Abstract:
Provided is an inexpensive device capable of accurately positioning a medical instrument relative to the head of a user. A head positioning device ( 7 ) is used. The head positioning device ( 7 ) is provided with: a pair of holding members ( 11, 12 ) which holds the face of a user from both sides by elasticity and prevents both the forward tilting of the user&#39;s head and the rotation of the neck; a neck rest ( 13 ) which comes into contact with the back side of the user&#39;s neck and determines the position of the neck in the front-rear direction; and a head-back rest ( 14 ) which comes into contact with the back of the head and which prevents the head from tilting backward.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a head positioning device, a medical system, a medical instrument positioning device, and a holding shell. 
       BACKGROUND ART 
       [0002]    Diagnosis or treatment of sickness or injury may require to position one or more of medical instruments on a body of a patient. Included is a transcranial magnetic stimulation (TMS) which is a non-invasive method of treatment of intractable disease such as nerve damage, for example. The transcranial magnetic stimulation is a method of treatment in which a symptom is ameliorated by giving a magnetic stimulation to a certain site (motor area) of the brain from the outside with a magnetic field generated by applying an electric current to a coil mounted on the head of a patient. 
         [0003]    The transcranial magnetic stimulation requires the magnetic field to be applied on the motor area of the brain corresponding to a disease. The coil is desirably disposed in as close contact as possible with the patient in terms of energy efficiency. For example, Patent Document 1 describes that a magnetic stimulation device used in the transcranial magnetic stimulation has a coil fixed to a shell like a cap or a helmet to be placed on the head of a patient. The shell should always be placed at a predetermined position on the patient. 
         [0004]    An appropriate position on which the medical instrument should be placed varies according to the symptom of the patient. Therefore, when using such shell described in Patent Document, it must be prepared for each patient or each symptom so that the shell can be held at a position to which the medical instrument should be fixed. 
         [0005]    Patent Documents 2 and 3 describe methods of positioning a medical instrument to a desired part of a patient by disposing a measurement device measuring a relative position to a marker applied to a patient&#39;s body along with the medical instrument and by achieving a predetermine relation of the relative position of the measurement device to the marker. However, these methods need adjustments of the positions of the medical instrument and the measurement device, which in turn requires that a patient&#39;s head be kept immobile during the adjustment. This makes it extremely difficult for a patient to perform the adjustments by himself/herself. 
         [0006]    Patent Document 4 describes an arrangement which measures a three-dimensional configuration of a human body, calculates a position at which the medical instrument should be disposed on the measured three-dimensional configuration, and positions a medical instrument. This arrangement, however, requires a measurement unit, a calculation, circuit, and an actuator, which results in a significantly complicated system. 
       PRIOR ART DOCUMENT 
     Patent Documents  
       [0007]    WO 2007/123147 A1 
         [0008]    JP 2003-180649 A 
         [0009]    JP 2004-634 A 
         [0010]    JP 2006-320425 A 
       SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention  
       [0011]    In view of the above, the present invention is to provide a device having a simple system configuration capable of accurately disposing a medical instrument on a head of a user such as a patient. 
       Means for Solving Problem  
       [0012]    The inventors conceived that a medical instrument can accurately be disposed relative to a head of a user by positioning and holding the medical instrument with a desired space from a head surface of the user, imaging a certain part of the user by an imaging means disposed in relation to the medical instrument, displaying a specified position at which the certain part should be located in an overlapping manner on the image, and allowing the user to move the held head by himself/herself within a range of the space so as to match the certain part to the specified position in the displayed image, and devised a head positioning device, a medical system, a medical instrument positioning device, and a holding shell for this purpose. 
         [0013]    A head positioning device according to the present invention comprises 
         [0014]    a pair of holding portions made of elastic material for supporting users face from outside to restrict a frontward tilting of a head of a user and a rotation of a neck of the user; 
         [0015]    a neck rest for supporting a back of the neck of the user to determine a position of the neck in the front-to-rear direction; and 
         [0016]    a head back rest for supporting a back of the head to prevent the head from tilting backward. 
