Shielding stray magnetic fields of open high field MRI magnets

We have developed a new magnet for open high field (0.7 T) MRI systems. Since MRI systems are installed in hospital sites, it is important to reduce stray magnetic fields of the magnets. We studied passive, active and hybrid shielding methods and compared them. In order to study feasibility of active shielding, we considered higher order multipole stray fields. We present details of the calculation method and the results.