A Standard Protocol Proposal for Reliable and Time-Saving Shielding Effectiveness Measurements for MRI Faraday Cages

An inadequate shielding of radio-frequency cabins for magnetic resonance imaging devices can affect clinical images with artifacts. For this reason, periodic measurements of shielding effectiveness are recommended. However, a wide gap exists between the international reference standard currently available for shielding effectiveness measurement (IEEE-Std 299/2006) and the practical approach, mainly because of the poor applicability of the standard to any situation.

The aim of this work is to suggest a novel procedure for the measurement of the shielding effectiveness of radiofrequency cabins for clinical magnetic resonance imaging devices. The application of the cabin door measurements for shielding effectiveness assessment is proposed.

Based on the only international standard currently available, some critical aspects of shielding effectiveness measurements are highlighted. Taking into account theoretical considerations, a novel approach is suggested in order to simplify the applicability of the standard. Frequency ranges and measurement points were reduced by considering the specific device inside the shield.

Results obtained by the application of the proposed protocol were compared with the results obtained by the application of the standard procedure IEEE-Std 299/2006. No significant discrepancies between measurements have been found. It was observed that the time to perform measurements reduced by almost three times.

A time-saving method for measurement of shielding effectiveness in a narrow range of frequencies is proposed.