Radiofrequency ablation device needle withdrawal system to avoid scarring

Abstract

This application relates to the field of medical devices and discloses a needle withdrawal system for radiofrequency ablation devices that avoids scarring. Based on a standard radiofrequency ablation device, the system integrates a needle position detection device (real-time monitoring of depth and speed) and a needle tip temperature sensor. During needle withdrawal, the radiofrequency power is dynamically adjusted according to the withdrawal speed (higher power for faster speed); when the needle tip depth is less than a predetermined threshold (close to the body surface), the radiofrequency output is automatically stopped and a prompt to wait for cooling occurs; once the temperature drops below a safe threshold, a prompt indicates that the needle can be completely withdrawn. Through this closed-loop control, the thermal coagulation and end-point cooling processes of the needle track are precisely managed, effectively preventing thermal damage to the skin and subcutaneous tissue and significantly reducing scar formation.

Description

Technical Field

[0001] This application relates to the field of medical devices, and in particular to the needle removal technology for radiofrequency ablation devices. Background Technology

[0002] This section is intended to provide background or context for understanding the implementation of this application and is for reference only. It should not be construed as an admission by the applicant that this section pertains to prior art that was disclosed before the filing date of this application.

[0003] Radiofrequency ablation (RFA) is a minimally invasive treatment technique widely used in clinical medicine. This technique involves introducing radiofrequency (RF) current into the target lesion tissue, using the thermal effect of the current to induce coagulative necrosis of the tissue cells, thereby achieving the therapeutic goal. Due to its advantages of minimal trauma, rapid recovery, and definite efficacy, radiofrequency ablation plays an important role in the treatment of various diseases, such as the local treatment of solid organ tumors like liver, lung, and kidney tumors, as well as the treatment of certain arrhythmias (such as atrial fibrillation).

[0004] A typical radiofrequency ablation system usually consists of a radiofrequency generator (RF generator) and one or more radiofrequency ablation needles (RF ablation needles, often simply called "ablation needles"), also known as radiofrequency electrodes. The RF generator is responsible for producing radiofrequency current at a specific frequency and power. The RF ablation needle is a specially designed puncture needle with an uninsulated active tip at its distal end, used to precisely conduct the energy generated by the RF generator to the target tissue. During treatment, the operator inserts the ablation needle percutaneously or through other routes to the lesion area, activates the RF generator to output energy, raising the temperature of the tissue around the active tip to the preset treatment temperature (usually between 60°C and 100°C) and maintaining it for a period of time to ensure sufficient necrosis of the target tissue.

[0005] After completing the ablation treatment of the target lesion, the process of removing the ablation needle from the patient's body, known as needle withdrawal, is a crucial step in the entire procedure. Improper handling can lead to bleeding along the needle tract or potential tumor cell implantation and metastasis. In clinical practice, needle tract ablation, also known as needle tract cauterization or needle tract coagulation, is often performed simultaneously with needle withdrawal. This is typically achieved by continuously delivering a low-power radiofrequency current during the slow and uniform withdrawal of the ablation needle. The aim is to thermally coagulate the needle tract and surrounding tissue, sealing blood vessels and interstitial spaces.

[0006] However, existing needle tract ablation techniques have certain limitations. During manual needle withdrawal, it is difficult for the operator to precisely control a constant withdrawal speed, and variations in the withdrawal speed can lead to uneven heating of different segments of the needle tract. If the withdrawal speed is too fast or the radiofrequency power is insufficient, incomplete coagulation of the needle tract may occur, failing to achieve the expected hemostasis or prevention of implantation. Conversely, if the withdrawal speed is too slow or the radiofrequency power is too high, especially when the ablation needle is close to the body surface (such as skin and subcutaneous tissue), excessive heat accumulation may cause excessive thermal damage to the normal tissue surrounding the puncture site. This excessive thermal damage close to the body surface is a major cause of noticeable scarring in the puncture site area post-procedure, affecting not only aesthetics but also sometimes accompanied by pain or discomfort.

[0007] Therefore, how to more effectively control the release of radiofrequency energy during the needle withdrawal stage of radiofrequency ablation surgery, ensure that the needle tract is fully and evenly coagulated, and precisely manage the heat release before the ablation needle is withdrawn from the body surface, so as to minimize thermal damage to the skin and subcutaneous tissue and thus avoid or significantly reduce the formation of postoperative scars, is a technical problem that urgently needs to be solved in the field of radiofrequency ablation equipment. Summary of the Invention

[0008] The purpose of this application is to provide a radiofrequency ablation device needle withdrawal system that avoids scarring, thereby solving the technical problems existing in the prior art.

[0009] This application discloses a radiofrequency ablation device needle withdrawal system to avoid scarring, including an ablation needle and a radiofrequency generator that provides radiofrequency power to the ablation needle. The device further includes:

[0010] A needle position detection device is used to detect the depth of the active tip of the ablation needle entering the human body and the movement speed of the ablation needle;

[0011] A temperature sensor, configured on the ablation needle, is used to detect the temperature of the active tip; and

[0012] The control device is electrically connected to the radio frequency generator, the needle position detection device, and the temperature sensor.

