Abstract:
There are provided an external cylinder for a probe equipped in a cryosurgical apparatus and a therapeutic-device unit, which are able to protect normal cells near a lesion, provide higher heat efficiency for the freeze and thawing, and simplify the structure. The external cylinder for the probe equipped in the cryosurgical apparatus and the therapeutic-device unit which includes the external cylinder for the probe equipped in the cryosurgical apparatus are provided. The external cylinder includes a given range in which the freezing gas enables an ice ball to be formed on an outer circumference including the distal end portion; and adiabatic means arranged in a range other than the given range so as to prevent heat from being exchanged between the inner space and an outside.

Description:
BACKGROUND 
       [0001]    1. Field of the Disclosure 
         [0002]    The present disclosure relates to an external cylinder for a probe equipped in a cryosurgical apparatus used for cryosurgery and a therapeutic-device unit including the external cylinder for the probe equipped in the cryosurgical apparatus. 
         [0003]    2. Discussion of the Background Art 
         [0004]    It is known that cells of biological bodies can be necrosed by freezing the cells, and this feature of cells is used in cryosurgical apparatuses. In such a cryosurgical apparatus, only cells of a lesion are frozen and then thawed, during which thawing step a difference between salt concentrations is caused thereby destroying the inside of the cells so that the cells die. When it is defined that one cycle consists of the freezing and thawing steps, performing two to three cycles of the forgoing freezing and thawing steps makes it possible to necrose the cells of a lesion, such as a tumor (for example, refer to a non-patent literature 1). 
         [0005]    The foregoing cryosurgical apparatus uses two types of high-pressure gases when the freeze and thawing are performed. In the high-pressure gasses, though depending on types of gas molecules, there is a gas whose temperature increases sharply and there is a gas whose temperature decreases sharply in response to rapidly expanding their volumes (which is known as Joule-Thompson effect). For instance, for decreasing the temperature, a high-pressure argon gas (whose temperature is approx. −160 degrees) is used, while for increasing the temperature, a helium gas (whose temperature is approx. +40 degrees) is used. 
         [0006]    The foregoing cryosurgical apparatus uses as an external cylinder a hollow stainless pipe of a diameter of approx. 2 mm. A probe which emits the high-pressure gas from a fine pore of its distal end is inserted through this external cylinder for being charged therein. In this case, since the distal end of the external cylinder is made to puncture a lesion in advance, the cells of the lesion being targeted can be frozen to be necrosed in an appropriate manner. 
         [0007]    By the way, the two sequences consisting of the freezing and thawing sequences are repeated through the distal end of the probe. In order to make effective use of energy, there is provided a heat exchanger (for example, refer to Patent Literature 1). Hence, in the probe, there are arranged an outward path through which the high-pressure gas is delivered toward the fine pore via the heat exchanger and a return path through which part of the gas emitted from the fine pore returns toward the base end of the probe via a space formed between the probe wall and the heat exchanger. 
         [0008]    At the distal end, the freezing and thawing sequences are repeated by the foregoing heat exchanging mechanism, in which the distal end is exposed to an ultralow temperature during the freezing sequence. Hence it is necessary not to cause damage to normal cells around a lesion. Conventionally, there have been known a technique of providing the cylinder with a heat distribution characteristic necessary for an application of focused heat energy depending on where a lesion is located, which focused application is realized by applying intensity changes to directional characteristics of heat which has directionality. With this intention, a protrusion is arranged on a part of the circumferential edge of the cylinder distal end (for example, refer to Patent Literature 2). 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         [PTL 1] JP-B-4607813 
         [PTL 2] JP-B-4744284 
       
     
       NPL 
       [0000]    
       
         [NPL 1] Seishi Nakatsuka, Kansei Iwata et. al “On freeze-thaw sequence of vital organ of assuming the cryoablation for malignant lung tumors by using cryoprobe as heat source”, CRYOBIOLOGY 61 (2010) 317-326 
       
     
         [0012]    However, the heat exchange process of the probe, which is performed in the external cylinder, causes the external cylinder to be cooled down. Due to this, on the outer surface of the external cylinder, frost formation or ice accretion is caused towards the base end thereof, which may damage normal cells around a lesion near the external cylinder. 
