公开(公告)号：US06326788B1

公开(公告)日：2001-12-04

申请号：US09428765

申请日：1999-10-28

申请人： Gerardus B. J. Mulder ,  Cornelis L. G. Ham ,  Aart J. Mateboer ,  Nicolaas B. Roozen ,  Johannes P. M. Verbunt

发明人： Gerardus B. J. Mulder ,  Cornelis L. G. Ham ,  Aart J. Mateboer ,  Nicolaas B. Roozen ,  Johannes P. M. Verbunt

IPC分类号： G01V300

CPC分类号： G01R33/4215

摘要： The MRI apparatus includes an actively shielded gradient system (40) with primary gradient coils and shielding coils (56). Despite the active shielding, such a system inevitably causes a magnetic field to some extent outside the shielding, so that eddy currents are generated in the conductive structures of the main magnet, said eddy currents causing heat dissipation and annoying noise. According to the invention, the gradient system also includes an eddy current shield (48) which consists of an electrically conductive, substantially closed plate; furthermore, the primary gradient coil (60) and the shielding coil (56) are arranged within the eddy current shield (48) and these three elements together constitute a mechanically rigid unit. As a result, eddy currents are avoided in the main magnet and annoying noise is strongly reduced.

摘要翻译： MRI装置包括主屏蔽梯度系统（40），其具有主梯度线圈和屏蔽线圈（56）。 尽管主动屏蔽，但这种系统不可避免地会在屏蔽外部导致一定程度的磁场，从而在主磁体的导电结构中产生涡流，所述涡流引起散热和烦人的噪音。 根据本发明，梯度系统还包括由导电的基本封闭的板组成的涡流屏蔽（48） 此外，主梯度线圈（60）和屏蔽线圈（56）被布置在涡流屏蔽（48）内，并且这三个元件一起构成机械刚性单元。 结果，在主磁体中避免了涡流，大大降低了烦人的噪音。