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Comparison of two fiber‐optical temperature measurement systems in magnetic fields up to 9.4 Tesla
Author(s) -
Buchenberg Waltraud B.,
Dadakova Tetiana,
Groebner Jens,
Bock Michael,
Jung Bernd
Publication year - 2015
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25314
Subject(s) - thermometer , temperature measurement , materials science , phosphor , magnetic field , optical fiber , ceramic , calibration , imaging phantom , analytical chemistry (journal) , nuclear magnetic resonance , optoelectronics , optics , chemistry , composite material , physics , chromatography , quantum mechanics
Purpose Precise temperature measurements in the magnetic field are indispensable for MR safety studies and for temperature calibration during MR‐guided thermotherapy. In this work, the interference of two commonly used fiber‐optical temperature measurement systems with the static magnetic field B 0 was determined. Methods Two fiber‐optical temperature measurement systems, a GaAs‐semiconductor and a phosphorescent phosphor ceramic, were compared for temperature measurements in B 0 . The probes and a glass thermometer for reference were placed in an MR‐compatible tube phantom within a water bath. Temperature measurements were carried out at three different MR systems covering static magnetic fields up to B 0 = 9.4T, and water temperatures were changed between 25°C and 65°C. Results The GaAs‐probe significantly underestimated absolute temperatures by an amount related to the square of B 0 . A maximum difference of Δ T = −4.6°C was seen at 9.4T. No systematic temperature difference was found with the phosphor ceramic probe. For both systems, the measurements were not dependent on the orientation of the sensor to B 0 . Conclusion Temperature measurements with the phosphor ceramic probe are immune to magnetic fields up to 9.4T, whereas the GaAs‐probes either require a recalibration inside the MR system or a correction based on the square of B 0 . Magn Reson Med 73:2047–2051, 2015. © 2014 Wiley Periodicals, Inc.