Patent Publication Number: US-2012035473-A1

Title: Laparoscopic hifu probe

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 10/380,031, filed on Sep. 19, 2001, which is expressly incorporated by reference herein. This application also claims the benefit of U.S. Provisional Application Ser. No. 60/686,499, filed on Jun. 1, 2005, which is also expressly incorporated by reference herein. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to instruments to conduct minimally invasive medical procedures with the aid of laparoscopic techniques, and to such procedures themselves. More particularly, the present invention relates to high-intensity focused ultrasound ablation of tissue using minimally invasive medical procedures. It is disclosed in the context of high-intensity focused ultrasound ablation of kidney tissue, but is believed to be useful in other applications as well. 
     Several minimally invasive and non-invasive techniques for the treatment of living tissues and organs with ultrasound, including high-intensity, focused ultrasound, sometimes referred to hereinafter as HIFU, are known. There are, for example, the techniques and apparatus described in U.S. Pat. Nos. 4,084,582; 4,207,901; 4,223,560; 4,227,417; 4,248,090; 4,257,271; 4,317,370; 4,325,381; 4,586,512; 4,620,546; 4,658,828; 4,664,121; 4,858,613; 4,951,653; 4,955,365; 5,036,855; 5,054,470; 5,080,102; 5,117,832; 5,149,319; 5,215,680; 5,219,401; 5,247,935; 5,295,484; 5,316,000; 5,391,197; 5,409,006; 5,443,069; 5,470,350; 5,492,126; 5,573,497; 5,601,526; 5,620,479; 5,630,837; 5,643,179; 5,676,692; 5,840,031. The disclosures of these references are hereby incorporated herein by reference. 
     HIFU Systems for the treatment of diseased tissue are known. An exemplary HIFU system is the Sonablate® 500 HIFU system available from Focus Surgery located at 3940 Pendleton Way, Indianapolis, Ind. 46226. The Sonablate® 500 HIFU system uses a dual-element, confocal ultrasound transducer which is moved by mechanical methods, such as motors, under the control of a controller. Typically one element of the transducer is used for imaging and the other element of the transducer is used for providing HIFU Therapy. 
     The Sonablate® 500 HIFU system is particularly designed to provide HIFU Therapy to the prostate. However, as stated in U.S. Pat. No. 5,762,066, the disclosure of which is expressly incorporated by reference herein, the Sonablate® 500 HIFU system and/or its predecessors may be configured to treat additional types of tissue. 
     Further details of suitable HIFU systems may be found in U.S. Pat. No. 5,762,066; U.S. Abandoned patent application Ser. No. 07/840,502 filed Feb. 21, 1992, Australian Patent No. 5,732,801; Canadian Patent No. 1,332,441; Canadian Patent No. 2,250,081; and U.S. Pat. No. 6,685,640, the disclosures of which are expressly incorporated by reference herein. 
     As used herein the term “HIFU Therapy” is defined as the provision of high intensity focused ultrasound to a portion of tissue. It should be understood that the transducer may have multiple foci and that HIFU Therapy is not limited to a single focus transducer, a single transducer type, or a single ultrasound frequency. As used herein the term “HIFU Treatment” is defined as the collection of one or more HIFU Therapies. A HIFU Treatment may be all of the HIFU Therapies administered or to be administered, or it may be a subset of the HIFU Therapies administered or to be administered. As used herein the term “HIFU System” is defined as a system that is at least capable of providing a HIFU Therapy. 
     According to an aspect of the invention, an apparatus and method employ first, second and third devices for introduction of equipment into, and removal of equipment from, a body region, an optical imaging system, a source of a relatively non-reactive fluid for expanding the body region to facilitate the introduction of components of the apparatus into the body region and manipulation of the introduced components of apparatus, and an ultrasound apparatus for at least one of visualization and treatment of the body region. A first of the devices facilitates passing of the component of the optical imaging system into and out of the body region. A second of the devices facilitates passing the fluid between the fluid source and the body region. A third of the devices facilitates passing the ultrasound visualization and/or treatment apparatus into and out of the body region. 
