MRI Compatible Machinery
Kiyoyuki CHINZEI,  Kazuhiro HOMMA, Ichiro IHARA*
Biomechanics Div., Mechanical Eng. Lab., MITI/ Japan,  *Dept. Mechanical Eng., Tokyo Science University
Key words: MRI compatibility, Magnetic susceptibility, Magnetic homogeneity, Nonmagnetic stainless steel
Abstract
  The authors have developed MRI compatible machines as research instruments such as hydraulic actuated stress machines. MRI compatibility requires the machines are both electrically and magnetically 'transparent'. It prohibits most of standard (also easily available and cheap) mechanical elements being used in MRI environment.
  We developed a nonmetallic linear hydraulic actuator which can locate very close to the imaging field. It equips an optical linear encorder and a conventional (electric) strain sensor. The latter was affected by strong RF pulses from MRI but other worked without giving any serious effects to imaging. We also manufactured a two-axes precision linear table. It was driven by two ultrasonic motors via screw shafts. Linear guides and the screw shafts were made from nonmagnetic stainless steel or beryllium copper. It can locate about 80 cm away from the imaging field.