Vapor ablation systems and methods

Abstract

To provide a vapor delivery system that can apply condensable vapor energy to tissues of a prostate or the like to shrink, damage or denature the tissues of the prostate.SOLUTION: A vapor delivery system comprises a handle portion (102) and a cartridge portion (104). The handle portion has a lumen (103), and a solenoid (112) configured to generate a magnetic field. The cartridge portion includes a shaft (114), and a magnet (118) fixed to a vapor delivery needle (116) disposed in the shaft. In an assembled configuration in which the cartridge portion is inserted in the lumen of the handle portion and the vapor delivery needle is in a retracted configuration, the magnet is aligned with the solenoid. A flow of current through the solenoid moves the magnet distally to deploy the vapor delivery needle.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 437,617, filed December 21, 2016, and U.S. Provisional Patent Application No. 62 / 538,517, filed July 28, 2017, both of which are incorporated herein by reference in their entireties.

[0002] This application is related to U.S. Patent Application No. 14 / 773,853, filed September 9, 2015, and International Patent Application No. PCT / US2016 / 067558, filed December 19, 2016, both of which are incorporated herein by reference in their entireties.

[0003] All references mentioned in this specification, including patents and patent applications, are herein incorporated by reference to the same extent as if each such reference was specifically and individually indicated to be incorporated by reference.

[0004] The present invention relates to devices and associated methods for the treatment of the prostate using minimally invasive techniques. [Background technology]

[0005] The prostate gland is the size and shape of a walnut early in life, weighing approximately 20 grams before the enlargement caused by BPH (benign prostatic hyperplasia). Prostatic enlargement appears to be a normal course. The size of the prostate increases gradually with age to twice or more its normal size. The fibromuscular tissue of the outer prostatic capsule limits the enlargement of the prostate gland after it reaches a certain size. This restriction during enlargement causes the intracapsular tissue to compress and pinch the prostatic urethra, thus creating resistance to the flow of urine.

[0006] The prostate is classified into three regions: the peripheral, transitional, and central regions. The peripheral zone (PZ) contains approximately 70% of the volume of the male prostate. This subcapsular portion of the posterior aspect of the prostate surrounds the distal urethra, and 70%-80% of cancers arise in the tissue of the peripheral zone. The central zone (CZ) surrounds the ejaculatory ducts and contains approximately 20-25% of the volume of the prostate. The central zone is often the site of inflammatory processes. The transition zone (TZ) is the site where prostatic hyperplasia develops and contains approximately 5-10% of the volume of the glandular elements of the normal prostate, but in cases of BPH, it may constitute up to 80% of such volume. The transition zone contains the two outer prostatic middle lobes and the periurethral glandular zone. Natural barriers surround the transition zone, namely the prostatic urethra, the anterior fibromuscular stroma FS, and the fibrous planum FP between the transition zone and the peripheral zone. The anterior fibromuscular stroma FS or fibromuscular region is primarily fibromuscular tissue.

[0007] Approximately 70% to 80% of prostate cancers develop within and may be confined to the surrounding area of ​​the prostate. In recent years, there has been increased interest in localized prostate cancer treatments that treat only the area of ​​tissue where cancer is found after a biopsy. Prior art localized treatment procedures, such as those using RF ablation energy, may not confine treatment to the surrounding area tissue. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent Application Serial No. 14 / 773,853 [Patent Document 2] International Patent Application No. PCT / US2016 / 067558 Summary of the Invention [Problem to be solved by the invention]

[0009] In patients with advanced prostate cancer, prostatectomy may be indicated and a surgical option is desirable. A device capable of ablating the entire prostate or the entire middle lobe of the prostate via a transurethral approach is desirable. This minimally invasive approach may treat both the transition and periprostatic regions. [Means for solving the problem]

[0010] A system and method for ablating tissue in the surrounding area without ablating tissue other than the surrounding area is disclosed.The transurethral approach uses a steam delivery device to access tissue in the surrounding area located adjacent to the prostatic urethra.

[0011] Treatment of the entire circumferential area may employ a steam delivery needle that extends up to 2.5 cm from the delivery device shaft placed within the urethra. Using ultrasound and needle position sensor guidance, steam may be delivered from multiple sites along the path of the needle.

[0012] The vapor delivery needle is capable of controlled movement along its path, including stops to deliver vapor. A system and method are disclosed for controlling digitally stepped movement of the vapor delivery needle to any point within the reach of the vapor delivery needle.

[0013] Blunt needles are disclosed that are capable of penetrating the urethral wall during initial shallow deployment, but do not penetrate the prostatic capsule when the needle is advanced using a current pulse to the needle delivery solenoid.

[0014] Most prostate cancer begins in the peripheral region, and steam delivered through the needle to the peripheral region does not cross the tissue barrier to other areas of the prostate where cancer may not be present.

[0015] All regions of the prostate can be treated with a single transurethral steam delivery device. Partial or total prostatectomy may be accomplished during a single therapeutic procedure in which steam is applied to some or all regions of the prostate.

[0016] A semi-disposable steam delivery device is also disclosed in which the handle and cable are reusable, and the barrel, needle delivery shaft, and attached water and irrigation lines comprise a disposable cartridge.

[0017] Inductive coupling is used to transfer RF power from an RF coil in the reusable handle to a vapor delivery coil in the disposable cartridge.

[0018] Magnetic coupling is employed to impart contactless needle deployment force from a solenoid coil in the reusable handle to a needle deployment magnet in the disposable cartridge.

