Erasmus MC-Daniel den Hoed Cancer Center, Department of Radiation Oncology, Section Hyperthermia, PO Box 5201, NL-3008 AE, Rotterdam, The Netherlands.
Phys Med Biol. 2011 Aug 7;56(15):4967-89. doi: 10.1088/0031-9155/56/15/020. Epub 2011 Jul 19.
To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body-averaged specific absorption rate (SAR(wb)) are provided to keep the whole-body temperature increase (T(body, incr)) under 1 °C during 30 min. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR(10g)) are provided to prevent excessive localized tissue heating. The objective of this study is to assess the localized peak temperature increase (T(incr, max)) in children upon exposure at the reference levels. Finite-difference time-domain modeling was used to calculate T(incr, max) in six children and two adults exposed to orthogonal plane-wave configurations. We performed a sensitivity study and Monte Carlo analysis to assess the uncertainty of the results. Considering the uncertainties in the model parameters, we found that a peak temperature increase as high as 1 °C can occur for worst-case scenarios at the ICNIRP reference levels. Since the guidelines are deduced from temperature increase, we used T(incr, max) as being a better metric to prevent excessive localized tissue heating instead of localized peak SAR. However, we note that the exposure time should also be considered in future guidelines. Hence, we advise defining limits on T(incr, max) for specified durations of exposure.
为了避免电磁场（EMF）可能带来的不良健康影响，国际非电离辐射防护委员会（ICNIRP）已经定义了 EMF 参考水平。限制诱导的全身平均比吸收率（SAR(wb))，以保持全身温度升高（T(body, incr))在 30 分钟内不超过 1°C。对峰值 10 g 空间平均 SAR（SAR(10g))的额外限制，是为了防止过度的局部组织加热。本研究的目的是评估参考水平下儿童暴露时局部峰值温升（T(incr, max))。使用时域有限差分建模来计算暴露于正交平面波配置下的六个儿童和两个成人的 T(incr, max)。我们进行了敏感性研究和蒙特卡罗分析，以评估结果的不确定性。考虑到模型参数的不确定性，我们发现，在 ICNIRP 参考水平的最坏情况下，最高温度可能会升高 1°C。由于指南是从温升推导出来的，因此我们使用 T(incr, max)作为防止过度局部组织加热的更好指标，而不是局部峰值 SAR。然而，我们注意到，未来的指南也应该考虑暴露时间。因此，我们建议为特定的暴露时间定义 T(incr, max)限制。