     The laparoscopic probe of the present invention is targeted for minimally invasive laparoscopic tissue treatments. However, the probe may also be used for non-laparoscopic procedures as discussed below. The probe is light weight, easy to use, and adaptable to the current Sonablate® 500 HIFU system. The laparoscopic probe, with the Sonablate® 500 system, illustratively provides laparoscopic ultrasound imaging, treatment planning, treatment and monitoring in a single probe. The probe fits through a trocar (illustratively an 18 millimeter diameter trocar). A coupling bolus covers the tip of the probe. The bolus is very thin and illustratively expands to about five or six times its size when water is introduced. This provides a water medium surrounding the probe which is needed for ultrasonic imaging and treatment. The probe is USP Class VI certified. Cooling the transducer that provides the imaging and treatment is achieved through a sterile, distilled, degassed passive recirculating water system. The entire probe is ethylene oxide (EO) sterilizable, and the cooling system is gamma-sterilizable. Therefore every component of the probe is able to withstand repeated EO sterilization. 
     The laparoscopic probe of the present invention provides an alternative solution to invasive surgery. As a result, recovery time is reduced and hospital visits are considerably shorter. In addition the ablation provided by the laparoscopic probe permits the surgeon to target tissue without stopping the blood supply to the organ. For example, to perform a partial nephrectomy in a conventional manner, the surgeon illustratively shuts off the supply of blood to the kidney and has a limited amount of time to excise the targeted tissue, seal the blood vessels and restart the blood supply to the kidney. If the surgeon takes too long, damage to the kidney and possible organ death may occur. Thus being able to treat large and small volumes of tissue while permitting blood flow to the organ is a significant contribution. 
     Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may best be understood by referring to the following detailed description and accompanying drawings which illustrate the invention. In the drawings: 
         FIG. 1  illustrates a partly block diagrammatic, partly fragmentary perspective view of a procedure according to the present invention; 
         FIG. 2  illustrates an exploded, fragmentary perspective view of a device useful in the conduct of the procedure illustrated in  FIG. 1 ; 
         FIG. 3  illustrates a perspective view of another device constructed according to the invention; 
         FIG. 4  illustrates a perspective view of another device constructed according to the invention; 
         FIG. 5  illustrates a perspective view of certain components of another device constructed according to the invention; 
         FIG. 6  illustrates a plan view of the components illustrated in  FIG. 5 ; 
         FIG. 7  illustrates an elevational view of the components illustrated in  FIGS. 5-6 ; 
         FIG. 8  illustrates an end elevational view of the components illustrated in  FIGS. 5-7 ; 
         FIG. 9  is a perspective view of a portion of a laparoscopic probe of another illustrated embodiment of the present invention including a controller, a drive mechanism, and a movable transducer; 
         FIG. 10  is a perspective view of a probe tip assembly of another illustrated embodiment of the present invention including an expandable bolus for acoustically coupling the transducer to a targeted area and for cooling the transducer during the procedure; 
         FIG. 11  is an exploded perspective view of the probe tip assembly of  FIG. 10 ; 
         FIG. 12  is a side elevational view of the probe tip assembly of  FIGS. 10 and 11 ; 
         FIG. 13  is a sample screen shot for planning a HIFU Treatment; 
         FIGS. 14A-14C  illustrate a treatment path along which the transducer is moved by the controller and drive mechanisms to treat a treatment zone; and 
         FIG. 15  is a screen shot illustrating a sample procedure in accordance with an illustrated embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTIONS OF ILLUSTRATIVE EMBODIMENTS 
     Although the illustrated embodiment is shown in connection with treatment of a kidney  40 , the illustrated probe, water circulation system and treatment is not limited to kidneys. The present invention is presently believed to be applicable equally readily to the ablation of tissue of the liver, the pancreas, the urinary bladder  32 , the gall bladder, the stomach, the heart, lungs, uterus or any other organ suitable for treatment by HIFU Therapy. In addition, the probe assembly and other features of the present invention described herein may be used in conventional non-laparoscopic HIFU Therapy of, for instance, the prostrate, esophagus, vagina, or the like. 
     In an illustrated minimally invasive, HIFU-based procedure, the patient  20  is first prepared by the insertion of a guide wire  24  through the urethra  28  and bladder  32  into the ureter  36  of a diseased kidney  40 . The guide wire  24  is, of course, radiopaque, so that its progress to the surgical field can be straightforwardly monitored. Then, using the guide wire  24 , a urological catheter  44  is inserted along the same path to permit the introduction of fluid species into the surgical site  48 . Next, three incisions  50 ,  52 ,  54  are made on the abdomen  56  below the diaphragm through trocars  60 . The trocars  60  are left in place, as is customary, to permit the sealing of the abdomen  56  when instruments are passed through the seals  64  of the trocars  60  into the abdomen  56  for the conduct of the procedure. 
