ABSTRACT
It is a difficult task, with the limited experience and experiments available, to set safe limits of exposure to static magnetic fields. Ventricular fibrillation is the most serious response to electric currents flowing through the body. Limits applicable to NMR operating conditions can be derived from these limits on current density. The currents are induced in the tissues of exposed individuals when the magnetic field changes with respect to tissue and can be estimated using Faraday’s Law of induction. British and Canadian guidelines also give recommendations about supervision of volunteers and patients undergoing NMR examination. Volunteers participating in experimental trials of NMR imaging techniques should be medically assessed and pronounced suitable candidates before exposure. Patients should be exposed only with the approval of a registered medical practitioner who should be satisfied that the exposure is likely to contribute to the treatment of the patient or is part of a research project approved by a local research ethical committee.