[0013] The control device is configured as follows:

[0014] When the ablation needle is withdrawn, the control device controls the radio frequency power supplied to the ablation needle by the radio frequency generator according to the movement speed of the ablation needle detected by the needle position detection device, wherein a higher movement speed of the ablation needle corresponds to a higher radio frequency power.

[0015] When the needle position detection device detects that the depth of the active tip entering the human body is less than or equal to a predetermined depth threshold, the control device controls the radio frequency generator to stop providing radio frequency power to the ablation needle and issues a prompt message indicating that the needle withdrawal has stopped and cooling is in progress; and

[0016] After the radio frequency generator stops supplying radio frequency power to the ablation needle, when the temperature of the ablation needle detected by the temperature sensor drops below a predetermined temperature threshold, the control device issues a prompt message indicating that the ablation needle can be removed.

[0017] In a preferred embodiment, the control device is further configured to activate the cooling system of the ablation needle when the depth of the active tip entering the body detected by the needle position detection device is less than or equal to a predetermined depth threshold, so that cooling liquid flows into the fluid channel inside the ablation needle to cool the active tip.

[0018] In a preferred embodiment, the needle position detection device includes:

[0019] The base is fixed to the patient's body surface near the puncture point before the ablation operation, and the base is provided with a channel for the ablation needle to pass through;

[0020] The first ultra-wideband module is integrated or fixed on the base;

[0021] A second ultra-wideband module is integrated or fixed to the handle of the ablation needle; and

[0022] The processing module is electrically connected to the second ultra-wideband module;

[0023] The processing module is configured to calculate the depth of the active tip entering the human body and the movement speed of the ablation needle based on the distance information determined by the ultra-wideband radio pulse signals transmitted and received between the first ultra-wideband module and the second ultra-wideband module.

[0024] In a preferred embodiment, the outer surface of the ablation needle has a periodic texture arranged along the axial direction;

[0025] The needle position detection device includes:

[0026] The base has an internal detection chamber and a coaxial through hole through which the ablation needle passes;

[0027] An optical illumination component, disposed within the detection chamber, is used to illuminate the textured area on the surface of the ablation needle passing through the penetration hole;

[0028] At least two photoelectric sensing components, mounted side-by-side along the axial direction of the ablation needle, are disposed within the detection chamber to receive light reflected from the surface texture of the needle and generate electrical signals; and

[0029] The processing circuit, electrically connected to the photoelectric sensing component, is configured to calculate the depth of the active tip entering the human body and the movement speed of the ablation needle based on the electrical signal generated by the photoelectric sensing component.

[0030] In a preferred embodiment, the axial spacing between the at least two photoelectric sensing components is set to a non-integer multiple of the period length of the periodic texture.

[0031] In a preferred embodiment, the axial spacing between the at least two photoelectric sensing components is set to one-quarter of the period length of the periodic texture.

[0032] In a preferred embodiment, the control device is configured to control the radio frequency power based on the movement speed of the ablation needle using a lookup table method. The control device stores at least one lookup table that defines a range or point of movement speed of the ablation needle and the corresponding radio frequency power value.

[0033] In a preferred embodiment, the control device is configured to control the radio frequency power based on the movement speed of the ablation needle using a mathematical function method. The control device is programmed to implement a monotonically non-decreasing mathematical function P=f(v), where v is the input movement speed of the ablation needle and P is the output radio frequency power.

[0034] In a preferred embodiment, the control device includes a display screen with a graphical user interface for displaying the depth, speed, temperature, radio frequency power, and prompt information in real time.

[0035] In a preferred embodiment, the prompts indicating that the needle withdrawal should be stopped and the needle should be allowed to cool down, and the prompts indicating that the ablation needle can be removed, include visual and / or auditory prompts.

[0036] In the embodiments of this application, by integrating a needle position detection device (for real-time monitoring of the depth and movement speed of the active tip of the ablation needle), a temperature sensor (for monitoring the needle tip temperature), and specific control logic into the needle withdrawal system of the radiofrequency ablation device (this logic can adjust the radiofrequency power according to the detected movement speed during needle withdrawal, ensuring that the power is higher or constant as the speed increases; automatically stop the radiofrequency output and issue a waiting cooling prompt when the needle tip reaches a predetermined superficial depth; and issue a prompt allowing needle removal after the temperature has sufficiently decreased), intelligent and precise closed-loop control of the radiofrequency ablation needle withdrawal process can be achieved. This solution ensures effective thermal coagulation of the entire needle tract to prevent bleeding or tumor dissemination, while precisely stopping heating in the final stage before the needle tip leaves the skin and forcibly waiting for the needle tip to cool to a safe temperature before allowing complete removal. This significantly reduces the risk of postoperative scarring caused by burns to the skin and subcutaneous tissue from the high-temperature needle, and significantly improves the safety of the procedure and the quality and aesthetics of the patient's postoperative recovery.

[0037] Furthermore, by detecting that the depth of the active tip is less than or equal to a predetermined depth threshold, in addition to stopping the radiofrequency power, the control device is also configured to activate the cooling system of the ablation needle itself. This can actively accelerate the cooling process of the active tip, shorten the waiting time for cooling after the needle is withdrawn, thereby improving the overall efficiency of the surgery and reducing the needle tip temperature more quickly and effectively, further consolidating the effect of preventing thermal damage to superficial tissues.