     A laparoscope  68  for providing visual observation of the surgical field is passed through one of the trocars  60 . The laparoscope  68  is conventionally coupled to a video camera  72  and a light source  76  for illuminating the surgical field and returning images to a surgical monitor  84 . The laparoscope provides a pair of fiberoptic ports, one an output port for light from source  76  to the surgical field, and one an input port for the returning image information to video camera  72 . A second of the trocars  60  provides, among other things, a passageway for the introduction into the abdomen  56  of a relatively inert gas, such as, for example, carbon dioxide, from a source  88  in order to permit the inflation of the abdomen  56  below the diaphragm. This increases the space inside the abdomen  56  for maneuvering surgical instruments including the laparoscope  68 , and provides a clearer view of the surgical field. 
     The third trocar  60  provides access through the abdominal wall and into the surgical field for a HIFU probe  90  which will be used to ablate the surgical site  48  of a diseased kidney  40 , for example, for the virtually bloodless ablation of (a) tumor(s) on the surface of, and/or within, the kidney  40 . Should the surgical procedure call for it, additional trocars  60  can, of course, be provided for passing into the body additional HIFU probes  90  to be used in conjunction with each other in an ablation procedure. The presence of the catheter  44  in the kidney  40  also permits the introduction into the surgical field of (an) ablation enhancing medium (media) and other media at (an) appropriate time(s) during the procedure. The same, or a different, medium (media) may also be introduced through the catheter  44  to improve the accuracy of the targeting of the surgical site  48  for ablation and provide feedback to the treating physician of the progress of the treatment. For example, lesions which are not on the surface of the tissue  40  being treated are not easily visible, or in many cases visible at all, in the laparoscopically informed monitor  84 . 
     In order to provide feedback to the treating physician of the progress of treatment of a site  48  not visible on the monitor  84 , the ultrasound probe  90  includes an ultrasound visualization capability. (An) additional mechanism(s) may be provided for essentially real-time monitoring of the progress of the treatment. For example, it is known in the ultrasound visualization and therapy arts that there are numerous mechanisms available to promote visualization of the progress of ultrasound treatment within an organ or tissue. These include the introduction of relatively inert gas-containing microcapsule- or microbubble-seeded species, such as sterile saline solution, the introduction of a relatively inert gas, again, such as carbon dioxide, and so on. Any suitable one or ones of these mechanisms can be used to introduce any of such media via the catheter  44  into the kidney  40  being treated. Such materials are known to create bright echogenic bands, strips, fields, and the like on, for example, B-mode ultrasound imaging scans  86 . Such phenomena can be used to indicate to the treating physician where the HIFU has been effective. The treating physician continues to expose the tissue  40  under treatment to the HIFU until the material produces a “bloom” or bright echogenic field (“popcorn”), band, strip or the like in the ultrasound image  86  of the treatment field. Then the HIFU probe  90  is repositioned to treat the next region which is to be treated according to the treatment regimen. Some of such species, such as relatively inert gas-containing microcapsule-seeded sterile saline solution, microbubble-seeded sterile saline solution, and the like, may also function to enhance the ablation effects of the applied HIFU. For example, some of such species readily produce cavitation, the bursting of bubbles created when the species are exposed to HIFU above certain field strengths and/or for certain lengths of time. The cavitation is known to cause further mechanical alteration of the character of the tissue at the surgical site  48  at a cellular level, enhancing the effects of the HIFU exposure. This ultimately results in reduced treatment times. 
     As discussed above, this treatment is not limited to kidneys. It is presently believed to be applicable equally readily to the ablation of tissue on the surface of, or in the bulk of, for example, the liver, the pancreas, the urinary bladder  32 , the gall bladder, the stomach, the heart, lungs, and so on. 
     Turning now to the construction of the HIFU probe  90  and related hardware, although the probe  90  was tested by manipulation by the treating physician, it is within the contemplation of the present invention that the probe  90  could be integrated into, or mounted to be manipulated by, a robotic mechanism  92 , and controlled, for example, by means of a joystick  94 , keypad  96 , programmable machine  100 , or any other appropriate control mechanism. Any of such mechanisms  92 ,  94 ,  96 ,  100  can incorporate feedback control (illustrated by broken lines), not only of a visual nature, provided via a laparoscope  68 , but also of the ultrasound imaging type via probe  90 . 
