Abstract:
A high-intensity focused ultrasound device with a translatory dive assembly and a rotary drive assembly mounted to a single-piece frame and disposed therewith inside a handle casing includes a focused ultrasound transducer driven by the drive assemblies via a pair of transducer shafts surrounded by an inner sleeve and outer sleeve that sandwich a bolus tube, the outer sleeve being slidably removable from atop the inner sleeve.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/137,962 filed 5 Aug. 2008 and U.S. Provisional Patent Application No. 61/188,734 filed 12 Aug. 2008. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    This invention relates to high-intensity focused ultrasound (HIFU) for use in treating patients&#39; internal tissue structures. More particularly the present invention relates to improvements in HIFU treatment probes. 
         [0003]    High-intensity focused ultrasound (HIFU) devices are used in medicine to remove or neutralize malignant or diseased tissue. All high-intensity focused ultrasound (HIFU) devices currently on the market include a therapy transducer, a diagnostic transducer and a computer controlled electrical signal generator with integrated diagnostic systems. In practice, both the diagnostic and therapy transducers are allowed two degrees of freedom. One degree is longitudinal with respect to the axis of the device and the second degree of freedom is radial or in an arc with respect to the axis. This radial motion is also called sector motion. 
         [0004]    Current HIFU treatment probes are difficult to sterilize particularly in the event that the bolus breaks while the distal end of the instrument is in contact with a patient&#39;s tissues. The bolus is an expandable chamber that contains the HIFU transducer. The bolus is expanded during a surgical procedure to enable the transmission of ultrasonic pressure waves into the patient from the transducer. 
         [0005]    A prior art HIFU treatment probe  100  is depicted in  FIGS. 1-4 . The instrument includes a handle portion  102  and a shaft section  104 . The handle portion  102  includes a handle casing or housing  106 , a translatory drive assembly  108  mounted to a frame  110  inside the casing, and a rotary drive assembly  112  mounted to the frame and disposed inside the casing. Translatory drive assembly  108  includes a rotary motor  113  for linear motion generation, the rotary motor having an output shaft  114  connected to a spline shaft  116  via a flexible shaft coupler  118 . Spline shaft  116  is journaled in a pair of rotary bearings  120  and  122  mounted to respective frame panels  124  and  126  in turn fixed to a plurality of longitudinally extending rails  128 ,  130  and  132  of multiple-piece frame  110 . Spline shaft  116  carries a linear slide member  136  that is connected to a rear or proximal end of a hex drive shaft section  138  for longitudinally shifting that shaft section. 
         [0006]    Rotary drive assembly  112  comprises a sector motor  140  and an encoder  142  with an encoder disk  144  for monitoring the angular excursion of a focused-ultrasound transducer  146  under the action of the rotary drive assembly. Motor  140  is mounted to frame  110  via a cylindrical frame extension  148 . Translatory drive assembly  108  also includes an encoder (not shown) for monitoring the linear excursion of transducer  146  under the action of motor  113 . 
         [0007]    A transmission train  150  extends from translatory or linear drive assembly  108  and rotary drive assembly  112  to transducer  146 . Transmission train includes hex drive shaft  138  and a forward or distal transducer drive shaft  152 . A transducer shaft coupling  154  connects drive shaft sections  138  and  152  to one another. A shaft sleeve  155  mounted at a proximal end to the handle casing  106  surrounds distal transducer drive shaft  152  and is held in part by a pair of contiguous support cylinders  156  and  158  each provided at a proximal or rear end with a respective seal  160  and  162  (seal  162  is essentially impossible to clean). Three screws  164  fix cylinders  156  and  158  to one another. The heads of screws  164  (not separately designated) are disposed along a bolus chamber  166  that contains transducer  146 . A rounded conical tip protector  168  is provided at the distal tip of sleeve  155 . 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention aims to provide an improved HIFU treatment probe of the above-described type. More particularly, the present invention contemplates a HIFU treatment probe that is readily sterilizable. 
         [0009]    A high-intensity focused ultrasound device in accordance with the present invention comprises (i) a frame, (ii) a handle casing surrounding the frame, (iii) a translatory drive assembly mounted to the frame and disposed inside the casing, (iv) a rotary drive assembly mounted to the frame and disposed inside the casing, (v) a focused ultrasound transducer, (vi) a transmission train including at least one transducer shaft operatively connected at an upstream or input end to the translatory drive assembly and the rotary drive assembly and at a downstream end to the transducer, (vii) a shaft sleeve assembly mounted to the handle casing and surrounding the shaft, and (viii) a bolus tube attached to the shaft sleeve assembly and surrounding the transducer. The shaft sleeve assembly includes an inner sleeve and an outer sleeve disposed over the inner sleeve, the outer sleeve being slidably removable from atop the inner sleeve. A proximal or handle end portion of the bolus tube is sandwiched between the inner sleeve and the outer sleeve. 