         [0017]    According to this arrangement, at least one physical feature point is positioned by any one of the holding portions, the neck rest, and the head back rest and at least the movement of the cheeks or the neck of the user can be restricted. For example, if the user receives treatment in a sitting position, the holding portions cause the user to face forward and the height of the head can be determined and fixed relative to a positioned medical instrument. The neck rest can determine a position of the neck in the front-to-rear direction, i.e., a supporting point of the backward tilting of the head. The head back rest determines a position of the back of the head, i.e., an angle of the head. The above features enable correct regulation of the direction of the head relative to the medical instrument. As a result, the position and posture of the head of the user can substantially constantly be held before and/or during treatment. The posture of the user is not limited to the sitting posture described above and, for example, the posture before treatment (during positioning) and during treatment may be a standing position or a recumbent position (such as a dorsal position and a prone position). The posture may be different between during positioning and during treatment and, for example, the head positioning device is applicable to such a treatment instrument that is positioned in the standing position before treatment followed by the dorsal position with the positioning maintained. 
         [0018]    In the head positioning device of the present invention, the holding portions may support a lower jaw or cheeks of the user from outside. 
         [0019]    In the head positioning device of the present invention, a position of a physical feature point may be specified by at least a portion of this device. For example, the occipital protuberance of the user may be supported on the head back rest for positioning. 
         [0020]    Since the user easily feels the contact pressure of the head back rest at the occipital protuberance, the contact pressure is made constant and the positioning accuracy is increased. 
         [0021]    In the head positioning device of the present invention, the holding portions and the neck rest may integrally be formed into a U-shaped configuration. 
         [0022]    The configuration including the neck rest and/or the holding portions holds the neck of the user in three directions and therefore produces an effect that the neck is favorably received while feeling of restraint is reduced. Since a user feels uncomfortable unless the device is correctly mounted, it is expected that the user&#39;s head is received each time at a correct position in the same way. Since the front side is opened, the user can immediately move away from the device without a release operation when some unexpected situation (such as a system defect and disaster) occurs. 
         [0023]    The head positioning device of the present invention may further comprise a chair having a seat and a backrest, and the holding portions, the neck rest, and the head back rest may be fixed to the backrest. This configuration allows the user to take a comfortable posture and maintain the same posture for a long time. For example, if the user receives the treatment in a sitting position, the height of the neck is constant in accordance with the seating height and, therefore, the supporting point of inclination of the head determined by the neck rest is located each time at the same position. Even in other postures, the supporting point of the head can be adjusted each time to the same position. In other cases, at least one rest may be configured to be in contact with one physical feature point to maintain the same posture. 
         [0024]    The head positioning device of the present invention can also have another positioning means so as to further increase the positioning accuracy during treatment. For example, the head positioning device may further comprise a camera for imaging a predetermined reference point on the head of the user, and a monitor for displaying an image taken by the camera and a position at which the reference point should be located. For another method of increasing the positioning accuracy, the device may include a monitor for displaying an image from the camera for imaging a relation between a predetermined reference point on the head of the user and a position at which the reference point should be located. In this case, the positions of the neck rest, the holding portions, and the head back rest for supporting the head can be changed in the vertical direction and left-to-right direction within ranges in which the functions are fulfilled, so as to enable the camera to image the predetermined reference point. 
         [0025]    In the head positioning device of the present invention, the holding portions or the neck rest, preferably at least a surface portion thereof, is preferably formed of an elastic member. In this case, the high positioning accuracy can be maintained without giving feeling of restraint or pain to the user. 
         [0026]    A medical system according to the present invention may have any of a plurality of the head positioning devices described above and a medical instrument positioning device for positioning a medical instrument used for treatment or diagnosis. Since this configuration keeps the head at a constant position with the head positioning device and keeps the medical instrument, at a constant position with the medical instrument positioning device, the relative positions of the head and the medical instrument are made constant. 
         [0027]    The medical system of the present invention has 
         [0028]    the head positioning device, and 
         [0029]    the medical instrument positioning device having an interface means between the head and the medical instrument, and 
         [0030]    the medical instrument positioning device may have at least one movable mechanism for mounting the medical instrument and making the medical instrument movable before and during treatment. 