     The ultrasound image  86  feedback may be not only of the more conventional type described above, but also, may be of a somewhat more highly processed nature, such as that described in, for example, PCT International Pub. No. WO 01/82777, titled Non-Invasive Tissue Characterization, assigned to the assignee of this application, and hereby incorporated herein by reference. It is contemplated that the feedback could provide the treating physician with highly detailed information on the progress of treatment, such as, for example, when the tissue being treated reaches a particular temperature, when the character of the tissue at a cellular level changes abruptly, and so on. 
     The illustrated probe  90  itself is, for example, a modified Sonablate 200 probe available from Focus Surgery, Inc., 3940 Pendleton Way, Indianapolis, Ind.,  46226 . The Sonablate 200 system is hereby incorporated herein by reference. The probe  90  includes a segmented, curved rectangular elliptical transducer  104  of the general type described in, for example, WO 99/49788. The transducer  104  has a central segment  108  which is used both for visualization and therapy and (an) outer segment(s)  112  which is (are) used for therapy, in accordance with known principles. However, it will immediately be appreciated that other single element or multi-segment transducer configurations, such as ones providing variable focal length, can be used to advantage in other embodiments of the invention. Some of such variable focal length configurations, and driving and receiving systems for them, are described in the prior art incorporated herein by reference. 
     The illustrated transducer  104  has a length of about 3 cm., a width of about 1.3 cm., and a focal length of about 3.5 cm. This is adequate to treat tumors of the kidney  40  to that depth. The HIFU treatment of deeper seated tissue will, of course, require longer focal length treatment transducers. The transducer  104  is mounted in a holder  116  having the same generally rectangular prism-shaped outline as the outer dimensions of the transducer  104  itself. The holder  116  is mounted on the end of a hollow shaft  120  through which the electrical leads to drive the transducer  104  for imaging  86  and therapy can be passed between the transducer  104  and the driver and imaging circuitry, for example, the driver and imaging circuitry of the above-mentioned Sonablate 200 system, in a controller  124  ( FIG. 1 ). The shaft  120  itself can serve as one of the conductors, for example, the ground conductor, for one or more of the ultrasound-generating segment(s)  108 ,  112  of the transducer  104 . The transducer  104 /holder  116 /shaft  120  assembly is housed in a housing  128  which illustratively is about 50 cm in length and has an outside diameter which is sufficiently small to fit through one of the standard trocar  60  seals  64 , for example, an 18 mm seal  64 , sufficiently tightly to seal the inside of the abdominal cavity in use. Of course, the dimensions of the illustrated transducer  104 , holder  116  and housing  128  given above are for a probe  90  for the treatment of certain kidney  40  tissue. The size, shape and focal length of the probe  90  and transducer  104  will depend to a great extent on the requirements of the tissue or organ which the probe  90  is intended to treat. For example, a liver probe may be required to be somewhat larger and have a longer focal length, and so on. 
     It should be recalled that it is contemplated that the abdominal cavity will be pressurized with gas during the procedure to increase the work space inside the abdominal cavity. Recalling that a gas will ordinarily be used during the procedure to inflate the abdomen  56 , provision must be made for coupling the ultrasound transducer  104  to the tissue being treated. This may be done by providing a cot or condom  132  over the window  136  through the housing  128  through which the ultrasound radiating face  140  of the transducer  104  transmits ultrasound, and filling the housing  128  with an appropriate coupling medium, for example, degassed and sterile water and permitting air to escape from the housing  128  as it is being filled. One or more ports may be provided in the housing  128  for filling it with coupling medium and bleeding air from it. The cot  132  may be sealed to the housing  128  longitudinally of the housing  128  on either side of the window  136  by elastomeric O-ring seals  144 . This reduces the amount of coupling fluid necessary inside the housing  128  to cause the cot  132  to bulge out sufficiently to bring it into intimate contact with the surface of the tissue  40  to be treated. 
     To reduce further the amount of coupling fluid necessary inside the housing  128  to cause the cot  132  to bulge out sufficiently to bring it into intimate contact with the surface of the tissue  40  to be treated, a sleeve  148  having an opening  152  corresponding generally in size, shape and orientation to the size, shape and orientation of the window  136 , such as, for example, a longitudinally slitted  152  sleeve  148 , is placed around the housing  128  in the region of the window  136 . The sleeve  148  illustratively is constructed of a thin, sterilizable or sterile disposable material, such as, for example, a resin or light metal. The sleeve  148  slides or snaps around the housing  128  in the region of the ultrasound window  136  after the cot  132  has been placed over the window  136 , and either before or after the O-rings  144  have been positioned adjacent the longitudinal ends of the window  136 . The sleeve  148  is intended to reduce the bulging of the cot  132  anywhere other than in the immediate vicinity of the window  136 . This reduces the amount of coupling fluid necessary to cause the cot  132  to bulge into intimate contact with the tissue  40  by reducing the volume of coupling fluid necessary to cause adequate bulging of the cot  132 . 