[0038] Furthermore, by employing a specific needle location detection device based on ultra-wideband (UWB) technology (including a base and a first UWB module fixed near the patient's body surface, a second UWB module fixed to the ablation needle handle, and a processing module for calculating distance and estimating depth and velocity), a non-contact, high-precision real-time positioning and velocity measurement solution for the ablation needle can be achieved. This provides accurate depth and velocity data for the control system, and requires minimal modification to the ablation needle itself (only integration of the module into the handle is needed). Installation and use are relatively convenient, and it is less susceptible to interference from other factors in the surgical environment (such as liquids or tissue obstruction).

[0039] Furthermore, by creating periodic textures on the outer surface of the ablation needle and using an optical needle position detection device comprising a base (with a detection chamber), an optical illumination component, at least two photoelectric sensing components, and processing circuitry, a needle position detection scheme based on the optical reading principle can be constructed. By directly reading the physical markings on the needle body to accurately track its axial displacement and velocity, very high measurement resolution and accuracy can be achieved, providing reliable input for the control algorithm.

[0040] Furthermore, by setting the axial spacing between the two photoelectric sensing components to a non-integer multiple of the periodic texture period length, a fixed phase difference can be ensured between the reflected light signals received by the two sensors. This specific sensor layout allows the processing circuit to accurately determine the current movement direction of the ablation needle (whether it is being inserted or withdrawn) based on the sequence of signal phases.

[0041] Furthermore, by precisely setting the axial spacing between the two photoelectric sensing components to one-quarter (P / 4) of the periodic texture period length, orthogonal signals with a phase difference of approximately 90 degrees can be generated. This not only enables very stable and reliable determination of the direction of motion, but also facilitates the subdivision of the orthogonal signals (e.g., counting the rising and falling edges of the pulses, or analyzing the phase angle), thereby achieving a higher depth measurement resolution than a single texture period.

[0042] Furthermore, by employing a lookup table (LUT) to map the ablation needle movement speed to radiofrequency power in the control device, a simple, efficient, and flexible method can be provided to achieve a speed-power monotonically non-decreasing control strategy. This method requires minimal computation, has a fast response speed, and allows for convenient customization and adjustment of complex, nonlinear speed-power relationships based on experimental data or clinical needs.

[0043] Furthermore, by employing a mathematical function method to realize the mapping relationship between the ablation needle movement speed and the radio frequency power in the control device, that is, by implementing a monotonically non-decreasing function P=f(v) (where v is the speed and P is the power) in the control program, continuous and smooth power adjustment can be achieved. Compared with the step power change that may occur by the lookup table method, the function method can make more precise power adjustment according to the subtle changes in speed, which helps to achieve a more uniform needle coagulation effect.

[0044] Furthermore, by equipping the control device with a display screen featuring a graphical user interface (GUI) for real-time visualization of depth, speed, temperature, current radiofrequency power value, and system prompts, the human-computer interaction performance of the system can be significantly improved. This allows the operating physician to clearly grasp all key parameters and system status during needle withdrawal, enhancing the transparency and controllability of the operation and improving the convenience and safety of use.

[0045] Furthermore, the system-issued prompts such as "Stop needle withdrawal and wait for cooling" and "Ablation needle can be removed" can be visual (e.g., flashing LED lights or color changes) and / or auditory (e.g., beeping sounds of different frequencies or rhythms). This ensures that the operator receives these critical safety instructions promptly and clearly. In noisy or poorly lit operating room environments, this improves the reliability and effectiveness of the prompts, ensuring that the operator follows a safe needle withdrawal procedure, thereby ultimately achieving the goal of avoiding scarring. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the needle withdrawal system of a radiofrequency ablation device for avoiding scarring according to an embodiment of this application. Detailed Implementation

[0047] In the following description, many technical details are presented to help the reader better understand this application. However, those skilled in the art will understand that the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0049] The embodiments of this application relate to a needle withdrawal system for radiofrequency ablation devices that avoids scarring, such as... Figure 1 As shown, the needle withdrawal system of this scar-avoiding radiofrequency ablation device includes:

[0050] ablation needle;

[0051] A radio frequency generator that provides radio frequency power to the ablation needle.

[0052] The needle position detection device is used to detect the depth of the active tip of the ablation needle entering the human body and the movement speed of the ablation needle;

[0053] A temperature sensor, mounted on the ablation needle, is used to detect the temperature of the active tip; and

[0054] The control device is electrically connected to the radio frequency generator, the needle position detection device, and the temperature sensor.

[0055] The control device is configured as follows:

[0056] When the ablation needle is withdrawn, the control device controls the radio frequency power supplied to the ablation needle by the radio frequency generator according to the movement speed of the ablation needle detected by the needle position detection device. A relatively high movement speed of the ablation needle corresponds to a relatively high radio frequency power, and a relatively low movement speed of the ablation needle corresponds to a relatively low radio frequency power.