[0019] Inductive coupling may be used to communicate temperature and identification data from the disposable cartridge to the reusable handle. Because the induction coil and force coil are cylindrical and symmetrical, their function is independent of the orientation of the disposable cartridge, and thus the disposable cartridge can be rotated relative to the reusable handle, thereby allowing treatment to be administered to both sides of the prostate without having to rotate the delivery device handle between the patient's legs. A sliding contact between the disposable cartridge and the reusable handle for reading the vapor coil temperature is also disclosed.

[0020] A physician can treat BPH or cancer by selecting a disposable cartridge designed for an indicated procedure using a single reusable handle. For example, a cartridge for BPH may be simpler and less expensive than a cartridge for prostate cancer because variable and controllable needle depth is not required for BPH procedures.

[0021] A vapor delivery device is provided that includes a handle portion having a lumen and an RF coil disposed within the lumen and connectable to a source of RF energy, and a cartridge portion configured to be inserted into the lumen of the handle portion, the cartridge portion including an elongate shaft configured to be inserted into a patient's urethra, a vapor delivery needle disposed within the elongate shaft, and a vapor coil fluidly connected to the vapor delivery needle and a fluid source, wherein insertion of the cartridge portion into the handle portion aligns and positions the vapor coil within the RF coil.

[0022] Application of RF energy to the RF coil can inductively generate vapor within the steam coil as fluid is pumped from a fluid source to the steam coil.

[0023] In some examples, the vapor delivery needle is configured to deliver vapor to tissue of a patient.

[0024] The cartridge portion further discloses that includes a first solenoid coil and a second solenoid coil, and a needle drive magnet attached to a proximal portion of the vapor delivery needle, the needle drive magnet being slidably disposed within the first solenoid coil when the vapor delivery needle is in a retracted position, and being slidably disposed within the second solenoid coil when the vapor delivery needle is in an extended position.

[0025] The device may further include a needle deployment switch in the handle portion.

[0026] In some examples, depression of the needle deployment switch can fully deploy the vapor delivery needle from a retracted position to an extended position. Each depression of the needle deployment switch can incrementally deploy the vapor delivery needle. For example, the vapor delivery needle is deployed in 1 mm increments.

[0027] The device may further include a position sensor disposed on the vapor delivery needle, the position sensor configured to determine a deployed position of the vapor delivery needle, A safety feature is provided whereby the vapor delivery needle is prevented from advancing if the position sensor indicates that the vapor delivery needle has not moved a desired incremental distance.

[0028] The steam coil may, for example, comprise Inconel® tubing.

[0029] The device may further include a latch configured to prevent lateral movement of the cartridge portion when the cartridge portion is inserted into the lumen of the handle portion.

[0030] When the cartridge portion is inserted into the lumen of the handle portion, the cartridge portion can be rotated, which can be done to deliver steam to multiple locations within the prostate and to deliver steam to both middle lobes of the prostate.

[0031] In one particular example, the delivery needle may not extend more than 24 mm from the elongate shaft when it is in the extended position.

[0032] The steam delivery needle includes an inflatable balloon configured to prevent steam from escaping through a puncture in the patient's tissue. The inflatable balloon is positioned within a recess of the steam delivery needle. The inflatable balloon is inflated by steam during steam delivery.

[0033] The vapor delivery device may further include an electronic controller configured to control the delivery of RF energy to the RF coil.

[0034] It is also contemplated that the vapor delivery device may further include a temperature sensor disposed at the outlet of the steam coil, the temperature sensor being electrically coupled to the electronic controller and configured to measure the temperature of the fluid or vapor at the outlet of the steam coil.

[0035] As a safety measure, the electronic controller may be configured to initiate a cessation of RF energy delivery when the measured temperature of the outlet vapor or fluid is outside a preferred temperature range.

[0036] Also provided is a method of delivering steam to a patient's prostate, the method including inserting a cartridge portion of a steam delivery device into a lumen of a handle portion of the steam delivery device to align and position a steam coil of the cartridge portion within an RF coil of the handle portion, inserting an elongate shaft of the cartridge portion into the patient's urethra, advancing a distal end of the elongate shaft to the patient's prostatic urethra, extending a steam delivery needle from the elongate shaft into the patient's prostate, delivering a fluid flow into the steam coil, applying RF energy to the RF coil to inductively generate steam in the steam coil, and delivering the steam through the steam delivery needle to the prostate.

[0037] The extending may include generating a magnetic field using at least one solenoid coil to extend the vapor delivery needle into the prostate.

[0038] The method may further include rotating the cartridge portion within the handle portion.

[0039] In order to better understand the invention and to see how it may be carried out in practice, some preferred embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings in which like reference characters indicate corresponding features consistently throughout like embodiments and in which: [Brief description of the drawings]

