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EMF Study
(Database last updated on Jun 17, 2019)

ID Number 645
Study Type In Vivo
Model Pulsed RF exposure to human models and animals and analysis of MW hearing and brainstem responses.

Cats, rats, and guinea pigs were restrained in a stereotaxic head restraining device and heads exposed to PW MWs. In some studies, 2450 MHz (PW- rectangular pulses of 3 kW peak power, 2.5 and 5.5 usec pulse duration) or 5.65 GHz (PW- rectangular pulses of 200 kW peak power, 0.5 usec duration) was used. A surgically implanted hydrophone transducer was used to detect associated acoustic pressure waves. In a study of cats exposed to 2450 MHz MW (PW-rectangular 2.5-25 usec pulses width) at 15 Kwatts of power, the average speed of thermoelastic pressure wave propagation was measured as 1522.77 m/sec, nearly identical to the reported mean for ultrasound propagation in cat brain tissue. Attenuation was exponential with a coefficient of 0.56/cm. The authors conclude that the results support to the thermoelastic theory of microwave-induced auditory effects in humans and animals. A summary of the thermoelastic expansion theory is given by Lin et al in (1984, IEEE Trans Microw Theory Tech 32:854-860; 1983, IEEE Trans Biomed Eng 30(5):289-294; 1981, IEEE Trans Microw Theory Tech 29:1114-1117; 1980, Proc IEEE 68(1):67-73; 1979, NTIS Document No. BES-1; 74; 1977, Radio Sci 12(6S):237-242; 1977, IEEE Trans Microw Theory Tech 25(7):605-613) and the potential use of this thermoelastic expansion for medical imaging in (1987, IEEE Trans Biomed Eng 34:179-182 and 1987, IEEE Eng Med Biol 6:52-57) AUTHORS' ABSTRACT: Lin and Wang 2010 (IEEE #6631): The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea. AUTHOR'S ABSTRACT: Lin 2004 (IEEE #6633):This d'Arsonval Medal acceptance presentation highlights several research themes selected from Dr. Lin's published works, focusing on the microwave portion of the nonionizing electromagnetic spectrum. The topics discussed include investigation of microwave effects on the spontaneous action potentials and membrane resistance of isolated snail neurons, effects on the permeability of blood brain barriers in rats, the phenomenon and interaction mechanism for the microwave auditory effect (the hearing of microwave pulses by animals and humans), the development of miniature catheter antennas for microwave interstitial hyperthermia treatment of cancer, the application of transcatheter microwave ablation for treatment of cardiac arrhythmias, and the use of noninvasive wireless technology for sensing of human vital signs and blood pressure pulse waves. The paper concludes with some observations on research and other endeavors in the interdisciplinary field of bioelectromagnetics. AUTHOR'S TEXT: Lin 2018 (IEEE #6914): Assuming that the reported events are reliable, there is actually a scientific explanation for the source of sonic energy. It could well be from a targeted beam of high-power microwave pulse radiation.

Findings Effects (only at thermal levels)
Status Completed With Publication
Principal Investigator University of Illinois, USA -
Funding Agency ?????
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  • Olsen, RG et al. IEEE Trans. Biomed. Eng., (1983) 30:289-294
  • Lin, JC et al. Radio Sci., (1982) 17:159-163
  • Olsen, RG et al. IEEE Trans. Microwave Theory Tech., (1981) 29:1114-1117
  • Lin, JC Proc. IEEE, (1980) 68:67-73
  • Lin, JC et al. J. Microwave Power, (1979) 14:291-295
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  • Lin, JC IEEE Trans. Microwave Theory Tech., (1977) 25:605-613
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  • Lin, JC J Microw Power, (1976) 11:295-298
  • Lin, JC Electromagnetic Interaction with Biological Systems, (1989) :165-177
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  • Lin, JC Advances in Electromagnetic Fields in Living Systems., (19xx) 4:41-76
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  • Lin, JC IEEE Microwave Magazine., (2018) January/February:18-19
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