Abstract:
The detachable cryosurgical probe includes a disposable probe assembly and a reusable probe assembly. The disposable probe assembly includes a breakaway collar which, when twisted away, activates a finger lock element which provides release of the disposable probe assembly from the reusable probe assembly. Additional features include a safety valve assembly for impeding cryogenic working fluid flow when the disposable probe assembly is detached from the reusable probe assembly and an electrical confirmation assembly for providing electrical confirmation that the disposable probe assembly is connected. Other embodiments include a sliding mechanism that allows for selectively positioning of the vacuum tube relative to the shaft to create an ice ball of the desired size and configuration.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a continuation-in-part of U.S. Ser. No. 10/603,883, entitled Detachable Cryosurgical Probe, filed Jun. 25, 2003. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to cryosurgical probes and more particularly to a detachable cryosurgical probe. 
   2. Description of the Related Art 
   Cryosurgery involving the use of a cryosurgical probe assemblies typically involves the use of cryoprobes that are each attached to a handle that are, in turn, connected to a high-pressure fluid line with a quick-disconnect for attachment to a fluid source. There is an inherent problem with this type of system inasmuch as each cryosurgical probe assembly should be used only once due to sterilization and performance factors. Therefore, typically, the entire cryosurgical probe assembly and high-pressure fluid line must be discarded after that single use. Due to these sterilization/performance requirements there is a need to assure that the cryosurgical probe assembly may be rendered non-useable after a single-use. 
   Previous attempts to mitigate this problem have involved utilizing a disposable sheath over a cryosurgical probe. For example, U.S. Pat. No. 5,910,104, issued to J. D. Doback, III et al, discloses a disposable, sterilizable sheath for use on a closed loop Joule-Thomson cryosurgical probe, and the combination of the disposable sheath and the closed loop probe. The sheath is slipped over the probe, thereby separating the probe from the environment. The sheath has a grip that fits over the handle of the cryosurgical probe. The sheath has a hollow multi-lumen catheter shaped and sized to fit snugly over the cannula of the cryosurgical probe. 
   U.S. Pat. No. 6,306,129 B1, issued to Little et al, also discloses the use of a disposable sheath over a cryosurgical probe. 
   Similarly, U.S. Pat. Publication US 2002/0022832 A1, to Mikus et al, discloses a cryoprobe assembly that includes a cryoprobe and an outer sheath assembly detachably connected thereto. 
   U.S. Pat. Publication US 2004/0267248, to Duong et al, entitled “Detachable Cryosurgical Probe”, discloses a cryosurgical probe system that includes a fluid supply line connectable at an inlet section to a source of cryogenic fluid; a fluid connector assembly securely connected to an outlet section of the fluid supply line for receiving fluid from the outlet section of the fluid supply line; and, a detachable cryosurgical probe detachably connectable to the fluid connector assembly. The cryosurgical probe system includes the capability of providing return fluid flow. 
   U.S. Pat. Publication US 2005/0010200, to Damasco et al, entitled “Detachable Cryosurgical Probe”, discloses a cryosurgical probe system that includes a fluid supply line connectable at an inlet section to a source of cryogenic fluid; a fluid connector assembly securely connected to an outlet section of the fluid supply line for receiving fluid from the outlet section of the fluid supply line; and, a detachable cryosurgical probe detachably connectable to the fluid connector assembly. The fluid connector assembly includes a substantially cylindrical lock housing securely attached to the outlet section of the fluid supply line, the lock housing having a fluid inlet conduit for receiving high pressure fluid from the fluid supply line and a fluid outlet conduit for transferring return fluid from the cryosurgical probe to the fluid supply line. A locking mechanism is positioned at a locking portion of the lock housing to provide detachable engagement of a cryosurgical probe positioned therein. The detachable cryosurgical probe receives fluid from the fluid connector assembly and manipulates the fluid to provide suitable temperatures for cryosurgical treatment. It includes a fluid delivery/return manifold assembly having a fluid delivery section and a return manifold section. The return manifold section is positioned over a portion of the fluid delivery section. The return manifold section includes an insulative vacuum sleeve. The fluid delivery/return manifold assembly has a proximal end section. An outer sheath is securely positioned over the vacuum sleeve and extends from the fluid delivery/return manifold assembly. A lock anchor is securely positioned over the outer sheath. The lock anchor provides detachable connection to the fluid connector assembly of a detachable cryosurgical system. During operation fluid is delivered through the fluid delivery/return manifold assembly, through a Joule-Thomson (J-T) port defined at a distal end of the fluid delivery section and is returned through the return manifold section and delivered out of the cryosurgical probe. The insulative vacuum sleeve is provided between the outer sheath and the return manifold section at a control region of the outer sheath proximal to a distally located treatment region of the outer sheath. Unlike previous cryosurgical probe systems, the operative portion of the present system, i.e. the detachable cryosurgical probe, can be discarded after a single use. However, the fluid supply line and the connector assembly can be reused. The cryosurgical probe system includes the capability of providing return fluid flow. Suitable passageways in the detachable cryosurgical probe and the fluid connector assembly provide this feature. 