[0040] [Figure 1A] 1A-1C illustrate one embodiment of a transurethral steam delivery device. [Figure 1B] 1A-1C illustrate one embodiment of a transurethral steam delivery device. [Figure 1C]1A-1C illustrate one embodiment of a transurethral steam delivery device. [Figure 2A] FIG. 1 illustrates a disposable cartridge for a vapor delivery device. [Figure 2B] FIG. 1 illustrates a disposable cartridge for a vapor delivery device. [Diagram 3] FIG. 1 illustrates a reusable handle of a vapor delivery device. [Figure 4] FIG. 1 illustrates a magnet of a vapor delivery device. [Diagram 5] FIG. 13 illustrates the direction of current passing through the push and pull coils of a magnetic actuator of a vapor delivery device. [Figure 6A] FIG. 13 shows the steam needle deployment length traveled from the BHP device to the cancer device. [Figure 6B] FIG. 13 shows the steam needle deployment length traveled from the BHP device to the cancer device. [Figure 7] FIG. 13 shows the changes to the solenoid moving from the BPH device to the cancer device. [Figure 8] FIG. 13 illustrates the resulting forces versus magnet position. [Figure 9A] FIG. 1 illustrates a technique for preventing steam leakage. [Figure 9B] FIG. 1 illustrates a technique for preventing steam leakage. [Figure 10] FIG. 2 shows an induction steam generator. [Figure 11] FIG. 13 shows an equivalent circuit for reading the outlet tube resistance temperature sensor. [Figure 12] FIG. 13 shows a delivery device inserted into the prostatic urethra adjacent to surrounding regional tissue. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Generally, methods of treating BPH (benign prostatic hyperplasia) or prostate cancer involve transurethrally introducing heated steam into the internal crevice of the prostate, where the steam controllably ablate the prostatic tissue. Such methods result in localized ablation of the prostatic tissue, and more specifically, localize the thermal energy imparted from the steam to ablate tissue adjacent the urethra without damaging prostatic tissue not adjacent the urethra.

[0042] The transurethral steam delivery device disclosed herein is used to transurethrally deliver steam into the prostate of a patient. An elongate shaft of the device is advanced into the patient's urethra and positioned within the prostatic urethra proximal to the prostate, and a steam delivery needle is inserted through the urethral wall into the prostate. Steam is then delivered through the steam delivery needle into the prostate.

[0043] Semi-disposable steam delivery device A transurethral steam delivery device 100 is shown in assembled form in Figure 1A and in Figure 1B, an exploded view, showing a reusable handle portion 102 and a disposable cartridge portion 104 of the steam delivery device. The handle portion 102 of the steam delivery device includes a lumen 103, an electrical cable 106 that plugs into an RF generator (not shown), a grip portion 107, a trigger 108 for irrigation, needle advancement / retraction, and RF power ON / OFF activation, an RF coil 110 (not shown) disposed within the lumen and configured to inductively generate steam, and a solenoid coil 112 (not shown) disposed within the handle portion and configured to advance and retract the steam needle.

[0044] The RF generator is configured to provide power and fluids to the transurethral steam delivery device for generating steam. For example, the RF generator is configured to provide RF energy to an RF coil in the handle portion. The RF generator is also connected to the steam delivery device to provide the system with power and other components essential for operation, such as irrigation / cooling fluids, suction, etc. The RF generator may include an electronic controller and a graphical user interface (GUI) to provide the user with operating parameters and control during steam therapy.

[0045] The RF generator includes an electrical connector that provides RF current to the vapor delivery device, sends or receives electrical signals to or from a switch of the vapor delivery device, and sends or receives measurements (e.g., the temperature of the vapor delivery device) and electrical signals to or from a controller of the vapor delivery device (e.g., its electrical connector), the measurements and electrical signals for identifying the vapor delivery device, tracking the history of vapor delivery, and preventing overuse of a given vapor delivery system. The RF generator may also include a peristaltic pump that provides a flow of cooling / irrigation fluid, such as saline, to the vapor delivery device.

[0046] The disposable cartridge 104 includes an elongated shaft 114 having a lumen for a cystoscope and a steam delivery needle 116, a needle drive magnet 118 (not shown) attached to the steam delivery needle and advanced or retracted by a magnetic field generated in a solenoid coil 112, a steam coil 120 inductively converting water to steam, and a plastic conduit 122 for irrigation and drainage of the bladder with sterile water or saline. The cartridge portion is configured to be inserted into the lumen 103 of the handle portion 102. When the cartridge portion is inserted into the handle portion, the steam coil 120 of the cartridge 104 may be aligned and positioned within the RF coil 110 of the handle portion, or alternatively (as shown in FIG. 10 ), the RF coil 110 may be aligned and positioned around the steam coil 120. The elongated shaft 114 is sized and configured to be inserted into the patient's urethra with a length that allows it to extend to the patient's prostatic urethra and prostate. As shown in FIG. 1B, the cartridge 104 may be rotated within the handle to facilitate delivery of steam to the left and right middle lobes of the prostate without having to rotate the handle between the patient's legs.

[0047] In some procedures, the steam treatment is at least partially guided by transrectal ultrasound (TRUS) imaging. In these procedures, the TRUS probe may prevent the steam delivery device handle from being in the vertically downward position shown in FIG. 1A. In some alternative embodiments, the delivery device handle may extend upward from the barrel of the delivery device. In other embodiments, the barrel may be modified to include a delivery device trigger and cable, eliminating the handle portion altogether.

[0048] In some procedures, the delivery device needle is advanced to deliver steam to two or more sites after initial puncture of the urethral wall. It is important that the steam delivery needle remain stable against the patient's anatomy to prevent steam leakage due to enlargement of the needle entry hole. FIG. 1C shows an adjustable delivery device holder 124 that is used to stabilize and hold the delivery device during needle delivery, advancement, and steam delivery. This adjustable delivery device holder allows the operator to focus on image-guided needle placement and treatment delivery. FIG. 1C shows an adjustable delivery device holder with a flexible, shape-changeable shaft 126 that is adjusted by the operator to maintain the position of the delivery device needle during treatment. In other embodiments, the holding device may be electronically adjusted. The holding device may be configured to advance and retract the delivery device from the urethra. The handle of FIG. 1C may be as simple as the adjustable holding device shown in FIG. 1C or as complex as a multi-axis robotic arm.