         [0031]    For example, the interface means may be a holding shell brought close to, brought into contact with, or put on the head of the user along with the medial instrument mounted thereon. The interface means may be a winding means for holding wound around a portion of the head of the user or a means put around ears such as a head gear, a strap, a mask, and eyeglasses other than the holding shell. 
         [0032]    The movable mechanism included in the medical instrument positioning device preferably enables the interface means to move on a virtual spherical surface covering the head, for example, along a virtual spherical surface around at least one point of the top of the head or a treatment part of the head. By way of example, the movable mechanism may be the following rail type movable mechanism. 
         [0033]    A specific example of the rail type movable mechanism may be, for example, a movable mechanism rotationally moving along a first rail to tilt the holding shell and having a second rail for moving along the second rail extending in a direction different from the first rail to tilt the holding shell (to operate the interface means at a certain position on the virtual spherical surface). The number of rails is not limited. 
         [0034]    The medical instrument positioning device maybe capable of moving and positioning the medical instrument to a desired position on the virtual spherical surface in any other way. The medical instrument positioning device may further have a restriction mechanism for making the medical instrument immovable from a specified position finer movement. The restriction mechanism may be, for example, a stopper of the movable mechanism or a mechanism limiting the movement within a certain extent. 
         [0035]    With this configuration, the interface means maybe tilted at any angle to adjust a relative position of the medical instrument to the head of the user. 
         [0036]    In the medical system of the present invention, the first rail and the second rail may extend above the holding shell, keeping a constant distance from the interface means. With this configuration, a distance between the head surface and the interface means can be kept constant. 
         [0037]    In the medical system of the present invention, the interface means may include a plurality of holding portions each capable of holding the medical instrument. With this configuration, an attachment position of the medical instrument to the interface means can be changed to enable treatment or diagnosis at different parts of the user. 
         [0038]    As described above, the present invention provides the medical instrument positioning device having the interface means put on the head of the user along with the medial instrument used for treatment or diagnosis mounted thereon as well as the support mechanism and movable mechanism described above. 
         [0039]    The present invention provides the interface means put on the head and including a plurality of holding portions each holding a medical instrument disposed in the vicinity of the head of the user and used for treatment or diagnosis, and only a portion of the medical instrument is held by the interface means in at least any of the plurality of the holding portions. 
         [0040]    The present invention provides a transcranial magnetic stimulation device for applying a magnetic stimulation to a certain part in a user&#39;s head by using a magnetic field generating means outside the head, the device having 
         [0041]    a holding mechanism holding the user&#39;s head during magnetic stimulation, 
         [0042]    a rotation preventing mechanism for preventing rotation of the head and/or neck of the user, and 
         [0043]    a head position determining mechanism for determining a position of the head of the user, 
         [0044]    the mechanisms being capable of abutting on the neck or the back of the head to retain a contacting state with the neck or the head during use, 
         [0045]    the head of the user being positioned so that a position of at least one physical feature point of the head and the neck is determined. 
         [0046]    According to the present invention, after determining the head position during the magnetic stimulation by the head position determining mechanism, the holding mechanism can hold the user&#39;s head at a desired position during the magnetic stimulation and the rotation preventing mechanism can prevent the rotary movement of the head or the forward and backward tilting of the neck. Therefore, the position of the certain part in the head subjected to the magnetic stimulation to the user can be held while the magnetic stimulation is applied. The holding mechanism is the holding portions and the neck rest and/or the head back rest described above, for example; the rotation preventing mechanism is the holding portions and the neck rest and/or the head back rest, for example; and the head position determining mechanism is a mechanism capable of contacting a certain position on the head to determine the head position and is the head back rest or the neck rest, for example. 
       Effect of the Invention  
       [0047]    As described above, the present invention enables the positioning of both the user&#39;s head and the medical instrument. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0048]      FIG. 1  is a schematic view of a treatment system according to an embodiment of the present invention. 
           [0049]      FIG. 2  is a detailed perspective view of a head positioning device of  FIG. 1 . 
           [0050]      FIG. 3  is a perspective view of holding portions and a neck rest. 
           [0051]      FIG. 4  is a schematic side view of a principle of positioning by the head positioning device of  FIG. 2 . 
           [0052]      FIG. 5  is a schematic side view of an alternative configuration of the head positioning device of the present invention. 
