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A low dielectric constant customized phantom design to measure RF coil nonuniformity
journal contribution
posted on 2023-06-07, 13:50 authored by P. S. Tofts, G. J. Barker, T. L. Dean, H. Gallagher, A. P. Gregory, R. N. ClarkeThe 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.
History
Publication status
- Published
Journal
Magnetic Resonance ImagingISSN
0730-725XPublisher
ElsevierExternal DOI
Issue
1Volume
15Page range
69-75Department affiliated with
- BSMS Publications
Full text available
- No
Peer reviewed?
- Yes