A case study on the influence of a magnetic shielding retrofit on the static magnetic field present in a Magnetic Resonance Imaging (MRI) suite

Purpose: The purpose of this research is to assess whether the practice of retro-fitting passive magnetic shielding to Magnetic Resonance Imaging (MRI) suites is effective in retaining the 0.5 mT footprint of the static magnetic field to within its designed position. Methodology: The research methodology involved identification of an MRI installation where passive magnetic shielding was to be fitted to an installation already in operational use. Site based physical measurements of the magnetic flux density of the static field were then taken both ante and post installation of the shielding, so as to be able to determine its effectiveness. Findings: The results identified areas in the retrofitted magnetic shielding where, as a result of its design, hot spots in excess of 0.5 mT occurred. Practical implications: This research highlights design, construction and safety issues that the designer could, if he had this prior knowledge, have eliminated at source. Value: At the planning stage of a new MRI suite, designers could use the information contained in this research as part of their design risk management process. This research serves to demonstrate the importance of eliminating any possible future need to install retrofitted passive magnetic shielding to an original MRI suite design. It also shows the need for designers to identify the location of any hot spots in the shielding installation where the magnetic flux density may exceed 0.5 mT and become a potential hazard to those individuals fitted with heart pacemakers or other electronic body implants. (C) 2010 Elsevier Ltd. All rights reserved.