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

Tofts, P. S., Barker, G. J., Dean, T. L., Gallagher, H., Gregory, A. P. and Clarke, R. N. (1997) A low dielectric constant customized phantom design to measure RF coil nonuniformity. Magnetic Resonance Imaging, 15 (1). pp. 69-75. ISSN 0730-725X

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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.

Item Type: Article
Keywords: Dimethylpolysiloxanes/chemistry Electric Conductivity Equipment Design Fires Glass/chemistry Humans Hydrocarbons/chemistry Industrial Oils Kerosene Magnetic Resonance Imaging/ instrumentation Magnetic Resonance Spectroscopy Oils/chemistry Phantoms, Imaging Plant Oils/chemistry Polyesters Pressure Silicones/chemistry Solutions/chemistry Surface Properties Thermodynamics Viscosity
Schools and Departments: Brighton and Sussex Medical School > Brighton and Sussex Medical School
Depositing User: Paul Stephen Tofts
Date Deposited: 28 Feb 2007
Last Modified: 30 Nov 2012 16:50
URI: http://sro.sussex.ac.uk/id/eprint/830
Google Scholar:12 Citations
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