On the Development of a Novel Leg Phantom for RF Safety Assessment for Circular Ring External Fixation Devices in 1.5 T

摘要

Tissue heating due to radio frequency (RF) energy absorption in the human body in a magnetic resonance imaging (MRI) environment is one of the primary concerns about MRI-related safety issues for patients, especially with the presence of sizable metal implants such as circular external fixation devices. This article proposes a novel method to evaluate the MRI RF-induced heating effects of circular external fixation devices utilizing an innovative leg phantom. The comparison of the E field distribution shows the validity of the novel leg phantom. A number of essential geometrical parameters, i.e., ring frame diameter, strut length, and insertion angle, were numerically investigated to study the RF-induced heating mechanism and behaviors of circular external fixation devices. Numerical results suggest that the maximum 1 g-averaged SAR is shown to be a reasonable indicator of the induced temperature rise. A thermal experiment for a testing rod inside the leg phantom shows good agreement with the numerical simulation.