         [0010]    The shaft sleeve assembly or shaft housing of the present invention eliminates the need for shrink tubing. The outer sheath or sleeve may be made of stainless steel, which is impervious to conventional steam sterilization processes. 
         [0011]    The shaft sleeve assembly or housing may include at least one support cylinder disposed inside the inner sleeve, the cylinder having a distal end face which bounds on a bolus chamber containing the transducer. The cylinder is formed at the end face with a seal about the transducer shaft. Preferably, the distal end face of the support cylinder is smooth and provided with a minimum of apertures consisting of only two openings for liquid flow into and out of the bolus chamber and an opening traversed by the transducer shaft. Thus, distal end face of the sleeve support cylinder is free of screws and screw heads. In addition, the bolus chamber is preferably free of temperature sensors. 
         [0012]    This construction essentially eliminates obstructions in the bolus chamber and facilitates the cleaning of the device. The bolus chamber being essentially free of structures that would trap blood and organic contaminants from a patient promotes cleaning and sterilization. 
         [0013]    The cylinder is preferably one of two support cylinders spaced longitudinally from one another along the transducer shaft. The other of the two support cylinders is likewise provided in a distal end surface with a seal about the transducer shaft. The sleeve or shaft housing construction of the present invention permits the removal of the outer and inner sleeves and enables access to the space between the two support cylinders for cleaning purposes. 
         [0014]    Pursuant to another feature of the present invention, the translatory drive assembly includes a rotary output shaft assembly having a single bearing. The bearing is disposed on the frame at a forward or distal end of the rotary output shaft assembly, while the translatory drive assembly includes a motor mounted to a rear or proximal end of the frame. The provision of a single bearing (elimination of a rear bearing) facilitates assembly of the device by accommodating misalignment. 
         [0015]    Another feature of a HIFU probe in accordance with the present invention that facilitates assembly is the use of a single piece frame in the handle. The frame supports the translatory drive assembly. A single piece reduces the necessity for fine tolerance manufacture of multiple frame pieces. 
         [0016]    A prior art HIFU device incorporates a liquid circulation system including an inlet coupling and an outlet coupling on the casing and tubing extending between the inlet coupling and a bolus chamber and between the bolus chamber and the outlet coupling, where the transducer is disposed in the bolus chamber. Pursuant to the present invention, a thermocouple is disposed in the handle casing in line between the bolus chamber and the outlet coupling. Thus, the temperature of the liquid in the bolus may be adequately monitored without having a temperature sensor in the bolus chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a longitudinal cross-sectional view of a prior art HIFU treatment probe. 
           [0018]      FIG. 2  is an isometric view of a multi-piece handle frame including a linear or translatory drive assembly, in the prior art HIFU probe of  FIG. 1 . 
           [0019]      FIG. 3  is an exploded view of a shaft section of the probe of  FIG. 1 . 
           [0020]      FIG. 4  is a perspective view of the portion of the shaft of  FIG. 3 , in an assembled configuration. 
           [0021]      FIG. 5  is a longitudinal cross-sectional view of a HIFU treatment probe in accordance with the present invention. 
           [0022]      FIG. 6  is an enlarged detail, in cross-section, taken from area VI in  FIG. 5 . 
           [0023]      FIG. 7  is a front side perspective view of internal components of the HIFU treatment probe of  FIG. 5 . 
           [0024]      FIG. 8  is a partially exploded front perspective view, on a slightly larger scale, of the internal components of  FIG. 7 . 
           [0025]      FIG. 9  is a rear side perspective view of a rear or proximal portion of the internal components of  FIGS. 7 and 8 . 
           [0026]      FIG. 10  is a rear perspective view, on a substantially larger scale, of a sleeve or sheath support assembly shown in  FIGS. 5 ,  7 , and  8 . 
           [0027]      FIG. 11  is a front perspective view, on a substantially larger scale, of the sleeve or sheath support assembly shown in  FIGS. 5 ,  7 ,  8 , and  10 . 
           [0028]      FIG. 12  is a perspective view, on a reduced scale, of the HIFU treatment probe of  FIG. 5 , showing an outer sleeve or sheath removed. 
           [0029]      FIG. 13  is a perspective view, similar to  FIG. 12 , of the HIFU treatment probe of  FIGS. 5 and 10 , showing a sleeve or sheath assembly in a disassembled or exploded configuration. 
           [0030]      FIG. 14  is an enlarged detail, in perspective, taken from area XIV in  FIG. 13 . 
           [0031]      FIG. 15  is an enlarged detail, in perspective, taken from area XV in  FIG. 12 . 