         [0013]    In addition, in the case of the foregoing probe, the heat exchanger is arranged in the narrow space of the probe, which leads to problems of making the probe complex in its inner structure and raising manufacturing costs. 
         [0014]    Moreover, due to the fact that the internal structure of the probe is made complex, the discharge path of the gas becomes narrower, thereby lowering a heat efficiency for the foregoing freeze and thawing. Hence, this may lead to cases in which Joule-Thompson effect is used insufficiently. 
         [0015]    With consideration of the foregoing, an object of the present disclosure is to provide an external cylinder for a probe equipped in a cryosurgical apparatus used for cryosurgery and a therapeutic-device unit, which are able to protect normal cells near a lesion, provide higher heat efficiency for the freeze and thawing, and simplify the structure. 
       SUMMARY 
       [0016]    In order to achieve the object, the external cylinder for a probe equipped in a cryosurgical apparatus according to the present disclosure is provided such that the external cylinder includes a hollow inner space in which the probe for the cryosurgical apparatus is loaded, the probe comprising a distal end portion which is able to puncture a lesion located inside an object, the probe emitting a freezing gas and a thawing gas alternately to each other, essentially characterized in that the external cylinder includes: a given range in which the freezing gas enables an ice ball to be formed on an outer circumference including the distal end portion; and adiabatic means arranged in a range other than the given range so as to prevent heat from being exchanged between the inner space and an outside. 
         [0017]    According to the foregoing configuration, in the external cylinder for the probe equipped in the cryosurgical apparatus, there is provided a portion positionally corresponding to the range in which an ice ball is formed. The outer surface of the portion can be avoided from being lowered in temperature due to an adiabatic effect provided by the adiabatic means when the freezing gas is injected into a lesion during a treatment therefor. 
         [0018]    Incidentally, the adiabatic means may have at least one of a closed space internally formed along a whole inner circumference of the external cylinder or a closed space formed to wholly cover an outer circumferential surface of the external cylinder. In addition, the closed space can be a vacuum layer and reflection means can be provided by applying specular finishing to a surface provided by the closed space. Alternatively, a vacuum layer can be formed in a whole circumference between the outer surface of a range other the given range and the inner space, and reflection means are arranged in the vacuum layer, the reflection means being composed of a barrier member. Still alternatively, the closed space can be loaded with an adiabatic material. 
         [0019]    The external cylinder for the probe equipped in the cryosurgical apparatus is advantageous in that the external cylinder is structured with simplicity, has a higher efficiency for the freeze and thawing, and is able to protect normal cells which are present near a lesion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a diagram showing a basic configuration of a cryosurgical apparatus. 
           [0021]      FIG. 2  is a side sectional view showing a state in which a guide needle is inserted through an external cylinder equipped in a cryosurgical apparatus according to the present invention. 
           [0022]      FIG. 3  is a side sectional view showing a state in which a probe is inserted through the external cylinder equipped in the cryosurgical apparatus according to the present invention. 
           [0023]      FIG. 4  is a partial perspective view showing specular finishing given to an inner side surface of the external cylinder for the probe equipped in the cryosurgical apparatus. 
           [0024]      FIG. 5  is a partial perspective view showing a barrier member arranged in a vacuum layer in the external cylinder for the probe equipped in the cryosurgical apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]      FIG. 1  is a diagram showing a basic configuration of a cryosurgical apparatus which employs a therapeutic-device unit according to the present invention. A reference  1  shows a therapeutic-device unit according to the present invention and, as described later, has a distal end made to puncture a lesion so as to penetrate therethrough, in a state of which a predetermined-type high-pressure gas is supplied to the unit. The therapeutic-device unit  1  is connected with gas supply sources G 1  and G 2  via a gas pressure regulator R which regulates the pressure of the predetermined-type high-pressure gas and a controller C which controls the gas pressure regulator R and controls an amount of gas being supplied and switching of gases being supplied. 
