Radiofrequency dosimetry in subjects implanted with metallic straight wires: A numerical study

Abstract

A numerical study to investigate the effects of the exposure to electromagnetic fields (EMF) at 900 and 1800 MHz on biological tissues implanted with thin metallic structures has been carried out, using the finite difference time domain (FDTD) solution technique. The results of the model show that the presence of a metallic wire yields to a significant increase in the local specific energy absorption rate (SAR). The present standards and/or guidelines on safe exposures of humans to EMF does not cover persons with implanted devices and thus the threshold levels to define safe exposure conditions might not apply in presence of high SAR gradients, such as the ones generated by thin metallic implanted objects. However, exposure to EMF fields below the actual safe levels even in presence of thin conductive structures cause rather low temperature rises (1 degrees C).

Reply

“…Dr. Irnich commented that “The deciding distance for considering heat induction is not the absolute length but the distance between lead tip and the metallic case in attached leads or between lead tip and the insulated lead connector of the abandoned lead respectively.” We respectfully disagree with this theory based on our findings, the previous findings of others 1–5 that highlight the effect of lead length on pacemaker lead tip heating, and the lack of peer‐reviewed published evidence favoring this theory.…”

The dependence of radiofrequency induced pacemaker lead tip heating on the electrical conductivity of the medium at the lead tip

“…Finite difference time domain computer simulations were used to examine the effect of a local conductivity change on the local electric field with and without a wire implant. A simple insulated wire is often used in computer simulation as a representation of pacemaker leads (4, 6, 18–20). Our electromagnetic modeling did not include a realistic pacemaker lead owing to the formidable complexity of including one in a finite difference time domain electromagnetic field simulation.…”

Effect of 2100 MHz mobile phone radiation on healing of mandibular fractures: an experimental study in rabbits

“…[41] It was reported that 900 and 1800 MHz plane waves can result in temperature rises around the implant with less than 0.25 C and 0.10 C, respectively. [42] On the other hand, compared to stainless steel, titanium alloy, which is frequently preferred in medical implants, have low magnetic permeability and electric conductivity. Therefore, lesser increases in temperature have been reported secondary to RF applications around implants with titanium alloy.…”