Steam therapy system and method

Abstract

A steam delivery system is provided that may include any of several features. [Solution] One feature of vapor delivery systems is that condensable vapor energy can be applied to tissues such as the prostate to shrink, damage, or denature the prostate. In some embodiments, the vapor delivery system may include safety features including prostatic capsule detection, needle tracking, and treatment tracking. A method for the safe and effective treatment of prostate tissue is presented.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the benefit of priority of U.S. Provisional Application No. 62 / 955,288, filed on 30 December 2019, which is incorporated herein by reference in its entirety.

[0002] Reference All publications, including patents and patent applications, referenced herein are incorporated herein by reference in whole to the same extent that individual publications are specifically and individually indicated to be incorporated by reference.

[0003] The present invention relates to an apparatus and related method for the treatment of prostate cancer using a minimally invasive approach. [Background technology]

[0004] The human male prostate can be classified into three regions: the peripheral zone, the transitional zone, and the central zone. The peripheral zone (PZ) makes up about 70% of the volume of the male prostate. The subcapsular portion of the posterior surface of this prostate surrounds the distal urethra, and 70-80% of cancers originate from the tissue of the peripheral zone. The central zone (CZ) surrounds the ejaculatory ducts and contains about 20-25% of the volume of the prostate. The central zone is often the site of inflammatory processes. The transitional zone (TZ) is where benign prostatic hyperplasia (BPH) develops. In a normal prostate, it contains about 5-10% of the volume of glandular elements, but in BPH it can account for up to 80%. The transitional zone includes the two lateral lobes of the prostate and the periurethral glandular region. Surrounding the transitional zone are natural barriers such as the prostatic urethra, the pre-fibromuscular stroma (FS), and the fibrous plane (FP) between the transitional zone and the peripheral zone. The pre-fibromuscular stroma (FS), or fibrous zone, is mainly fibromuscular tissue. [Overview of the project] [Problems that the invention aims to solve]

[0005] Approximately 70% to 80% of prostate cancers originate in the peripheral region of the prostate, and are often confined to this region. In recent years, there has been growing interest in localized treatment of prostate cancer, which involves treating only the area of ​​tissue in which cancer is found after biopsy. Prior localized treatments using RF ablation energy may not be limited to peripheral tissue or tissue within the prostate. [Means for solving the problem]

[0006] A prostate treatment system is provided, the system comprising: an introduction shaft sized and configured for transurethral access to a patient; a handle coupled to the introduction shaft; a vapor generator located within the handle and configured to generate condensable vapor; a vapor delivery needle communicating with the vapor generator and slidably located within the introduction shaft; a magnet attached to the needle; and a solenoid actuator located around the magnet, the solenoid actuator providing controlled motion to the needle, allowing it to deploy into tissue, advance at a constant speed or in pulsed steps, and retract into the shaft; and further comprising: sensors located on the needle, the shaft, and the handle, providing data on the position and orientation of the needle tip within the tissue; and electronic equipment located on the handle and an external console, communicating with each other and with the user to ensure safe and effective delivery of vapor to target tissue and prevent vapor delivery outside the target tissue.

[0007] A prostate treatment device is provided, the prostate treatment device comprising: an introduction shaft sized and configured for transurethral access to a patient; a treatment needle slidably disposed within the introduction shaft; an advancement mechanism coupled to the treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate; at least one sensor located on the distal portion of the treatment needle and configured to sense parameters of one or more tissues of the prostate; and an electronic controller operably coupled to the at least one sensor and configured to determine whether the treatment needle contacts the prostatic capsule of the prostate based on the sensed parameters.

[0008] In some embodiments, the parameter comprises electrical impedance of one or more tissues of the prostate.

[0009] In one embodiment, sensing the electrical impedance of the one or more tissues of the prostate further comprises: passing a constant current amplitude sine wave at a fixed frequency through the at least one sensor; measuring a voltage amplitude of the at least one sensor; determining an impedance amplitude by calculating a ratio of the voltage amplitude to the current amplitude; determining a phase shift between the voltage amplitude and the current amplitude; and calculating the electrical impedance of the one or more tissues using the phase shift and the impedance amplitude.

[0010] In one embodiment, the at least one sensor comprises at least one bioimpedance electrode.

[0011] In some embodiments, the controller is configured to determine that the treatment needle has contacted the prostatic capsule of the prostate when there is a sudden change in the electrical impedance.

[0012] In one embodiment, the sudden change comprises a sudden change of more than 25%.

[0013] In some examples, the parameter comprises electrical resistance of one or more tissues of the prostate. In another example, the parameter comprises capacitance of one or more tissues of the prostate. In still another example, the parameter comprises a force applied by one or more tissues of the prostate to the at least one sensor.

[0014] In some embodiments, the at least one sensor comprises a force sensor. In one embodiment, the force sensor is embedded behind a flexible tip of the treatment needle, and the flexible tip is configured to flex when a critical force is applied to the flexible tip.

[0015] In some embodiments, the treatment needle is configured to deliver vapor to the prostate gland.

[0016] In one embodiment, the device further comprises a magnet coupled to the proximal portion of the treatment needle, the advancement mechanism comprises a solenoid actuator arranged around the magnet, the solenoid actuator comprises a push winding coupled to the current source and a pull winding coupled to the current source, the push winding configured to apply a first magnetic field to the magnet, and the pull winding configured to apply a second magnetic field to the magnet, the first and second magnetic fields moving the distal tip of the treatment needle between a retracted position within the introduction shaft and an extended position at least partially outside the introduction shaft.

[0017] A method for treating a patient's prostate is also provided, which includes the steps of: inserting the shaft of a treatment device transurethral into the patient; advancing the treatment needle from the shaft through the patient's prostatic urethra into the patient's prostate; measuring at least one parameter of the prostatic tissue with a sensor placed on the treatment needle; determining, based on the at least one parameter, that the treatment needle has come into contact with the prostatic capsule; and stopping the advancement of the treatment needle when it comes into contact with the prostatic capsule.

[0018] In some embodiments, the at least one parameter includes the electrical impedance of the prostate tissue.

[0019] In another embodiment, the step of determining that the treatment needle has come into contact with the prostatic capsule further includes the step of detecting a sudden change in the measured electrical impedance. In some embodiments, the sudden change includes a sudden change of more than 25% of the measured electrical impedance.

[0020] In one embodiment, the at least one parameter includes the force applied to the treatment needle by the prostate tissue.

[0021] In some embodiments, the step of determining that the treatment needle has come into contact with the prostatic capsule further includes the step of detecting a critical force with the sensor.

[0022] In some embodiments, the method further includes the step of delivering vapor to the prostate from the treatment needle.

[0023] A prostate treatment system is provided, the prostate treatment system comprising a treatment device, the treatment device comprising: an introduction shaft sized and configured for transurethral access to a patient; a treatment needle slidably disposed within the introduction shaft; an advancement mechanism coupled to the treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate; and at least one transmitter disposed on the treatment needle, further comprising an external tracking system configured to sense the position of the at least one transmitter within the prostate.

[0024] In some embodiments, the at least one transmitter includes a magnet, and the external tracking system is configured to sense a pulsed magnetic field from the magnet to determine the position of the at least one sensor within the prostate.

[0025] In another embodiment, the external tracking system comprises an array of transmitter coils configured to sense changes in the magnetic field surrounding the magnet as the magnet moves within the prostate.

[0026] In some embodiments, the external tracking system is located on or within the transrectal probe.

[0027] In another embodiment, the transrectal probe includes a transrectal ultrasound probe.

[0028] In some embodiments, the magnet includes an electromagnet.

[0029] A prostate treatment device is provided, comprising: an introduction shaft sized and configured for transurethral access to a patient; a treatment needle slidably disposed within the introduction shaft; a forwarding mechanism coupled to the treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate; at least one transmitter disposed on the treatment needle; and a tracking sensor disposed on the distal portion of the introduction shaft and configured to sense the position of the at least one transmitter on the treatment needle relative to the distal portion of the introduction shaft.

[0030] In some embodiments, the at least one transmitter includes a magnet, and the tracking sensor is configured to sense a pulsed magnetic field from the magnet to determine the position of the at least one sensor.

[0031] In another embodiment, the external tracking system includes an array of transmitter coils configured to sense changes in the magnetic field surrounding the magnet as the magnet moves through the prostate.

[0032] In some embodiments, the magnet includes an electromagnet.

[0033] A method for treating a patient's prostate is provided, comprising the steps of: inserting a shaft of a treatment device transurethrally into the patient; advancing a treatment needle from the shaft through the patient's prostatic urethra into the patient's prostate; determining the real-time position of the treatment needle within the prostate; displaying the real-time position of the treatment needle and the prostate; and providing cauterization treatment to the prostate from the treatment needle.

[0034] In some embodiments, the advancing step further includes advancing the treatment needle and the transmitter positioned on the treatment needle into the prostate.

[0035] In another embodiment, the step of determining the real-time position of the treatment needle further includes the step of sensing the ambient magnetic field of the transmitter in the tracking system.

[0036] In some embodiments, the method further includes the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on the shaft of the treatment device.

[0037] In some embodiments, the method further includes the step of sensing the ambient magnetic field of the transmitter with a tracking system external to the therapeutic device.

[0038] In some embodiments, the method further includes the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on a transrectal probe.

[0039] In some embodiments, the method further includes the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on a transrectal ultrasound probe.

[0040] In some embodiments, the method further includes the step of registering the real-time position of the treatment needle on an ultrasound image from the transrectal ultrasound probe.

[0041] In another embodiment, the method further includes the step of displaying the real-time position of the treatment needle within the prostate gland.

[0042] A method is provided for tracking a patient's prostate treatment, comprising the steps of: generating steam in a steam therapy system; delivering steam from the steam therapy system to a first location in the patient's prostate; injecting a first volume of air from the steam therapy system to the first location; and visualizing the first volume of air in the prostate to track the prostate treatment.

[0043] In one embodiment, the step of delivering steam further includes the step of introducing the shaft of the steam therapy system transurethrally into the patient, and the step of advancing the steam therapy needle from the shaft to a first position in the prostate.

[0044] In one embodiment, the method further includes the steps of delivering steam from the steam therapy system to a second location within the prostate; injecting a second volume of air from the steam therapy system to the second location; and visualizing the second volume of air within the prostate to track the prostate treatment.

[0045] In one embodiment, the first air volume is greater than the second air volume.

[0046] In another embodiment, the first air volume is smaller than the second air volume.

[0047] In another embodiment, the method further includes the step of creating a map of the locations of treated prostates.

[0048] In some embodiments, the step of injecting the first volume of air is performed after the steam is delivered to the first position. In other embodiments, the step of injecting the first volume of air and the step of delivering the steam to the first position are performed simultaneously.

[0049] To better understand the present invention and to grasp how it can actually be put into practice, several preferred embodiments are described below, with reference to the accompanying drawings, by non-limiting examples only, where similar reference letters consistently indicate corresponding features throughout similar embodiments in the accompanying drawings. [Brief explanation of the drawing]

[0050] [Figure 1A] ~ [Figure 1E] This figure shows one embodiment of a steam delivery system. [Figure 2A]~ [Figure 2C] This figure shows one embodiment of a TRUS probe used with a steam delivery system to provide real-time tracking of the steam delivery needle tip. [Figure 3A] ~ [Figure 3B] This diagram shows the injection of steam-fueled air to track the area being cauterized. [Figure 4A] ~ [Figure 4C] This figure shows one embodiment of tracking the position of a vapor delivery needle using a needle tip magnet or coil. [Figure 5A] ~ [Figure 5C] This figure shows a vapor delivery needle with a tip coil sensor for motion tracking. [Figure 6A] ~ [Figure 6E] This figure shows another embodiment of tracking the position of a steam delivery needle using a transrectal probe. [Figure 7] ~ [Figure 8] This figure shows a further embodiment of a vapor delivery needle having a contact sensor configured to detect when the needle tip makes contact with the prostate wall. [Figure 9A] ~ [Figure 9B] This is a diagram of one embodiment of a vapor delivery needle having a non-Newtonian tip configured to deform upon contact with the prostatic capsule. [Figure 10] This is a flowchart illustrating an alternative method for treating prostate tissue. [Modes for carrying out the invention]

[0051] Generally, one method for treating prostate cancer involves intermittently introducing heated steam into the prostate gland to cauterize the prostate tissue in a controlled manner. In this method, steam can be used for applied thermal energy of 50 to 600 calories per individual steam treatment (assuming multiple treatments for each prostate lobe) in an outpatient-based procedure. This method can cause localized cauterization of prostate tissue without damaging the prostatic urethra or the tissues outside the prostate.

