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From virtual models to real people: safety factors for patient safety in MRI


Signal generation in magnetic resonance imaging (MRI) scanners relies on strong radio frequency fields. Monitoring and limiting the local energy deposition in the patient's body, measured via the specific absorption rate (SAR), represents a major challenge, especially when working with several transmit antennas in parallel. The SAR distribution cannot be measured directly but must be calculated in advance by field simulation in digital human models. As the real patient in the MR scanner is not identical to the models simulated, new uncertainties are created that are difficult to quantify. Johannes Petzold (PTB 8.11) together with colleagues, e.g. from OVGU Magdeburg, developed a systematic approach by selecting from a pool of 11 digital models every possible combination of two disjoint subsets. Safety limits were determined on subset 1 and then tested on subset 2. A procedure was thus presented with which manufacturers of MRI transmitter coils can determine robust safety factors. The work with entitled "Investigation of alternative RF power limit control methods for 0.5 T, 1.5 T, and 3 T parallel transmission cardiac imaging: a simulation study" has now been published in Magnetic Resonance in Medicine: (doi: 10.1002/MRM.29932).


Johannes Petzold, E-Mail: 📧 johannes.petzold(at)ptb.de