         [0026]    The gas supply source G 1  is a liquid gas cylinder charged with a freezing gas (in the present embodiment, helium gas), which is to be supplied to the therapeutic probe unit  1 , whilst the gas supply source G 2  is a liquid gas cylinder loaded with a thawing gas (in the present embodiment, argon gas), which is to be supplied the therapeutic probe unit  1 . 
         [0027]    The freezing gas and the thawing gas are supplied alternately supplied to the therapeutic-device unit  1  from the gas supply source G 1  and the gas supply source G 2 . Meanwhile the controller C controls both switching valves (not shown) for the gasses being supplied and opening and closing valves (not shown) of the gas supply sources G 1  and G 2 . A pressure of the gas supplied to the switching valve is detected by a not-shown pressure detecting section, and sent as data to the controller C. Further, an amount of supply of the gas which is sent out from the switching valve and an amount of return of the gasses returning to the switching valve are detected by a not-shown flow detecting section, and sent as data to the controller C. The controller C controls the switching valve, opening and closing valves, and gas pressure regulator R to maintain the detected data at values which are previously set or provided. The control for these members can be instructed by an operator, such as a practitioner in medicine, who instructs a man-machine interface including screens such as a touch panel. 
         [0028]      FIG. 2  shows a state where a guide needle is inserted through an external cylinder according to the present invention, and  FIG. 3  shows a state where a probe is inserted through the external cylinder according to the present invention. 
         [0029]    The therapeutic-device unit  1  is provided with, at least, a probe  12  to which the gasses are supplied and an external cylinder  11  through which the probe  12  is inserted. The external cylinder  11  is composed of, for example a stainless-steel cylindrical tube with no bottoms. The external cylinder  11  has a longitudinal direction and an opening end  11   a  located on the distal end side thereof in the longitudinal direction. The opening end  11   a  is formed in a taper-shaped end whose outer diameter is gradually reduced and whose shape is sharpened such that the tip end can be made to puncture a lesion. The opening end  11   a  has an inner diameter squeezed so that the opening end is circumscribed to a halfway position on sharpened distal end portions  12   b  and  13   b  of the probe  12  and the guide needle  13 , which will be described later. The distal end portions are therefore supported by the opening end so that body portions  12   a  and  13   a  of the probe and the guide needle, which are larger in diameters than the distal end portions  12   b  and  13   b , are not allowed to pass through the opening end  11   a . Meanwhile the external cylinder  11  has a further opening end  11   b  formed on a base end side thereof in the longitudinal direction, and the opening end  11   b  has an outer diameter which makes it possible that the opening end  11   b  is closed by a tap member  12   g  of the probe  12 , which will be described later. The sizes of the external cylinder  11  will not be limited to particular values as long as those sizes do not go beyond the gist of the present invention, and, as an approximate example, those sizes are set to be a whole length of 150 mm, an outer diameter φ of 3 mm, and a tube wall thickness of 0.3 mm. 
         [0030]    In the external cylinder  11 , there is formed an adiabatic section  11   c  which extends from the base end side to a given position in the longitudinal direction and which extends along the whole inner circumference. In the present embodiment, the adiabatic section  11   c  is formed by a vacuum layer  11   d  produced in an inner side portion and located in a closed space between the inner side portion and the outer side portion of the external cylinder  11 . The closed space may be loaded with an adiabatic material as long as the adiabatic function is available. Alternatively, in addition to the closed space formed in the inner side portion of the external cylinder  11 , it is possible to produce the closed space by covering the outer side portion of the external cylinder  11  on the whole circumference (not shown). In the external cylinder  11 , there is thus provided a remaining end-side section with which the adiabatic section  11   c  is not formed and which is located close to the distal end in the longitudinal direction. As will de described later, ice balls are formed on the outer surface of the end-side section. Practically, the external cylinder  11  is provided to include an ice-ball formation range A 1  and an adiabatic range A 2  in the longitudinal direction. Additionally, the sizes of both of the ice-ball formation range A 1  and the adiabatic range A 2  can be decided adequately depending on applications. For example, when the ice balls are formed fully in a range of approx. 40 mm from the tip end of the external cylinder  11 , the length of the adiabatic range A 2  may be 110 mm or thereabouts. Further, the adiabatic section  11   c  has a thickness which is set depending on dimensional relationships with the outer diameter of the probe  12  described later. For example, in cases where the vacuum layer is formed with a width of approximately 0.1 mm, the adiabatic wall may be a thickness of approximately 0.1 mm. 