   U.S. Pat. No. 5,978,697, issued to Maytal, et al, discloses an MRI-guided cryosurgical system. The Maytal system includes: (a) an MRI magnet for accommodating a patient, the MRI magnet having at least one opening for enabling access of a surgeon to the patient, the MRI magnet including at least one channel extending therethrough for receiving a line member of a surgical device; (b) a surgical device, including: (i) an operating member for operating the patient; (ii) a control member for controlling the operating member, the control member being positioned externally to the MRI room; and, (iii) a line member having a first end connectable to the operating member and a second end connectable to said control member, wherein at least a portion of the line member is received within the channel of the MRI magnet. 
   SUMMARY OF THE INVENTION 
   In a broad aspect, the present invention is embodied as a detachable cryosurgical probe, including a disposable probe assembly, having a gas delivery assembly, comprising a stem and a fluid conduit subassembly bonded to the stem, the fluid conduit subassembly for delivering and returning cooling fluid used for cryogenic cooling. A finger lock element includes a distal finger lock element section having a threaded inner surface for engagement with a threaded outer surface of the stem; and, a plurality of radially spaced fingers extending proximally from the distal finger lock element section. Each finger has a ramped surface for operatively engaging an associated ramp section on the stem during use; and, a female lip at a proximal end thereof. A disposable handle assembly, includes: 1) a proximal handle section having a distal end having an inner surface that is operatively engaged with an outer surface of the finger lock element so as to resist relative rotation and axial motion therebetween; 2) a distal handle section having an inner surface that is operatively engaged with another outer surface of the stem so as to resist relative rotation and axial motion therebetween; and, 3) a breakaway collar positioned between the proximal handle section and the distal handle section. 
   A reusable probe assembly of the detachable cryosurgical probe, includes: a manifold assembly for receiving a cryogenic working fluid and transmitting the cryogenic working fluid to the gas delivery assembly. The manifold assembly includes a male lip at a distal end thereof; and, a reusable handle assembly secured about the periphery of the manifold assembly. 
   During operation, when the disposable probe assembly is attached, the breakaway collar is an integral unit which prevents relative rotation between the proximal handle section and the distal handle section. The female lip engages the male lip, thereby securing the reusable probe assembly to the disposable probe assembly. During an initial stage of detachment of the disposable probe assembly, the user rotates the proximal handle section in a first direction relative to the distal handle section to break away breakaway surfaces of the breakaway collar, allowing the breakaway collar to radially expand. During an intermediate stage of detachment of the disposable probe assembly the user counter rotates the proximal handle section in an opposite second direction relative to the distal handle section. The relative rotation between the proximal handle section and the distal handle section provides axial movement of the proximal handle section toward the distal handle section via the engagement of the threaded inner surface of the distal finger lock element section and the threaded outer surface of the stem, the axial movement being enabled by the radial expansion of the breakaway collar. The ramped surfaces of the radially spaced fingers engage the associated ramp section on the stem during the axial movement thereby urging the fingers to open. During a final stage of detachment the fingers open sufficiently to allow disengagement of the male lip from the female lip, thus enabling the disposable probe assembly to be detached from the reusable probe assembly. 
   Use of the finger lock element provides space savings relative to previous detachable mechanisms. The fingers extend in an axial direction along the cryoprobe. The cryoprobe has redundant safety features such as contacts for providing electrical confirmation of connections. The disposable probe assembly has a single use feature that prevents it from being reused without compromising its safety and performance. 
   A safety valve assembly is provided to minimize gas leakage and prevent “whipping” of the disposable probe assembly. 
   In one embodiment ice size and configuration can be modified as desired by selectively positioning a vacuum tube. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective illustration of a first embodiment of the detachable cryosurgical probe with the disposable probe assembly attached to the reusable probe assembly. 