[0052] This disclosure relates to the treatment of prostate cancer, and more specifically, to the ablation of peripheral prostate tissue without ablating central or transitional prostate tissue.

[0053] The system may include a steam delivery mechanism for delivering a steam medium containing water vapor. The system may utilize a steam source configured to provide steam having a temperature of at least 60°C to 140°C. In another embodiment, the system further includes a computer controller configured to deliver steam at intervals ranging from 1 second to 30 seconds.

[0054] In some embodiments, the system further comprises a source of pharmacological agents or other chemical agents or compounds to be delivered along with the vapor. These agents include, but are not limited to, anesthetics, antibiotics, or toxins such as Botox (registered trademark), or chemical agents capable of treating cancerous tissue cells. The agents may also be sealants, adhesives, glues, cyanoacrylate adhesives, etc.

[0055] In some embodiments, a prostate treatment device may be provided comprising: an introduction shaft sized and configured for transurethral access to a patient; a steam generator configured to produce condensable steam; a steam delivery needle communicating with the steam generator and slidably positioned within the introduction shaft; and an actuator configured to move the steam delivery needle between a retracted position within the introduction shaft and an expanded position at least partially outside the introduction shaft, thereby continuously or stepwise advancing or retracting the needle to tissue at any position between the prostatic urethra and the prostatic capsule.

[0056] This disclosure relates to the safe and effective delivery of vapor for tissue ablation. A vapor delivery device may include a shaft configured for transurethral access to a patient's prostate, a vapor generator, and a vapor delivery needle which may include one or more vapor delivery ports. In one embodiment, vapor is delivered through the port(s) of the vapor delivery needle to ablate cancerous or precancerous tissue. In a preferred embodiment, the vapor delivery needle is configured to puncture the prostatic urethra and advance to one or more sites within the prostate to which vapor is to be delivered. Multiple puncture sites may be spaced apart to provide overlapping areas of tissue ablation within the prostate without being too close together, so that vapor delivered at one site can exit through the entrance hole of a previous puncture site.

[0057] More specifically, this disclosure concerns the navigation of a vapor delivery device, including a vapor delivery needle, into and throughout the prostate without the possibility of penetrating the prostatic capsule. In some embodiments, the tip of the vapor delivery needle is blunted to the extent that it can penetrate the prostatic urethra under a large deployment force, but not to the extent that it can puncture the prostatic capsule under a smaller navigation force. In other embodiments, an electrode is placed at the tip of the needle to measure the electrical impedance of the tissue adjacent to the tip. Tissue impedance (both resistance and capacitance) changes abruptly as the tissue changes from cellular in the prostate to fibrous in the capsule wall.

[0058] A system and method are disclosed for sensing the force exerted by tissue on the tip of a vapor delivery needle and alerting the user when a force sufficient to puncture the prostatic capsule is approaching. In one embodiment, a linear force sensor or displacement sensor may be located on the vapor delivery device, including on the vapor delivery needle. Alternatively, the system may include a switch-closing function that is activated when a specified tip force is exceeded.

[0059] In another embodiment, the needle is advanced by applying a force to it via an electronic solenoid to which the needle is attached. A sensor adjacent to the solenoid measures the displacement of the solenoid's magnet and the needle. Using a closed-loop algorithm, the needle is advanced by a specified distance or a specified speed. If the needle hits an obstacle, the solenoid current is automatically increased to continue the needle's movement. The critical current corresponds to a critical force on the needle that is equal to and opposite to the force exerted on the needle by the prostatic tissue. The critical force can be defined as indicating that the needle has encountered the prostatic capsule. At this point, the solenoid force is set to zero, and the operator may be alerted that a critical obstacle, which may be the wall of the prostatic capsule, has been encountered.

[0060] In another embodiment, the needle tip may be constructed from a non-Newtonian material that maintains its needle-tip shape when rapidly advanced during needle deployment to puncture the urethra, but deforms to a blunt tip when a smaller, slower force is applied. The blunt tip shape prevents penetration of the prostatic capsule.

[0061] In a preferred embodiment, the vapor delivery needle tip is blunted to such an extent that penetration of the prostatic capsule cannot occur under the force applied by the needle driver during navigation of the prostatic tissue. On the other hand, the much higher needle speed achieved during the initial needle deployment is sufficient for the blunted tip to penetrate the urethral wall. In one embodiment, the needle driver includes a solenoid. The initial deployment of the needle may occur in 10–15 milliseconds, and the needle can reach a speed of over 1 m / sec, sufficient for the blunt needle tip to penetrate the urethral wall. As it passes through the prostatic tissue, the solenoid operates for about 1–2 milliseconds, sufficient time for the needle to travel a small specified distance, and due to frictional force, the needle does not reach its maximum limit speed during the short pulse duration, and the needle reaches a speed of less than 1 m / sec or less than 0.5 m / sec. In one embodiment, the needle is advanced in continuous motion through the prostatic tissue, which requires a solenoid force much smaller than the initial deployment force. This force is measured and controlled via an algorithm to prevent a force high enough to penetrate the capsule wall.

[0062] Experiments using human and simulated prostate tissue suggest that hemispherical tips with diameters ranging from 0.020 to 0.035 inches effectively penetrate the urethral wall without piercing the prostatic capsule. In this example, a 0.050-inch needle tapers at an angle of approximately 17 degrees, resulting in a hemispherical tip with a diameter ranging from 0.20 to 0.35 inches. In our experiments, the most preferred diameter was 0.032 inches. Blunting the needle tip is a simple, passive measure to prevent rupture of the prostatic capsule during steam therapy. The needle shown in Figure 1D is an example of a blunted tip.

[0063] Steam delivery system Figure 1A shows one embodiment of the vapor delivery system 100. The vapor delivery system 100 may have an elongated shaft 102 configured for insertion into a patient's urethra and a handle portion 104 for human gripping. The handle may be an ergonomically designed swept-back handle that allows the user to comfortably rotate the delivery device from side to side to deliver vapor to the right and left lobes of the prostate. The vapor delivery system 100 may include a vapor delivery needle 106, shown in Figure 1B, which is positioned within the shaft and configured to extend from the distal portion of the elongated shaft 102.

[0064] The vapor delivery system 100 may further include one or more triggers, buttons, levers, or actuation mechanisms configured to activate various functions of the system, including vapor delivery, needle advance / retraction, saline or cooling fluid flushing, etc. In some embodiments, needle advancement may be visualized through a cystoscope 117 via markings along the distal length of the needle. In other embodiments, one or more magnetic sensors detect the magnetic field of a magnet 107 that drives the vapor delivery needle. Electronic equipment translates the magnetic field measurement into the position of the magnet (and needle), which may be displayed on a monitor.

[0065] The steam delivery system 100 may include a sterile water source 10, a suction source 20, a fluid cooling or irrigation source 30, a light source 40, and an electronic controller 50 configured to control the generation and supply of steam from the steam source through the lumen of the shaft, through the steam delivery needle, and to the tissue. In some embodiments, the electronic controller may be located on or within the steam delivery system, and in other embodiments, the electronic controller may be located in an external console as shown in Figure 1E. In a preferred embodiment, the controller electronics are located partly within the delivery system and partly in the external console, and the two electronic circuit boards are connected by a cable 60.

[0066] The steam delivery system 100 shown in Figures 1A-1E may further include a solenoid needle driver 110 and a steam generator 112. The solenoid needle driver 110 may be configured to advance and retract the steam delivery needle 106 of the steam delivery system. The solenoid needle driver may include a steam delivery needle, a pull winding 116, a push winding 118, and a magnet 107 positioned on the steam delivery needle. The magnet 107, and thus the steam delivery needle, can move laterally by generating a magnetic field in the push winding 116 and the pull winding 118, thereby advancing and retracting the steam delivery needle. During retraction, the current through the solenoid is reversed, with coil 116 becoming the push winding and coil 118 becoming the pull winding. The solenoid current may be controlled in real time in response to one or more sensors 124 that detect the position of the needle drive magnet. In a preferred embodiment, one or more Hall magnetic field sensors are used to measure the magnetic field of the magnet 107 and thereby calculate its position relative to the retracted position. In some embodiments, the solenoid current is measured and used to compensate the Hall sensor signal for the magnetic field generated by the current in the solenoid coil. Closed-loop control of the needle magnet position is achieved by a PID control loop, which is driven by continuous adjustment of the solenoid current so that the difference between the commanded magnet position and the actual magnet position is zero. In closed-loop control mode, pulsed and continuous needle movement can thereby be achieved at variable speeds with known and carefully controlled magnet and needle positions relative to the retracted position. In some embodiments, the needle can be commanded to move at a speed of 0.5 mm / second, or in a speed range of 0.1 mm / second to 10 mm / second, or in a speed range between 0.25 mm / second and 4 mm / second. Since the speed is maintained by the control loop, the solenoid current will automatically increase if the needle tip encounters an obstacle, such as the prostatic capsule wall. As a safety feature, the solenoid current can be monitored in real time, and if the solenoid current exceeds a critical value indicating the presence of an obstacle, an alert or automatic shutdown can be triggered. This is especially important if the obstacle is a coated wall.

[0067] The steam generator 112 may include a coiled metal tube 120 through which sterile water flows, which is converted into high-quality steam when a direct current or alternating current is passed through the tube walls. The steam passes through a delivery device needle for delivery to target tissue. The steam generator 112 may include a coiled tube 120 of Inconel 625 stainless steel, with electrical leads for direct current or alternating current attached to its ends. The Inconel tube is covered with a thin-walled, electrically insulating material 122 such as polyimide to ensure that current flows through the entire length of the tube without short-circuiting between adjacent tube windings. Inconel 625 is an example of a metal with a very low temperature coefficient of electrical resistance, so that ohmic heat is applied uniformly along the length of the tube, regardless of a substantial temperature gradient along the length of the tube. Polyimide is an excellent electrical insulator over a thickness small enough to provide good thermal conductivity between adjacent tube windings, thereby minimizing the temperature gradient along the heating element tube. The polyimide insulator may have a thickness of 10 to 100 microns. Sterilized water is introduced into the steam generator coil 120, and a DC or AC current is applied through the wall of the steam generator coil tube to dissipate ohmic heat in the electrical resistance of the tube material along the length of the tube. The steam coil may be connected to a source of sterilized water via a plastic tube 10 extending from the inner coil to a fluid source. The steam exits from the distal end of the tube into a steam delivery needle 106, for example, made of PEEK. A consistent calorific steam output is ensured by measuring and controlling the ohmic heating power dissipated in the tube. The heating power is measured as the product of the current flowing through the tube and the voltage across the tube. The heating power is controlled to a set value in real time.

[0068] Figure 1B shows one embodiment of a vapor delivery system 100 comprising two separable systems: a delivery device handle 103 and a cartridge 104 that can be removed from the handle 103. The handle 103, along with electronics in an external console, includes buttons and actuators that engage with a circuit board 50 which controls the movement of the needle and vapor delivery, and processes and / or relays information from sensors such as a thermocouple (not shown) on a heating element 112 and a sensor located on a needle 106 (e.g., Figure 6) that senses the position and orientation of the needle relative to prostate tissue. Cable 60 connects the sensors and electronics in the delivery device handle 103 to the external control system. Cable 70 connects the cartridge heating element 112 and sensor to the external console. Alternatively, cable 70 may be plugged into the delivery device handle 103, with some of the lead wires passing through cable 60 to the console. Cables 60 and 70 from the handle 103 and cartridge 104 converge at a point between the delivery system and the external console and can enter the external console via a single connector.

[0069] In one embodiment, the handle 103 is reusable, while the cartridge 104 is disposable. Generally, a two-piece design allows the cartridge to be inserted for different types of procedures. For example, in a prostatectomy procedure, the cartridge containing needle 126 in Figure 1D may be used to treat the peripheral region of the prostate, while the cartridge containing needle 106 is used for treating other areas of the prostate. Cartridges may contain needles with different hole patterns and various needle lengths for treating other tissues. Some cartridges may contain advanced sensor systems, for example, to track the needle tip or to measure the vapor temperature or pressure at the needle tip. Cartridges can have a variety of functions and costs. The two-piece design in Figure 1B allows for the replacement of application-specific cartridges without discarding a handle that contains relatively expensive electronic equipment.