         [0031]    The guide needle  13  is a puncture device which used to guide the external cylinder  11  to a lesion before a treatment performed using the therapeutic-device unit  1 . As described before, the guide needle  13  has the cylindrical body portion  13   a , the distal end portion  13   b  formed by sharpening the one end, and a flange portion  13   b  formed at the other end so as to have a diameter larger than the outer diameter of the base-side opening end  11   b.    
         [0032]    The probe  12  has the body portion  12   a  which is a hollow and cylindrical tool, the distal end portion  12   b  formed by sharpening the distal end of the body portion  12   a . Inside the body portion  12   a , an outward pipe  12   c  is inserted in such a manner that the outward pipe is approximately coaxially to the body portion  12   a  so that there is no contact between both the body portion and the outward path. The outward pipe  12   c  supplies the high-pressure gases (the freezing and thawing gasses) towards the distal end portion  12   b . The distal end of the outward pipe  12   c  has an emission hole  12   d  so that the supplied high-pressure gas is emitted from the distal end of the probe  12 . The probe  12  has an outward path  12   e  provided within the internal space of the outward pipe  12   c  and a return path  12   f  provided between the body portion  12   a  and the outward pipe  12   c . The type of a material composing the probe  12  is not limited to a specific one, but by way of example, the probe may be a stainless-steel tube in the same way as the external cylinder  11 . Further, since the probe is inserted and loaded through the external cylinder  11 , the outer diameter φ may be 2.4 mm or thereabout, as an example. 
         [0033]    Procedures of a treatment using the therapeutic-device unit  1  will now be explained. The guide needle  13  is inserted into the external cylinder  11  from its base-side opening end  11   b  such that the distal end portion  13   b  of the guide needle  13  is exposed from the tip-side opening end  11   a  of the external cylinder  11 . The exposed distal end portion  13   b  of the guide needle  13  is percutaneously inserted toward a lesion which is a target being treated. With the guide needle  12  made to puncture the lesion, the external cylinder  11  is delivered in the puncture direction which is set coaxially to the guide needle  13 . The process of puncture of both the guide needle  13  and the external cylinder  11  is repeated until they reach the lesion. 
         [0034]    Under a known CT monitoring condition, the guide needle  13  is pulled out from the external cylinder  11  and it is confirmed that the external cylinder  11  has reached the lesion. After the confirmation that the external cylinder has reached the lesion, the probe  12  is inserted into the external cylinder  11  from its base-side opening end  11   b . Distilled water or saline is injected in the external cylinder  11  before the puncture. Hence, this injection discharges air from the inside of the external cylinder  11  and produces a water screen between the external cylinder  11  and the probe  12 . This production makes it possible to reduce friction caused therebetween, thus enabling the probe  12  to be inserted in a smoother manner. 
         [0035]    In a state where the probe  12  is made to puncture the lesion, when the controller C described with  FIG. 1  is instructed to act in a cryosurgery mode, the helium gas is supplied to the outward pipe  12   c  of the probe  12  from the gas supply source G 1 . The helium gas is given a predetermined pressure, which results in that the helium gas passes through the outward path  12   e  to reach the emission hole  12   d  and is emitted into the inside of the distal end portion  12   b . The emitted helium gas expands rapidly therein, resulting in that Joule-Thompson effect makes both the distal end portion  12   b  of the probe  12  and the portion near the distal end of the external cylinder  11  (, which is the ice-ball formation range A 1 ) cool down to an ultralow temperature, thereby freezing the lesion. 
         [0036]    The frozen lesion tissue produces ice balls I containing the ice-ball formation range A 1  of the external cylinder  11 , but the adiabatic range A 2  is not subjected to formation of ice balls and frost formation or ice accretion. Accordingly normal cells and tissue which are present close to the adiabatic range A 2  will not be damaged by the ultralow temperature. 