[0057] When the needle position detection device detects that the depth of the active tip entering the human body is less than or equal to a predetermined depth threshold, the control device controls the radiofrequency generator to stop providing radiofrequency power to the ablation needle and issues a prompt message indicating that the needle withdrawal has stopped and cooling is in progress; and

[0058] After the radio frequency generator stops supplying radio frequency power to the ablation needle, when the temperature of the ablation needle detected by the temperature sensor drops below a predetermined temperature threshold, the control device issues a prompt message indicating that the ablation needle can be removed.

[0059] The ablation needle in a radiofrequency ablation device, also often referred to as a radiofrequency electrode, is designed to precisely deliver radiofrequency current to the target tissue area. The generated heat causes the tissue to coagulate and necrose, while protecting surrounding non-target tissue. Its structure typically includes the following key components:

[0060] Needle body: This is the main part of the needle, shaped like a long rod, usually made of metals with good rigidity and biocompatibility, such as medical-grade stainless steel. It is used to puncture tissue and reach the target ablation area. The diameter (commonly expressed as Gauge value, such as 17G, 18G) and length of the needle body vary depending on the clinical application (such as liver, lung, kidney, bone tumor, or heart ablation).

[0061] Insulation layer: Most of the outer surface of the needle body is covered with an electrically insulating and high-temperature resistant material (such as a polymer coating, such as PEEK, Teflon / PTFE, polyimide, etc.). The insulation layer is used to limit the radio frequency current to flow only from a specific area of ​​the needle tip, prevent the current from burning non-target tissues (such as skin, muscle, needle tract) along the needle body path, and concentrate energy in the target area.

[0062] Active tip / bare electrode: Located at the far end of the ablation needle, this is the portion of the needle body not covered by the insulating layer. This is where the radiofrequency current actually flows into the tissue, and it is the core area that generates the thermal effect for tissue ablation. The length and shape of the active tip affect the size and morphology of the ablation zone. Common sizes range from a few millimeters to several centimeters, and shapes can be simple cylindrical, conical, or more complex "shovel-shaped," to optimize energy distribution for specific applications.

[0063] Internal conductors: The internal conductors that extend from the pin shank / connector to the active tip are responsible for conducting the RF current generated by the RF generator to the active tip.

[0064] Handle (or "needle shank"): Located at the proximal end of the ablation needle (the end held by the operator), providing the grip and manipulation area. It also includes a standard or dedicated connector for connecting to the output cable of the RF generator to transmit RF energy and, if possible, sensing signals.

[0065] Temperature sensor: A temperature sensor (such as a thermocouple) is embedded inside or near the active tip to monitor the temperature of the ablation area in real time, providing feedback to the physician to help control the ablation process, ensuring that the target temperature (usually 60-100℃) is reached to effectively destroy tissue, while avoiding overheating (such as exceeding 105-110℃) which could lead to tissue carbonization and vapor bursts, affecting energy transmission and safety. Its signal is transmitted back to the radiofrequency generator via internal circuitry.

[0066] Cooling System: Some radiofrequency ablation needles (called "cold circulation" or "perfusion" electrodes) are designed with internal fluid channels. During ablation, a cooling liquid (such as saline) is circulated through these channels to cool the electrode tip. This prevents the electrode surface temperature from becoming too high, which could lead to tissue carbonization and a sharp increase in impedance, allowing for higher power output, longer ablation times, and the creation of larger ablation foci. The cooling system requires additional tubing connected to the perfusion pump.

[0067] The statement "higher needle withdrawal speed corresponds to higher radio frequency (RF) power" describes a strategy where, during the needle withdrawal process (removing the ablation needle from the body), the control device adjusts the RF generator's output power based on the real-time detected needle movement speed. In other words, there is a largely positive correlation between withdrawal speed and RF power. When the operator removes the needle faster, the control device instructs the RF generator to output higher power; conversely, when the withdrawal speed is slower, the output power is correspondingly lower. This means that as the withdrawal speed *v* increases, the corresponding RF power *P* either increases or at least remains constant; there is no situation where the speed increases but the power decreases. Mathematically, if the withdrawal speed *v1* > *v2*, then the corresponding power *P1* ≥ *P2*. This monotonicity ensures the consistency and predictability of the control logic.

[0068] The purpose of this design is typically to ensure sufficient thermal effect on the tissue along a specific path by increasing the energy output rate (power) when the needle moves rapidly and the time spent acting on that tissue path is shortened. This achieves the desired coagulation or ablation effect, resulting in a uniform and continuous ablation zone along the entire needle withdrawal path. This is crucial for sealing the needle tract, preventing bleeding or tumor cell dissemination along the tract, and ultimately, through precise subsequent control (such as stopping heating and waiting for cooling), the goal of reducing scarring can be achieved.

[0069] Control devices can achieve this monotonically non-decreasing mapping relationship between speed and power in various ways. Several common techniques are listed below:

[0070] Lookup Table (LUT): One or more tables are pre-stored in the memory of the control device. These tables define different needle retraction speed ranges (or specific speed points) and their corresponding RF power values. The control device obtains the speed value measured by the needle position detection device in real time, then looks up the interval where the speed value is located or the closest speed point in the preset table, and reads the corresponding power setting value, and instructs the RF generator to output at this power.