[0070] In the two-piece design shown in Figure 1B, the cartridge 104 can rotate within the handle 103. This feature allows the handle 103 to be held stationary while the cartridge and needle tip are rotated to penetrate the prostatic tissue surrounding the prostatic urethra. The single-piece system shown in Figure 1A requires the user to rotate the entire device to address all prostatic tissue.

[0071] Figure 1C is a close-up view of the distal portion of the shaft of the steam system 100, including a steam delivery needle 106 that extends beyond the shaft and exposes steam delivery ports 108. The steam delivery needle may extend approximately perpendicular to the shaft or laterally from the shaft. The needle tip may include one or more steam delivery ports 108 configured to deliver a flow of steam medium from the needle to the prostatic tissue. The steam delivery ports 108 may be arranged in a pattern that optimizes the delivery of steam to the tissue in a given application. Generally, each steam delivery port may have a unique diameter. In one embodiment, all steam delivery ports have the same diameter. In one embodiment, the steam delivery holes occupy a reduced length near the needle tip to deliver steam to the thin portion of the prostatic margin without allowing steam to pass through adjacent prostatic areas.

[0072] Figure 1D compares a typical hole pattern of vapor delivery ports 115 in a needle 106 having three rows of four vapor delivery ports spaced equally around the needle circumference, occupying 4 mm along the distal end of the needle. Figure 1D also illustrates an embodiment of a peripheral needle 126 having vapor delivery ports 115 spaced in a staggered pattern. In the illustrated example, needle 126 includes nine vapor delivery ports occupying only 2 mm at the distal end of the needle. The hole diameters of the nine-hole pattern are selected so that the total cross-sectional area of ​​all vapor holes remains the same as that of the twelve-hole pattern, thereby ensuring that the vapor outlet velocity is approximately the same in both needles.

[0073] System 100 may further include a lumen (lumen 117 in Figure 1A) large enough to house an endoscope or camera to provide additional display and feedback to the physician. This endoscope or camera can provide a view of the distal end of the shaft and adjacent tissue, including a view of the vapor delivery needle when deployed, and markings on the needle indicating the deployed length of the needle.

[0074] Figure 1E shows an example of various electronic components incorporated into the vapor delivery system described above. This system may include, as described above, an electronic controller or external console 151, a handle 103, and a cartridge 104. For illustrative purposes, the cartridge and handle are schematically illustrated together, as in some embodiments these components are not separate, and many of the electronic components may be interchangeably located in either the system's handle or cartridge. While the electronic components are distributed between the console, cartridge, and delivery device handle in Figure 1E, it should be understood that the electronic components can be moved between various components. FPGAs 152 located in the console and 153 located in the handle are configured to communicate with each other to monitor and process the system's sensors and actuators, and to control the needle movement and vapor delivery. The advantages of FPGAs include their extremely high speed for real-time feedback of rapidly changing signals, their small size, and their parallel processing architecture for simultaneously handling multiple delivery system functions.

[0075] The steam generator of this system may include a steam coil 120 and a steam controller 121 configured to heat the coil and generate steam by controlling the DC power supply to the coil. In some embodiments, the steam coil may be located within the system's handle. Delivery of saline or fluid from the console to the generator can be achieved by controlling the saline pump with FPGA 152. The steam generator current required to deliver the maximum steam flow rate to the tissue may reach up to 25 amperes in some applications. Relatively heavy energized leads with low electrical resistance may include two parallel strands of AWG#22 magnet wire for both the outgoing and return leads. These leads may pass through the delivery device handle or may be wired to the console without entering the delivery device handle. Similarly, some or all of the leads from the sensor in the delivery device cartridge may be wired through the handle for processing at FPGA 153 or wired directly to the console for processing at FPGA 152.

[0076] The system may incorporate a solenoid 156 within the handle / cartridge to advance / retract the vapor delivery needle. The magnet on the needle may be moved by the solenoid as described herein. The operation of the vapor delivery needle for advancement and retraction may be controlled by a solenoid controller 157.

[0077] These systems may include multiple sensors located in the console, handle, and / or cartridge. For example, a sensor with lead wires terminating in the cartridge includes a needle tip bioimpedance electrode 154 configured to sense the proximity of the needle to the prostatic capsule. The corresponding bioimpedance electronic device 155 may be located in either the handle / cartridge or the console. Needle tip tracking electronic device 158 and one or more coils 159 may be configured to sense an external magnetic field used to track the position and orientation of the needle tip (alternatively, this coil may transmit an alternating magnetic field sensed by an external sensor). In some embodiments, the external magnetic field is generated by a tracking coil 162 in the console. These tracking coils may be located outside the console, for example. In some embodiments, one or more thermocouples 160 located on the steam generator coil 120 measure the steam outlet temperature and enable automatic shutdown of the heating current if the temperature is out of range. Lead wires attached to the end of the steam generator may be configured to measure a voltage across the steam generator in order to calculate the power supplied to the steam generator. The sensor leads may consist of thin insulated wires, such as AWG#30 magnet wire. These leads may also be wired to a delivery device handle, where they can be digitized and processed by FPGA153 and transmitted to FPGA152 as needed. A magnetic field sensor 161 (e.g., a Hall sensor) may be configured to sense the magnetic field of solenoid 156, from which the position of the magnet relative to the retracted position can be calculated by FPGA153 and relayed to FPGA152 for real-time feedback of the solenoid current to control the magnet position.

[0078] The switch states for activating the steam and saline flush and the control of needle movement are sensed by FPGA153 and can be transmitted to the console and FPGA152 for activating these functions.

[0079] The console in Figure 1E may further include a microprocessor 163 (MCU) capable of communicating with both the FPGA 152 and a single-board computer 164 (SBC) that controls the graphical user interface 165 (GUI). In one embodiment, the MCU communicates with a one-wire security chip, which is typically located near a cable connector, which may be a cable connecting the cartridge and the handle and / or a cable connecting the handle and the console. The MCU reads security chip information, such as the serial number, treatment mode, and information about previous use, and writes information, such as the number of vapor shots and parameters for each shot.

[0080] Accessory sensor inputs and coil driver outputs may be connected via the console shown in Figure 1E. For example, the tracking coil 162 shown in Figure 1E may function as an electromagnetic field sensor or as a current driver for generating an alternating magnetic field. Needle tip tracking data may be calculated in the console SBC and displayed to the user on a GUI or external monitor. Other data that may be input to the console include real-time images such as ultrasound or cystoscopy images, and sensing and controlling the irrigation of saline solution to the tissue surrounding the prostate for cooling during vapor delivery.

[0081] Please understand that the electronic component shown in Figure 1E can communicate with some or all of the other illustrated electronic components.

[0082] Real-time tracking of vapor delivery needles The vapor delivery needle of a vapor delivery system is configured to advance into the prostate through the prostatic urethra for vapor delivery. However, care must be taken to prevent the needle from advancing completely through the prostate and puncturing the prostatic capsule, resulting in the vapor being accidentally delivered outside the prostate into the patient's body. This specification describes systems, techniques, and methods for accurately tracking the position of the vapor delivery needle, particularly the tip of the vapor delivery needle, to prevent the vapor delivery needle from accidentally puncturing or penetrating the prostatic capsule.

[0083] Transrectal ultrasound imaging In some embodiments, a transrectal ultrasound imaging system (TRUS) is used in adaptive mode to maintain focus on a plane containing the needle tip. The plane of the needle tip is kept in focus by adjusting the ultrasound field of view. Mechanisms for translating and rotating the image sensor facilitate autofocus. In some embodiments, a sensor or transmitter may be placed on the TRUS to track the position of the needle tip relative to the ultrasound image. In other embodiments, both the position of the needle tip and the TRUS are tracked and superimposed. In this case, sensors may be placed on the TRUS to track the probe position with a sensor array that also tracks the movement of the needle tip.

[0084] In one embodiment, the vapor delivery needle tip can be imaged by a TRUS probe. The vapor delivery needle tip can be visualized in real time on the ultrasound image when it is within the imaging plane of the TRUS transducer. The image of the vapor delivery needle may be enhanced by an ultrasound contrast agent (e.g., a porous material) placed at or near the needle tip. In other embodiments, a reflective material placed at the needle tip can enhance the visibility of the tip. For example, features of the electrode tip, such as a gold-plated tip electrode or copper GPS coil(s), can enhance the reflectivity and visibility of the needle tip. Furthermore, since vapor is a good ultrasound contrast agent and shows a bright cloud around the tip in the image, the vapor delivery needle tip can be clearly identified by emitting steam or vapor from the needle tip hole. The Doppler ultrasound image may further show a map of the vapor velocity that is maximum at the vapor outlet hole of the needle tip. The head of the ultrasound transducer can be translated and / or rotated to focus on the needle tip. This technique allows the needle tip, which is at the center of the vapor cautery, to be identified before, during, and after vapor cautery. The movement of the needle to the next ablation site can be clearly identified on the ultrasound image by maintaining focus on the needle tip during the movement. In some embodiments, a computer controller may be configured to identify the needle tip in the ultrasound image and automatically adjust the translation and rotation of the TRUS probe to maintain focus on the tip image during needle movement.

[0085] One embodiment of the autofocused TRUS probe 200 is shown in Figure 2A, which includes a transducer 202, a stationary sheath 204, an inflatable stabilizing balloon 206 located at the distal end of the TRUS probe, an inflatable cuff balloon 208 located at the proximal end of the TRUS probe, a translational / rotational actuator 210, electronic equipment 212, and an optional battery (for wireless operation), as well as an optional flexible cable 214 (for wired operation). As shown, the ultrasonic transducer head of the TRUS probe can be rotated and translated within the rigid stationary sheath by a small computer-controlled linear and rotational actuator 210 controlled by the electronic equipment 212. Power and data can be transmitted to a control computer via a flexible cable. In some embodiments, power is supplied by a battery contained within the probe, and data is communicated by a wireless transceiver, eliminating the need for a flexible cable.

[0086] The TRUS probe is inserted into the patient's rectum and positioned close to the patient's prostate. Once positioned, the TRUS probe can be stabilized by inflating the distal stabilization balloon 206. If gas is used to inflate the balloon, no part of the balloon should be between the ultrasound transducer and the prostatic tissue being imaged, as the gas attenuates and scatters the ultrasound beam. If part of the balloon is between the transducer and the prostatic tissue, it is preferable to inflate the balloon with a fluid that does not distort the ultrasound image, such as degassed water or saline. An inflatable cuff balloon 208 can be inflated to further stabilize the TRUS probe. The system controller may automatically maintain focus of the vapor delivery needle tip using the composite electromagnetic tip tracking and ultrasound imaging system presented below, or the user may adjust the focus via a user interface.

[0087] Figure 2B is a cross-sectional view showing the interior of a TRUS probe, including features that allow translation and rotation of the TRUS transducer 202 within a balloon-stabilized sheath. The TRUS transducer may include a pair of stepper motors 222 and 224 configured to engage with a central rod or cable 226. Stepper motor 222 may be configured to radially rotate / translate the transducer 220 relative to the rod or cable 226, and stepper motor 224 may be configured to linearly advance / reverse the transducer along the rod or cable 226.

[0088] Figure 2C shows an embodiment in which a physician or system user can use a foot pedal 216 to activate the translation and / or rotation of the TRUS transducer 200 to maintain a portion of the ultrasound image, such as the needle tip, in focus during treatment.

[0089] Methods for Steam Therapy Guidance Methods for safe and effective vapor delivery to the prostate include avoiding prolonged or excessive vapor delivery to tissues near the prostatic capsule to avoid damage to tissues outside the capsule, including nerves and rectal tissue. Vapor is not delivered within a critical distance from the prostatic capsule. Short vapor delivery shots with sufficient time for tissue cooling between shots prevent excessive heat conduction to the outside of the prostatic capsule.

[0090] Steam therapy may be delivered locally to areas within the prostate that have been identified as cancerous through MRI imaging analysis and / or tissue biopsy. Alternatively, a specific region of the prostate or a hemisphere of the prostate may be ablated in a single steam therapy delivery session. In some procedures, the entire prostate may be ablated using steam therapy. In all these cases, it is important to deliver steam to a selected target location within the prostate. A single steam therapy shot can ablate a nearly spherical area of ​​tissue with a diameter of 1–2 cm, depending on the power and duration of the therapy delivery. Steam may be reflected from the prostatic capsule or from tissue boundaries between prostatic regions. In these cases, the lesion may not be spherical and may follow a pathway through the tissue of a specific prostatic region. The peripheral regions of the prostate, where prostate cancer primarily develops, may consist of a thin layer adjacent to the prostatic capsule, which extends over most of the prostate. The goal of any cancer treatment is to ablate all cancer while minimizing damage to non-cancerous tissue.

