PNAS：评估手机辐射对脑组织的效应

科研人员开发出了一种非侵入式核磁共振（NMR）方法，从而测量手机辐射对脑组织的效应。为了验证这种技术，David H. Gultekin 和Lothar Moeller测量了被牛脑组织和具有类似的电和热参数的凝胶吸收的手机辐射电磁能量的数量。手机是射频（RF）场暴露的主要来源之一，而世界卫生组织最近根据与使用手机有关的脑癌风险增加而把射频（RF）场归类为可能致癌。脑组织吸收的手机射频（RF）能量转化成了热，这组作者使用核磁共振（NMR）建立了手机辐射造成的热场的高分辨率3D图像，并使用光纤温度传感器证实了这些测量的准确度。常规的手机无法在核磁共振（NMR）产生的强磁场中使用；因此这组作者开发出了一个天线配置，让他们可以以非侵入的方式使用核磁共振（NMR）测量手机辐射的吸收。这组作者说，该研究提示核磁共振（NMR）可以用于描述脑组织和凝胶吸收手机辐射导致的热点区域，而且这种方法可以加以改良从而用于测量人类大脑活组织。

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NMR imaging of cell phone radiation absorption in brain tissue
ABSTRACT
A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance frequency shift of hydrogen protons in brain tissue. This proposed application of NMR thermometry offers sufficient spatial and temporal resolution to characterize the hot spots from absorbed cell phone radiation in aqueous media and biological tissues. Specific absorption rate measurements averaged over 1 mg and 10 s in the brain tissue cover the total absorption volume. Reference measurements with fiber optic temperature sensors confirm the accuracy of the NMR thermometry.

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