           [0053]      FIG. 6  is a perspective view of an embodiment of a medical instrument positioning device of the present invention. 
           [0054]      FIG. 7  is a simplified side view for explaining a geometric shape of a holding shell of  FIG. 2 . 
           [0055]      FIG. 8  is a perspective view of a holding shell applicable to the head positioning device of the present invention. 
           [0056]      FIG. 9  is a perspective view of a state in which an exciting coil is mounted on the holding shell of  FIG. 8 . 
           [0057]      FIG. 10  is a perspective view of an embodiment of a head back rest including a head back rest adjustment mechanism. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0058]    An embodiment of the present invention will now be described with reference to the drawings. First,  FIG. 1  schematically depicts a basic configuration of a transcranial magnetic stimulation (TMS) system  1  according to an embodiment of a medical system of the present invention. The transcranial magnetic stimulation system  1  is a system which supplies electric power from a drive device  3  to a coil  2  adjacent the head of the user P to generate a magnetic field around the coil  2 , thereby magnetically stimulating the brain of a user P. 
         [0059]    The transcranial magnetic stimulation system  1  has a chair  4  on which the user P sits, a supporting member  5  fixed to the chair  4 , a medical instrument positioning device  6  held by the supporting member  5  for positioning the coil  2 , and a head positioning device  7  fixed to a backrest  4   a  of the chair  4  for positioning the head of the user P. The medical instrument positioning device  6  includes a camera  8  for imaging the head of the user P and a monitor  9  for displaying an image taken by the camera  8 . 
         [0060]      FIG. 2  depicts a detailed configuration of the head positioning device  7 . The head positioning device  7  includes a pair of holding portions  11 ,  12  for holding a lower part of the head or, in particular, the neck and/or the lower jaw, of the user P from his or her left and right sides, a neck rest  13  for supporting a back portion of the neck of the user P, and a head back rest  14  for supporting the occipital protuberance of the user P. The holding portions  11 ,  12 , the neck rest  13 , and the head back rest  14  are preferably supported by a fixed member  15 . The fixed member is preferably attached to the backrest  4   a  of the chair  4  or the supporting member  5 , for example. The fixed member  15  may be eliminated if there is a replacement member capable of functioning in the same way, e.g., where the head back rest  14  is attached to the neck rest  13 . 
         [0061]    The holding portions  11 ,  12  and the neck rest  13  are formed integrally (eventually into a single piece), forming a U-shaped configuration. The holding portions  11 ,  12  and the neck rest  13  may not have the same height as depicted in  FIG. 2 , namely, they may have different heights. More specifically, as depicted in  FIG. 3 , the holding portions  11 ,  12  and the neck rest  13  are preferably formed of a U-shaped internal frame  16  made by assembling metal plates, a cushioning material (not depicted) such as urethane foam disposed to around the internal frame  16 , and a cover  17  made from a material such as fabric and leather and covering the cushioning material. 
         [0062]    The internal frame  16  has a base portion  16   a  acting as a core member of the neck rest  13 , arm portions  16   b ,  16   c  extending forward from opposite ends of the base portion  16   a  and acting as core members of the holding portions  11 ,  12 , and reinforcing portions  16   d ,  16   e  attached to internal upper and lower ends of the base portion  16   a  and the arm portions  16   b ,  16   c  to reinforce the U-shaped internal frame  16 . The reinforcing portions  16   d ,  16   e  terminate at approximately mid portions of the arm portions  16   b ,  16   c , spaced away from the distal ends of the arm portions  16   b ,  16   c , increasing a deformability of the distal sides of the holding portions  11 ,  12 . For the connection of the base portion  16   a  to the fixed member  15 , no cushioning material is provided on the rear side of the base portion  16   a.    
         [0063]    The internal frame may be eliminated from the holding portions  11 ,  12  and/or the neck rest  13  provided each is capable of holding user&#39;s head immobile while maintaining its shape. For this reason, portions of the holding portions  11 ,  12  and/or the neck rest  13  which will be in contact with the user&#39;s head is preferably made of an elastic material rather than a hard material so that, when in use, the user does not suffer from painful or uncomfortable feeling. 
