MR safety: simultaneous B 0, dΦ/dt, and dB/dt measurements on MR-workers up to 7 T

Abstract

The findings in this work indicate that both translations and rotations in the vicinity of an MR system should be taken into account, and that a single regulatory action level might not be sufficient.

Comparison of two fiber-optical temperature measurement systems in magnetic fields up to 9.4 Tesla

“…, Table ) measured temperature shifts of −4.5°C on average at 9.4T which is in very good agreement with our results at the isocenter of the small animal imaging system of −4.4°C on average (Table ). In Groebner et al a decrease of 2.6°C was observed at a 7T whole‐body system which is in excellent agreement with our measurements at 7T in the fringe field (9.4T system) and at isocenter (7T system) of −2.6°C and −2.7°C (Table ). Thus, these temperature differences are solely related to the magnetic field strength, and do not depend on the MR system type.…”

“…In this work, we showed that the precision of the measurement is critically dependent on the type of fiber‐optical sensor that is applied for temperature measurements in the magnetic field. If sensors with a semiconductor measurement method are used, and sensor calibration is performed outside the magnetic field, field‐strength dependent deviations will occur, as was partly also described in earlier works .…”

“…For example, correct temperature measurements next to implants are crucial for the development of MR‐safe devices, and calibration of MR temperature measurements during thermal therapies are needed to ensure a safe and effective MR therapy guidance. However, there is evidence from the literature that some fiber‐optical probes underestimate absolute temperature in strong magnetic fields .…”

Gradient and shim technologies for ultra high field MRI

“…There is evidence that physiological effects, such as vertigo, metallic taste, and dizziness are related to the spatial fall-off ( dB 0 / dz ) of the fringe field and to the diamagnetic force B 0 * dB 0 / dz (Kangarlu et al, 1999; Liu et al, 2003; Cavin et al, 2007; Glover et al, 2007; Glover and Bowtell, 2008; Groebner et al, 2011; Budinger et al, 2016). …”

A novel tool for estimation of magnetic resonance occupational exposure to spatially varying magnetic fields

“…Moreover, since the growing interest of the MR scientific community in developing devices for measurement of static magnetic fields and personal MR dosimeters [22,23], this tool can be used to validate and calibrate this kind of instrument.…”