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Development of an Active Magnetic Noise Shielding System for a Permanent Magnet Based MRI  

이수열 (경희대학교 동서의학대학원 의료공학전공)
전인곤 (경희대학교 동서의학대학원 의료공학전공)
이항노 (경희대학교 동서의학대학원 의료공학전공)
이정한 (건국대학교 의학공학부)
Publication Information
Journal of the Institute of Electronics Engineers of Korea SC / v.40, no.3, 2003 , pp. 181-188 More about this Journal
Abstract
In this paper, we introduce a magnetic noise shielding method to reduce the noise effects in permanent magnet based MRI systems. Through FEM electromagnetic analyses, we have shown that the magnetic noise component parallel to the main magnetic field is the major component that makes various artifacts in the images obtained with a permanent magnet based MRI. Based on the FEM analyses, we have developed an active magnetic noise shielding system composed of a magnetic field sensor, compensation coils, and a coil driving system. The shielding system has shown a noise rejection ratio of about 30dB at the frequency below several Hz. We have experimentally verified that the shielding system greatly improves the image quality in a 0.3 Tesla MRI system.
Keywords
MRI; permanent magnet; magnetic moise; active shielding;
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