           [0032]      FIG. 16  is an enlarged detail, in perspective, taken from area XVI in  FIG. 12 . 
           [0033]      FIG. 17  is a perspective view of a frame and drive assembly shown in  FIGS. 5 and 8 . 
           [0034]      FIG. 18  is an exploded perspective view of a portion of the frame and drive assembly of  FIGS. 5 ,  8 , and  17 . 
           [0035]      FIG. 19  is an exploded perspective view of another portion of the frame and drive assembly of  FIGS. 5 ,  8 , and  17 . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    As depicted in  FIG. 5 , a high-intensity focused ultrasound device  200  comprises a frame  202 , a handle casing or housing  204  surrounding the frame, a translatory drive assembly  206  mounted to the frame and disposed inside the casing, a rotary drive assembly  208  mounted to the frame and disposed inside the casing, and a focused ultrasound transducer  210 . Translatory drive assembly  206  and rotary drive assembly  208  are operatively connected to transducer  210  via a mechanical transmission train  212  including an upstream or proximal transducer shaft section  214  and a downstream of distal drive shaft section  216 . The transducer drive sections  214  and  216  are linked to one another via a transducer shaft coupling  218 . Upstream or proximal transducer drive shaft section  214  is operatively connected at an upstream or input end to translatory drive assembly  206  and rotary drive assembly  208 , while downstream or distal transducer shaft section  216  is connected at a forward or distal end to transducer  210 . 
         [0037]    A shaft sleeve assembly  220  is mounted to handle casing  204  via an outer-sleeve attachment nut  222  and surrounds transducer shaft sections  214  and  216 . A bolus tube  224  ( FIG. 13 ) is attached to shaft sleeve assembly  220  and contains transducer  210  in a bolus chamber  226 . Shaft sleeve assembly  220  includes an inner sleeve  228  and an outer sleeve  230  slidably disposed over the inner sleeve. A proximal or handle end portion (not separately designated) of bolus tube  224  is sandwiched between inner sleeve  228  and outer sleeve  230  as best illustrated in  FIG. 6 . 
         [0038]    Shaft sleeve assembly or shaft housing  220  eliminates the need for shrink tubing that exists in the prior art HIFU treatment probe  100  depicted in  FIGS. 1-4 . Outer sheath or sleeve  230  may be made of stainless steel. 
         [0039]    Shaft sleeve assembly or housing  220  includes a sleeve or sheath support assembly  232 , best depicted in  FIGS. 10 and 11 . Sleeve or sheath support assembly  232  includes a proximal support cylinder  234  and a distal support cylinder  236  that are spaced from one another and rigidly interconnected by a pair of rods  238  and  240  and a pair of tubes  242  and  244 . Tubes  242  and  244  communicate on a distal side with bolus chamber  226  via respective end openings  246  and  248  in a distal end face  250  of distal support cylinder  236 , distal end face forming a proximal-side boundary of the bolus chamber. Tubes  242  and  244  communicate on a proximal side with respective nipples  252  and  254  that project from a proximal end face  256  of proximal support cylinder  234 . Nipples  252  and  254  are connected to respective hoses or tubing segments  258  and  260  ( FIG. 9 ) that extend through handle casing  204  and communicate with respective coupling ports  262  and  264  on a rear end cap  266  of the handle casing. These various components define a fluid flow path that extends in a distal direction from inlet coupling port  262  and through hose or tubing segment  258 , nipple  252 , tube  242 , and opening  246  to bolus chamber  226  and back in a proximal direction from the bolus chamber through opening  248 , tube  244 , nipple  254  and hose or tubing segment  260  to outlet port  264 . A thermocouple  268  is disposed in handle casing  208  in line with hose or tubing segment  260  and outlet port  264 , for monitoring the temperature of the liquid flowing from bolus chamber  226 . In contrast with the prior art model ( FIGS. 1-4 ), there is no temperature sensor in bolus chamber  226 . A liquid such as sterile water is circulated along the flow path through bolus chamber  226  for purposes of enabling bolus distension, for effectuating ultrasonic wave transmission into organic tissue, and for cooling transducer  210 . 
         [0040]    Distal cylinder  236  is formed at end face  250  with a seal  270  ( FIG. 11 ) about transducer shaft section  216 . Distal end face  250  is smooth and provided with a minimum of apertures, namely, openings  246  and  248  for liquid flow into and out of bolus chamber  226  and an opening  272  traversed by transducer shaft section  216 . Thus, distal end face of sleeve support cylinder  236  is free of screws and screw heads, in contrast to the prior art treatment probe of  FIGS. 1-4 . As described above, bolus chamber  226  is free of temperature sensors, thermocouple  268  being disposed inside handle casing  204 . Bolus chamber  226  is therefore essentially empty of obstructions that could trap blood and organic contaminants (in the event of a bolus tube rupture during an ultrasonic ablation procedure. In addition, seal  270  ( FIG. 11 ) is at the front of sleeve support cylinder  236 , which substantially facilitates cleaning of the seal. 
