can be generated after the multi-level throttling. The maximum cooling capacity Q that can be generated by the fluid after the multi-level throttling is t It can be expressed as follows: Among them, △H is the enthalpy change of the fluid before and after each stage of throttling, f(P x , T x ), f(P tx , T tx ) are the energy values ​​of the fluid before and after the xth throttling respectively; T t and P t are the final fluid temperature and pressure after multi-stage throttling; T x 、T tx and P x 、P tx are the fluid temperature and pressure before and after the xth stage throttling respectively; c p is the specific heat capacity of the fluid at constant pressure, v is the specific volume of the fluid; Final fluid temperature after multi-stage throttling T t It can be expressed as: T t =Φ -1 (Q t ,P t ) When the total cooling capacity Q generated by multi-stage throttling is not less than Q t , the fluid temperature after multi-stage throttling does not exceed T t , the throttling levels selected by the system meet the requirements.

20. The cryotherapy system according to claim 13, wherein: One or more pre-cooling modules are arranged in the throttling module of the cryotherapy device and / or in the throttling module of the cryocatheter.

21. The cryotherapy system according to claim 20, wherein: The pre-cooling module is connected to the cold supply module, and the pre-cooling temperature of the pre-cooling module is adjustable.

22. The cryotherapy system according to claim 20 or 21, characterized in that The pre-cooling module is a heat exchanger, and the heat exchanger includes at least one of a downstream heat exchanger, a countercurrent heat exchanger, a fin heat exchanger, a shell and tube heat exchanger, and an immersion heat exchanger.

23. The cryotherapy system according to claim 21, wherein The cold supply module includes at least one of a micro semiconductor refrigeration pre-cooling module, a cold storage pre-cooling module, a throttling pre-cooling module, a phase change pre-cooling module, and a reflux pre-cooling module.

24. The cryotherapy system according to claim 20, wherein: The pre-cooling level of the cryotherapy system is adjustable during the pre-cooling process.

25. The cryotherapy system according to claim 13, wherein The dryness of the refrigerant in the cryotherapy system before and after multi-stage throttling meets the following relationship: 0≤X(P tn ,T tn )<X(P t0 ,T t0 ) Where: X(P t0 ,T t0 ) is the dryness of the refrigerant after throttling in the single-stage throttling refrigeration pipe, X(P tn ,T tn ) is the refrigerant dryness in the refrigeration pipe after multi-stage throttling by the last stage throttling mechanism.

Images