     It should also be recalled that ultrasound tissue imaging  86  is deep tissue imaging, not surface imaging. Surface imaging in the illustrated application is provided by the laparoscope  68 &#39;s vision system  76 ,  72 ,  84 . It is helpful for both gross and fine positioning of the probe  90 , including tissue contact with the cot  132  filled with coupling medium, and for monitoring the progress of treatment. For example, visualization permits the physician to determine when the tissue  40  being treated exhibits surface blanching  156  ( FIG. 1 ). The presence of blanching  156  provides visual feedback to the treating physician that the tissue  40  being treated has received an amount of heat, at least on its surface, to achieve a particular level of ablation. Instead of this surface imaging being provided laparoscopically, this surface imaging could also be provided by means of a light source and video return on the probe  90  itself. The light source and video return on the probe  90  itself might take the form of an LED or other light source provided on the probe  90  adjacent the window  136 , and a miniature video image generator of some type also adjacent the window  136 , or some other combination of image-generating components. 
     In another embodiment, illustrated in  FIG. 3 , the probe  180  takes the form of one jaw of a forceps-like clamp  184 . The other jaw  188  of the clamp  184  serves with the clamping jaw/probe  180  to capture the tissue  192  to be treated between the two jaws  180 ,  188 . Then, the transducer  104  in the jaw  180  is energized in the same way as discussed above by a driver/receiver/visualization system  124  to treat the tissue  192  with HIFU. In another embodiment, illustrated in  FIG. 4 , both jaws  280 ,  288  can take the form of probes so that the tissue  292  to be treated could be treated by both probes  280 ,  288  or by whichever one of the probes  280 ,  288  is optimally positioned to treat the tissue  292  to be treated. The ultrasound transducers  104 ,  104  in the two probe/jaws  280 ,  288  could have different characteristics, for example, different power handling capabilities or focal lengths, in order to provide a greater number of treatment options to the physician when the probes/jaws  280 ,  288  are in position to treat the tissue  292 . 
     In another embodiment, illustrated in  FIGS. 5-8 , a probe  90 ′ includes a holder  116 ′ for mounting part-spherical visualization and treatment transducers  302 ,  304  having radii of, for example, 30 mm for transducer  302  and 15 mm for transducer  304 . Both of transducers  302 ,  304  are capable of operation in visualization and HIFU treatment modes. And, of course, either or both of transducers  302 ,  304  can be a multi-element transducer of any of the known types including transducer  104  illustrated in  FIGS. 1-2 . In this embodiment, the end cap and the end O-ring seal  144  of the embodiment illustrated in  FIGS. 1-2  are omitted to permit the cot  132  to bulge from the end of probe  90 ′ when the cot  132  is filled with coupling medium, in order that ultrasound may better be coupled from/to the transducer  304  to/from tissue being visualized and/or treated. Holder  116 ′ also includes its own fiberoptic passageway  306  having a diameter of, for example, 0.5 mm. Passageway  306  extends out to the surface of transducer  304  to provide optical visualization of tissue being treated, which tissue may also be visualized by ultrasound and/or treated by transducer  304 . The optical fiber(s) which extend(s) through passageway  306  is (are) coupled to an illumination/optical visualization system of known type, such as the system  72 ,  76 ,  84  illustrated and briefly described in connection with the embodiment illustrated in  FIGS. 1-2 . 
     Turning now to the construction of another embodiment of the HIFU probe and related hardware shown in  FIGS. 9-12 , the probe  390  is illustratively integrated into, or mounted to be manipulated by, a drive mechanism  92 , and controlled, for example, by means of a joystick  94 , keypad  96 , touch screen  100 , or any other appropriate control mechanism such as controller  93 . Any of such mechanisms  92 ,  93 ,  94 ,  96 ,  100  can incorporate feedback control (illustrated by broken lines), not only of a visual nature, provided via a laparoscope  68 , but also of the ultrasound imaging type via probe  90 . 