[0091] For these reasons, it is important to evaluate the ablated tissue to understand where the steam is delivered within the prostate and to plan the location of subsequent steam delivery. As mentioned above, the steam delivered from the steam delivery needle can be seen on ultrasound images as bright reflections from steam bubbles and / or from Doppler images of the steam velocity. In ultrasound images taken after steam treatment, ablated tissue may appear as dark areas due to the presence of condensed steam. Digital subtraction images showing the difference between before and after treatment can enhance the contrast of ablated tissue.

[0092] In one embodiment, the steam generator of the system may be configured to introduce air into the steam flow. Referring to Figure 3, the steam generator 312 may include a coil 320 consisting of multiple loops of an insulating tube 321 configured to receive a fluid such as sterile water through an inlet 322. By applying an electric current to the coil via lead wires 323, the coil can be heated to generate steam at an outlet 324. In this embodiment, air can be introduced into the steam flow by opening an electronic valve 325 to the air and closing the electronic valve immediately before the end of steam delivery. The air is drawn into the steam flow by the Venturi effect. In other embodiments, air may be injected into the steam flow by, for example, using a pump or fan to inject or deliver air. During use, the air remains in the cauterized tissue after steam delivery. The air is slowly reabsorbed over a period of time (e.g., several minutes). Ultrasonic images observed after steam delivery will be brightly displayed in areas of cauterization reflected from the air, thereby providing a map of the cauterized tissue. Such images may be saved and retrieved for later evaluation.

[0093] Similarly, referring to Figure 3B, a flowchart illustrating a method for tracking prostate treatment is presented. This method may be performed using any of the systems and apparatus described herein. Referring to operation 302, the method may include the steps of generating vapor in the treatment system and, in operation 304, delivering the vapor to a location within the prostate in the treatment system. As described herein, the vapor delivery system may include a transurethral shaft and a vapor delivery needle configured to access the prostate through the prostatic urethra. During treatment, the user of the system can move the shaft to a desired location within the patient's urethra and extend the vapor delivery needle from the shaft into the prostate.

[0094] In operation 306 of the flowchart, the method may include the step of injecting a predetermined volume of air into the prostate at that location. This injection of air may occur before, during, or after the steam is delivered to that location in operation 304. As described above, in one embodiment, the steam therapy system may include a steam generator having an air inlet that allows air to be injected into the steam flow by opening and closing a valve. In some embodiments, the method may include injecting a known volume of air into the prostate at that location. In other embodiments, the user of the device may inject any volume of air into that location. For example, it may be desirable to inject a larger volume of air into the prostate at the first or last treatment location.

[0095] In operation 308, the method may optionally include a step of repeating operations 304 and 306. Specifically, the method may include a step of positioning a vapor delivery needle at one or more additional locations within the prostate and delivering vapor at each of those locations. Furthermore, the method may include a step of injecting a predetermined volume of air at each of these additional locations. In some embodiments, the volume of air injected may be the same at each location. In other embodiments, more or less volume of air may be injected. For example, it may be desirable to inject a larger volume of air than usual at the first or last location. This can then be used later to determine where the prostatic procedure began or ended.

[0096] In flowchart operation 310, the method may include a step of visualizing the injected air within the prostate to track the location of the treated prostate. In some embodiments, the step of visualizing the injected air may include visualizing the prostate with an ultrasound imaging system. As described above, the injected air within the prostate will appear in the ultrasound image as a bright or white volume within the prostate tissue. Thus, the location within the prostate that has been treated with vapor and injected with air will be easily visible in the ultrasound image. In some embodiments, the method may further include a step of creating a map of the treated locations within the prostate. The map can then be displayed to the system user to provide real-time feedback on the progress of the procedure.

[0097] Tracking of the needle tip using a delivery device shaft sensor Methods and techniques for the safe and effective navigation of vapor delivery needles may include image guidance using real-time ultrasound and / or preoperative MRI images. In one embodiment, referring to Figure 4A, tip tracking of the vapor delivery needle may be facilitated by a magnet 428 embedded in or near the tip of the vapor delivery needle. The illustrated embodiment shows a permanent magnet in the needle, but it should be understood that this component may also be called a magnetic field transmitter.

[0098] Furthermore, referring to Figure 4B, one or more sensors 430, such as magnetic sensors, may be positioned at or near the distal end of the vapor delivery device shaft and / or in strategic locations around the surgical site. Sensor lead wires 432 along the shaft of the device can electrically couple the sensors 430 to, for example, a console or electronic controller. The sensors 430 may include, for example, axial windings 430a (e.g., coil windings on the outer circumference of the shaft) or lateral windings 430b (e.g., coil windings located on the side of the shaft). The position of the sensors may be fixed relative to the position where the vapor delivery needle exits the shaft.

[0099] In one method of use, the navigation of the device may occur in pulse steps in which the tip of the vapor delivery needle moves a predetermined distance in a short time. Changes in the position of the vapor delivery tip may be sensed during the pulsed movement of the needle. For example, the magnetic field generated by the pulsed movement of the magnet at the tip of the needle may be sensed by a sensor on the shaft of the device, and the sensed value of the magnetic field may be used to determine how far the tip of the vapor delivery needle is from the sensor, and therefore how far the needle tip has advanced from the shaft of the vapor delivery device. In some embodiments, as described above, the distance the needle has moved is known from a measurement made by a Hall sensor of the position of the needle drive magnet. In this case, the sensor 430 on the tip of the shaft may indicate the lateral deflection of the needle from the nominal needle tip position along a line perpendicular to the delivery device shaft.

[0100] In the embodiment shown in Figure 4B, the sensor 430 may include multiple orthogonal coils of wire located on or near the distal end of the shaft. In one embodiment, as shown, two coils may be wound around the side of the shaft tip, and a third coil may be wound around the axis of the shaft. By sensing the magnetic field of the needle tip magnet 428 in motion, the assumption that the needle path is known is relaxed, and the x, y, and z coordinate trajectory of the tip relative to the shaft tip is provided. The measured trajectory of the needle tip may be oblique or curved relative to the shaft, and can be registered on the TRUS image since the shaft is visible in the ultrasonic image.

[0101] In some embodiments, the needle tip magnet 428 may be a coil 528 of wire positioned near the needle tip, as shown in Figure 5A. Referring to Figure 5A, the coil may be positioned proximal to the needle tip, including a vapor delivery port 515 and a bioimpedance electrode 554. As shown in Figure 5A, in one embodiment, lead wires 532 for the bioimpedance electrode and coil 528 may be wired into the needle through the vapor delivery port. However, in another embodiment shown in Figure 5B, the needle may include a slot 536 having channels 538 for housing the coil and lead wires, respectively. A sinusoidal current of a given frequency can be passed through the needle tip coil in Figures 5A-5B to form an alternating magnetic field that can be sensed by a shaft tip sensor (e.g., an axial or lateral coil sensor 430) in Figure 4B. In one embodiment, the shaft tip is not more than about 26 mm away from the needle tip. In this case, a relatively large signal with a very large signal-to-noise ratio is received by the sensor in Figure 4B.

[0102] In one embodiment, the shaft sensor in Figure 4B may be a coil of N=100 turns of AWG#50 wire with a diameter of 0.001 inches. In this example, the coil radius is 4 mm and the coil area is A=5 × 10⁻⁶. -5 m 2 Therefore, since the coil has no core, the relative permeability μ = 1. The voltage induced in the probe coil is as follows: V = dΦ / dt = 2πfμNAB (1)

[0103] At a frequency of 5000 Hz, which is the upper limit of the frequency range typically used for magnetic tracking within the human body, equation (1) can be written as follows: V / B = Sensitivity = 160 volts / Tesla (2)

[0104] The lateral magnetic field at a distance r from the needle tip transmitter coil in Figure 6, which is considered a magnetic dipole, is equal to the following: B = m / (4πr) 3 ) (3)

[0105] Here, the magnetic moment m of the needle tip coil is as follows. m=μ0μnaI (4)

[0106] In one preferred embodiment, the magnetic permeability μ of the needle-shaped coil in FIG. 5A is equal to 3, the coil is wound with n=300 turns of AWG#51 magnetic wire, a=1×10 -6 m 2 is the coil cross-sectional area at the wall of a vapor delivery needle of 1.25 mm. The current I is selected as the maximum alternating current at 5,000 Hz that can be supplied before the coil becomes hot. A typical safe current for this coil is 0.04 amperes rms. The magnetic permeability of the coil may be provided by winding the coil over a magnetic permeable foil 540, or by winding the coil with a magnetically permeable wire such as a nickel magnetic wire, for example. In embodiments using a magnetically permeable foil, a gap 542 may be provided in the magnetically permeable foil to prevent circumferential eddy currents in the foil that tend to cancel the magnetic field generated by the coil. In this example, the magnetic moment of the needle tip coil in equation (4) is then m=4.5×10 -11 T‐m 3 and the magnetic field of equation (3) at a maximum separation of 0.026 m is 2×10 -7 Tesla rms, and the voltage induced in the shaft tip sensor from equation (2) is V=32×10 -6 Volts rms. The noise voltage of a typical low-noise amplifier is generally in the range of 3×10 -9 ×sqrt(BW) volts rms, where BW is the output signal bandwidth. When averaging the measured effective voltage at a rate of 10 samples per second, the bandwidth is 10 Hz, and the effective noise of the amplifier is about 9.5×10 -9 volts rms. And the expected signal-to-noise ratio at the maximum separation between the needle tip and the shaft sensor is as follows. S / N=32×10 -6 / 9.5×10 -9 =3,400

[0107] In other words, at relatively small distances between the needle tip transmitter coil and the shaft tip sensor, the received signal is more than 3000 times louder than the noise. This can be seen by differentiating equations (2) and (3) together and converting it to the expected uncertainty of the calculated position of the transmitter coil, as follows: Since δr = r / (3S / N) = 0.0025 mm or a very small amount, sensor noise does not become a limiting factor in positioning the needle tip relative to the shaft tip.

[0108] In the case of the needle-tip magnet in Figure 4A, the magnetic field of the stationary magnet is DC, and it is well known that many noise sources, both natural and artificial, make it difficult to distinguish a DC signal from such a small magnet. The induction coil axis sensor in Figure 4B has zero sensitivity to DC and generates an induction signal that increases with frequency. If the needle is moved rapidly in small steps at high speed, the sensor in Figure 4B will see an AC signal corresponding to the rise time of the magnet's step movement. In the embodiment of Figure 4A, the embedded permanent magnet has no lead wires and does not require electronic equipment at the needle tip. This is advantageous compared to a needle-tip coil because it is difficult to place lead wires inside the needle without affecting the function of other needles. When the magnet moves in pulse steps, the voltage induced in these coils is the rate of change over time of the magnetic flux coupling the coils.

[0109] V ind =-dΦ / dt=-(dΦ / dx)(dx / dt) (5) In the formula, Φ=magnetic flux (Tesla-m 2 It is a unit. dx / dt = Magnet velocity (in m / s) V ind = Induction voltage (in volts)

[0110] To estimate the magnitude of the magnetic flux connecting one of the coils, the magnet is considered a point dipole having the following minimum (lateral) magnetic field at a distance x from the needle tip.