         [0064]    An operation of the head positioning device  7  will be described with reference to  FIG. 4 . The user P sits on the chair  4  and leans the upper body against the backrest  4   a . Then, the user P preferably moves his or her neck into a space between the holding portions  11 ,  12 . During this motion, the holding portions  11 ,  12  deform due to the elasticity of the cushion material to accommodate the user&#39;s lower jaw therebetween, thereby holding the lower jaw from the opposite sides and supporting the lower jaw from its below. This results in that the user P is unable to rotate his or her head in left-to-right or nod by tilting his or her head forward. 
         [0065]    Then, when the portion of the user&#39;s neck abuts on the neck rest  13 , it is properly positioned with respect to the front-to-rear direction. The height of the user&#39;s neck is determined by the seating height of the user. Also, the neck rest  13  defines a supporting point for fixing the head of the user P. In order for a number of users to use the same system, the height of the fixed member  15  relative to the backrest  4   a , for example, may be adjustable by using one or more screws or pins provided for one of the neck rest  13  and the fixed member  15  and one or more associated screw-holes or pin-holes provided for the other of the neck rest  13  and the fixed member  15 . Of course, it is preferable that the neck rest  13  is maintained at a constant level to ensure that the same person can use the system repeatedly without any need to adjust the height of the neck rest  13 . 
         [0066]    The head back rest  14  preferably abuts on the occipital protuberance of the user P for the positioning of the head of the user P. The head hack rest  14  supports the head of the user P from its back to prevent the head from tilting backward. The head back rest  14  may act to tilt the head of the user P forward around the supporting point defined by the neck rest  13 . This allows the user&#39;s head to be held tightly with his or her lower jaw of the user P forcedly supported between the holding portions  11 ,  12 . 
         [0067]    Eventually, the head of the user P is held facing forward while maintaining a constant front-to-rear tilt angle. In this condition, however, since the holding portions  11 ,  12  have elasticity and the skin of the user P can move relative to his or her skull, the user P with the head held by the head positioning device  7  can slightly move his or her head. 
         [0068]    The shape of the occipital protuberance or the shape and convexity and concavity of the back of the head including or excluding the occipital protuberance varies from person to person. Then, as depicted in  FIG. 10 , a head back rest adjustment mechanism may be provided which allows the head back rest  14  to move in a front-to-rear direction or an up-and-down direction in order to move the contact point of the head. The head back rest may have a recessed or concave portion, or a protruded, expanded, or convex portion, corresponding to the configuration of the occipital protuberance or the back of the head. This allows the occipital protuberance or the back of the head to fit on the concave or convex portion, preventing a displacement of the occipital protuberance or the back of the head relative to the contacting head back rest. To ensure the occipital protuberance or the back of the user&#39;s head to make contacts at a fixed position, the head back rest may be tailor-made for each user. 
         [0069]    According to the embodiment, the contact between the head back rest  14  and the occipital protuberance or the back of the head is reproduced at the same position, which ensures that a magnetic field can be applied to the same position as the previous treatment. Also, the stable reproduction of the contact between the head back rest and the occipital protuberance or the back of the head at the same position ensures that the magnetic field is maintained at the same position during a long time treatment of several tens of minutes or several hours, for example. 
         [0070]    The transcranial magnetic stimulation system  1  uses the camera  9  to image an area including a predetermined reference point on the head of the user P, such as a mark made by art-makeup or a seal behind the ear and displays the image on the monitor  9 . The monitor  9  displays the image captured by the camera  8  and also an indication or marker indicative of a position at which the reference point should be located when the head is properly positioned. The user P slightly moves the user&#39;s head to place the reference point on the indication within a permissible positional error which may be caused due to the elasticity of the head positioning device  7 . This results in that the head of the user P is positioned and postured properly. A plurality of the cameras  8  may be provided to display images captured in different angles. The provision of the plural cameras ensures to obtain a large amount of positional information, ensuring a more accurate positioning. 
         [0071]    The holding portions  11 ,  12  may permit a certain amount of rotation and front-to-rear movement of the user&#39;s head. For example, as shown in in  FIG. 5 , the holding portions  11 ,  12  may be designed so that it supports the opposite lower cheek portions of the user P from their outside, which allows the user P can slightly open his or her mouth in this condition. 