     As shown in  FIG. 9 , the probe  390  includes a segmented, curved rectangular elliptical transducer  400  of the general type described in, for example, WO 99/49788. The transducer  400  has a central segment  402  which is used both for visualization and therapy and outer segment(s)  104  which is (are) used for therapy, in accordance with known principles. However, it will immediately be appreciated that other single element or multi-segment transducer configurations, such as ones providing variable focal length, can be used to advantage in other embodiments of the invention. Some of such variable focal length configurations, and driving and receiving systems for them, are described in the prior art incorporated herein by reference. Other systems are disclosed in U.S. application Ser. No. 11/070,371 and PCT Application US 2005/015648 both of which are incorporated by reference herein. 
     The structure of the laparoscopic probe  390  is composed of two main components, the main body or frame, and the probe tip assembly  410 . The frame is illustratively constructed of aluminium plates and cylindrical pieces coupled with stainless steels rails. The aluminum plates are located near the rear of the probe. The plates hold a linear motor in place and create the space necessary for a linear screw drive to achieve the desired linear, back and forth, motion. The linear motion is translated to a hexagonal shaft which passes through a rotor enclosed by a sector motor. The sector motor controls a series of magnets bonded to the rotor which enables the rotor to rotate, creating the angular (sector) motion. The electronics are relayed through a circuit board mounted atop the stainless steel rails that support the frame plates. The main body is enclosed by a housing consisting of two shells that are currently made from a stereo lithography process. The shells are illustratively made from injection molded material such as Ultem® resin. 
     The frame illustratively provides a drive mechanism  92  for moving the transducer  400  back and forth in the direction of double headed arrow  406  in  FIG. 2  (50 mm minimum movement), and also to rotate the transducer  400  about its axis  407  as illustrated by arrow  408 . It is understood that other suitable drive mechanism(s)  92  may be used to move the transducer  400  (90° minimum rotation (+/−45°). 
     The probe tubing assembly  410  is primarily made from stainless steel. There are illustratively two bushings that guide the water tubing to the transducer as well as provide support for access to the coupling of the transducer shaft  409  and the hexagonal shaft. The transducer shaft  409  is coupled to the hex shaft (mentioned above) and is able to rotate and translate for both imaging and continuous HIFU Treatment. 
     The probe tip consists of two components: a main stainless steel tubing  410  shown in  FIG. 9  which has a 17 mm diameter or less to fit into an 18 mm trocar  60 , and a removable tip assembly  411  shown in  FIGS. 10-12 . The main tubing  410  has a threaded end  413  that connects with threads formed in distal end  414  of the removable tip  411 . The removable tip  411  also includes a distal end  416  having a rounded tip  148  coupled thereto. The internal threading  415  (best shown in  FIG. 11 ) has the threads removed on opposite sides of the tubing (see area  419 ) to permit the transducer to pass into the tip. A coupling water bolus  418 , a curved thin stainless steel shim material  420 , and two short pieces of very thin heat shrink tubing  422 ,  424  complete the illustrated removable tip  411  components. The removable tip  411  is illustratively made from stainless steel but may be molded from a resin such as Ultem® resin or other suitable material. The bolus  418  is illustratively formed from a polyurethane membrane or condom inserted over the end of probe tip  411 . Bolus  418  is illustratively a tubular membrane with a sealed end  441  best shown in  FIG. 11 . The shim  420  is then located over the bolus membrane  418  on an opposite side of a treatment aperture  417 . Shim  420  is coupled to the tip  411  only by two heat shrinking tubes  422  and  424  best shown in  FIGS. 10-12 . Tubes  422  and  424  have a thickness of about 4-5 thousandths of an inch. Illustratively the membrane is made from HT-9 material available from Apex Medical. The heat shrink tubing is illustratively made from ultra thin polyester tubing and is made by Advanced Polymers. 
     The tubes  422  and  424  are very thin and facilitate insertion of the probe tip  411  through the trocar  60 . It is understood that other securing members, such as o-rings or other suitable devices may be used to secure the bolus and the shim to the tip assembly  411 . However, the tubes  422  and  424  minimize the thickness of the tip  411  which is desirable for laparoscopic procedures. Additional adhesives or other securing means are not required to secure the shim  420  to the bolus  418  or tip  411 . Use of adhesives can cause weakness in the bolus membrane  418  and are therefore not desirable. 