         [0041]    Inner sleeve  228  is a most distal of two inner sleeve sections  228  and  274 , where the proximal sleeve  274  is attached to handle casing  204 . As depicted in  FIGS. 12-15 , proximal sleeve support cylinder  234  is disposed inside a distal end of proximal inner sleeve  274  and inside a proximal end section of distal inner sleeve section  228 . Distal inner sleeve section  228  may optionally slide over a distal end of proximal inner sleeve section  274 . As depicted in  FIG. 13 , bolus tube  224  is slid over distal inner sleeve section  228  after that sleeve section has been secured to proximal inner sleeve section  274  at proximal support cylinder  234 . Then outer sleeve  230  is slidably and removably inserted over bolus tube  224  and distal inner sleeve section  228  and coupled to handle casing  204  by means of attachment nut  222 . Inner sleeve section  228  and outer sleeve  230  are provided at distal ends with elongate lateral windows  276  and  278  ( FIG. 13 ) that are alignable with one another and with transducer  210 . Bolus tube  224  is expandable out through the aligned windows  276  and  278  to form an effective pressure-wave-transmitting contact with target organic tissues of a patient. The bolus rolls over outer sleeve  230  without the need for shrink tubing. 
         [0042]    The sleeve construction of  FIG. 13 , wherein stainless outer sleeve  230  is easily and quickly removably from inner sleeve section  228 , facilitates cleaning and bolus tube replacement. Access is thus provided to the space between support cylinders  234  and  236 . 
         [0043]    At its distal tip ultrasound probe  200  is provided with a tip protector  280  ( FIG. 5 ) that is partially inserted into an aperture  282  at the distal end of outer sleeve  230  ( FIGS. 12 and 13 ). Tip protector  280  has a flat end face  284  that occupies reduced space relative to a rounded conical tip protector of the prior art (see  FIGS. 104 ). 
         [0044]    As depicted in  FIG. 5 , translatory drive assembly  206  includes a rotary output shaft assembly  286  having a single bearing  288 . Bearing  288  is disposed on frame  202  at a forward or distal end of rotary output shaft assembly  286 . Translatory drive assembly  206  includes a motor  290  mounted to a rear or proximal end of frame  202 . The provision of a single bearing  288  (elimination of a rear bearing) facilitates assembly of the device by accommodating misalignment. 
         [0045]    As shown in  FIGS. 17 and 18 , frame  202  is a single molded or machined piece comprising a sectioned cylindrical wall  292 , a pair of sectioned or truncated circular end panels  294  and  296  and a middle panel or brace  298  all integral with cylindrical wall  292 . Motor  290  has an output shaft  300  connected to a spline shaft  302  via a flexible shaft coupler  304 . Spline shaft  304  is journaled at a forward or distal end in bearing  288 , which is disposed in end panel  294 . Spline shaft  304  carries a linear slide member  306  that is connected to a rear or proximal end of hex transducer drive shaft section  214  for longitudinally shifting that shaft section and consequently shaft section  216  and transducer  210 . Linear slide member  306  moves along a pair of longitudinal guide rods  316  that are fixed to frame panels  294  and  298 . 
         [0046]    Rotary drive assembly  208  comprises a sector motor  308  and an encoder  310  with an encoder disk  312  ( FIG. 5 ) for monitoring the angular excursion of focused-ultrasound transducer  210  under the action of the rotary drive assembly. Motor  308  is mounted to frame  202  via a cylindrical frame extension  314 . Translatory drive assembly  206  also includes an encoder (not shown) for monitoring the linear excursion of transducer  210  under the action of motor  290 . 
         [0047]    A printed circuit board  318  is fastened to frame  202  ( FIGS. 5 ,  7  and  8 ) for controlling translatory drive assembly  206  and rotary drive assembly  208  pursuant to programmed instructions from an operator. 
         [0048]    As depicted in  FIGS. 6 and 11 , proximal cylinder  234  is provided at a distal side with a shaft seal  271 . As shown in  FIG. 6 , a first pair of O-ring seals  320  is provided at a rear end of proximal cylinder  234  for sealingly engaging proximal inner sleeve section  274 , while a second pair of O-ring seals  322  is provided at a forward end of proximal cylinder  234  for sealingly engaging distal inner sleeve section  228 . Another O-ring seal  324  engages cylinder  234  and bolas tube  224 . 
         [0049]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.