         [0072]      FIG. 6  depicts details of the medical instrument positioning device  6 . The medical instrument positioning device  6  has a medical instrument assembly or magnetic head  22  including the coil  2  and having two exhaust fans  21 , a holding shell  23  holding the magnetic head  22  and being designed to be placed on the head of the user P to act as an interface means between the user&#39;s head and the magnetic head  22 , a first supporting mechanism  24  supporting the holding shell  23  so that it can tilt in the front-to-rear direction, and a second supporting mechanism  25  supporting the first supporting mechanism  24  so that it can tilt left-to-right direction. Although the holding shell  23  has a helmet structure covering the head of the user P in  FIG. 6 , the holding shell  23  may instead have a structure only mainly covering a bottom surface of the magnetic head  22 . 
         [0073]    The first supporting mechanism  24  includes a frame  26  holding the holding shell  23 , a pair of arch portions  27 ,  28  arranged on the left and right sides of the user and extended upward from the frame  26 , a pair of first rails  29 ,  30  attached respectively to the arch portions  27 ,  28 , and supporting plates  32 ,  34  supporting slide rollers  31 ,  33  (depicted in part) engaged respectively-with the first rails  29 ,  30 . The first supporting mechanism  24  also has fixing screws  35 ,  36  capable of press-fixing the arch portions  27 ,  28  and the supporting plates  32 ,  34 . Fixing tools  37 ,  38  are provided to the left and right portion&#39;s of the frame  26  for holding the cameras  9  (not depicted in  FIG. 6 ). 
         [0074]    The second supporting mechanism  25  includes a connection plate  39  integrally holding the supporting plates  32 ,  34  of the first supporting mechanism  24 , a second rail  40  attached to the connection plate  39 , a slide roller  41  (depicted in part) engaged with the second rail  40 , a fixing plate  42  supporting the slide roller  41 , and a fixing screw  43  capable of press-fixing the connection plate  39  and the fixing plate  42 . The fixing plate  42  has at its upper end a fixing unit  42   a  which is designed to be fixed to the supporting member  5  of  FIG. 1 . 
         [0075]      FIG. 7  depicts a relation between the holding shell  23  and the first rails  29 ,  30 . In order to clearly depict the relation between the holding shell and the rails, one of two rails (i.e., rail  29 ) is eliminated from the drawing. The first rails  29 ,  30  are arranged symmetrically on the left and right sides of the frame  26 . The holding shell  23  is constructed similar to the shape of the human head so that the holding shell  23  fits closely on the head of the user P. For example, in the front-to-rear cross section of the holding shell  23 , as indicated at arrows in the drawing the front portion extending forward from the top of the head has a curvature which is smaller to that of the rear portion extending rearward from the top of the head. Correspondingly, the first rail  30  is constructed so that it has a front-to-rear cross section of which curvature varies with that of the holding shell  23 , leaving a certain distance between front-to-rear extending lines of the first rail  30  and the holding shell  23  indicated at the arrows. 
         [0076]    This ensures that, during the front-to-rear movement of the first rails  29  and  30  while being supported by the slide rollers  31 ,  33 , a constant distance is maintained between the highest portion of the holding shell  23  and the slide rollers  31 ,  33  irrespective of the tilting angles of the holding shell  23  and the first rails  29 ,  30 . Although three slide rollers  31 ,  33  are used in the embodiment in  FIG. 7 , the number of the slide rollers is not restrictive provided that the rails can slide on the rollers. Also, instead of slide rollers, another slide mechanism or slide rails may be used. 
         [0077]    Although not depicted, the second rail  40  extends in a coronal plane to leave a certain distance between the second rail  40  and the holding shell  23 . Although the external surface of the holding shell  23  has various uneven portions such as concave and convex portions (see  FIGS. 8 and 9 ), they should be neglected in the discussions of the relations between the holding shell  23  and the rails  29 ,  30 ,  40 , and instead the discussions should be made in terms of the internal configuration of the holding shell. 
         [0078]    With the configurations of the first rails  29 ,  30  and the second rail  40 , a fitting condition of the holding shell  23  on the user P positioned by the head positioning device  7  is maintained substantially constant irrespective of the front-to-rear or left-to-right tilting angle of the holding shell  23 . This means that the head positioning device  7  ensures an accurate selection and adjustment of the portion where the magnetic field generated by the coil  2  will be applied. 