[0071] Example:

[0072] Speed range (0, v1] -> Power P1

[0073] Speed range (v1, v2] -> Power P2

[0074] Speed range (v2, v3] -> Power P3 ...

[0076] Where v1 < v2 < v3... and P1 ≤ P2 ≤ P3..., which ensures monotonicity. The table can be accurately set according to experimental data or simulation results, and can achieve various forms of monotonic relationships such as piecewise constant or piecewise linear.

[0077] Mathematical function / formula method: Implement a mathematical function P = f(v) in the control device, where v is the input needle retraction speed and P is the output RF power. The function f is designed to be a monotonic non-decreasing function. After the control device measures the speed v, it directly substitutes it into the function to calculate the required power P, and controls the RF generator to output. The advantage is that continuous and smooth power adjustment can be achieved.

[0078] Example:

[0079] Linear function: P = a×v + b, where a is a non-negative constant (a ≥ 0) and b is the base power or intercept. When a > 0, the power increases linearly with the speed.

[0080] Piecewise function: Different monotonic functions for different speed intervals can be defined.

[0081] Or other forms of monotonic functions (such as non-linear functions).

[0082] Optionally, in one embodiment, the control device is further configured to start the cooling system of the ablation needle when the depth of the active tip detected by the needle position detection device entering the body is less than or equal to a predetermined depth threshold, so that the cooling liquid flows into the fluid channel inside the ablation needle to cool the active tip. The predetermined depth threshold can be set according to different patient conditions or doctor experience, for example, it can be set to 2 - 4 mm.

[0083] Optionally, in one embodiment, the needle position detection device includes: a base, a first UWB module, a second UWB module, and a processing module.

[0084] The base is fixed to the patient's body surface near the puncture site before the ablation procedure, and its position remains stable relative to the patient's body during needle withdrawal. The base has a channel through which the ablation needle can pass. During ablation and needle withdrawal, the ablation needle slides axially relative to the base. The base can be injection molded from medical-grade engineering plastic.

[0085] The first UWB module is integrated or fixed on the base.

[0086] The second UWB module is integrated or fixed to the handle of the ablation needle.

[0087] The processing module is electrically connected to the second UWB module and serves for calculation, control, and communication. The processing module can be integrated or fixed on the handle of the ablation needle, or it can be located outside the handle (e.g., close to the control device).

[0088] The first and second UWB modules perform high-precision real-time ranging by transmitting and receiving UWB radio pulse signals. Since the base is relatively fixed in position during the procedure (e.g., it can be considered to represent a reference plane of the skin surface or puncture site), while the handle moves as the operator moves the ablation needle, the change in the linear distance between the first and second UWB modules (or the component of its projection onto the axial direction of the ablation needle) directly reflects the displacement of the ablation needle relative to the base.

[0089] The processing module can be calibrated before system initialization or operation begins. For example, when the active tip of the ablation needle just touches the skin surface, the distance d0 between the two UWB modules is recorded. During subsequent insertion and withdrawal, the needle position detection device measures the distance d(t) between the two UWB modules in real time. The depth D(t) of the active tip entering the body can then be calculated using D(t) = f(d(t) − d0), where f is a transformation function. In the simplest case (assuming the needle's axis of motion is aligned with or nearly aligned with the UWB ranging direction), the depth can be approximated as D(t) ≈ d(t) − d0 or D(t) ≈ d0 − d(t) (depending on the specific arrangement of the UWB modules and the distance definition). This depth information is transmitted to the control device.

[0090] In addition to calculating continuous depth data D(t) based on the signal from the second UWB module, the processing module can also process the data at continuously sampled time points t1, t2, ..., t3. n The corresponding depth values ​​are D(t1), D(t2), ..., D(tn The control device can calculate the velocity V(t) of the ablation needle after processing. For example, the instantaneous velocity can be calculated using the finite difference method. Where i is the sampling point number. The processing module outputs the depth data D(t) and velocity information V(t) to the control device for power adjustment.

[0091] In this embodiment, the needle position detection device uses UWB technology to accurately measure the relative position between the base (reference point) and the ablation needle handle (moving point), and thereby calculates the insertion depth and movement speed of the active tip. This information is provided to the control device to adjust the radio frequency power according to the speed during needle withdrawal, stop power output and issue a prompt when a predetermined depth threshold is reached, and determine the final timing of needle removal based on temperature sensor information, thereby effectively avoiding scarring caused by needle tract burns.

[0092] Optionally, in another embodiment, the needle position detection device includes:

[0093] Ablation needle body with periodic texture: On the outer surface of the ablation needle's outer tube (or its rigid part), in the area requiring depth monitoring, alternating light and dark ring or stripe textures with a fixed period length P (e.g., P = 1 mm) are uniformly set along its axial direction by laser marking (or ink printing). This texture produces periodically changing reflective properties under illumination.

[0094] The motion detection unit further includes a base, an optical illumination component, and a processing circuit.