[0049] The disposable cartridge 104 is shown in cross-section in Figures 2A and 2B. The vapor delivery needle 116 is rigidly mounted to a needle drive magnet 118, which is moved laterally by a magnetic field generated by a coil in the handle portion 102 (shown in Figure 3). A vapor coil 120 is also shown in Figure 2B. The disposable cartridge includes a resistance thermometer (RTD) 119, which is wired in series with a conductive metal ring 121 via leads 123. The resistance thermometer (RTD) 119 can measure the temperature of the vapor exiting the vapor coil 120. In one embodiment, the resistance thermometer (RTD) may be wrapped around the outlet of the vapor coil.

[0050] An inductive read coil may be provided within the reusable handle. A thermocouple may be located above the RF coil in the reusable handle portion. Experience has shown that the first component to show signs of overheating (usually smoke) is the RF coil, even when it is at a somewhat lower temperature than the adjacent inner coil. Thus, the RF coil is the preferred location for a thermometer, preferably a thermocouple.

[0051] When the disposable cartridge 104 is inserted into the reusable handle portion 102, the cartridge 104 engages the diagonal coil in the handle. Cartridge insertion and withdrawal forces should be specified within strict ranges so that all cartridges are within a repeatable mechanical force range. The diagonal coil acts as a sliding electrical contact that allows rotation of the cartridge within the handle while maintaining electrical contact of the RTD outlet thermometer lead from the cartridge to the handle. When the cartridge is rotated, there is some change in the contact resistance between the ring and the coil. However, accurate temperature measurement during rotation is not necessary, thus the contact resistance or any change in contact resistance during rotation should be nulled in software. Although the outlet thermometer is shown as a resistance thermometer (RTD), other miniature sensors such as thermistors or thermocouples may be employed.

[0052] The steam coil shown in Figure 2B is connected to a supply of sterile water running through a plastic tube extending from the cartridge as shown in Figure 1A and to an RF generator. The steam coil's turns are constructed of metal tubing, such as 18 gauge plain gauge (RW) 304 stainless steel tubing or 18 gauge thin gauge (TW) plug-drawn Inconel 625 tubing. The individual coil turns may be in physical contact and may be soldered or welded together to ensure good electrical contact, but the RF current passes through a sufficiently thin oxide layer separating the turns.

[0053] The water in the steam coil 120 is converted to steam by ohmic heating caused by electrical currents flowing around the steam coil. These currents are induced by RF currents flowing in a concentric RF coil located in the delivery device handle. The alternating magnetic field caused by the electrical currents in the RF coil may be enhanced by fabricating the steam coil from a magnetically permeable material. The magnetic permeability of 300 series stainless steels changes with cold working, so it is difficult to obtain tubing lots with identical magnetic permeability. Since consistency of caloric output from device to device is very important, non-magnetic tubing is preferred for this application. Stainless steels such as 304 may be annealed to eliminate magnetic properties, or non-magnetic steels such as Inconel® 625, MP35N, Elgiloy, etc. may be selected for the steam coil. Inconel® 625 is preferred because its electrical resistance is nearly independent of temperature over the range of temperatures (20°C to 350°C) that may be experienced at the distal (steam) end of the steam coil, allowing for consistent steam delivery from shot to shot and device to device.

[0054] One or more electrical leads extend from the disposable cartridge along with the sterile water line. Wires or electrical leads are connected to an RF generator to transmit or receive signals from an EPROM in the cartridge that provide cartridge identification and usage data. Other wires in the cable can provide signals from the cartridge to a thermocouple located on a steam coil in the cartridge and other diagnostic data. In another embodiment, the EPROM and thermocouple wires can include a small cable that extends from the disposable cartridge and plug and connects to the non-disposable handle and runs through the non-disposable handle to the main delivery device handle cable. Alternatively, data can be inductively coupled from the cartridge without the need for physical leads, as disclosed below.

[0055] The reusable handle portion 102 of the delivery device is shown in more detail in FIG. 3. The solenoid coil 112 is configured in a push / pull configuration for the needle drive magnet shown in FIG. 2B. In the fully retracted needle position, the proximal end of the needle drive magnet is aligned with the proximal / push solenoid coil 112. In the fully extended needle position, the distal end of the needle drive magnet is aligned with the distal / pull solenoid coil 112. Currents are passed in opposite directions in the push and pull coils as shown in FIG. 5. The push coil induces a magnetic field that repels the opposite polarity needle drive magnet and pushes it out of the coil. Due to the repulsive forces, the magnet is not in a stable equilibrium along the axis of the push coil and tends to move laterally, which can increase the frictional resistance to contact and axial advancement between the needle drive magnet and its surroundings. The pull coil generates a magnetic field that attracts the needle drive magnet to the pull coil. The pull coil attracts the needle drive magnet to the coil axis, thereby eliminating the instability of the push coil. The combination of push and pull coils nearly doubles the force imparted by a single coil. As can be seen in Figure 5, the push / pull pair of coils also creates a backward force identical to the forward force by simply reversing the direction of the current to the coil pair.

[0056] FIG. 3 shows potential positions of a linear magnet position sensor 113 adjacent to the solenoid coil. The linear magnet position sensor 113 is configured to detect the magnetic field created by the needle drive magnet. A relatively small magnetic field is generated by the solenoid coil. The magnetic fields created by the two solenoid coils cancel each other on average and in the central plane between the coils. The voltage output of the linear magnet position sensor is a linear function of the position of the magnet (and the needle attached to the magnet). By performing a single calibration, the sensor voltage can be converted to the magnet position relative to the sensor's most proximal position.

