一种用于测量射频线圈不均匀性的低介电常数定制体模设计。

A low dielectric constant customized phantom design to measure RF coil nonuniformity.

作者信息

Tofts P S, Barker G J, Dean T L, Gallagher H, Gregory A P, Clarke R N

机构信息

Institute of Neurology, London, UK.

出版信息

Magn Reson Imaging. 1997;15(1):69-75. doi: 10.1016/s0730-725x(96)00220-2.

DOI:10.1016/s0730-725x(96)00220-2

PMID:9084027

Abstract

The selection of a suitable low dielectric constant liquid for radiofrequency coil nonuniformity measurements is described. Measurements of dielectric constant (relative permittivity) were made on a range of candidate liquids. After excluding liquids that were too inflammable or too viscous, Esso Bayol 82 oil (dielectric constant epsilon' = 2.37) was chosen. At 1.5 T, a 27 cm diameter cylindrical phantom (test object) filled with Bayol 82 has a maximum nonuniformity of 1.9% arising from radiofrequency standing waves. The maximum diameter cylinder that can be used without the nonuniformity exceeding 2% is given for a range of liquids and field strengths. The construction of customized containers that fit closely inside a radiofrequency head coil from glass fiber reinforced resin ("fiberglass") is described. Thermal expansion of the liquid takes place without a rise in the internal pressure in the container.

摘要

本文描述了用于射频线圈不均匀性测量的合适低介电常数液体的选择。对一系列候选液体进行了介电常数（相对电容率）测量。排除了易燃性过高或粘性过大的液体后，选择了埃索贝约尔82油（介电常数ε' = 2.37）。在1.5 T时，一个直径27 cm、充满贝约尔82的圆柱形体模（测试对象）由于射频驻波产生的最大不均匀性为1.9%。给出了一系列液体和场强下，在不均匀性不超过2%的情况下可使用的最大直径圆柱体。描述了由玻璃纤维增强树脂（“玻璃纤维”）紧密贴合在射频头部线圈内部的定制容器的构造。液体发生热膨胀时，容器内的压力不会升高。