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

P.S. Tofts, neurology Barker, T.L. Dean, H. Gallagher, A.P. Gregory, R.N. Clarke

Research output: Contribution to journalArticlepeer-review

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 ϵ′ = 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.
Original languageEnglish
Pages (from-to)69-75
Number of pages6
JournalMagnetic Resonance Imaging
Volume15
Issue number1
DOIs
Publication statusPublished - Jan 1997

Keywords

  • dielectric constant, relative permittivity, test object, phantom, nonuniformity, head coil

Fingerprint

Dive into the research topics of 'A low dielectric constant customized phantom design to measure RF coil nonuniformity'. Together they form a unique fingerprint.

Cite this