as shown in fig1 - 5 , a mri guided high - intensity focused ultrasonic therapeutic system of the present invention comprises a mri apparatus 1 and a high - intensity focused ultrasonic therapeutic apparatus . a first treatment bed 2 in the bore of the mri apparatus 1 is supported by a supporting means 3 , which is fixed on the mri apparatus 1 . the high - intensity focused ultrasonic therapeutic apparatus comprises an ultrasound transducer 6 and a moving and positioning means for driving ultrasound transducer 6 to move in multiple - orientations and the moving and positioning means is placed outside of the bore of the mri apparatus 1 and is connected to a supporting rod 4 , which may extend into the bore of the mri apparatus and is connected to the ultrasound transducer 6 at the other end . the moving and positioning means comprises a control means 9 for driving supporting rod 4 to move in x , y and z - directions and rotate around x - direction . the moving and positioning means may comprise an adjusting device 10 for moving said moving and positioning means upward and downward . the moving and positioning means may comprise a sliding device at the bottom for moving the moving and positioning means horizontally . the sliding device includes a pulley 11 and a slide rail 12 . the pulley 11 is installed at the bottom of moving and positioning means and the pulley 11 is placed on the slide rail 12 . said moving and positioning means may further comprise a rotating device 8 for driving the supporting rod to rotate around the axis of mri or the parallel lines of the axis . preferably , supporting rod 4 is made of non - magnetic material or non - metal material . the mri guided high - intensity focused ultrasonic therapeutic system of the present invention further comprises the second treatment bed 13 . the ultrasound transducer 6 is placed within a container 5 , which is full of fluid and connected to the supporting rod 4 . when the container 5 is placed under the treatment bed used by a patient ( the first treatment bed or the second treatment bed ), this treatment bed has an aperture 16 thereon . the position of the ultrasound transducer 6 corresponds to that of the aperture 16 of that treatment bed . the container 5 is an open one , which is open at the end faced to the aperture 16 and enables a patient to directly contact with the fluid in the container 5 . when the container 5 is placed above the treatment bed used by a patient ( the first treatment bed or the second treatment bed ), the container is a close one . the open end of container 5 is closed by a flexible acoustically transparent membrane 15 adapted to be in direct contact with the patient . wherein , the fluid may be degassed water . the present invention is further described in detail taking in conjunction with the following embodiments and accompanying drawings . as shown in fig1 , the system in this embodiment comprises a mri apparatus 1 and a high - intensity focused ultrasonic therapeutic apparatus . wherein , the high - intensity focused ultrasonic therapeutic apparatus comprises an ultrasound transducer 6 , a moving and positioning means , which is located behind the mri apparatus and is connected to a supporting rod 4 . the supporting rod 4 is connected to a control means 9 of the moving and positioning means at its one end and is connected to ultrasound transducer 6 at the other end . the moving and positioning means comprises the control means 9 , which drives the supporting rod 4 to move in x , y and z - directions and rotate around x - direction . as shown in fig1 and fig2 , each motion structure for movement in x , y and z directions of the control means 9 comprises a motor , a screw rod , a sliding block and a slide rail , which are integrated with the supporting rod . the screw rod is connected to the motor and the sliding block on the slide rail engages with the screw rod . driven by a motor 18 , a screw rod 19 drives the supporting rod 4 to move along a slide rail 20 in x - direction . driven by a motor 21 , a screw rod 22 drives the supporting rod 4 to move along a slide rail 23 in y - direction . as shown in fig1 , driven by a motor 24 , a screw rod 25 drives the supporting rod 4 to move along a slide rail 26 in z - direction . the structure for rotating around x - direction of the control means 9 comprises a motor 27 , a synchronization belt 28 and a synchronization belt - wheel 29 . the synchronization belt - wheel 29 is integrated with the supporting rod 4 . through the synchronization belt 28 , an output