     As discussed above, the removable tip  411  includes a housing  435  formed to include an opening or aperture  417 . The transducer  400  is movable within the aperture as controlled by the drive mechanism  92  and controller  93  to provide the HIFU Therapy. Transducer  400  is configured to emit ultrasound energy through the aperture  417  in the direction of arrow  437  which is referred to as a treatment direction. 
     The housing  435 , the tubes  422 ,  424  and the shim  420  work together to cause the bolus  418  to expand only in the treatment direction  437 . The shim  420  forces the bolus  418  to expand in the direction of the opening  417  in the removable tip  411 . The heat shrink tubes  422 ,  424  hold the shim  420  in the desired position as well as constraining the ends of the bolus membrane  418 . The expansion of the water bolus  418  acoustically couples the ultrasound to the patient. It also changes the location of the transducer focus with respect to the target targeted area, thereby changing the position of the targeted tissue with respect to distance from the transducer  400 . 
     As discussed above, the stainless steel shim  420  is an element used to control expansion of the water bolus  418  during a treatment. Removing the stainless steel shim  420  would result in a uniform expansion of the water bolus  418  around the probe tip  411  in the presence of no external objects. With no shim  420  applying pressure to hold the probe against tissue for treatment at a specific distance would result in the bolus  418  reacting by shifting water behind the probe tip and away from the tissue. This may result in a poor and uncontrolled acoustic coupling of the transducer  400  to the tissue and the inability to accurately place the HIFU Treatment zones in their desired locations. 
     The bolus membrane material  418  illustratively has a memory characteristic. This provides a substantially flat elevated position of bolus  418  above aperture  417  for uniform contact and coupling with a larger tissue area. Once the probe  390  is positioned within a body, a controller controls drive mechanisms to move the transducer  400  to provide HIFU Therapy. 
     Providing a sterile, distilled, degassed water recirculation system for cooling and acoustic coupling during treatment is another illustrated aspect of the present invention. The water should be sterile due to the required sterile surgical environment and degassed for the successful operation of the HIFU transducer. 
     The user plans and performs the HIFU treatment using software running on the Sonablate® 500 system connected to the laparoscopic probe  390 . The physician uses the real time image capability of the laparoscopic probe to aid in the final placement of the probe. When the positioning is complete, an articulated arm holding the probe  390  is locked into place. The physician judges a real time image in both sector (rotating side to side transverse to the probe axis) and linear (back and forth along probe axis) motion (“bi-plane” images). The physician then optimizes the images. Depending on the positioning and physician preference, either the linear or sector image may be chosen or the physician may alternate between the two. After physically moving the probe, fine tuning to the position of the treatment region is achieved by moving the treatment region using software controls  501  shown in  FIG. 13 . This adjusts the position of transducer  400  within the probe housing  435  resulting in fine tuning of the tissue treatment area.  FIG. 13  displays an illustrated user interface with the treatment zones moved from the default center positions. Additional probe positioning control in depth is provided by adjusting the water volume in the coupling bolus. 
     Once the treatment zone is positioned and resized by the physician to cover the desired tissue region (for example, a tumor), the HIFU Treatment is started and the probe begins to apply HIFU Therapy within the chosen region. The transducer trajectory is calculated by a series of algorithms that permit it to cover the entire treatment zone in a pattern illustrated in  FIGS. 14A-14C . The trajectory is also designed to ensure constant equal trace spacing, meaning the spacing between the lines of the trajectory is substantially uniform throughout the region. 
       FIGS. 14A-14C  illustrate an exemplary pattern of HIFU Therapy application during HIFU Treatment with the laparoscopic probe.  FIG. 14A  is representative of the treatment path  575  soon after the start of the treatment.  FIG. 14B  is representative of the treatment path  575  midway, and  FIG. 14C  is representative of the treatment path  575  near the end. The tracings depict the linear (vertical) and the sector (angular) positions of the transducer  400  during the treatment. This user feedback is continuously updated during the treatment. 