[0095] The base is injection molded from medical-grade opaque engineering plastic, forming a detection chamber that almost completely blocks external ambient light. Coaxial penetration holes are located at both ends of the base, with a diameter slightly larger than the outer diameter of the ablation needle. This ensures the ablation needle can move freely and smoothly axially within the chamber while effectively blocking external light from entering. The base can be fixed to the surface of the human body using adhesive or other methods.

[0096] The optical illumination component consists of one or more infrared LEDs fixed to the inner wall of the detection chamber. The beams of these LEDs are appropriately designed (e.g., using microlenses) to be focused near the central axis of the penetration hole, so as to continuously illuminate the textured area of ​​the surface of the ablation needle that has passed through.

[0097] In the detection chamber, at least two photoelectric sensors are mounted side-by-side along the axis of the ablation needle, near the illumination area. The sensitive areas of these two sensors are aligned with the surface of the ablation needle to receive light reflected from the needle's surface texture. The axial distance L between the two sensors is precisely set to a non-integer multiple of the texture period P, preferably P / 4, to form orthogonal signals with a phase difference of approximately 90 degrees, facilitating the determination of the direction of movement. To reduce crosstalk between the sensors, a light-blocking plate can be placed between them.

[0098] The processing circuit includes: a signal conditioning circuit for amplifying and filtering the weak signal from the photodiode; a distance determination component (e.g., a microcontroller (MCU)) for processing the signals from the two sensors to obtain depth and speed; and an interface circuit for transmitting the processing results (depth and speed) to the needle retraction system control device via a wired connection.

[0099] The reset button, located on the base, is used to manually set the current ablation needle position as the zero-point reference for depth calculation.

[0100] The working principle of the needle position detection device is as follows:

[0101] Depth measurement:

[0102] 1. Fixation and Initialization: The moving detection unit is fixed using a specific structure (e.g., the thread at one end of the base penetration hole matches the interface of the vascular sheath, or medical tape is used to fix it to the skin puncture point). When the active tip of the ablation needle first contacts the skin surface or reaches the preset reference depth, the operator presses the reset button or sends a command through the main control system. The processing unit then resets the internal cumulative displacement counter to zero, which is defined as the depth zero point.

[0103] 2. Signal Generation: As the ablation needle moves axially, the light and dark textures on its surface alternately pass through the detection areas of the two photodiodes. Due to the different reflectivities of the light and dark textures, the intensity of the reflected light received by the two photodiodes changes periodically, outputting a periodic electrical signal that is approximately a sine wave or square wave. Due to the spatial difference between the two sensors (L=P / 4), there will be a phase difference of approximately 90 degrees between their output signals.

[0104] 3. Direction Determination and Counting: The processing unit (MCU or dedicated circuit) analyzes the two signals with a phase difference in real time. By determining which signal's phase is leading or lagging, it can be determined whether the ablation needle is advancing (inserting) or retracting (pulling out). Simultaneously, the number of complete cycles for one of the signals (or the combined processing of the two signals) is accurately counted.

[0105] 4. Depth Calculation: Each time the signal completes a full cycle, it represents the ablation needle moving one texture cycle length P (e.g., 1 mm). The processing unit calculates the total displacement of the ablation needle relative to the zero point based on the detected direction of movement (increase for forward movement, decrease for backward movement) and the accumulated number of cycles N: Depth = N × P. Through subdivision processing of the signal phase, even higher precision measurements of less than one cycle can be achieved.

[0106] Speed ​​measurement:

[0107] 1. Real-time depth acquisition: The processing unit updates and stores the current depth value Depth(t) at a fixed high frequency (e.g., every 10ms), where t represents time.

[0108] 2. Differential Calculation: By comparing the current depth value Depth(t) with the depth value Depth(t-Δt) at the previous sampling time, the displacement change within the time interval Δt is calculated. Velocity V = [Depth(t) - Depth(t-Δt)] / Δt. This velocity value is the average velocity of the ablation needle during this time interval, which can be approximated as the instantaneous velocity.

[0109] Optionally, in one embodiment, the core of the control device is a microcontroller unit (MCU).

[0110] The control unit includes a microcontroller, input interface circuitry, output interface circuitry, memory, and a power management unit.

[0111] The MCU is responsible for receiving signals from various sensors, executing control algorithms, and outputting control commands.

[0112] The input interface circuit is used to connect to the needle position detection device. Depending on the type of output signal from the needle position detection device (e.g., digital pulse signal, analog voltage signal, or data transmitted via a serial communication interface such as SPI / I2C), the corresponding interface circuit (e.g., digital I / O port, analog input port with analog-to-digital converter (ADC), or serial communication interface) is configured. The MCU processes these signals to calculate the real-time depth of the ablation needle's active tip entering the human body and the needle's movement speed (e.g., obtaining the speed by differentiating the position information over time). The input interface circuit is also used to connect to a temperature sensor. Depending on the output type of the temperature sensor (e.g., analog voltage, resistance change, or digital signal such as I2C / SPI), the corresponding interface circuit (e.g., analog input port with ADC, or digital communication interface) is configured so that the MCU can read the temperature data.