       FIG. 2  is perspective illustration of the  FIG. 1  embodiment of the detachable cryosurgical probe shown with the disposable probe assembly detached from the reusable probe assembly. 
       FIG. 3  is a cross-sectional view of the disposable probe assembly shown attached to the reusable probe assembly, the view being broken away in a few sections to emphasize the showing of the attaching portions of the detachable cryosurgical probe. 
       FIG. 4  is a cross-sectional view showing respective attaching portions of the disposable probe assembly and the reusable probe assembly, in a detached configuration. 
       FIG. 5  is an enlarged cross-sectional view showing respective attaching portions of the disposable probe assembly and the reusable probe assembly, in an attached configuration. 
       FIG. 6  is a view taken along line  6 — 6  of  FIG. 5 . 
       FIG. 7  is a view taken along line  7 — 7  of  FIG. 5 . 
       FIG. 8  is an enlarged perspective view of the portion of detachable cryosurgical probe where the detachment takes place. 
       FIG. 9  shows an initial stage of detachment wherein the breakaway surfaces are detached. 
       FIG. 10  shows an intermediate stage of detachment showing relative counter rotation of the disposable probe assembly and the reusable probe assembly. 
       FIG. 11  shows the counter rotation resulting in relative axial motion of the disposable probe assembly and the reusable probe assembly. 
       FIG. 12  is a perspective view of the breakaway collar of the present invention. 
       FIG. 13  is a cross-sectional view of the detachable cryosurgical probe just after the breakaway collar has been detached. 
       FIG. 14  is a cross-sectional view of the detachable cryosurgical probe at the intermediate stage of detachment when the fingers are opening. 
       FIG. 15  is a cross-sectional view of the detachable cryosurgical probe at the final stage of detachment when the fingers have opened sufficiently to enable the disposable probe assembly to be detached from the reusable probe assembly. 
       FIG. 16  is a side perspective view of a portion of an alternate embodiment of the detachable cryosurgical probe in which the vacuum tube may be repositioned as desired relative to the shaft, the vacuum tube being in a first position. 
       FIG. 17  is a front perspective view of the detachable cryosurgical probe of  FIG. 16  in the first position and including a showing of the shaft tip. 
       FIG. 18  shows the detachable cryosurgical probe of  FIG. 16  in a second, extended position. 
       FIG. 19  is a cross-sectional view of the detachable cryosurgical probe of  FIG. 16  in the first position. 
       FIG. 20  shows the detachable cryosurgical probe being moved between two positions. 
       FIG. 21  shows the detachable cryosurgical probe moved to a second position. 
   

   The same elements or parts throughout the figures are designated by the same reference of characters. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings and the characters of reference marked thereon,  FIG. 1  illustrates a preferred embodiment of the detachable cryosurgical probe of the present invention, designated generally as  10 . The detachable cryosurgical probe  10  includes a disposable probe assembly, designated generally as  12  and a reusable probe assembly, designated generally as  14 . The reusable probe assembly  14  includes a fluid supply line  16  that is connected at an inlet section  18  to a source (not shown) of cryogenic fluid. The fluid source may be, for example, a cryosurgical system such as that manufactured by present assignee, Endocare, Inc., Irvine, Calif. Such a cryosurgical system typically utilizes argon gas from an argon gas source to provide Joule-Thomson cooling of the cryosurgical probes. Alternatively, nitrogen can be used. Alternatively, a fluid supply system can be utilized that does not require an external fluid supply source. Heating of the cryosurgical probes is typically provided by a helium gas source for providing a helium gas flow through the Joule-Thomson nozzle of the cryosurgical probe. This provides a heating effect. Such heating of the cryosurgical probes is provided to unstick the probes from the treated tissue for cryoprobe removal. A gas delivery assembly of the disposable probe assembly  12  includes a shaft  20  that has a freezing zone. Spaced markings  21  may be provided on the outer surface of the cryosurgical probe  10 . These markings  21  may be, for example, at 1 cm intervals. 
     FIG. 2  shows the disposable probe assembly  12  detached from the reusable probe assembly  14 , as will be described in detail below. 