     Once the treatment starts, the transducer is continuously moving at constant speed and continuously applying HIFU to the tissue treatment area. This continuous application of acoustic power is interrupted during regular intervals to image for the following reasons: 1) the images confirm that the probe has not moved with respect to the desired treatment region and 2) the images permit the user to see changes in the echogenicity (“popcorn”) of the tissue within the treatment region. This increased echogenicity (see the bottom images in  FIG. 15 ) is an indication of the success of the application of HIFU. In other words, the system uses a “continuous on” treatment, stopping after a predetermined time interval (illustratively about every 30 seconds) for imaging. Imaging typically takes about 1 second or less. During a HIFU “continuous on” treatment, tissue ablation starts at the focal zone of the transducer. As additional HIFU energy is deposited into the tissue during the HIFU “continuous on” mode, the tissue located in the transducer pre-focal zone (located between the transducer focal zone and the transducer) is also ablated until the ablation zone extends all the way to the tissue surface (or tissue/bolus interface). This “continuous on” treatment modality has the advantage of ablating large tissue volumes in a short period of time in a controlled way (i.e. as defined by the treatment plan and treatment path), and is especially suitable for HIFU treatments in which intervening tissue is not to be spared, but ablated as well. (Compare to transrectal HIFU treatments of the prostate, in which the rectal wall/mucosa, located between the transducer and its focal zone must be spared. A “continuous on” treatment for such applications would not be prudent.) Finally, tissue surface blanching is a direct consequence of the tissue ablated region propagating all the way from the transducer focal zone to the tissue surface, and provides additional treatment feedback to the physician. Note that once the initial focal zone tissue ablation occurs, tissue properties change (absorption, impedance, attenuation), preventing the additional HIFU energy being delivered to the tissue to ablate tissue located behind the transducer focal zone. Thus, in this manner, such “continuous on” HIFU therapies are also self-limiting, as only the tissue located between the transducer face and its focal zone is ablated. 
       FIG. 15  illustrates an image update taken with the imaging transducer during treatment. The upper panels show the tissue before application of HIFU Treatment. The lower panels display the images acquired during the HIFU Treatment. Treatment progress may be gauged by the tracing in position  500  the lower left corner, by the time remaining  502  along the right side of the screen, and by the HIFU-induced echogenic tissue changes visible in the “during/after” image  503 . 
     The screenshot shown in  FIG. 15  was taken about half way through a HIFU Treatment. In the bottom left HIFU run time indicates that this particular treatment has lasted 1 minute and 55 seconds and the time remaining  502  (on the right side) shows 57 seconds. 
     The treatment algorithms of the present invention are designed to substantially fill a treatment zone or region selected by the physician. Often, these treatment zones or regions are not symmetrically shaped. Software of the present invention controls a controller  93  to move the transducer  400  back and forth in the direction of double headed arrow  406  in  FIG. 9  and to rotate the transducer about its axis  407  as illustrated by arrow  408  in  FIG. 9  to provide a continuous treatment path within the selected treatment region. As illustrated in  FIGS. 14A ,  14 B and  14 C, the transducer moves at constant speed, (about 1-2 mm/sec.) to provide spacing between the treatment path followed by the transducer of about 1.5-2.0 mm. The algorithm is designed to keep the spacing between adjacent portions of treatment path  575  substantially constant and to cross or intersect a previous portion of the treatment path  575  at an angle as close to 90 degrees as possible (see, for example, intersections  577  in  FIGS. 14B and 14C ) to avoid retracing the path  575 . This pattern of path spacing at essentially 90 degree crossing provides a more uniform heat distribution with respect to depth inside the treatment region. When path  575  hits a boundary edge of a treatment zone defined by a physician, the path  575  changes directions at an angle of about 90°. In  FIGS. 14A-14C , the physician defined a square treatment zone best shown by the filled zone in  FIG. 14C . It is understood, however, that the treatment regions may be defined in any desired shape (typically rectangular) and are often not square. 
     The efficacy, performance, utility, and practicality of these newly developed Sonablate® Laparoscopic (SBL) probes and treatment methodologies was evaluated in-vivo using a pig model. Pre-selected kidney volumes (1 cm 3  to 18 cm 3 ) were targeted for ablation (including the upper and lower poles, and regions adjacent to the collective system and ureter), and treated laparoscopically with HIFU in a sterile environment using the laparoscopic probes operating in the “continuous on” mode. Integrated ultrasound image guidance was used for probe positioning, treatment planning, and treatment monitoring. The kidneys were removed either 4 or 14 days post-HIFU, and the resulting lesions were compared to the treatment plan. Results indicate that HIFU can be used laparoscopically to ablate tissue at a rate of approximately 1 to 2 cm 3 /minute, even in highly perfused organs like the kidney. Results also indicate that treatment methodologies vary depending on the target location, intervening tissue, probe location, and port location. 
     Although the invention has been described in detail with reference to certain illustrated embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.