Uusitupa TM, Ilvonen SA, Laakso IM, and Nikoskinen KI. (2008). The effect of finite-difference time-domain resolution and power-loss computation method on SAR values in plane-wave exposure of Zubal phantom. Phys Med Biol 53:445-452.
The International Electrotechnical Commission is a leading global organization that sets international standards for electronic technologies. Currently, the organization is working to develop a standard method to measure and compute human exposure to radiofrequency (RF) fields. Exposure to RF fields is often measured as specific absorption rate (SAR), defined as the power absorbed per mass of tissue, and is expressed in watts per kilogram. SAR can be averaged over the entire body or over a small sample volume, often 10 grams. Before this standard can be put into practice, factors that can influence accurate measurement of SAR must be understood.
To investigate the effects of two computational methods, finite-difference time-domain (FDTD) and power-loss computation, on SAR values using computer modelling.
A model of the human body was exposed to waves similar to those that would be emitted from a mobile phone antenna in a computer simulation. Whole body averaged SAR and 10g SAR values were calculated for different model settings and using both computation techniques.
Values of whole body averaged SAR and of SAR averaged over 10g varied depending on the methods and model settings used. Values of SAR averaged over 10g were more sensitive to changes due to differences in measurements that were made in the fingers versus in thicker areas of the body such as the torso.
The results of this simulation study show that values of SAR depend on the computational method. This should be considered when calculating human exposure to RF fields.