Shielding of Low-Frequency Magnetic Interference in Weak-Field MRI by a Single-Layer Cylindrical Coil
✍ Scribed by Gorazd Planinšič
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 168 KB
- Volume
- 126
- Category
- Article
- ISSN
- 1090-7807
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✦ Synopsis
Shielding of detection coil from low-frequency magnetic-field son, shielding of the detection coil from low-frequency maginterference is one of the main problems in weak-field MRI methnetic-field interference is one of the main problems in veryods that utilize cycling of main magnetic field (MRI in the Earth's weak-field MRI. One possible solution of this problem is to magnetic field, for example). In such cases, the best solution is choose one of the resistive coils (usually magnetization coil) usually to shield the detection coil by shorting one of the resistive which is parallel to detection coil axis and shorts it during coils of the system, typically the magnetization coil. The optimizasignal detection. In this case, the magnetic-field interference tion of this shielding method has been done by studying the total inside the coil is partially shielded by the currents that this magnetic field on the axis of a shorted single-layer cylindrical coil same interference induces in the shorted coil. Though this placed in a homogeneous oscillating magnetic field parallel to the approach is well known in weak-field MRI (1-3, 5, 7), the coil axis. The results are generalized for the case when series imfull description and optimization of shielding the oscillating pedance is added to the shielding coil. The optimal added impedance that gives the largest shielding factor in the center of the coil magnetic field by the coil has not been described before, to is calculated. Because the theoretical treatment is confined to the the author's knowledge. coil axis, the results are in simple form ready to use in applications. The results of the calculation are verified experimentally and im-THEORY plemented in Earth's field MRI system.