[0111] B = m / (4πx 3) (6) dB / dx = -3m / (4πx 4 ) During the ceremony, B = dipole magnetic field (in Tesla units) m = dipole moment of the tip magnet (Tesla - m) 3 unit) x = distance between the tip magnet and the sensor (in meters)

[0112] For oriented rare-earth magnets, the dipole moment is given by the following equation. m = MV (7)

[0113] In the formula, M is the magnetization of the magnet and V is the volume of the magnet. The magnetization M is the residual induction B of these oriented magnets. r It is equal to . The magnetic material is selected to withstand the heating of the tip during vapor delivery. In the case of such a magnet, the residual induction can be as low as M = 1.3 Tesla. Considering the cylindrical tip magnet of Figure 4A with dimensions of 0.030 inches in diameter × 0.030 inches in length, the magnetic moment in equation (7) is as follows: m = 3.5 × 10 -10 Tesla-m 3

[0114] The distance between the tip magnet and the sensor placed at the tip can be as small as x=25mm=0.025m, and at this distance, the magnetic field and its gradient can be obtained using equation (6). B = 1.8 × 10 -6 Tesla (8) dB / dx = -2.1 × 10 -4 Tesla / m

[0115] In the case of a coil sensor, the magnetic flux coupling a coil with N turns in area A is as follows: Φ=NAB dΦ / dx = NAdB / dx

[0116] Considering a coil with a radius of 4 mm and 100 turns, the following applies: Φ = 9 × 10 -7 Tesla m 2 dΦ / dx = -1.1 × 10 -4 Tesla-m

[0117] Equation (5) gives an estimated value of the voltage induced in the sensor coil when the tip speed is assumed to be approximately 0.5 m / sec. V ind ≈ 5.3 × 10 -5 bolt

[0118] The input voltage noise of a typical precision amplifier chip is 3 nV / Hz. 1 / 2 Therefore, within a 100Hz bandwidth centered around the expected frequency (=1 / pulse travel time) of 1000Hz, the sensor noise is 30nV or less. V noise = 3 × 10 -8 bolt

[0119] Therefore, the minimum signal / noise ratio expected for the localization of the needle tip sensor by the shaft tip coil sensor is estimated as follows: Signal / Noise = V ind / V noise =1,800

[0120] The accuracy of the needle tip position is equal to the distance between the needle tip and the shaft coil sensor divided by three times the signal-to-noise ratio. Therefore, the coil tip sensor of this embodiment is expected to have the following tracking accuracy. δx = x / 5400 = 0.005 mm (9)

[0121] This is negligible and indicates that sensor noise does not affect the accuracy of needle tip positioning relative to the delivery device shaft. While users may perceive needle tip movement as continuous, at a microscopic level, the movement consists of pulses. For example, these pulses are fast, each potentially ranging from 0.1 to 0.3 mm. The induction coil at the shaft tip tracks changes in the needle magnetic field or changes in the position of the magnet relative to the coil at the shaft tip.

[0122] The position of the shaft tip can be observed using transrectal ultrasound imaging. A point-and-click device allows the user to indicate the shaft tip position on the ultrasound monitor, while the needle tip position relative to the shaft tip is input and displayed on the monitor.

[0123] In another embodiment shown in Figure 4C, the position and orientation of the shaft tip are tracked using an external antenna array separate from the steam device and steam needle. In some embodiments, the external array may be located outside the patient. For example, the external array may be integrated into the patient table, or alternatively, it may be located below or adjacent to the patient during the procedure. The external array may include coils 434, which are transmitting coils or receiving coils. Conventionally, external tracking coils are generally transmitters that transmit sequentially or simultaneously at separate frequencies in the range of 1 to 5 kHz. Pulsed magnetic fields from tip sensors or tip magnets may be sensed at frequencies below 1 kHz and may be distinguished from external signals by filtering. Alternatively, the external magnetic field may be sequentially pulsed in accordance with the movement of the magnet and separated in the time domain. The position and orientation of the shaft tip are calculated in relation to the external array. This data can be transposed to an image such as an ultrasound image by placing a magnetic sensor on the ultrasound probe and tracking the coordinates of both the shaft tip and the ultrasound probe. The tracking data may be transposed to other images, such as preoperative MRI, by a registration process described later.

[0124] In another embodiment, the tracking sensor may include a microchip magnet sensor, such as a GMR, TMR, or AMR sensor. The sensor noise requirements for these sensors can be calculated from equations (1) to (9) above. The advantage of magnetoresistive sensors is that their response goes down to DC. However, because these sensors have 1 / f noise, the signal-to-noise ratio is low at DC. Also, at DC, background noise cancels out the signal from the tip magnet. Pulsing the movement of the needle (and magnet) yields a signal in the bandwidth around 1 kHz where the sensor noise is minimized.

[0125] Both the solenoid coil current and the movement of the solenoid magnet are sensed by the shaft tip sensor as changes in the surrounding magnetic field, which can thus become a source of noise for the needle tip magnet or electromagnet. These magnetic fields are reduced by the relatively large separation between the solenoid and the shaft tip and the rapid decrease in the magnetic field with distance. These signatures are also known and can be compensated for as they are measured by one or more sensors in the delivery device handle. The displacement and velocity of needle deployment are obtained from the delivery device sensor and can be used to improve the tracking of the tip sensor.

[0126] The number of lead wires required for the shaft and / or needle depends on the number of sensors. For example, three sensors at the tip of a shaft require a minimum of six lead wires. Multiple lead wires entering a disposable delivery device cartridge require a low-cost method for transferring signals from the cartridge to a reusable handle and / or external system controller. Inexpensive wireless telemetry chips are available that can multiplex and digitize the sensor signals and transmit the bitstream over short distances with good resolution.

[0127] Tracking of the needle tip using a transrectal magnetic sensor or transmitter. In one embodiment, as shown in Figure 6A, a vapor delivery needle (such as the vapor delivery needles shown in Figures 5A-5B) may be tracked by a transrectal probe 600 which includes an array of magnetic sensors 630 positioned on or within the probe. In the illustrated embodiment, the sensors 630 are also shown near the distal end of the probe and near the center of the probe between balloons 606 and 608. However, it should be understood that the sensors may be positioned anywhere on or within the probe. The magnetic sensors of the transrectal probe may be configured to sense changes in the ambient magnetic field as the magnet or electromagnet at the tip of the vapor delivery needle moves through the tissue. The probe's electronics 612 can process the sensed signals to provide the x, y, z coordinates of the needle tip relative to the rectal probe. For the coil in Figure 5A, equations (2) and (3) may be evaluated by r, which is equal to the maximum expected separation between the distal sensor of the rectal probe and the needle tip. At the largest prostate at the needle position furthest from the rectal probe, the separation r will be less than 10 cm. At r=100mm, the signal-to-noise ratio (SNR) is equal to 60, and the calculated positional uncertainty is equal to 0.56mm. Since the SNR increases with the cube of the distance and the positional uncertainty decreases with the fourth power of the distance, precise (sub-millimeter) tracking is achieved at all points accessible by the needle tip, even in large prostates.

[0128] In the embodiment shown in Figure 6A, a transrectal probe including a magnetic sensor array can be inserted into the patient's rectum with the distal end of the probe positioned near the prostate. Balloons 606 and 608 can be inflated to stabilize the probe, as described above. However, unlike transrectal ultrasound imaging, good tissue contact is not required for the probe in Figure 6A, and the pressure applied to the probe can be minimal or nonexistent. In contrast to TRUS, the prostate is not mechanically moved or altered by the force of the probe. Nevertheless, the stabilizing balloons prevent movement of the magnetic sensor array, and the rigid framework for the sensors provides a rigid coordinate system for tracking the position of the vapor delivery needle.

[0129] The reference sensor 631 may be configured to provide a measurement that can be separated from the sensor 630, which is close to the prostate, when the probe is inserted into the patient, and can be subtracted from the primary tracking sensor measurement to compensate for ambient magnetic noise. This is particularly important when a DC field sensor is employed to sense a magnet in the needle tip. A microchip or electronic device 212 may be included in the transrectal probe to provide the x, y, z coordinates and orientation angle of the needle tip.

[0130] Sensors within the transrectal probe may include, for example, a fine-wire multi-winding coil as shown in the coil in Figure 6B, or any solid-state magnetic field sensor with a suitable signal-to-noise ratio (SNR). Adding more sensors provides redundant information that improves the SNR of tracking. Referring to Figure 6B, the coil may include a +y coil 630a, a -y coil 630b, a +x coil 630c, a -x coil (not shown), a +z coil 630d, and a -z coil 630e. The transrectal probe may have a key 633 and a hollow 635 relative to the ultrasound probe and be adapted to accept the ultrasound probe. Coils 630a-630e may be configured as transmitters when an alternating current is applied to the coils. A small coil on the vapor delivery needle may be configured to measure the alternating magnetic field of coils 630a-630e in order to calculate the position and orientation of the vapor delivery needle tip relative to the transmitter coil and therefore relative to the ultrasound image. The MRI image may further be fused with the ultrasound image to show the needle tip trajectory and current position on the fused MRI / ultrasound image. In some procedures, the needle tip may be displayed on an ultrasound image without an MRI image, or the tip may be displayed on a preoperative MRI image without employing ultrasound imaging.

[0131] In one embodiment shown in 6C, a preoperative MRI 3D image of the prostate can be displayed on a monitor. A stabilized rectal probe 600 having a coil sensor 630 (such as the sensor in Figure 6B) provides tracking of a needle 606 that can collect data from a needle tip transmitter coil 628 and display or overlay it on the MRI image. In one embodiment shown in Figure 6C, the ultrasound image registered in the needle tip tracking is also co-registered with the preoperative MRI image. The MRI image may indicate the location of cancerous tissue. With the needle retracted, the delivery device shaft is advanced in a position and direction within the urethra where it is predicted that the tracked and delivered needle will be positioned in the cancerous area, where vapor can be delivered.

[0132] Even without simultaneously displaying the ultrasound and MRI images shown in Figure 6C, if the coordinates of this tissue are known relative to the preoperative MRI image, and the coordinates of the MRI image are registered to the coordinates of the ultrasound image, for example by comparing the coordinates of known landmarks in the two images, the location of the cancerous tissue can be manually entered into the ultrasound image.

[0133] Registering the needle tip trajectory on preoperative MRI images is crucial to ensure that the calculated needle tip trajectory is always close to the true position of the needle tip as displayed on the MRI image. Since MRI images are taken before the steam therapy procedure, some prostate tissue may be displaced. Furthermore, the delivery device shaft may also alter the position of the prostate tissue. Registration involves electromagnetically measuring the coordinates of anatomical features appearing on the MRI image.

[0134] In one registration process, the steam therapy probe is moved to a location identifiable on the MRI image, such as the bladder neck or cusp, as viewed on a cystoscopy monitor. In one embodiment, the trajectory determined by the rectal probe sense coil is scaled so that the trajectory matches the anatomical features of the MRI image. In another embodiment, the MRI image is morphed to match a point determined by an electromagnetic track. In some embodiments, the rectal probe sense coil is replaced by a solid-state or other magnetic field sensor. In some examples, the rectal probe coil is energized with an alternating current to provide an alternating magnetic field that induces a voltage in the needle tip coil. The rectal coils may be energized sequentially or simultaneously if they are energized at different frequencies that can be resolved by the needle tip coil signals.

[0135] The needle tip coil (or magnet), particularly located within the tip of the delivery device shaft and visible on a cystoscope, may be used in a separate registration process. In an additional embodiment shown in Figure 6D, the TRUS probe 601 may be used to register MRI images to the patient's anatomical structures. The TRUS probe 601 may include an ultrasound transducer 602, a coil 603, lead wires 605a and 605b for the transducer and coil, and an optional protective sheath 606 (e.g., a condom). In some embodiments, the tool may include additional imaging capabilities such as an optical fiber camera. The probe can be moved within the rectum to locations that can be identified in the MRI images. These locations can be identified via ultrasound imaging or optionally via rectal probe optical fiber camera imaging. The probe coil or magnetic sensor 603 may be used to determine the coordinates of visible anatomical features. In some embodiments, the probe is maneuverable by operating a lever on the device. Its small profile prevents mechanical damage to prostate tissue during the registration process. Electromagnetic localization can be facilitated by a set of external transmitter coils, such as the external array shown in Figure 4C. The external transmitter coils may be positioned at other locations around the patient as needed to optimize tracking accuracy.

[0136] Other registration markers may be attached to points on the skin over bony structures that appear on the MRI image, such as the hip bone and coccyx. In some embodiments, a coil of thin wire is bonded to the skin position before the MRI procedure. The metal of the coil is visible on the image, especially if the coil is short-circuited. If these markers are left in place until the time of vapor therapy, they can be located by an external or internal electromagnetic (EM) tracking system. Since the markers are visible on the MRI image, either EM coordinate scaling or an MRI map can be modified so that the calculated EM position overlaps with the marker on the MRI image. This process may be repeated if the patient moves or if the position of a device, such as a delivery device shaft, changes sufficiently to significantly alter the position of the prostate tissue.

[0137] In the example in Figure 6D, coil 603 is wound around the probe to transmit an alternating magnetic field at a specific frequency. Because the frequencies used are unique, the sensor output can be tightly filtered at these frequencies to increase the signal-to-noise ratio. Driving a sinusoidal current to a small coil at a preferred location on the probe is sufficient to position the plane of the TRUS image relative to the probe, particularly the tip of the delivery device needle. The coil leads are required on the TRUS probe, which can be plugged into the external console in Figure 1E.