   Referring now to  FIG. 3 , the disposable probe assembly  12  is shown attached to the reusable probe assembly  14 . This figure is broken away in a few places for the purposes of clarity. The disposable probe assembly  12  includes a gas delivery assembly  22 , a finger lock assembly including finger lock element  24 , and a disposable handle assembly  26 . The gas delivery assembly  22  includes a stem  28  and a fluid conduit subassembly  30  bonded to the stem  28 . The fluid conduit subassembly  30  is for delivering and returning cooling fluid used for cryogenic cooling. The finger lock element  24  includes a distal finger lock element section  32  (see also  FIG. 6 ) having a threaded inner surface for engagement with a threaded outer surface of the stem  28 . Four radially spaced fingers  34  (see also  FIG. 7 ) extend proximally from the distal finger lock element section  32 . Each finger  34  has a ramped surface  36  for operatively engaging an associated ramp section on the stem  28  during use; and, a female lip  38  at a proximal end thereof. 
   The disposable handle assembly  26  includes a proximal handle section  40 , a distal handle section  42 ; and, a breakaway collar  44 . The proximal handle section  40  has a distal end having an inner surface that is operatively engaged with an outer surface of the finger lock element  24  (this region of engagement designated  46 ) so as to resist relative rotation and axial motion therebetween. As can be seen in  FIG. 6 , hex shaped surfaces are utilized to prevent relative rotation; however, obviously other geometric shapes and other means can be used to prevent such rotation such as radial bumps, pins, etc. 
   The distal handle section  42  of the disposable handle assembly  26  has an inner surface that is operatively engaged with another outer surface of the stem  28  (this region of engagement designated  48 ) so as to resist relative rotation and axial motion therebetween. Again, this region of engagement may be hex shaped. The breakaway collar  44  is positioned between the proximal handle section  40  and the distal handle section  42 . 
   The fluid conduit subassembly  30  includes a Joule-Thomson (J-T) tube  50  bonded to the stem  28 . It may be welded thereto, as shown by numeral designation  52 . The J-T tube  50  receives the cooling fluid from the reusable probe assembly  14 . The distal end of the J-T tube  50  comprises a J-T nozzle  54 . A safety washer  56  is positioned within a front end of an elongated central opening  58  of the distal handle section  42  of the disposable handle assembly  26 . 
   A shaft  60  of the fluid conduit subassembly  30  is secured to the safety washer  56  within an opening of the safety washer  56  and within the elongated central opening  58 . The shaft  60  extends beyond the distal handle section  42  to provide a cooling surface for cryogenic cooling. In this embodiment a vacuum tube  62  is integrally connected with an inner surface of the shaft  60 . (As will be disclosed below in another embodiment there may alternatively be a slideable connection.) A high pressure seal comprising a high pressure o-ring  63  is positioned about a proximal end section of the stem  28  for sealing cooperation (as shown by numeral designation  64  in  FIG. 5 ) with an inner surface of a manifold assembly  66  of the reusable probe assembly  14 . The vacuum tube  62  has a desired insulative air gap formed therein. The air gap provides selected non-cooling areas of the cryosurgical probe. 
   Referring now to  FIG. 4 , the reusable probe assembly  14  includes the manifold assembly  66  and a reusable handle assembly  68  secured about the periphery of the manifold assembly  66 . The reusable handle assembly  68  includes a first end portion  67  and a second end portion  69 . The manifold assembly  66  includes an outer covering  71 . 
   The reusable probe assembly preferably includes a safety valve assembly, designated generally as  70 , operatively engaged with the manifold assembly  66  for impeding cryogenic working fluid flow when the disposable probe assembly  12  is detached from the reusable probe assembly  14 . The safety valve assembly  70  includes a conical surface  72  formed in a proximal penultimate section  74  of a proximal end portion of the manifold assembly  66 . The manifold assembly  66  terminates, at its proximate end, with a proximal ultimate section  76 . The proximal ultimate section has a ball retaining cavity  78  formed therein. A ball  80  is positioned within the ball retaining cavity  78 . The function of this safety valve assembly  70  will be discussed below in detail. 
   The reusable probe assembly also preferably includes an electrical confirmation assembly, designated generally as  82 , operatively engaged with the disposable probe assembly  12  for providing electrical confirmation that the disposable probe assembly  12  is connected. The electrical confirmation assembly  82  includes a slideable electrically conductive ring  84  positioned about an outer surface of the reusable probe assembly  14  and normally distally biased by a spring  86 . The electrical confirmation assembly  82  includes stationary electrically conductive lever spring contacts  88  and plastic housing  89  for the lever spring contact  88 . The lever spring contact  88  is electrically connected to the cryosurgical system by wires  85 . The function of this electrical confirmation assembly  82  will be discussed below in detail. 
