Health effects of Ultra High Magnetic fields (MRI as Case Study)

Abstract

One of the most rapidly advancing available imaging techniques is Magnetic resonance imaging (MRI). This technique has many side effects can be digested in to main categories: The first is the High Magnetic field effects: these effects contain personal safeties, electrical induced voltage, forces effects of any none ferromagnetic implant material. The second is the High power Electromagnetic Signal effects, which is needed for atoms Excitation. The useful tools of evaluation such side effect is Specific Absorption Rate (SAR) and the increasing of the body temperature. In this paper, the first issue of high magnetic field was discussed; simulation of high magnetic time variant achieved using specialized tools, while the non-variant time magnetic effect is out of our scope. These tools used to evaluate the satisfied requirement levels of the magnetic field characteristics with the aid of some useful software such COMSOL Multiphysics and Matlab. The simulation results show a good agreement with the empirical formulas used to calculate the maximum rate of magnetic field charges. New assumption adopted to calculate the overall magnetic field taking in the account the three magnetic gradient components in X, Y and Z directions The simulation shows that the maximum rate of change in the magnetic field occurs at the edges of the region of interest, while it at lowest level at the isocenter axis. The worst case (more than 50% of the volume beyond the limits) occur at T=100 msec and τ=140 Micro sec (fast imaging case). The generated E field, on the other hand, increased as we far from the center, where a homogenous model was assumed with some none expectable decreasing at the edges. This degradation in the E filed is clearer in non –homogeneous model due to the boundary condition problem. More studies are required, on the effects of Electromagnetic power used in such equipment such as SAR.