shaft of motor 27 is connected to the synchronization belt - wheel 29 . under the drive of the motor 27 and the force of the synchronization belt 28 and synchronization belt - wheel 29 , the supporting rod 4 can rotate 0 - 360 ° around x - axis . in this embodiment , the supporting rod 4 adopts a nickel - zinc - copper alloy in order to minimize the interference to the magnetic field of mri apparatus 1 . as shown in fig1 , there is a first treatment bed 2 and a second treatment bed 13 in the bore of the mri apparatus 1 and the second one 13 is placed above the first one 2 . the first treatment bed 2 is connected to the second one 13 by an adjustable fastening device 14 , which can be used to adjust the position between the first treatment bed 2 and the second treatment bed 13 . the first treatment bed 2 is fixed on a supporting means 3 , which is fixed on the mri apparatus 1 . wherein , there is an aperture on a section of the second treatment bed 13 , which doesn &# 39 ; t overlap with the first treatment bed 2 . fig6 is a schematic structural diagram of adjustable fastening device 14 . the adjustable fastening device 14 comprises a transition piece 30 , a pulley 31 , a pulley support 32 , a bolt 33 , a nut 34 and a compressible spring 35 . the transition piece 30 is embedded in the first treatment bed 2 and the pulley 31 is installed on the transition piece 30 . the pulley support 32 is connected to a pulley shaft . the bolt 33 passes through the second treatment bed 13 and the pulley support 32 and is connected to the nut 34 . the compressible spring 35 encases the bolt 33 and is sandwiched between the second treatment bed 13 and the pulley support 32 . the transition piece 30 is embedded in the first treatment bed 2 so that the pulley 31 can move thereon . there are the bolt 33 , the nut 34 and the compressible spring 35 installed between the pulley support 32 and the second treatment bed 13 . when the second treatment bed 13 is pushed , under that pushing force , the second treatment bed 13 is driven by the pulley 31 and moves in x - direction . by adjusting the bolt 33 and the nut 34 , the compressible spring 35 deforms and accordingly the distance between the two beds changes . multiple sets of devices which include the bolt 33 , the nut 34 and the compressible spring 35 can be installed between the two beds and by adjusting different bolts 33 and nuts 34 , the compressible springs deform to different extents and accordingly the different angles can be formed between the two beds . as shown in fig1 and fig2 , the moving and positioning means further comprises a sliding device , which facilitates an operator to manually operate the ultrasound transducer during treatment . said sliding device comprises a pulley 11 and a slide rail 12 for the pulley 11 sliding on . as shown in fig1 , a rotating device 8 is connected to the control means 9 by a screw thread and the like . under the drive of a motor 36 and the force of a synchronization belt 37 and a synchronization belt - wheel 38 , the rotating device 8 drives the whole control means 9 to be rotatable 0 - 360 ° around the axis of mri apparatus 1 or the parallel lines of the axis . because the supporting rod 4 is connected to the control means 9 , under the drive of the control means 9 , the supporting rod 4 can also rotate 0 - 360 ° around the axis of mri apparatus 1 or the parallel lines of the axis . as shown in fig2 , the adjusting device 10 comprises a motor 39 , a screw rod 40 and a slide rail 41 . under the drive of motor 39 , the screw rod 40 drives the rotating device 8 to move upward and downward along the slide rail 41 in z - direction . because the control means 9 is connected to the rotating device 8 and the supporting rod 4 is connected to the control means 9 , under the movement transmission , the supporting rod 4 can also move upward and downward in z - direction . the sliding device is located under the moving and positioning means and comprises the pulley 11 installed under the moving and positioning means and the slide rail 12 for the pulley 11 sliding on . when the force is applied to the moving and positioning means in x - direction , the whole moving and positioning means will move in x - direction . after the ultrasound transducer 6 is positioned under the second treatment bed 13 , the ultrasonic therapy can be applied to the nidus of the patient from the bottom up . in this embodiment , the ultrasound transducer 6 is placed into a container 5 , which contains fluid . the container 5 is a water bag , which is open at the end faced to the aperture 16 of the treatment bed 13 . the container is full of degassed water . the degassed water is used as ultrasound propagation medium with a controlled temperature of about 25 ° c . because the ultrasound transducer 6 is placed in the water bag , the water bag is connected to the supporting rod 4 through a flexible matter 7 . wherein , ultrasound transducer 6 adopts spherical shell focusing piezoelectric transducer with a focal distance ranging from 80 mm to 200 mm , a diameter ranging from 80 mm to 300 mm and a working frequency ranging from 0 . 