[0057] The RF coil 110 shown in FIG. 3 is designed to be located as close as possible to the steam coil (steam coil 120 in FIG. 2B) when the disposable cartridge is inserted into the handle portion 102, resulting in maximum induction of current in the steam coil. The relationship of the RF coil and steam coil in the assembled device is shown in FIG. 10. In one embodiment, the steam coil includes 6 turns of #18 TW Inconel® 625 tubing and the RF coil includes 11 turns of #22 copper Litz wire made up of individual strands of #44 copper magnet wire. These dimensions are selected to optimize the electromagnetic coupling between the RF coil and the steam coil at operating frequencies ranging from 425 kHz to 475 kHz. The insulation on the RF coil Litz wire can be 0.002″ thick extruded PFA with a temperature rating of approximately 250° C.

[0058] In the particular embodiment shown in Figure 4, the needle drive magnet 118 is made from grade N52 neodymium-iron-boron and has an outer diameter of 15mm and a length of 18mm. The internal notch is shaped to fit over the needle mount. The residual magnetic induction (residual magnetic flux density) Br of the magnet material in this particular orientation may be approximately 1.5 Tesla.

[0059] Other features of the reusable delivery device handle include a locking latch that prevents lateral movement of the cartridge within the handle, and detents that define every 30 degrees of rotation of the cartridge within the handle.

[0060] Increased Needle Length and Pulse Delivery Because steam for cancer treatment needs to reach the surrounding middle lobe of the prostate from within the urethra, the steam needle needs to extend further from the steam delivery needle than in a BPH procedure. The position of the steam needle after deployment through the urethral wall and the fully extended position of the needle are shown in Figures 6A and 6B.

[0061] The increase in travel from 12 mm for the BPH vapor delivery needle (FIG. 6A) to 24 mm for the cancer vapor delivery needle is achieved by increasing the needle length and increasing the gap width between the two coils of the solenoid as shown in FIG. 7. For example, each solenoid coil in the BPH device includes 408 turns of #30 magnet wire, resulting in 12 mm of needle travel, and each solenoid coil in the cancer device includes 605 turns of #28 magnet wire, resulting in 24 mm of needle travel. In some embodiments, the needle cannot extend beyond 24 mm to avoid piercing the prostate capsule. However, the force required to deploy the needle with enough force to overcome friction and pierce the urethral wall cannot be achieved with the #30 gauge coil of the BPH system. In one embodiment, this force is increased by winding the bobbin with more turns of lower gauge wire. The resistance remains the same for the cancer coil and the BPH coil and is selected to optimize the current delivered from the generator 24 volt power supply.

[0062] Since the diameter of #28 gauge wire is slightly larger than that of #30 gauge wire, placing more turns of #28 gauge wire requires increasing the outer diameter of the bobbin and decreasing the wall thickness of the bobbin inner wall. The calculated forces versus magnet position are shown in FIG. 8, and the initial force of deployment and retraction is over 2 pounds, which is enough to overcome friction. The peak force is 7.1 pounds, which is more than the peak BPH needle force. The greater force is achieved by using a power supply capable of delivering more current and optimizing the wire gauge of the solenoid coil to increase the force. The power (voltage x current) delivered to the solenoid should be in the range of 100 watts to 250 watts, and the current should be ON for a time period ranging from 10 msec to 250 msec, preferably 50 msec to 150 msec.

[0063] In one embodiment, separate disposable cartridge parts using the same reusable handle part may be provided for BPH and prostate cancer vapor delivery procedures. Each disposable cartridge part includes a vapor delivery needle length that varies depending on the procedure. In an alternative embodiment, the distance between the solenoid coils in FIG. 7 may be adjustable by the operator to select the appropriate needle delivery length for both BPH and cancer procedures while using the same disposable cartridge part.

[0064] As described above, the steam delivery device is inserted transurethrally into the patient to gain access to the prostate. The steam delivery needle is deployed across or through the wall of the urethra, guided by real-time ultrasound imaging of the steam delivery needle within the prostate, and advanced to its most distal location within the prostate. Steam is delivered to perform treatment during advancement of the needle or during subsequent retraction. A user may prefer to advance the steam delivery needle in small increments rather than a very rapid deployment over a large distance as occurs during initial deployment. To achieve this goal, pulses of current are delivered from an RF generator to a solenoid coil in response to a user depressing a trigger on the handle portion of the device. A magnetic position sensor can be used to measure the movement of the magnet and the steam delivery needle and control the size of the increment. In a preferred embodiment, each pulse of current deploys the needle by 1 mm, and the rate at which the pulses are delivered when the trigger is pressed is 1-5 pulses per second. Both of these parameters may be user adjustable.

[0065] As can be seen in Figures 6A and 6B, the tip of the steam delivery needle can be blunt, which can be achieved by needle design or by removal of material at the sharp tip. The needle can be designed sharp and forceful enough to pierce the urethral wall during initial deployment, but blunt enough so that the needle advancement step with the pulse cannot penetrate the prostate capsule. The needle tip hitting the prostate capsule can be observed by the user as "tenting" on the ultrasound image. If the needle position sensor records an abnormally small needle advancement after applying the pulse, a second indication can be provided by the needle position sensor. The system can stop further advancement steps and / or provide a warning message to the user.

