| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a magnetic resonance imaging apparatus capable of obtaining high-quality MRI images by stabilizing the uniformity of a static magnetic field under photographing while securing safety to prevent an electric leakage caused by dew condensation without making excessively large a means for suppressing the temperature rise of shim iron pieces of a shimming apparatus for correcting the uniformity of the static magnetic field. <P>SOLUTION: The magnetic resonance imaging apparatus includes a shim cooling tube that has a passage for the flow of a refrigerant for cooling the shim iron pieces in shim trays arranged in circular shape between a main coil and a circular shield coil of an elliptical gradient magnetic field coil, by abutting on the shim trays. The shim cooling tube abuts on the shim tray, and the shim iron pieces are fixed into shim slots. Since the temperature of the shim iron pieces is highest on an X-axis which is the major axis of an ellipse of the elliptical main coil and lowest on a Y-axis which is the minor axis of the ellipse due to the calorific value of the main coil, a contact area of the shim cooling tube and shim tray is made largest on the X-axis and made smaller toward the Y-axis direction, and the shim cooling tube is eliminated on the Y-axis. Further, the temperature of the refrigerant is controlled to a temperature causing no dew condensation. <P>COPYRIGHT: (C)2012,JPO&INPIT |