   In operation, when the disposable probe assembly is attached, as can be seen in  FIGS. 5 ,  8 , and  12  the breakaway collar  44  is an integral unit that prevents relative rotation between the proximal handle section  40  and the distal handle section  42 . In this configuration, the female lip  38  engages a male lip  90  of the manifold assembly  66 ; thereby securing the reusable probe assembly  12  to the disposable probe assembly  14 . 
   Referring now to  FIGS. 9 and 13 , during an initial stage of detachment of the disposable probe assembly, the user rotates the distal handle section in a first direction relative to the proximal handle section to “break away” breakaway surfaces of the breakaway collar  44 , allowing the breakaway collar  44  to radially expand. In  FIG. 13  the breakaway collar  44  is shown removed; however, during actual operation it may possibly dangle at that location. 
   Referring now to  FIGS. 10 and 14 , during an intermediate stage of detachment of the disposable probe assembly  12  the user counter rotates the distal handle section  42  in an opposite second direction relative to the proximal handle section  40 . The relative rotation between the distal handle section  42  and the proximal handle section  40  provides axial movement of the distal handle section  42  toward the proximal handle section  40  via the engagement of the threaded inner surface of the distal finger lock element section  32  and the threaded outer surface of the stem  30 . The axial movement is enabled by the radial expansion of the breakaway collar  44 . The ramped surfaces  36  of the radially spaced fingers  34  engage the associated ramp section on the stem  30  during the axial movement thereby urging the fingers  34  to open. 
   Referring now to  FIGS. 11 and 15 , during a final stage of detachment, the fingers  34  open sufficiently to allow disengagement of the male lip  90  from the female lip  38 , thus enabling the disposable probe assembly  14  to be detached from the reusable probe assembly  12 . 
   As mentioned above, the safety valve assembly  70 , is operatively engaged with the manifold assembly  66  for impeding cryogenic working fluid flow when the disposable probe assembly  12  is detached from the reusable probe assembly  14 . As can be seen in  FIG. 15 , when the disposable probe assembly  12  is detached from the reusable probe assembly  14  and no cooling gas is flowing within manifold assembly  66 , the ball  80  is free to float freely within the ball retaining cavity  78 . However, when the disposable probe assembly  12  is detached from the reusable probe assembly  14  and cooling gas is flowing within the manifold assembly  66  (as indicated by arrow  92 ), the ball  80  is urged into a volume defined by the conical surface  72 , thus providing sufficient sealing to prevent “whipping” of the disposable probe assembly  12 . As perhaps best seen in  FIG. 5 , when the disposable probe assembly  12  is connected to the reusable probe assembly  14  the Joule-Thomson (J-T) tube  50  bonded to the stem  28  maintains the ball  80  in a position away from the conical surface  72 , thus allowing the free flow of cooling gas  92  into the disposable probe assembly  12 . 
   As mentioned above, and referring again to  FIG. 4 , an electrical confirmation assembly, designated generally as  82 , is operatively engaged with the disposable probe assembly  12  for providing electrical confirmation that the disposable probe assembly  12  is connected. When the disposable probe assembly  12  is not connected, the conductive ring  84  is not in contact with the lever spring contact  88 . When the disposable probe assembly  12  is connected, the conductive ring  84  is urged by the disposable probe assembly  12  in a proximal direction so that it contacts the lever spring contacts  88  providing a closed electrical circuit and electrical confirmation of the connection. 
   A heat exchanger or cryostat  94  is utilized to provide heat exchange between inlet gas and outlet gas. Although, as shown, the heat exchanger is preferably a coiled fin tube heat exchanger various other types of heat exchangers may be utilized such as a tube-in-tube sintered cryostat, threaded cryostat, coiled/sintered cryostat, or stacked coil cryostat. These different types of cryostats are disclosed and claimed in U.S. Ser. No. 10/828,031, entitled Detachable Cryosurgical Probe, filed on Apr. 20, 2004, incorporated herein by reference in its entirety. 
   Referring now to  FIGS. 16–21  a second embodiment of the detachable cryosurgical probe system is illustrated, designated generally as  100 . In this system  100  the vacuum tube may be repositioned as desired relative to the shaft. This is accomplished by actuating a button assembly, designated generally as  102 , along a guideway  104 .  FIGS. 16 and 17  show the vacuum tube in a first position (i.e. labeled P 5 ).  FIG. 18  shows the vacuum tube moved to a second position (i.e. labeled P 2 ). 
