The effect of authentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field

Abstract

As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on active implants like pacemakers have been discussed but the studies of passive metallic (i.e. conductive) implants are rare. However, some studies have shown that the EM power absorption in tissues may be enhanced due to metallic implants. In this study, the effect of authentic passive metallic implants in the head region was examined. A half-wave dipole antenna was used as an exposure source and the specific absorption rate (SAR, W kg(-1)) in the near field was studied numerically. The idea was to model the presumably worst cases of most common implants in an accurate MRI-based phantom. As exposure frequencies GSM (900 and 1800 MHz) and UMTS (2450 MHz) regions were considered. The implants studied were skull plates, fixtures, bone plates and ear rings. The results indicate that some of the implants, under very rare exposure conditions, may cause a notable enhancement in peak mass averaged SAR.

Enhancement of Apoptosis by Titanium Alloy Internal Fixations During Microwave Treatments for Fractures: An Animal Study

“…The implant may reflect microwave and a current is induced on the implant surface. The induced current further produces a secondary electromagnetic field and so the implant acts as weak radiating antenna in tissues [8]. Cells that are undergone to hyperthermia can occur apoptosis or necrosis, and it relates with temperature of the tissue and the time interval of the treatment (CEM 43 = Δt à R 43-T ).…”

“…Previous in vitro studies have shown that tissue ambustion can be caused by the temperature of a metal plate at frequencies near 900 MHz and 27 MHz [7]. However, in vitro studies of radio frequency (RF) electromagnetic fields showed that the metal implants caused little risk using 1800 MHz [8] and 2450 MHz [9,10] microwave radiation. Furthermore, shortwave diathermy, also a high frequency electrotherapy, was clinically applied by some doctors and therapist to the cure and rehabilitation in injuries bone with surgical implanted metal [11,12].…”

Analysis of Materials Effects on Radio Frequency Electromagnetic Fields in Human Head

“…The FDTD method with scaled models of an adult head was used to consider the effects of metallic spectacles on adults and children with a mobile phone placed by the ears [18]. Metallic implants inside the human head have been found to increase the SAR in different human head models [18][19][20][21].…”

The SAR effects of popular jewellery on the human head

“…She considered metallic loops and pins inside a cylindrical head. The same author has reviewed the area of passive implants [10] and investigated implants in a heterogeneous anatomical model of a head [11]. Tay [12] has investigated the change in radiation efficiency using a passive reflector and directive element.…”

“…In the same paper, he also considered passive implants by the ear. Metallic ear rings have previously been considered with a source by the ear [11] [21] [22].…”