[0113] The output interface circuitry is used to control the RF generator. The MCU generates control signals (e.g., analog voltage signals, PWM pulse width modulation signals, or digital instructions sent via UART / SPI) to the RF generator to precisely adjust its output power. The amplitude or parameter of the control signal corresponds to the required RF power calculated based on the ablation needle's movement speed. The output interface circuitry is also used to drive prompt messages. The MCU connects to user interface elements, such as light-emitting diodes (LEDs), buzzers, or small speakers. By controlling the state of these elements (e.g., lighting up LEDs of a specific color, emitting sounds of a specific frequency or pattern), prompt messages such as "Stop withdrawing the needle and wait for cooling" and "The ablation needle can be removed" are emitted.

[0114] The memory includes program memory (such as Flash) for storing control algorithm firmware, and data memory (such as RAM) for runtime data processing. Non-volatile memory (such as EEPROM or Flash) can be used to store preset parameters, such as predetermined depth thresholds, predetermined temperature thresholds, and speed-power correspondence data (e.g., lookup tables or function parameters).

[0115] The power management unit provides a stable power supply for the entire control device.

[0116] The firmware running inside the MCU includes the following main modules:

[0117] Signal acquisition and processing module: Periodically reads data from the needle position detection device and temperature sensor, and performs necessary filtering, conversion and calculation to obtain real-time depth, speed and temperature values.

[0118] Control Decision Module:

[0119] During the needle withdrawal phase, the target radio frequency power is calculated based on the real-time detected movement speed of the ablation needle and a preset mapping relationship (e.g., a piecewise function stored in a lookup table or a continuous function P=f(v), where P is the radio frequency power, v is the speed, and f(v) is a monotonically increasing function), and a corresponding control signal is generated and sent to the radio frequency generator.

[0120] Continuously monitor the depth of the active tip of the ablation needle. Once the depth is detected to be less than or equal to a predetermined depth threshold (e.g., 2 mm subcutaneously), immediately set the control signal sent to the radiofrequency generator to the "stop output" state (e.g., output 0V analog voltage or send a command with 0 power) and trigger a "stop needle withdrawal and wait for cooling" prompt (e.g., light up a yellow LED and emit a short beep).

[0121] After the radio frequency power is stopped, the temperature sensor readings are continuously monitored. When the temperature is detected to drop below a predetermined temperature threshold (e.g., 45°C), a "the ablation needle can be removed" prompt is triggered (e.g., a green LED is lit and a long beep is emitted).

[0122] User interface management module: Controls the operation of prompting elements such as LEDs and buzzers.

[0123] Alternatively, in another embodiment, the control device is a more complex embedded system, possibly integrated into a medical console with a graphical user interface (GUI).

[0124] The control device includes:

[0125] Microprocessor (MPU) or high-performance MCU: It has stronger processing power and can support operating systems and graphical interfaces.

[0126] Memory: Larger capacity RAM and Flash / hard disks are used to run the operating system, applications, and store data.

[0127] Input / output interfaces: Similar to previous embodiments, but may include more standard interfaces (such as USB, Ethernet) for data transmission or system expansion.

[0128] Display: Such as an LCD or OLED touchscreen, used to display real-time status information (depth, speed, temperature, power, system prompts) and may allow limited user interaction (e.g., confirmation prompts).

[0129] Speaker: Used to provide clearer voice prompts or different tones.

[0130] The microprocessor (MPU) or high-performance MCU runs an embedded operating system (such as Linux or RTOS). The control application not only implements the core control logic of the MCU in the previous embodiments, but also includes: a graphical user interface (GUI) driver that updates the ablation needle depth, speed, temperature, and current radiofrequency power level in real time on the display screen (either numerically or graphically); a prompt message display that clearly shows messages such as "Please stop needle withdrawal and wait for the needle to cool down" and "The needle has cooled down and can be safely removed" in text or icon form on the screen, possibly accompanied by audible prompts; a parameter configuration interface (optional) that may allow authorized users (such as doctors or technicians) to view or adjust preset depth and temperature thresholds within a certain range (handled with caution to ensure safety); and a data logging function (optional) that can record key parameters (speed, depth, temperature, power curves) during each operation for subsequent analysis or quality control.

[0131] Alternatively, in another embodiment, the control device may combine an MCU and an FPGA (Field-Programmable Gate Array).

[0132] The control unit includes: an MCU, responsible for high-level decision-making logic, user interface, and communication with the RF generator; an FPGA, specifically designed for high-speed, real-time processing of signals from the needle detection device, accurately calculating instantaneous speed and depth, and potentially directly implementing a speed-power fast lookup table (LUT) or complex calculations; the FPGA then transmits the processed speed and depth information to the MCU; and other interfaces and memory, similar to those previously described.

[0133] FPGAs can process high-speed sensor signals with extremely low latency, which is particularly advantageous for pin detection that requires fast response (such as detection based on optical encoders or high-frequency sensors). Computationally intensive or time-critical tasks (such as high-speed differentiation operations and complex filtering algorithms) can be offloaded to FPGAs, reducing the burden on MCUs and improving the overall response speed and stability of the system.

[0134] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, if it refers to performing an action according to an element, it means performing the action at least according to that element, including two cases: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

[0135] This specification includes combinations of various embodiments described herein. Individual references to embodiments (e.g., “one embodiment”, “some embodiments”, or “preferred embodiments”) do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated to be mutually exclusive or are readily apparent to those skilled in the art. It should be noted that the word “or” is used in a non-exclusive sense throughout this specification unless the context explicitly indicates or requires it.