   Referring now to  FIG. 19 , the button assembly  102  can be seen in cross-section in the first position. A button  104  of the button assembly  102  is biased by a spring  106 . A slider assembly  108  is mechanically connected to the vacuum tube  110  and to the button assembly  102 . Thus, the shaft  112  and the vacuum tube  110  are capable of moving relative to each other. The button assembly  102  can be locked into position to prevent unintentional movement. A safety washer assembly  114  is securely connected to the shaft  112 . It includes an o-ring  116  for sealing the shaft  112  and the vacuum tube  110 . Another o-ring  118  at the front of the stem  120  seals the vacuum tube  110  and stem  120 . 
   Referring now to  FIG. 20 , the vacuum tube  110  is shown having been moved toward a second position relative to the shaft  112  by the actuation of button assembly  102 . Referring now to  FIG. 21 , the button assembly  102  is shown moved to position P 4 . Thus, the size and shape of the generated iceball can be varied in accordance with a specific desired need. 
   During operation, with the disposable probe assembly  12  attached to the reusable probe assembly  14 , cryogenic fluid originating from (typically) an argon tank flows through the supply line  16  within the cryostat  94  and through the manifold assembly as shown by arrow  92  (in, for example,  FIG. 5 ). The flow is directed through the safety valve assembly  70  and then through the central passageway in the high pressure stem  28  via J-T tube  50 , and out of the J-T port  54  (see  FIG. 3 ). 
   After being expelled from the J-T port  54  the return fluid is directed in the space between the inner surface of the vacuum tube  62  and the outer surface of the J-T tube  50 . It then flows through openings in the manifold assembly  66 , as indicated by arrow  114  ( FIG. 5 ) and adjacent to the heat exchanger  94 . The return fluid is eventually expelled via the hose  16 . 
   In the device illustrated the cryosurgical probe is shown with a pointed tip to provide insertion into the patient&#39;s tissue for the desired application. However, it is understood that the tip may be blunt, depending on the application. For example, for certain applications direct insertion is desirable. For other applications, insertion via a cannula/introducer is preferred. 
   Although application of this device utilizing CT guidance is preferred, the cryosurgical probe  10  may be used with a variety of guidance tools, such as MRI and ultrasound. In one preferred implementation ultrasound is used for initial guidance, followed up with CT for final confirmation. 
   Although the present invention has been discussed above with respect to a cryosurgical probe having a rigid outer sheath, the cryosurgical probe may be made to be malleable by including at least one malleable segment thereon. Malleable segments are formed of material that permit reshaping and bending to reposition the ablating surface for greater ablation precision. An example of a cryosurgical probe having malleable characteristics is disclosed and claimed in our co-pending patent application Ser. No. 09/957,337, Pub. No. US 2003/0055415 A1, filed on Sep. 20, 2001 entitled Malleable Cryosurgical Probe, incorporated in its entirety herein by reference. 
   One method for providing malleable characteristics includes providing a malleable shaft with a bellows portion. U.S. Pat. No. 6,767,346, filed Jul. 27, 2002 entitled Cryosurgical Probe With Bellows Shaft, incorporated in its entirety herein by reference, discloses use of a bellows portion for providing the necessary reshaping and bending. 
   If the detachable cryosurgical probe is utlilized in combination with ultrasound the outer sheath may have an echogenic coating with, for example, a porous microstructure having the ability to trap microscopic air bubbles. This creates thousands of highly efficient ultrasound reflectors on the surface of the sheath. 
   Thus, while the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the invention. 
   For example, even though the finger lock element has been described specifically with respect to the present cryosurgical probe it is understood that it can be used on other types of cryosurgical probes that, for example, may not be single use. Further, the finger lock element may be used for many applications which require a quick disconnect (both single use and multiple use). These may include, for example, control valves for water heaters, pneumatic systems for controls that require quick disconnects, electrical connectors, etc. 
   Although the cryostat  94  has been shown positioned within the manifold assembly  66  it may be positioned in other locations, notably, for example, in the hose  16  or within the fluid source. 
   Although the cryosurgical probe system is particularly advantageous for prostate cryosurgery it is also advantageous for many other types of ablation applications, such as radiological applications. 
   Other embodiments and configurations may be devised without departing from the spirit of the invention and the scope of the appended claims.