Engineering for safety assurance in MRI: analytical, numerical and experimental dosimetry

Magnetic resonance imaging (MRI) is considered a safe technology since it does not use ionizing radiation with high energy to detach electrons from atoms or molecules. However, as in any healthcare intervention, even in an MRI diagnostic procedure there are intrinsic hazards that must be understood and taken into consideration. Moreover, given the increasing number of clinical MRI examinations and the widespread availability of MR scanners with high static magnetic fields (>3T), the consideration of possible risks and health effects associated with MRI procedures is gaining in importance and the term "dosimetry" has begun to be used also for non ionizing techniques as MRI. Engineering techniques are increasingly used in MRI to explain the interactions between electromagnetic fields and the human body, analyze aspects relative to signal and image generation, and assure patient and staff safety and comfort. In this review some engineering methods to quantify the interactions between MR fields and biological tissues will be reviewed and cataloged to aid the readers in finding resources for their own applications in MRI safety assurance. This paper should not be intended as another review of the biological effects of MRI but, for the reader's convenience, the possible hazards for each kind of MR magnetic field, will be briefly described.