5 mhz to 2 mhz . the work process of the therapy system in the present embodiment is : firstly , placing the patient on the second treatment bed 13 of the mri apparatus 1 , adjusting the supporting means 3 and / or the adjustable fastening device 14 to position the nidus of the patient within the magnet resonance volume and using the mri apparatus 1 to image the nidus of the patient . then , driving the supporting rod 4 by the moving and positioning means to move the ultrasound transducer 6 in the space under the second treatment bed 13 , moving the ultrasound transducer 6 until it aims at the aperture 16 of the second treatment bed 13 , and overlapping the focus of the ultrasound transducer 6 with the nidus of the target area to be treated within the magnetic resonance volume . finally , transmitting the therapeutic ultrasonic waves and applying therapy to the patient . as shown in fig3 , in this embodiment , the moving and positioning means is located behind the mri apparatus 1 . it is different from the embodiment 1 that in this embodiment , there is only the first treatment bed 2 in the bore of the mri apparatus 1 and the ultrasound transducer 6 is located above the first treatment bed 2 to apply the ultrasonic waves to the nidus of the patient from the top down . because the ultrasound transducer 6 is located above the first treatment bed 2 to apply the ultrasonic waves to the nidus of the patient from the top down , the first treatment bed 2 in the mri apparatus 1 may not have an aperture and it may be used for performing normal treatment . the container 5 adopts a water bag , which is full of degassed water . in order to avoid the overflow of the degassed water in that bag , a flexible acoustically transparent membrane 15 is used to seal the open end of the water bag and that membrane can be in direct contact with the patient . other components in this embodiment are the same as those in the embodiment 1 . as shown in fig4 and fig5 , in this embodiment , the moving and positioning means is in front of the mri apparatus 1 during treatment . the mri apparatus comprises a first treatment bed 2 and a second treatment bed 13 . the moving and positioning means comprises a bed moving means for moving the second treatment bed 13 and a control means 9 for driving an ultrasound transducer to move in x , y and z - directions and rotate around x - direction . the second treatment bed 13 is connected to the moving and positioning means through the bed moving means . wherein , the structure of the control means 9 is the same as that in the embodiment 1 . the bed moving means comprises a structure of pulley and slide rail for moving the second treatment bed 13 rightward and leftward and a structure of pulley and slide rail for moving the second treatment bed 13 forward and backward . as shown in fig4 , a slide rail 17 is fixed on the control means 9 and a fluid container 5 is placed in an aperture of the second treatment bed 13 . when the whole high - intensity focused ultrasonic therapeutic apparatus is pushed by hand , under the driving of a pulley 43 , the whole apparatus moves rightward and leftward along a slide rail 12 horizontally and is located in front of the mri apparatus 1 . as shown in fig5 , when the second treatment bed 13 is pushed by hand , the pulley 42 moves along the slide rail 17 forward and backward . because the second treatment bed 13 is connected to the moving and positioning means , the whole moving and positioning means also moves along the slide rail 12 forward and backward by this force . and finally , the second treatment bed 13 enters into the bore of the mri apparatus 1 and is positioned in the optimal position for treatment on the patient . after the ultrasound transducer 6 is positioned under the second treatment bed 13 , the ultrasonic therapy can be applied to the nidus of the patient from the bottom up . other components and functions in this embodiment are the same as those in the embodiment 1 .