[0138] The clinical goal is to track the path of the needle tip and display that path on a TRUS image of the prostate, whether or not it is registered in an MRI image. In one embodiment, an inertial sensor chip equipped with an accelerometer and a solid gyroscope may be mounted on the vapor delivery device. Translation along the axis of the delivery device shaft and rotation about the axis of the shaft can be measured by the inertial sensor chip. Registration in imaging, such as MRI imaging or ultrasound imaging, can be performed by identifying prostate landmarks using the delivery device cystoscope. The bladder neck and seminal fold are excellent landmarks that can be uniquely identified. The rotation of the delivery device within the urethra can be measured by the inertial sensor chip. A magnetic sensor located on the handle of the delivery device is configured to measure the magnetic field of the solenoid needle drive magnet described above. The sensor measurement can be translated into the position of the magnet in the delivery device cartridge. In this way, the length of the needle that has entered the prostate can be determined. It can be assumed that the needle moves through the prostate tissue in a straight line perpendicular to (or at a known angle to) the delivery device shaft, or in a curved but predictable path. Based on this assumption and the output of the inertial sensor, the position of the needle tip can be estimated and registered in the image. In other embodiments, a magnetic field sensor may be attached to the cartridge 104 in Figure 1B. A magnetic field transmitted from an external antenna, such as in Figure 4C, can be used to position the cartridge, and by extension, the tip of the delivery device shaft, relative to an external reference frame. One or more cartridge sensors will also provide orientation for the cartridge and the needle tip.

[0139] Remote sensor for leadless needle tip tracking While multi-turn coils with a transparent core can achieve the highest sensitivity to magnetic fields, arrays of fluxgates or solid-state magnetic sensors placed near the patient can also be used to measure the pulsed motion of the vapor delivery needle tip and to limit the five degrees of freedom of the needle tip, which are the x, y, and z coordinates of the needle tip and the polar and azimuth angles of the needle tip relative to the sensor coordinate system. A typical effective magnetic field noise in a 100 Hz bandwidth centered at 1 kHz is 6 × 10⁻⁶. -10This is Tesla. The lateral magnetic field from the 25 mm tip magnet shown in equation (3) can be extrapolated to other distances r. For example, at a distance of 150 mm (approximately 6 inches) from the tip, the magnetic field is 8.3 × 10⁻⁶. -9 Tesla can divide the signal-to-noise ratio (SNR) at 83 / 6=14 using commercially available sensors, such as the Honeywell HMC1003 sensor. In one embodiment, two 3-axis sensors may be spaced apart on a rigid non-magnetic base and positioned on or near the patient's lower torso. For example, the external coil array in Figure 4C may include two or more 3-axis solid magnetic sensors. These two sensors provide six measurements of the magnetic field of the tip magnet, which is sufficient to resolve the five degrees of freedom of the magnet. This enables needle tip tracking with a passive magnetic component embedded in the needle tip, without any lead wires on the needle or the probe of the delivery device. Various magnetic sensor technologies, such as fluxgates and saturable core sensors, can be employed to detect the alternating magnetic field generated in the moving permanent magnet or needle tip coil.

[0140] Bioelectrical impedance tissue sensing Figure 5B also shows an improved vapor delivery needle tip, which includes a needle tip bioimpedance electrode 554 configured to measure the impedance of the tissue surrounding the tip. Furthermore, the bioimpedance electrode of the vapor delivery system can be used to distinguish between tissues of the prostate, for example, prostate tissue and prostatic fibrous capsular tissue. By sensing the resistance and capacitance of the tissue, the needle tip electrode can be configured to sense a change in impedance when the tip touches the wall of the prostatic capsule. Impedance is measured by passing a constant-frequency, constant-current amplitude sinusoidal wave between the tip electrodes and measuring its voltage amplitude. The impedance amplitude is the ratio of the voltage amplitude to the current amplitude. From the phase difference between the voltage and current and the impedance amplitude, the capacitance and resistance of the tissue can be calculated. The electrical resistance of the prostatic fibrous capsular tissue is greater than the resistance of the prostate tissue. The capacitance originates from the cellular tissue membrane. Less cellular capsule results in less capacitance than prostate tissue, i.e., greater capacitive reactance. Both increased resistance and decreased capacitance of the capsule lead to an increase in the magnitude of the impedance.

[0141] In one embodiment, the advance of the vapor delivery needle can be automatically stopped when the electrodes detect an increase in impedance indicating that the needle is in contact with the prostatic capsule.

[0142] When the needle tip contacts the prostatic capsule from within the prostate, both the resistance and capacitance within the prostatic tissue can change abruptly by up to 40%. The contrast is greatest in the frequency range between approximately 15 and 30 kHz. The possible frequency range is approximately 1 kHz to 10 MHz. Depending on the frequency, changes in impedance may be observed in the tissue after ablation. Impedance may differ between cancerous and non-cancerous tissue. Therefore, in one embodiment, the bioimpedance measured at the needle tip may be used by the system to both detect the presence of cancerous tissue and evaluate the success of steam therapy in tissue ablation.

[0143] Figure 5C is a flowchart providing one method for treating a patient's prostate. This method may be performed using any of the systems or apparatus described herein. In operation 502, the method of Figure 5C may include the step of transurethral insertion of the shaft of the treatment device into the patient. In operation 504, the method may further include the step of advancing the treatment needle from the shaft into the patient's prostate.

[0144] Next, in operation 506, the method may further include the step of measuring parameters of prostate tissue with a sensor placed on the treatment needle. In some embodiments, the sensor may include a bioimpedance sensor, and the measured parameter may be the electrical impedance of the prostate tissue. In other embodiments, other electrical parameters of the tissue, such as electrical resistance or capacitance, may be measured by the sensor. In yet another embodiment, the sensor may include a force sensor, and the parameter may be the force exerted by the prostate tissue on the tip of the needle. The parameters of the tissue may be monitored continuously or periodically as the needle is advanced into the prostate.

[0145] Next, in operation 508, the method may include a step of determining, based on the measured parameters, that the treatment needle has made contact with the patient's prostatic capsule. In one embodiment, when electrical impedance is being measured, the method may include a step of determining that the needle has made contact with the patient's prostatic capsule if there is a sudden change in the measured impedance. In some embodiments, this sudden change may include a change of more than 25% of the measured impedance. In some embodiments, this sudden change may include a change of more than 25-40% or more than 20-50% in the measured impedance. In another embodiment, if the sensor includes a force sensor, the determination step may include determining that the needle has made contact with the prostatic capsule when a force is applied to the needle that matches the force at which the needle advances to contact the prostatic capsule. This “critical force” may be known to the system, for example.

[0146] In some embodiments, the method may include a step of alerting the user that the prostatic capsule has been contacted by the needle tip. The alert may be, for example, a visual alert, an audible alert, or an alarm.

[0147] Next, in operation 510, the method may include the step of stopping the advancement of the treatment needle when it comes into contact with the prostatic capsule. In some embodiments, the advancement of the needle is stopped automatically. For example, the system's controller can detect contact with the prostatic capsule and automatically stop the advancement of the needle. For example, as described above, the vapor delivery system may include a solenoid needle advancement mechanism. In one embodiment, the system's electronic controller is operably coupled to a sensor and an advancement mechanism so that the system automatically stops the advancement of the needle when it detects contact of the needle with the prostatic capsule.

[0148] Tracking coil integrated with TRUS probe As described above, the embodiment in Figure 6D includes a TRUS probe 601 in which an electromagnetic coil 603 is integrated with a TRUS ultrasound imaging probe. The coil may be either a transmitter or a receiver, and the needle tip coil of the vapor delivery device may be either a receiver or a transmitter. In the former, the TRUS coil 603 may be driven by a sinusoidal current having a frequency of less than approximately 10 kHz. The low frequency limitation prevents significant induction of current in conductive body tissue. In one embodiment, the coil may be driven at a prime frequency that cannot be a lower frequency harmonic. The TRUS transmitter coil may be driven sequentially at a single frequency or simultaneously at separate frequencies. In one embodiment, the coils are driven sequentially at a frequency of 5 kHz. If localization data is to be obtained at a rate of 10 Hz, all data must be collected at 0.1-second intervals, so each coil may only be on for a maximum time of 0.1 / 6 = 16.7 milliseconds. By introducing a 1.7-millisecond blanking time between coil excitations, each coil remains on for 15 milliseconds. The time for one cycle of a sine wave is 1 / 5 millisecond = 0.2 milliseconds. The number of periods during which each coil is on is 15 / 0.2 = 75, and averaging the data over 75 periods results in a noise reduction of 8.7, which is the square root of 75. In this method, one sine wave current generator is multiplexed into each of the six coils. The needle tip coil sensor signal is tuned by amplification and filtering at the coil drive frequency, and the output is collected in segments synchronized with the coil multiplexer.

[0149] The calculations using equations (1) to (4) can be used to calculate the signal-to-noise ratio and expected localization accuracy in the system shown in Figure 6D. The coil current of the transmitter coil is ohmic I 2 The R heating is limited to a value that does not damage rectal tissue. In one embodiment, the heating power is limited to 1 watt. Since the coil is wound with approximately 150 turns of #42 magnetic wire with a resistance of approximately 70 ohms, the critical current that dissipates 1 watt of power in the coil is 0.12 amperes rms. The positioning accuracy at the needle tip coil is also sub-millimeters in this case.

[0150] The needle tip coil may be wound with magnet wire in the range of #48 to #58, and a high-permeability, low-hysteresis foil may be placed beneath the coil to amplify the signal from the needle tip coil by 2 to 10 times. As shown in Figure 5A, a 10-micron thick single-layer foil of alloy 48 may be placed beneath the needle tip sense coil 528. In this embodiment, the sensed signal can be amplified by approximately 3 times. In this regard, it is important to leave a small gap along the foil length to avoid inducing circumferential currents within the foil that could cancel out the signal. The increased signal relative to noise provides an opportunity to reduce the area of ​​the transmitter coil. A disadvantage of using a high-permeability foil beneath the sense coil is that the foil may saturate in the relatively large magnetic field found near the transmitter coil. Instead of winding a copper coil on a high-permeability foil, another method is to wind the coil with a high-permeability wire such as nickel. As a sensor, the coil is connected to a high-impedance amplifier, so little current flows through the coil that could reduce the sensed voltage.

[0151] The transmitting coil in Figure 6D may be wound with magnet wire that provides sufficient flexibility to the coil and may be driven at AC current and voltage levels that are provided safely and economically. In some embodiments, the transmitting coil in Figure 6D may be wound using magnet wire in the range of #42 to #52. The transmitting coil may include any conveniently windable shape, including circles, ellipses, squares, rectangles, and even irregular shapes that can be quantified for calculating the magnetic field using the Biot-Savart law.

[0152] In some embodiments, the transmitting coil may be integrated into the wall of the transrectal tube, as shown in Figure 7B. In other examples, the ultrasound probe is inserted into the tube shown in Figure 6B, which has an electromagnetic field winding. The outer diameter of the tube may be in the range of 2.5–3 cm, and the inner diameter may be in the range of 2.3–2.8 cm. The ultrasound probe may be inserted into the transmitter coil tube in a keyed manner to prevent the probe from translating or rotating relative to the transmitter coil. In some embodiments, the ultrasound wavelength is greater than the thickness of the tube wall, and the tube and integrated coil are inherently transparent to ultrasound. In other embodiments, for example in Figure 6D, the coil may be wound in a pattern such that the ultrasound beam does not intersect with the coil wires. The tube material may be selected so that the velocity of ultrasound is approximately the same inside the tube material and inside the body tissue. An ultrasound gel having this acoustic impedance matching property may be applied to the outside and inside of the tube between the inner diameter of the tube and the ultrasound probe.

[0153] In some embodiments of Figure 6B, the inner diameter of the tube is keyed to the transrectal ultrasound probe inserted into the transmitter tube. Locking the transmitter coil to the ultrasound probe ensures that the ultrasound image is registered in the sensor tracking coordinate system even when the TRUS probe is moved relative to the patient's anatomical structure. In other words, after factory calibration, the coordinate system of the magnetic field tracking system is the same as the coordinate system of the ultrasound image. This joint registration is advantageous over placing the magnetic field transmitter coil outside the patient or in other locations that do not move with the ultrasound probe. The user may routinely translate or rotate the ultrasound probe within the patient's anus to find the optimal field of view for a given procedure. Without a physically locked probe, such movements would need to be tracked and described by an algorithm, or the tracking system and ultrasound system may need to be re-registered after each movement of the ultrasound probe. In some embodiments of Figure 6D, the electromagnetic coil may be housed in a thin wall of flexible material impedance-matched to the ultrasound frequency. The coil may be wound around the wall of a “condom” or protective sheath that can be rolled over the ultrasound probe after the ultrasound gel has been applied to the probe. In this embodiment, the condom needs to be positioned on the ultrasonic probe so that the electromagnetic coil is properly aligned with the TRUS transducer crystal, avoiding the coil crossing the crystal and providing a reproducible coil pattern on the probe.