         [0037]    The helium gas is continuously supplied and emitted into the distal end portion  12   b  from the emission hole  12 , whereby the emitted gas is forced to be delivered toward the return path  12   f , with the delivered gas sent into the return path. The helium gas passing through the return path  12   f  is subjected to an adiabatic effect by the adiabatic section  11   c , which results in cooling down the helium gas passing through the outward gas  12   e  so that the heat exchange action is accelerated, thus being effective use of the energy. The helium gas which has passed through the return path  12   f  is discharged into the atmosphere from a discharge hole  12   h  formed at the tap member  12   g  via not-shown discharge means. 
         [0038]    The controller C is configured such that the controller is brought into a thawing treatment mode responsively to an elapse of a previously programmed duration of supply of the helium gas. The thawing treatment mode switches the switching valves, whereby the current gas supply source is switched to the gas supply source G 2  which supplies an argon gas, and the argon gas is then supplied through the outward pipe  12   c  of the probe  12 . The argon gas has also a given gas pressure which makes the argon gas reach the emission hole  12   d  after passage through the outward path  12   e . The argon gas is emitted into the distal end portion  12   d  of the probe  12 , where the gas expands rapidly so that Joule-Thompson effect enables the distal end portion  12   b  of the probe  12  and the distal end range of the external cylinder  11  to be heated. Hence, the frozen lesion is thawed. In addition, the argon gas delivered through the return path  12   e  accelerates the heat exchange action, which is the same as that of the helium gas. The argon gas is also discharged via the discharge hole  12   h , which is the same method as that of the helium gas. 
         [0039]    The foregoing gas supply procedures are repeated at constant periods, with the result only the cells of the lesion become necrotic due to Joule-Thompson effect. 
         [0040]    As described, in the conventional therapeutic-device unit, the heat exchange is performed in the heat exchanger provided in the outward pipe. In this case, the heat exchanger is obliged to be provided in a narrow space, thus making the structure complex and thus raising manufacturing costs. In this respect, the present invention overcomes the conventional difficulties such that arranging the simplified-structure adiabatic section  11   c  at the external cylinder  11  makes it possible to have the same actions as the conventional heat exchange action, which suppresses the manufacturing costs. Additionally, since the external cylinder  11  has the outer surface at which the adiabatic section  11   c  is provided, this limited-range outer surface does not undergo influence of the heat exchange action caused inside the cylinder, which prevents frost and/or ice from being formed and/or accreted, which realizes higher-accuracy treatment. Still additionally, the structure can be simplified as described, with the result that the inner volume of the return path  12   f  can be raised, reducing the discharge pressure, resulting in that the Joule-Thompson effect is effected more strongly than the conventional case. 
         [0041]    With reference to  FIGS. 4 and 5 , a practical embodiment of the external cylinder  11  according to the present invention will now be described. In this description, the common components to those in  FIGS. 1 ,  2  and  3  are given the same reference numbers for omission of redundant explanations.  FIG. 4  shows a partial perspective view of the external cylinder  11 , in which the adiabatic section  11   c  has a surface  11   e  arranged in the wall of the external cylinder  11  via the vacuum layer  11   d  and specular finishing is applied to the surfaced  11   e .  FIG. 5  shows a partial perspective view, in which the vacuum layer  11   d  is charged with a barrier member  11   f  which is composed of beaten copper materials for example. In the structures shown in  FIGS. 4 and 5 , radiation heat generated by the foregoing heat exchange action in the probe  12  is reflected to confine the heat energy more effectively within the probe  12 , which prevents the heat from being transmitted easily to the outside of the external cylinder  11 . 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  therapeutic-device unit 
           11  external cylinder 
           11   c  adiabatic section 
           11   d  vacuum layer 
           12  probe 
           13  guide needle 
         C controller 
         R gas pressure regulator 
         G 1 , G 2  gas supply source 
         A 1  gas supply sources 
         A 2  adiabatic range