[0136] All references to this application are considered to be incorporated in their entirety into the disclosure of this application so that they can serve as a basis for modifications if necessary. Furthermore, it should be understood that after reading the contents of this application, those skilled in the art can make various alterations or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A radiofrequency ablation device needle withdrawal system to avoid scarring, comprising an ablation needle and a radiofrequency generator providing radiofrequency power to the ablation needle, characterized in that, The device also includes: A needle position detection device is used to detect the depth of the active tip of the ablation needle entering the human body and the movement speed of the ablation needle; A temperature sensor, configured on the ablation needle, is used to detect the temperature of the active tip; and The control device is electrically connected to the radio frequency generator, the needle position detection device, and the temperature sensor. The control device is configured as follows: When the ablation needle is withdrawn, the control device controls the radio frequency power supplied to the ablation needle by the radio frequency generator according to the movement speed of the ablation needle detected by the needle position detection device, wherein a higher movement speed of the ablation needle corresponds to a higher radio frequency power. When the needle position detection device detects that the depth of the active tip entering the human body is less than or equal to a predetermined depth threshold, the control device controls the radio frequency generator to stop providing radio frequency power to the ablation needle and issues a prompt message indicating that the needle withdrawal has stopped and cooling is in progress; and After the radio frequency generator stops supplying radio frequency power to the ablation needle, when the temperature of the ablation needle detected by the temperature sensor drops below a predetermined temperature threshold, the control device issues a prompt message indicating that the ablation needle can be removed.

2. The needle withdrawal system for radiofrequency ablation devices that avoid scarring as described in claim 1, characterized in that, The control device is further configured to activate the cooling system of the ablation needle when the depth of the active tip entering the body detected by the needle position detection device is less than or equal to a predetermined depth threshold, so that cooling liquid flows into the fluid channel inside the ablation needle to cool the active tip.

3. The needle withdrawal system for radiofrequency ablation devices that avoid scarring as described in claim 1, characterized in that, The needle position detection device includes: The base is fixed to the patient's body surface near the puncture point before the ablation operation, and the base is provided with a channel for the ablation needle to pass through; The first ultra-wideband module is integrated or fixed on the base; A second ultra-wideband module is integrated or fixed to the handle of the ablation needle; and The processing module is electrically connected to the second ultra-wideband module; The processing module is configured to calculate the depth of the active tip entering the human body and the movement speed of the ablation needle based on the distance information determined by the ultra-wideband radio pulse signals transmitted and received between the first ultra-wideband module and the second ultra-wideband module.

4. The needle withdrawal system for radiofrequency ablation devices that avoid scarring as described in claim 1, characterized in that, The outer surface of the ablation needle has periodic textures arranged along the axial direction; The needle position detection device includes: The base has an internal detection chamber and a coaxial through hole through which the ablation needle passes; An optical illumination component, disposed within the detection chamber, is used to illuminate the textured area on the surface of the ablation needle passing through the penetration hole; At least two photoelectric sensing components, mounted side-by-side along the axial direction of the ablation needle, are disposed within the detection chamber to receive light reflected from the surface texture of the needle and generate electrical signals; and The processing circuit, electrically connected to the photoelectric sensing component, is configured to calculate the depth of the active tip entering the human body and the movement speed of the ablation needle based on the electrical signal generated by the photoelectric sensing component.

5. The scar-avoiding radiofrequency ablation device needle withdrawal system as described in claim 4, characterized in that, The axial spacing between the at least two photoelectric sensing components is set to a non-integer multiple of the period length of the periodic texture.

6. The scar-avoiding radiofrequency ablation device needle withdrawal system as described in claim 5, characterized in that, The axial spacing between the at least two photoelectric sensing components is set to one-quarter of the period length of the periodic texture.

7. The needle withdrawal system for radiofrequency ablation devices that avoid scarring as described in claim 1, characterized in that, The control device is configured to control the radio frequency power based on the movement speed of the ablation needle using a lookup table method. The control device stores at least one lookup table that defines the movement speed range or speed point of the ablation needle and the corresponding radio frequency power value.

8. The needle withdrawal system for radiofrequency ablation devices that avoid scarring as described in claim 1, characterized in that, The control device is configured to control the radio frequency power based on the movement speed of the ablation needle using a mathematical function method. The control device is programmed to implement a monotonically non-decreasing mathematical function P=f(v), where v is the input movement speed of the ablation needle and P is the output radio frequency power.

9. The scar-avoiding radiofrequency ablation device needle withdrawal system as described in any one of claims 1-8, characterized in that, The control device includes a display screen with a graphical user interface for displaying the depth, speed, temperature, radio frequency power, and prompt information in real time.

10. The scar-avoiding radiofrequency ablation device needle withdrawal system as described in any one of claims 1-8, characterized in that, The prompts indicating that the needle withdrawal has stopped and the temperature is waiting for to drop, and the prompts indicating that the ablation needle can be removed, include visual prompts and / or auditory prompts.

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