[0154] One advantage of integrating electromagnetic positioning with TRUS or other rectal probes is that the transmitting and receiving coils are close to each other. As seen in equation (3), the magnitude of the magnetic field, and therefore the coil sensor voltage, decreases as the cube of the distance between the transmitting and receiving coils. Systems using external coils typically require more than 30 watts of power to drive the transmitting coil. In the example above, less than a watt of power is required to achieve sub-millimeter positioning accuracy. Low power reduces the size, cost, and cooling requirements of the electronic equipment.

[0155] Another advantage of the transrectal coil system of the present invention is that interference with the transmitted signal by external metals present within the surgical area and that may change position during the procedure is negligible. The transmitted signal is distorted by metal components in close proximity to the transmitter. In the system of the present invention, no metal objects are expected in or near the prostate, and external metal objects are outside the scope of the system, so distortion is not expected.

[0156] Another advantage of the transrectal coil system of the present invention is that the sensor leads and electronic components are exposed to a small magnetic field from the transmitter. In an external transmitting coil system like the one in Figure 4C, the leads extending from the needle-tip sensor and electronic components in the delivery device handle in Figure 1 may be exposed to a magnetic field that distorts the received signal by inducing current in the leads, connectors, electronic components, and the ground surface.

[0157] Another advantage of the transrectal coil system of the present invention is that transrectal images are automatically registered to the EM track after calibration, and, in contrast to external coil systems, the registration cannot be changed during the procedure.

[0158] Needle tip coil as a transmitting coil In some embodiments, the needle tip coil in Figure 5A may be a sinusoidal magnetic field transmitter, as shown in Figure 6D, and the coil set in the rectal probe may be a receiver. Since the needle tip coil is truly much smaller than the distance between the sense coil and the transmitter coil, the equation for the magnetic field dipole applies. Combining the equations for the transmitting and sensing magnetic fields, the estimated magnitude of the sensor voltage at the far magnetic field is as follows: V = μ t N t A t μ s N s A s (μ0fI / r 3 ) (12)

[0159] This configuration is perfectly symmetrical in terms of the product of the permeability, number of turns, and area of ​​the transmitting and sensing coils. The transmitter current is determined by the power dissipation allowed in the transmitter, which can be as small as 1 watt for a rectal probe transmitter and 0.1 watts for a needle-tip transmitter. The current and induced voltage signals are scaled by the square root of the power, or, in this example, reduced to SQRT(10) = 1 / 3.2. In this configuration, the rectal probe coil may contain more turns of thinner wire. As transmitters, the resistance of these coils is limited to operate at a safe voltage, but this limitation does not apply to coils as sensors. The advantage of using a needle-tip coil as a transmitter is that it uses a continuous sinusoidal transmit current with the sensor voltage measured simultaneously, rather than a transmit current multiplexed across multiple coils. Compared to sequentially operating rectal probe transmitter coils, a continuously operating rectal receiving coil samples for a multiple of the number of coils for a longer time, thereby improving the signal-to-noise ratio. It can be shown that the localization calculation is the same whether the measured voltage is induced from the needle tip transmitter to an array of external coils, or whether the voltage induced in the needle tip coil is sensed for each external transmitter coil.

[0160] Typical needle tip tracking Figure 6E is a flowchart providing one method for treating a patient's prostate. This method may be performed using any of the systems or apparatus described herein. In operation 62, the method of Figure 6E may include the step of transurethral insertion of the shaft of the treatment device into the patient. In operation 64, the method may further include the step of advancing the treatment needle from the shaft into the patient's prostate.

[0161] Next, in operation 66, the method may further include the step of determining the real-time position of the treatment needle within the prostate. In some embodiments, the step of determining the real-time position of the treatment needle may include the step of determining the position of a sensor placed on or within the treatment needle. For example, the needle may include a magnet or electromagnet placed on or within the needle. In some embodiments, the tracking system can detect the ambient magnetic field of the sensor as the needle moves through the prostate. The tracking system may include, for example, an array of transmitter coils. In some embodiments, the tracking system can be integrated into the treatment device itself (e.g., on the shaft of the device), placed outside the device, or alternatively, integrated into a transrectal probe or transrectal ultrasound imaging probe.

[0162] Next, in operation 68, the method may include the step of displaying the real-time positions of the treatment needle and the prostate. In some embodiments, this operation includes the steps of imaging the prostate with an ultrasound imaging system and displaying the image of the prostate by overlaying the position of the treatment needle onto the image of the prostate.

[0163] Next, in operation 70, the method may include cauterization treatment of the prostate from a treatment needle. As described herein, this treatment may include, for example, the step of delivering steam from a treatment system to one or more locations on the prostate in order to treat the prostate.

[0164] Ultrasound imaging of vapor superimposed on MRI images The vapor that emerges from the needle tip and spreads into adjacent tissue can be visualized in an ultrasound image. In one embodiment, the needle tip position sensed by the tracking system may be superimposed on a real-time ultrasound image (which may be fused with an MRI image). The ultrasound monitor can display the predicted path of vapor into the tissue surrounding the needle tip. It can also display how the actual vapor spreads within the tissue and can display previously cauterized tissue. In some embodiments, the tracking system is integrated with the ultrasound system and monitor. In other embodiments, a video combiner superimposes the output of the ultrasound monitor with tracking data from the EM system computer, and the combined image is displayed on a separate system monitor.

[0165] The user can view an ultrasound image with superimposed tracking of the needle tip. An arrow may be placed at the current position of the needle tip to indicate it. Alternatively, the trajectory of previous needle positions, including the current position, may be a suitable indicator of the needle's orientation. The user may observe the needle as it approaches the prostatic capsule and stop its advance when the tip is close to touching the capsule, for example, about 5 mm. In another embodiment, the position of the needle tip relative to tissue such as the prostatic capsule may be generated in an image processing device programmed to recognize the capsule in the ultrasound image. The vapor delivery device or system may be configured to alert the user and / or automatically stop the needle's movement when the vapor delivery needle approaches or touches the prostatic capsule, thereby preventing capsule puncture with the possibility of vapor delivery to tissue outside the prostate.

[0166] In some embodiments, the delivery device handle may be mounted on a robotic arm or platform that controls the movement of the delivery device probe and needle tip, and automatically delivers the needle tip to a position specified by the user via a point-and-click or other input device. The robot may be programmed with user alarms or automatic needle movements to prevent damage to tissue.

[0167] Force sensor or electrical contact sensor at the tip of the needle The force acting on the tip of the vapor delivery needle may also be measured in the system described herein to alert the operator of needle contact with the prostate wall or capsule. A vapor delivery needle 700 having an electrical contact force sensor 702 is shown in Figure 7. In this example, the tip may be made of a flexible material 704 configured to flex very slightly when the tip contacts the prostate wall or capsule. When a critical tip force is applied, electrical contact is made between a hemispherical electrode 706 and a contact switch 708 inside the needle tip, and an alert is sent to the user via a lead wire 710. The hemispherical shape of the electrode compensates for off-axial contact between the needle tip and the tissue. The selection and width of the tip material, the nominal gap between the tip electrodes, and the tip shape determine the force required for electrical contact and user alert. Two lead wires are used to pass through grooves on the side of the needle, or channels in the needle wall, or within the vapor lumen of the needle to a microprocessor that determines that contact has been made.

[0168] Another embodiment of a vapor delivery needle with a force sensor is shown in Figure 8, in which a sensitive material 802 is sandwiched between two electrodes 804, allowing the outer electrode to bend when a force is applied at the tip 806 of the vapor delivery needle. Examples include capacitors, where the material is a dielectric, or air or vacuum. Capacitance is measured and changes with the distance between the electrodes. Piezoelectric materials generate a voltage between the electrodes when a force is applied. Piezoresistive materials change the measured electrical resistance between the electrodes when a force is applied. Sensor technology includes a magnetic field sensor at the tip that measures the distance from a magnetic source, such as the tip magnet described above. In another embodiment, the sensor may include a miniature integrated circuit including a microfabricated film or cantilever that measures acceleration, displacement, or force. The minimum number of leads from the needle tip sensor to the electronics in the delivery device is two, extending along grooves on the side of the needle, through channels in the wall of the delivery tube, or through the vapor lumen of the needle. Three leads are required when a Wheatstone bridge is integrated with the needle tip sensor. In some embodiments, the optical fiber is replaced by a lead wire, and the sensor includes a reflective film that bends under needle-tip force.

[0169] In the example above, a critical force is detected, indicating that an obstacle, such as the prostatic capsule wall, is colliding with the needle tip. It is possible to immediately stop the advance of the vapor delivery needle by stopping the needle drive force, confirm the position of the needle tip by referring to an ultrasound or MRI image, and correct the trajectory of the needle tip to prevent penetration of the capsule.

[0170] As previously described, the force exerted by the tissue on the needle can be determined by measuring the current flowing through solenoid coils 116 and 118 in Figure 1A as the needle advances through the tissue at a constant speed. At a constant speed, the net force on the needle is zero; that is, the force exerted by the tissue on the needle is equal to and inversely opposite to the force exerted by the solenoid on the needle. Since the force of the solenoid is proportional to the solenoid coil current, measuring the solenoid current provides a measure of the force on the tissue. A sharp increase in the solenoid current (the current required to maintain a constant speed) indicates that the needle tip has encountered an obstacle, which may be the prostatic capsule.

[0171] As previously mentioned, measuring the electrical impedance of the tissue placed between the electrodes in Figure 5B can provide yet another indicator of the approaching prostatic capsule. It is worth noting that the electric field surrounding the needle tip extends to some extent in front of the needle tip. The voltage between the electrodes begins to rise somewhat before the needle tip encounters the capsule. This bioimpedance measurement provides an early alert of interfering capsular tissue.

[0172] Non-Newtonian needle tip materials In one embodiment, the vapor delivery needle tip can be passively prevented from penetrating the prostatic capsule wall by configuring the needle tip to flatten when it comes into contact with the prostatic wall or capsule under relatively small pulsed or continuous navigation forces, as shown in Figures 9A-9B. When a large and rapid needle deployment force is applied, such as when the needle is first advanced into the prostate, the needle maintains its pointed shape to penetrate the urethral wall, as shown in Figure 9A. However, when the needle is slowly pressed against a more rigid tissue such as the prostatic capsule, the needle tip may be configured to flatten or blunt itself, as shown in Figure 9B. In this embodiment, the material is called non-Newtonian (a material that maintains rigidity under large, rapidly applied forces but relaxes and deforms under small, slowly applied forces). A common example of such a material is wet beach sand. An example of a non-Newtonian material is a biocompatible material such as PMMA beads, which can be used at the tip when surrounded by a shape-memory polymer coating that returns the needle to its original shape when stress is relieved. PET is a candidate for shape memory polymers.

[0173] A shortened needle tip for delivering vapor to the thin tissue areas of the prostate. The peripheral region of the prostate may be adjacent to the prostatic capsule and may be thinner compared to other regions of the prostate. When a steam therapy needle is advanced perpendicular to the urethra, the needle may enter the peripheral region parallel to its thin dimensions, which may be less than 10 mm thick. Due to the added length of the tapered needle tip, when this product is used to treat peripheral region tissue, it may inadvertently treat adjacent region tissue, cauterize the pseudocapsule separating the prostatic region, or even penetrate the capsule. The steam delivery needle described herein, as shown in Figure 1D, is designed to treat peripheral region tissue by shortening the length of the needle segment with the steam delivery hole to approximately 2.5 mm compared to 4 mm of a standard needle. The total area of ​​the hole can be made the same for various tip designs, thus ensuring that the steam velocity at the needle surface is approximately the same.

[0174] Safe and effective methods of delivering steam therapy The puncture-resistant needle tip design and needle tip tracking superimposed on real-time ultrasound and / or MR images of the prostate reduce the possibility of puncturing the prostatic capsule and delivering vapor to surrounding tissues. Nevertheless, there is still a possibility that vapor can conduct through the capsule wall, heating and damaging the tissues outside the prostate. Adjacent rectal tissues are susceptible to thermal damage and can lead to serious complications. Ejaculatory nerves are adjacent to the outer wall of the prostatic capsule, and thermal damage to these nerves can cause sexual dysfunction.

