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

doi:10.1016/S0730-725X(96)00220-2

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

SHLS School Office

Research output: Contribution to journal › Article › peer-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 language	English
Pages (from-to)	69-75
Number of pages	6
Journal	Magnetic Resonance Imaging
Volume	15
Issue number	1
DOIs	https://doi.org/10.1016/S0730-725X(96)00220-2
Publication status	Published - Jan 1997

Keywords

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

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10.1016/S0730-725X(96)00220-2

Cite this

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title = "A low dielectric constant customized phantom design to measure RF coil nonuniformity",

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.",

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T1 - A low dielectric constant customized phantom design to measure RF coil nonuniformity

AU - Tofts, P.S.

AU - Barker, neurology

AU - Dean, T.L.

AU - Gallagher, H.

AU - Gregory, A.P.

AU - Clarke, R.N.

N1 - YYYY only for pub date - MM/YYYY from CrossRef, CKB 23/11/2021

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N2 - 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.

AB - 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.

KW - dielectric constant, relative permittivity, test object, phantom, nonuniformity, head coil

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DO - 10.1016/S0730-725X(96)00220-2

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JF - Magnetic Resonance Imaging

SN - 0730-725X

IS - 1

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

Abstract

Keywords

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