[0066] In some procedures, it can be difficult to prevent steam from escaping through the needle entry hole in the urethral wall. Movement of the delivery device and needle after puncturing enlarges the entry hole, facilitating steam leakage. A technique for preventing steam leakage is shown in Figures 9A and 9B. In this embodiment, an inflatable balloon material 130 is provided at a distance of 4-24 mm proximal to the steam delivery hole and in the recess of the steam delivery needle 116. During steam delivery through the steam port 117, steam also enters the balloon 130 through the hole 132 in the needle wall, causing the balloon to expand and impinge on the tissue adjacent to the needle, preventing steam from escaping back through the puncture site. The balloon material may be non-compliant and may be inflated to a diameter set during manufacture. The non-compliant balloon material may be selected from PET (polyethylene terephthalate), nylon, or other materials used in non-compliant medical balloons. The balloon material and thickness may be selected to provide thermal insulation between the steam and the surrounding tissue.

[0067] The number of steam delivery holes and their diameter may be selected for a particular application. Figures 9A and 9B show a needle with three rows of two steam delivery holes. The shorter the hole length, the more precise the steam delivery, which may be especially important when treating small perimeter areas or portions of narrow areas.

[0068] Improved Consistency of Therapeutic Delivery The caloric output of the vapor delivery device of the present invention is related to the power input of the RF generator during treatment delivery through an efficiency factor. Caloric output is consistent or invariant from shot to shot if the delivered power is a constant independent of changes in component values ​​due to thermal cycling of the device. Caloric output is consistent or invariant from device to device if the input power is always the same for a given treatment and if the efficiency factor is consistent from device to device. Consistency or invariance from device to device is achieved through consistency in device manufacturing. Furthermore, consistency improves when the power coupling efficiency approaches 100%, provided the input power is held constant. In other words, variations in device parameters have less impact on the output when the percentage of constant input power delivered to the output approaches 100%.

[0069] The RF coil 110 and steam coil 120 of FIG. 10 have the advantage of efficient and consistent therapy delivery. First, the relatively small number of turns of the steam coil (six turns shown in FIG. 10) means that excess heat generated at the distal end of the steam coil can pass through the heat conducting metal of the six turns back to preheat the preheated room temperature water entering the coil. It has been observed that the steam coil outlet temperature for cancer is lower than the steam coil outlet temperature for BPH for a given calorie output from the device due to thermal feedback in some cases. Furthermore, the change in transformer coupling coefficient between the RF coil and the steam coil caused by the change in separation between the coils is smaller for larger diameter coils.

[0070] Vapor Delivery System Sensors The temperature of the steam at the outlet of the steam coil and the temperature of the steam coil should be continuously measured and monitored by the system controller. Temperatures outside of set ranges may indicate damage to the steam coil or insufficient delivery of steam therapy and should trigger automatic shutdown and guidance to the user for corrective action. For example, excessive temperature may indicate a kink or blockage in the water line tubing. Insufficient temperature may indicate loss of RF power to the RF coil. The semi-disposable design of the described device measures and transmits the temperature in the disposable cartridge to a wireless sensor that communicates through a wireless read mechanism in the delivery device handle. The wireless approach allows free rotation of the disposable cartridge in the handle, an important clinical feature with no additional cost.

[0071] FIG. 11 shows an equivalent circuit for temperature reading of the injected vapor RTD (resistance temperature sensor). With appropriate selection of circuit parameters, the sensed voltage can be shown to be a monotonic function of Rsense, i.e., the resistance of the copper wire RTD, which is a linear function of temperature through the temperature coefficient of the copper wire. Invert the equation for Vsense to show the equation for the temperature of the inner coil as a function of the sensed voltage Vsense. Typically, the single frequency of the oscillator is selected to be different from any other frequencies that may be present in the treatment room, including the generator frequency. On the other hand, in one embodiment, the single frequency oscillator of FIG. 11 can take a negligible RF power supply voltage to reduce cost and minimize the number of components. In this case, care must be taken to manage any inductive pickup from the RF coil during treatment.

[0072] The 1 kOhm resistor in FIG. 11 converts the single frequency oscillator voltage to a single frequency current source. The oscillator and 1 kOhm resistor can be replaced by the single frequency current source in FIG. 11. A single frequency current in the range of 10 mA to 100 mA will result in good signal to noise ratio in the Vsense measurement and the outlet temperature reading calculated from Vsense. Temperature is averaged over a 0.5'' length of the sensor winding. This spatial averaging smooths out temperature fluctuations that can occur at multiple points due to erroneous steam behavior at the outlet.

[0073] Wireless read / write RFID tags are commercially available. Some of these can perform temperature measurements. Such devices should be economically priced when added to disposable cartridges. In another embodiment, the ID of the disposable cartridge is read by the RF generator but written to the e-cloud through an internet connection to the RF generator. Every generator in use can connect to the cloud before every treatment procedure to retrieve usage information for the disposable device inserted in the delivery device handle. At the end of the treatment, the number of treatment shots delivered by the device will be relayed to and stored in the cloud.

[0074] Methods of using a transurethral system FIG. 12 shows the delivery device inserted into the prostatic urethra adjacent to the surrounding area tissue. Catheter placement may be guided by ultrasound imaging and the cystoscope camera, and may also be guided by the location of access to the surrounding area just behind the verumontanum, a visible landmark. Initially, the needle is advanced over a travel distance of approximately 11 mm, as measured by the needle position sensor. The initial travel distance may be in the range of 6-12 mm, and should deploy the needle from the urethral lining into the surrounding area tissue.