         [0079]    Scales or vernier scales may be provided to readily determine relative angles between the arch portions  27 ,  28  and the supporting plates  32 ,  34  and a relative angle between the connection plate  39  and the fixing plate  42 , allowing the holding shell  23  to be adjusted at predetermined angles at each treatment, which in turn ensures an enhanced treatment effect. 
         [0080]    When the magnetic coil  22  together with the holding shell  23  supporting the magnetic coil  22  is required to be moved from the top of the head to, for example, the temporal, occipital, or front portion of the head for moving the magnetic field irradiation site, it is tilted to a large extent and, even in this condition, the magnetic head  22  is needed to be held stably in the vicinity of the irradiation site. To this end, as shown in  FIG. 8 , preferably the holding shell  23  has one or more supporting portions  51 ,  52  in the form of, for example, recesses. Of course, the supporting positions correspond to the irradiation sites and therefore that the magnetic stimulation is applied to the aimed position in a reliable manner simply by mounting the magnetic head  22  at the associated supporting position. 
         [0081]    In this embodiment, each of the supporting portions  51 ,  52  may be designed to retain the magnetic head  22  with one portion (for example, one half) of the magnetic head  22  in close contact with the holding shell  23  and the remaining portion of the magnetic head  22  slightly away from the holding shell  23 . With the arrangement, even when the magnetic stimulation is required to be applied to a treatment site which is positioned outside a zone surrounded by the holding shell, a part of the magnetic head is retained by the holding shell  23  at the supporting portion  51 ,  52  in a stable manner, allowing the magnetic stimulation to be applied to the treatment site. 
         [0082]    In this embodiment, each of the supporting portions  51 ,  52  is designed so that only a portion of the magnetic head  22  is held in close contact with the holding shell  23  and the remaining portion is slightly spaced apart from the holding shell  23 . This arrangement allows that, as depicted in  FIG. 9 , the magnetic heads  22  and  22 ′ (indicated by solid and alternate long and two short dashed lines, respectively) are supported at the supporting portions  51 ,  52  and the floating (unfixed) portion of the magnetic head  22 ′ extends over the magnetic head  22 . 
         [0083]    The number of the supporting portions is not restrictive and a plurality of supporting portions may be overlapped with each other. Evidently, the magnetic head supporting positions and the corresponding stimulating sites increase in proportion to the number of the supporting portions. 
         [0084]    The shape and the position of the magnetic head  22  vary depending upon, in particular, the shape of the coil. Various shapes of coils are proposed such as a planar coil in which a conductive wire is extended spirally on a flat surface, a spherical coil in which the conductive wire is extended spirally on a spherical surface, and a special coil which is designed in consideration of, for example, treatment effect, power consumption, and convenience. Among others, one or more coils may be selected according to the treatment and mounted at respective proper positions. Although a conventional apparatus can apply the magnetic stimulation to a limited part, the transcranial magnetic stimulation system of the present invention enables selection from a larger number of parts to which the magnetic stimulation can be applied and, therefore, the magnetic coil can be disposed in a wider range. Thus, the magnetic stimulation can be applied to positions appropriate for various diseases and symptoms. 
       PARTS LIST 
       [0000]    
       
           1 : transcranial magnetic stimulation system (medical system) 
           2 : coil 
           4 : chair 
           4   a : backrest 
           5 : supporting member 
           6 : medical instrument positioning device 
           7 : head positioning device 
           8 : camera 
           9 : monitor 
           11 ,  12 : holding portion 
           13 : neck rest 
           14 : head back rest 
           15 : fixed member 
           16 : internal frame 
           17 : cover 
           22 : magnetic head (medical instrument) 
           23 : holding shell 
           24 : first supporting mechanism 
           25 : second supporting mechanism 
           29 ,  30 : first rail 
           31 ,  33 : slide roller 
           32 ,  34 : supporting plate 
           35 ,  36 : fixing screw 
           39 : connection plate 
           40 : second roller 
           41 : slide roller 
           42 : fixing plate 
           51 ,  52 : supporting portion