[0175] Safe and effective methods and systems for protecting sensitive tissue include limiting heat conduction to these areas. Since heat conduction is a time-dependent process, reducing the time the treatment is applied to tissue adjacent to the prostatic wall and increasing the time for cooling between treatment shots are effective means of mitigating damage to the periprostatic tissue. In a preferred embodiment, image guidance determines when the needle is adjacent to sensitive tissue that requires protection from overheating. Cauterization of prostatic tissue is performed in multiple steps that may constitute a variable cauterization time with a fixed energy vapor delivery rate of calories / second.

[0176] In some embodiments, ordinary saline solution is injected into the tissue surrounding the prostate to provide a heat sink that prevents excessive temperature rise in the tissue surrounding the prostate. The saline solution may be injected via one or more saline needles inserted into the prostate through the perineum. The saline solution injected close to the prostate physically separates the prostate from the surrounding tissue and forms a protective layer of saline. The saline solution also forms a less reflective, i.e., dark liquid layer on the ultrasound image, providing a clear image of the prostatic capsule. The clear visualization of the prostatic capsule, along with needle tip tracking superimposed on the ultrasound image, provides further protection of the capsule against needle rupture. The three-dimensional outline of the prostate can be stored in a system computer and, if the ultrasound imaging plane is changed during the procedure, can be mathematically transformed and displayed in a new figure.

[0177] Figure 10 provides a flowchart of a method for treating the prostate. This method may be performed using any of the systems and apparatus described herein. In operation 1002, the method may include the step of injecting saline solution into the tissue adjacent to the patient's prostate. The saline solution may be injected, for example, with a transperineally inserted needle. In some embodiments, enough saline solution may be injected into the tissue adjacent to the prostate to completely surround the prostate. In some embodiments, the injection of saline solution forms a fluid layer between the prostate tissue and the adjacent tissue.

[0178] Referring to operation 1004, the method may include a step of generating steam in the treatment system. In operation 1006, the method may further include a step of visualizing the prostate and the injected saline solution using the treatment system. In one embodiment, visualization includes visualization by an ultrasound imaging system. In this embodiment, the saline solution injection forms a fluid layer between the prostate and adjacent tissue, which is visualized as a dark or minimally reflective area of ​​the patient under ultrasound imaging.

[0179] In operation 1008, the method may further include the step of advancing a therapeutic needle from the treatment system into the prostate while under visualization. In some embodiments, the position of the therapeutic needle can be tracked, and a dark or minimally reflective area provided by the injected saline can be used to ensure that the needle does not advance beyond the prostatic capsule into adjacent tissue.

[0180] In operation 1010, the method may further include the step of delivering vapor to the prostate using a treatment system. As described herein, the vapor delivery system may include a transurethral shaft and a vapor delivery needle configured to access the prostate through the prostatic urethra. During treatment, a user of the system can move the shaft to a desired position in the patient's urethra and extend the vapor delivery needle from the shaft into the prostate. Vapor can then be delivered into the prostate from the vapor delivery needle.

[0181] While embodiments of the present invention have been described in detail above, it should be understood that this description is for illustrative purposes only and is not exhaustive. Certain features of the present invention are shown in some drawings and not in others, for convenience only, and any feature may be combined with other features in accordance with the present invention. Variations and alternatives will be obvious to those of ordinary art in the art. Such alternatives and variations are intended to be included in the claims. Features shown in dependent claims can be combined and are included in the scope of the present invention. The present invention also includes embodiments in which dependent claims are alternatively described in the form of multiple dependent claims by reference to other independent claims. [Explanation of Symbols]

[0182] 50 Electronic Controllers 60 Cables 100 Steam Delivery Systems 102 Shaft 104 Handle section 106 Vapor delivery needle 107 Magnets 110 Solenoid Needle Driver 112 Steam Generator 116 Pull winding 117 Cystoscope 118 Push winding 124 sensors

Claims

1. It is a prostate treatment device, An introduction shaft sized and configured for transurethral access to the patient, A treatment needle is slidably disposed within the introduction shaft, A forward mechanism, coupled to the treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate, At least one sensor is positioned at the distal end of the treatment needle and configured to sense parameters of one or more tissues of the prostate, An electronic controller operably coupled to at least one of the sensors and configured to determine whether the treatment needle contacts the prostatic capsule of the prostate based on the sensed parameters, A device equipped with.

2. The apparatus according to claim 1, wherein the parameter includes the electrical impedance of one or more tissues of the prostate.

3. Furthermore, sensing the electrical impedance of one or more tissues of the prostate gland is possible. The steps include passing a sine wave with a fixed frequency and constant current amplitude through at least one of the sensors, The steps include measuring the voltage amplitude of at least one of the sensors, The steps include determining the impedance amplitude by calculating the ratio of the voltage amplitude to the current amplitude, A step of determining the phase shift between the voltage amplitude and the current amplitude, The apparatus according to claim 2, comprising the step of calculating the electrical impedance of one or more tissues using the phase shift and the impedance amplitude.

4. The apparatus according to claim 2, wherein the at least one sensor includes at least one bioimpedance electrode.

5. The apparatus according to claim 2, wherein the controller is configured to determine that the treatment needle has come into contact with the prostatic capsule of the prostate when there is a sudden change in the electrical impedance.

6. The apparatus according to claim 5, wherein the aforementioned rapid change includes a rapid change exceeding 25%.

7. The apparatus according to claim 1, wherein the parameter includes the electrical resistance of one or more tissues of the prostate.

8. The apparatus according to claim 1, wherein the parameter includes the electrical capacitance of one or more tissues of the prostate.

9. The apparatus according to claim 1, wherein the parameter includes a force applied to the at least one sensor by one or more tissues of the prostate.

10. The apparatus according to claim 9, wherein the at least one sensor includes a force sensor.

11. The apparatus according to claim 10, wherein the force sensor is embedded behind the flexible tip of the treatment needle, and the flexible tip is configured to bend when a critical force is applied to the flexible tip.

12. The apparatus according to claim 1, wherein the treatment needle is configured to deliver vapor to the prostate gland.

13. The apparatus according to claim 1, further comprising a magnet coupled to the proximal portion of the treatment needle, the advancement mechanism comprising a solenoid actuator disposed around the magnet, the solenoid actuator comprising a push winding coupled to a current source and a pull winding coupled to a current source, the push winding configured to apply a first magnetic field to the magnet, the pull winding configured to apply a second magnetic field to the magnet, and the first and second magnetic fields move the distal tip of the treatment needle between a retracted position within the introduction shaft and an extended position at least partially outside the introduction shaft.

14. A method for treating a patient's prostate, The steps include inserting the shaft of the treatment device transurethra into the patient, The steps include advancing the treatment needle from the shaft through the patient's prostatic urethra into the patient's prostate, The steps include measuring at least one parameter of the prostate tissue using a sensor placed on the treatment needle, The steps include determining that the treatment needle has come into contact with the prostatic capsule based on at least one of the aforementioned parameters, A method comprising the step of stopping the advancement of the treatment needle when it comes into contact with the prostatic capsule.

15. The method according to claim 14, wherein the at least one parameter includes the electrical impedance of the prostate tissue.

16. The method according to claim 15, wherein the step of determining that the treatment needle has come into contact with the prostatic capsule further includes the step of detecting a sudden change in the measured electrical impedance.

17. The method according to claim 16, wherein the abrupt change includes a abrupt change exceeding 25% of the measured electrical impedance.

18. The method according to claim 14, wherein the at least one parameter includes the force applied to the treatment needle by the prostatic tissue.

19. The method according to claim 18, wherein the step of determining that the treatment needle has come into contact with the prostatic capsule further includes the step of detecting a critical force with the sensor.

20. The method according to claim 14, further comprising the step of delivering vapor to the prostate gland from the treatment needle.

21. It is a prostate treatment system, The device is equipped with a treatment device, and the treatment device is An introduction shaft sized and configured for transurethral access to the patient, A treatment needle is slidably disposed within the introduction shaft, The device comprises a forward-moving mechanism connected to the aforementioned treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate gland, At least one transmitter positioned on the treatment needle, A system comprising: an external tracking system configured to sense the position of the at least one transmitter within the prostate gland.

22. The system according to claim 21, wherein the at least one transmitter includes a magnet, and the external tracking system is configured to sense a pulsed magnetic field from the magnet to determine the position of the at least one sensor in the prostate.

23. The system according to claim 22, wherein the external tracking system comprises an array of transmitter coils configured to sense changes in the magnetic field surrounding the magnet as the magnet moves within the prostate.

24. The system according to claim 21, wherein the external tracking system is located on or inside the transrectal probe.

25. The system according to claim 24, wherein the transrectal probe includes a transrectal ultrasound probe.

26. The system according to claim 22, wherein the magnet includes an electromagnet.

27. It is a prostate treatment device, An introduction shaft sized and configured for transurethral access to the patient, A treatment needle is slidably disposed within the introduction shaft, A forward mechanism, coupled to the treatment needle and configured to advance the treatment needle from the introduction shaft through the prostatic urethra into the patient's prostate, The treatment needle comprises at least one transmitter, A system comprising: a tracking sensor positioned at the distal portion of the introduction shaft and configured to sense the position of at least one transmitter on the treatment needle relative to the distal portion of the introduction shaft.

28. The system according to claim 27, wherein the at least one transmitter includes a magnet, and the tracking sensor is configured to sense a pulsed magnetic field from the magnet and determine the position of the at least one sensor.

29. The system according to claim 28, wherein the external tracking system includes an array of transmitter coils configured to sense changes in the magnetic field surrounding the magnet as the magnet moves through the prostate.

30. The system according to claim 28, wherein the magnet includes an electromagnet.

31. A method for treating a patient's prostate, The steps include inserting the shaft of the treatment device transurethra into the patient, The steps include advancing the treatment needle from the shaft through the patient's prostatic urethra into the patient's prostate, The steps include determining the real-time position of the treatment needle within the prostate gland, The steps include displaying the real-time position of the treatment needle and the prostate gland, The steps include providing cauterization treatment to the prostate gland from the aforementioned treatment needle, A method that includes this.

32. The method according to claim 31, wherein the step of advancing the treatment needle and the transmitter positioned on the treatment needle further comprises the step of advancing them into the prostate gland.

33. The method according to claim 32, wherein the step of determining the real-time position of the treatment needle further includes the step of sensing the surrounding magnetic field of the transmitter with a tracking system.

34. The method according to claim 33, further comprising the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on the shaft of the treatment device.

35. The method according to claim 33, further comprising the step of sensing the ambient magnetic field of the transmitter with an external tracking system of the treatment device.

36. The method according to claim 33, further comprising the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on a transrectal probe.

37. The method according to claim 33, further comprising the step of sensing the ambient magnetic field of the transmitter with a tracking system positioned on a transrectal ultrasound probe.

38. The method according to claim 37, further comprising the step of registering the real-time position of the treatment needle in an ultrasound image from the transrectal ultrasound probe.

39. The method according to claim 31, wherein the step of displaying the real-time position further includes the step of displaying the real-time position of the treatment needle in the prostate.

40. A method for tracking a patient's prostate treatment, The steam therapy system involves the step of generating steam, The steps include delivering steam from the steam therapy system to a first location within the patient's prostate gland, The steps include injecting a first volume of air from the steam therapy system into the first position, A method comprising the step of visualizing the first air volume within the prostate gland to track the prostate treatment.

41. The steam delivery step is further, The steps include: introducing the shaft of the steam therapy system into the patient via the urethra; Steps include advancing the steam therapy needle from the shaft to a first position in the prostate, The method according to claim 40, including the method described in claim 40.

42. Furthermore, the steam therapy system delivers steam to a second location within the prostate gland. The steps include injecting a second volume of air from the steam therapy system into the second position, The steps include visualizing the second air volume within the prostate and tracking the prostate treatment, The method according to claim 40, including the method described in claim 40.

43. The method according to claim 42, wherein the first air volume is greater than the second air volume.

44. The method according to claim 42, wherein the first air volume is smaller than the second air volume.

45. The method according to claim 42, further comprising the step of creating a map of the locations of treated prostates.

46. The method according to claim 40, wherein the step of injecting the first volume of air is performed after the steam has been delivered to the first position.

47. The method according to claim 40, wherein the step of injecting the first volume of air and the step of delivering steam to the first position are performed simultaneously.

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