[0075] Further depression of the deployment trigger switch causes the solenoid to activate a current pulse at a fixed or user selected rate, which may range from 1 to 5 pulses per second. In one embodiment, the current pulse has a maximum amplitude that the system generator can provide and a fixed or user selected initial pulse width. In one embodiment, the initial pulse width T is 1.5 msec. When a pulse is delivered to the solenoid, the needle position sensor measures the needle travel distance and increases the width of the next pulse if the needle has not traveled more than the target travel distance, e.g., 1 mm, and decreases the width of the next pulse if the needle has traveled more than the target travel distance. On average, the needle travels the target travel distance with each pulse. The target travel distance may be fixed or user selected, and in a preferred embodiment is 1 mm. At any time, the user may allow the needle to pulse back or fully retract. At any time, the user may release the trigger to stop the needle pulsing forward / backward, e.g., to deliver a steam treatment. The output of the needle position sensor may be displayed to inform the user of the distance along the needle between the needle tip and the delivery device shaft.

[0076] A safety feature may be implemented that limits the pulse width, and therefore the force applied to the needle, to a value that will not allow it to penetrate the prostate capsule. If the needle has not moved more than a target travel distance of 1 mm for a series of N pulses, a needle blockage condition is indicated and the user is alerted. Alternatively, further advancement of the vapor delivery needle may be prevented if a needle blockage condition is indicated. A needle blockage condition may be due to the needle hitting the outer capsule of the prostate, with the value of N being selected to limit the pulse width to a safe maximum value determined in a tissue study, for which the needle will not be able to penetrate a healthy or cancerous capsule. N may be in the range of 4-10 pulses, with a corresponding maximum pulse width in the range of 2-5 msec. The user may verify that the needle has hit the capsule by observing tissue tenting on the ultrasound image.

[0077] In an alternative embodiment, the user may directly control the pulse width and the number of pulses per second. This manual needle movement mode may preserve the safety features of the automatic mode described above.

[0078] Transurethral steam treatment may be used with a thermocouple inserted through the perineum outside the prostate capsule to warn of temperatures high enough to damage nerves on the outer surface of the capsule. Saline can be delivered to the outside of the prostate capsule to cool and protect the nerves. Transurethral prostate ablation treatment, on the other hand, can be performed using multiple shots, each shot sufficient with sufficient time between shots to prevent significant heat conduction through the capsule to the nerves. For example, individual treatments lasting 10 seconds or less with at least 30 seconds between shots can result in complete cauterization of prostate tissue without the need for thermocouples or saline injection needles outside the capsule.

[0079] In some embodiments, the surrounding region and the transition region can be treated separately. In other embodiments, the steam delivery needle is long enough to reach the surrounding cancer region tissue after passing through the transition region. Treatment can be administered to both the surrounding region tissue and the transition region tissue during pulse deployment or pulse retraction. In other embodiments, the central region tissue that impinges on the urethra may be cauterized during the cancer treatment procedure. The central region can be treated separately or in some cases after passing through the transition region. Both the central region and the transition region tissue can be treated during a single needle deployment or retraction.

[0080] In some embodiments, ultrasound imaging is used to guide the delivery of steam to the prostate tissue. Additionally, needle position measurements by needle position sensors have sub-mm accuracy and can be used to measure the distance between treatment shots. It is important to space the steam delivery by a distance that would result in overlapping obstructions with sufficient separation between shots to prevent excessive heating and potential conduction across the prostate capsule. In some embodiment procedures, shots are performed using a 1 cm separation between shots.

[0081] The therapeutic methods and means disclosed in Provisional Patent Application 720 can be used in transurethral procedures. For example, a sensor that senses tissue capacitance can be added to the needle tip to distinguish between prostatic and non-prostatic tissue and prevent steam delivery to non-prostatic tissue to prevent inadvertent passage through the prostatic capsule. Tissue type sensing can be used in conjunction with the needle / magnet position sensor to confirm that the magnet is in prostatic tissue and, in particular, to determine when the needle is adjacent to the prostatic capsule. Pre-operative images can be used to determine optimal puncture sites along the urethra and the number of steam treatment shots that need to be delivered to each puncture site. The transurethral prostate resection procedure can then be performed without external image guidance with a prescribed distance between treatment shots. The delivery device probe is advanced to a prescribed position in the urethra by identifying anatomical landmarks in the cystoscope image, as in the BPH procedure. The needle is advanced a prescribed distance through the urethral wall while guided by the magnet / needle position sensor output and / or by markings on the needle as viewed through the cystoscope. Treatment can be administered during needle advancement, or the needle can be advanced to the prostate capsule wall as indicated by the sensor and treatment can be administered during retraction.

[0082] In another example, an electromagnetic sensor or transmitter placed at or near the needle tip can facilitate tracking the tip position relative to pre-operative or real-time images of the prostate. In the case of ultrasound, a second sensor or transmitter can be placed adjacent to the ultrasound transducer so that the needle tip position and orientation can be found relative to the transducer, facilitating autofocus and image enhancement. Needle tip tracking can enable robotic guidance or needle navigation. In advanced steam therapy delivery systems, the needle can be robotically advanced to a point on the image selected by the operator and a prescribed steam dose can be delivered at the site. The tip of the delivery device needle can be made steerable using pull wires when used with other catheter systems. Image guidance with steering can allow treatment to be performed using optimally separated locations in a three-dimensional pattern. More specialized steering means can be used, for example, by attaching a magnetic needle tip and using a large external magnet to steer the tip.

