B1 field homogeneity and SAR calculations for the birdcage coil
B1 field homogeneity and SAR calculations for the birdcage coil
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DOI：
10.1088/0031-9155/46/2/324
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发表时间：
2001-02-01
影响因子：
3.5
通讯作者：
Robitaille, PML
中科院分区：
文献类型：
--
作者：
Ibrahim, TS;Lee, R;Robitaille, PML
采用时域有限差分（FDTD）方法对鸟笼谐振器进行建模。所有线圈元件，包括导线、集总电容器和电源，都以几何形状建模在一起。这样，鸟笼内的耦合效应，包括线圈，源和人的头的相互作用，得到了准确的计算。研究了横向磁（B-1）场均匀性和比吸收率（SAR）的解剖详细的人体头部模型在64和200 MHz分别代表1.5和4.7 T MRI系统。与64 MHz不同，在200 MHz时B1场分布是不均匀的。此外，由于源和头部之间在200 MHz的耦合，在源附近的组织中观察到高局部SAR值。
The finite-difference time-domain (FDTD) method is used to model a birdcage resonator. All the coil components, including the wires, lumped capacitors and the source, are geometrically modelled together. As such, the coupling effects within the birdcage, including the interactions of coil, source and human head, are accurately computed. A study of the transverse magnetic (B-1) field homogeneity and the specific absorption rate (SAR) is presented on an anatomically detailed human head model at 64 and 200 MHz representing 1.5 and 4.7 T MRI systems respectively. Unlike that at 64 MHz, the B1 field distribution is found to be inhomogeneous at 200 MHz. Also, high local SAR values are observed in the tissue near the source due to the coupling between the source and the head at 200 MHz.