Superconducting magnet apparatus and magnetic resonance imaging apparatus using the same

Abstract

An MRI apparatus is characterized in that magnet members for compensating the magnetic field are disposed to a thermal shield system of the superconducting apparatus. It is another feature of the present invention that the magnet members for compensating the magnetic field are disposed at positions where temperature change in the vacuum chamber is not transferred to the interior of the vacuum chamber.

1 . A superconducting magnet apparatus comprising annular superconducting coils; coil containers for accommodating the annular superconducting coils together with a coolant; thermal shields so disposed as to surround the coil containers; and a vacuum chamber surrounding the coil containers and the thermal shields, the interior of the vacuum chamber being kept vacuum; wherein the coil containers are so arranged as to oppose to each other to form a magnetic space therebetween, and wherein magnetic members for compensating a magnetic field in the magnetic space are disposed to the thermal shields.  
   
   
       2 . (canceled)  
   
   
       3 . The superconducting magnet apparatus according to  claim 1 , wherein cooling conduits are disposed to the thermal shields  
   
   
       4 . The superconducting magnet apparatus according to  claim 1 , wherein the magnet members are located at the axis symmetric position with respect to a center axis of the magnetic space formed between the coil containers.  
   
   
       5 . (canceled)  
   
   
       6 . A superconducting magnet apparatus comprising annular superconducting coils; coil containers for accommodating the superconducting coils together with a coolant; thermal shields so disposed as to surround the coil containers; and a vacuum chamber surrounding the coil containers and the thermal shields, the interior of the vacuum chamber being kept vacuum, wherein the coil containers are disposed to oppose to each other to form a magnetic field therebetween, and wherein magnet members for compensating a magnetic field in the magnetic field are disposed outside the coil containers but in the vacuum chambers.  
   
   
       7 . The superconducting magnet apparatus according to  claim 1 , wherein the magnet members for compensating the magnetic field are disposed outside the coil containers but inside the thermal shields.  
   
   
       8 . (canceled)  
   
   
       9 . The superconducting magnet apparatus according to  claim 8 , wherein supporting members support the magnet members for compensating the magnetic field from the thermal shields.  
   
   
       10 . The superconducting magnet apparatus according to  claim 6 , wherein the magnet members are provided with cooling conduits.  
   
   
       11 . The superconducting magnet apparatus according to  claim 6 , wherein the magnet members are located at the axis symmetric position with respect to the center axis of the magnetic space formed between the coil containers.  
   
   
       12 . (canceled)  
   
   
       13 . A magnetic resonance imaging apparatus that uses the superconducting magnet apparatus according to  claim 1 .  
   
   
       14 . A superconducting magnet apparatus comprising annular superconducting coils; coil containers for accommodating the annular superconducting coils together with a coolant; thermal shields so disposed as to surround the coil containers; and a vacuum chamber surrounding the coil containers and the thermal shields and a magnetic space formed between the coil containers, the interior of the vacuum chamber being kept vacuum; wherein the coil containers each accommodating the coil containers and the thermal shields are so arranged as to oppose to each other to form a magnetic space therebetween, and wherein magnet members for compensating the magnetic field are so disposed between the thermal shields.  
   
   
       15 . The superconducting magnet apparatus according to  claim 14 , wherein the magnet members are supported by supporters from the thermal shields.  
   
   
       16 . The superconducting magnet apparatus according to  claim 14 , wherein there is disposed a coolant conduit for cooling the thermal shields.  
   
   
       17 . The superconducting magnet apparatus according to  claim 14 , the magnet members are arranged at positions symmetric with respect to the center axis of the magnetic field.  
   
   
       18 . (canceled)  
   
   
       19 . A magnetic resonance imaging apparatus that uses a magnet apparatus according to  claim 14 .  
   
   
       20 . A superconducting magnet apparatus, which comprises a pair of upper and lower magnet units each comprising an annular superconducting coil; an annular coil container for accommodating the annular superconducting coil together with a coolant; a first magnet member extending along a center axis of the magnet unit and located on the center axis; an annular second magnet member disposed in an axial symmetric relation with respect to the first magnet member; a thermal shield so disposed as to surround the coil container, the first magnet member and the second magnet member; and a vacuum chamber surrounding the thermal shield with a vacuum gap between the thermal shield and the vacuum container, the interior of the vacuum chambers being kept vacuum; wherein the magnet units constitute to form a magnetic space therebetween, and wherein the first and second magnet members for compensating the magnetic field are fixed to the thermal shield.  
   
   
       21 . The superconducting magnet apparatus according to  claim 20 , wherein each of the magnet units further comprises a third magnet member disposed near the magnetic space and outside the second magnet member.  
   
   
       22 . The superconducting magnet apparatus according to  claim 20 , wherein each of the magnet units further comprises a gradient coil at a position facing the magnetic space.  
   
   
       23 . A magnetic resonance imaging apparatus that uses the superconducting apparatus according to  claim 20 .  
   
   
       24 . A superconducting magnet apparatus comprising annular superconducting coils; coil containers for accommodating the annular superconducting coils together with a coolant; thermal shields so disposed as to surround the coil containers; and a vacuum chamber(s) surrounding the coil containers and the thermal shields and a magnetic space formed between the coil containers, the interior of the vacuum chamber being kept vacuum; wherein the coil containers each accommodating the coil containers and the thermal shields are so arranged as to oppose to each other to form a magnetic space therebetween, and wherein magnet members for compensating the magnetic field are disposed between the thermal shields.  
   
   
       25 . A magnetic resonance imaging apparatus that uses the superconducting apparatus according to  claim 23.