[0083] Although certain embodiments of the present invention have been described above in detail, it will be understood that this description is for illustrative purposes only and that the above description of the present invention is not exhaustive. Certain features of the present invention are shown in some drawings and not in others, and this is for convenience only, as any feature may be combined with other features in accordance with the present invention. Several variations and alternatives will be apparent to those skilled in the art. Such alternatives and variations are intended to fall within the scope of the appended claims. Certain features shown in the dependent claims may be combined to fall within the scope of the present invention. The present invention also encompasses embodiments as if the dependent claims were instead written in a multiple dependent claim format with reference to other independent claims. [Explanation of symbols]

[0084] 100 Vapor Delivery Device 102 Handle part 103 Lumen 104 Cartridge part 110 RF coil 112 Solenoid coil 114 Long and thin shaft 116 Steam delivery needle 118 Needle Drive Magnet 120 Steam coil 122 Plastic Pipes

Claims

1. 1. A vapor delivery device comprising: The handle part, a cartridge portion; the handle portion having a lumen and an RF coil disposed within the lumen and connectable to a source of RF energy; the cartridge portion is configured to be inserted into a lumen of the handle portion; the cartridge portion includes an elongate shaft configured to be inserted into a patient's urethra, a steam delivery needle disposed within the elongate shaft, and a steam coil fluidly connected to the steam delivery needle and a fluid source; A vapor delivery device, wherein insertion of the cartridge portion into the handle portion aligns and positions the vapor coil within the RF coil.

2. 10. The vapor delivery device of claim 1, wherein vapor is generated within the steam coil by inductive application of RF energy to the RF coil when fluid is delivered from the fluid source to the steam coil.

3. The vapor delivery device of claim 2 , wherein the vapor delivery needle is configured to deliver vapor to tissue of a patient.

4. the cartridge portion further includes a first solenoid coil and a second solenoid coil and a needle drive magnet attached to a proximal portion of the vapor delivery needle; 2. The vapor delivery device of claim 1, wherein the needle drive magnet is slidably disposed within the first solenoid coil when the vapor delivery needle is in a retracted position and is slidably disposed within the second solenoid coil when the vapor delivery needle is in an extended position.

5. The vapor delivery device of claim 4 , further comprising a needle deployment switch in the handle portion.

6. The vapor delivery device of claim 5 , wherein the vapor delivery needle is fully deployed from the retracted position to the extended position by depression of the needle deployment switch.

7. The vapor delivery device of claim 5 , wherein the vapor delivery needle is incrementally deployed with each depression of the needle deployment switch.

8. 8. The vapor delivery device of claim 7, wherein the vapor delivery needle is deployed in 1 mm increments.

9. The vapor delivery device of claim 7 , further comprising a position sensor disposed on the vapor delivery needle, the position sensor configured to determine a deployed position of the vapor delivery needle.

10. 10. The vapor delivery device of claim 9, wherein the vapor delivery needle is prevented from advancing if the position sensor indicates that the vapor delivery needle has not moved a desired incremental distance.

11. The vapor delivery device of claim 1 , wherein the steam coil comprises Inconel tubing.

12. The vapor delivery device of claim 1 , further comprising a latch configured to prevent lateral movement of the cartridge portion when the cartridge portion is inserted into the lumen of the handle portion.

13. The vapor delivery device of claim 1 , wherein the cartridge portion can be rotated when the cartridge portion is inserted into the lumen of the handle portion.

14. 6. The vapor delivery device of claim 5, wherein the delivery needle cannot extend more than 24 mm from the elongate shaft when the delivery needle is in the extended position.

15. 10. The steam delivery device of claim 1, wherein the steam delivery needle includes an inflatable balloon configured to prevent steam from escaping through a puncture in the patient's tissue.

16. The vapor delivery device of claim 15 , wherein the inflatable balloon is positioned within a recess in the vapor delivery needle.

17. 16. The vapor delivery device of claim 15, wherein the inflatable balloon is inflated by vapor during vapor delivery.

18. The vapor delivery device of claim 1 , further comprising an electronic controller configured to control the delivery of RF energy to the RF coil.

19. 20. The vapor delivery device of claim 18, further comprising a temperature sensor disposed at an outlet of the vapor coil, the temperature sensor being electrically coupled to the electronic controller and configured to measure a temperature of fluid or vapor at the outlet of the vapor coil.

20. 20. The vapor delivery device of claim 19, wherein the electronic controller is configured to initiate a cessation of RF energy delivery when a measured temperature of the outlet vapor or fluid is outside a preferred temperature range.

21. 1. A method for delivering steam to a prostate of a patient, comprising: inserting a cartridge portion of a vapor delivery device into a lumen of a handle portion of the vapor delivery device to align and position a vapor coil of the cartridge portion within an RF coil of the handle portion; inserting an elongate shaft of the cartridge portion into the urethra of a patient; advancing a distal end of the elongate shaft to a prostatic urethra of a patient; extending a vapor delivery needle from said elongate shaft into the patient's prostate; delivering a fluid flow into the steam coil; applying RF energy to the RF coil to inductively generate vapor within the vapor coil; and delivering steam to the prostate through said steam delivery needle.

22. 22. The method of claim 21, wherein the extending comprises generating a magnetic field with at least one solenoid coil to extend the vapor delivery needle into the prostate.

23. The method of claim 21 , further comprising rotating the cartridge portion within the handle portion.

Images