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Abstract
| Introduction: This note describes performance test of B-RAD, a commercial γ-survey meter/portable γ-spectrometer designed to operate in strong magnetic field. The
instrument consists of an active probe housing a cylindrical LaBr3 crystal, and a central unit connected by a cable.
Methods: The measurements were performed at an MR-Linac Elekta Unity (1.5 T) and a Philips Ingenia (3 T) MRI system, by measuring the H*(10) rate and the
gamma energy distributions using two certified radioactive sources of 57Co and 137Cs providing a reference irradiation while the detector was exposed to increasing
values of the magnetic field. Measurements were performed in various configurations, with probe and central unit either kept close together or separate, and either
aligned or orthogonal to the magnetic field.
Results: The results outline stable H*(10) rates and gamma spectrometry performances in the entire magnetic field range. The device’s performance is unaffected
when only the probe is exposed to the static magnetic field while the central unit is in a lower field zone. When the latter is exposed to a strong field, the loss in dose
rate remains within 10% for all configurations tested.
Conclusion: The results demonstrate the potential application of the instrument for operational and decommissioning measurements at MRI-Linac and PET-MRI
systems. |