Guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz)

Radiofrequency electromagnetic fields (EMFs) are used to enable a number of modern devices, including mobile telecommunications infrastructure and phones, Wi-Fi, and Bluetooth. As radiofrequency EMFs at sufficiently high power levels can adversely affect health, ICNIRP published Guidelines in 1998 for human exposure to time-varying EMFs up to 300 GHz, which included the radiofrequency EMF spectrum. Since that time, there has been a considerable body of science further addressing the relation between radiofrequency EMFs and adverse health outcomes, as well as significant developments in the technologies that use radiofrequency EMFs. Accordingly, ICNIRP has updated the radiofrequency EMF part of the 1998 Guidelines. This document presents these revised Guidelines, which provide protection for humans from exposure to EMFs from 100 kHz to 300 GHz

Guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz)

Radiofrequency electromagnetic fields (EMFs) are used to enable a number of modern devices, including mobile telecommunications infrastructure and phones, Wi-Fi, and Bluetooth. As radiofrequency EMFs at sufficiently high power levels can adversely affect health, ICNIRP published Guidelines in 1998 for human exposure to time-varying EMFs up to 300 GHz, which included the radiofrequency EMF spectrum. Since that time, there has been a considerable body of science further addressing the relation between radiofrequency EMFs and adverse health outcomes, as well as significant developments in the technologies that use radiofrequency EMFs. Accordingly, ICNIRP has updated the radiofrequency EMF part of the 1998 Guidelines. This document presents these revised Guidelines, which provide protection for humans from exposure to EMFs from 100 kHz to 300 GHz

Uncertainty in computational RF dosimetry

Radio-frequency (RF) electromagnetic field dosimetry studies the absorption of electromagnetic energy inside the human body. The absorbed energy is measured in terms of the specific absorption rate (SAR), which is linked to the possible adverse thermal effects of the exposure to RF electromagnetic fields. With advances in computational power and accurate numerical models of the human anatomy, computational methods have gained an increasingly significant role in RF dosimetry in recent years. Nowadays, the finite-difference time-domain (FDTD) method is the most widely used numerical technique in computational RF dosimetry. Computational analysis of the SAR features many modelling and approximation phases that may introduce error and uncertainty. The emphasis of this thesis is to study how reliably the SAR can be assessed by the FDTD method, and how various modelling choices affect the accuracy of the simulated results. In addition to the SAR, also the temperature rise due to the electromagnetic power absorption and its modelling by the bioheat equation is studied. The results of the thesis help to evaluate and identify the possible uncertainty factors and sources of error in computational RF dosimetry, which will produce new information on the reliability and repeatability of computational exposure assessment. Studying the uncertainty and accuracy of the methods also allows, for example, lessening the computational requirements and improving the accuracy of the simulations

A model for estimating ultrasound attenuation along the propagation path to the fetus from backscattered waveforms

Accurate estimates of the ultrasound pressure and/or intensity incident on the developing fetus on a patient-specific basis could improve the diagnostic potential of medical ultrasound by allowing the clinician to increase the transmit power while still avoiding the potential for harmful bioeffects. Neglecting nonlinear effects, the pressure/intensity can be estimated if an accurate estimate of the attenuation along the propagation path ͑i.e., total attenuation͒ can be obtained. Herein, a method for determining the total attenuation from the backscattered power spectrum from the developing fetus is proposed. The boundaries between amnion and either the fetus' skull or soft tissue are each modeled as planar impedance boundaries at an unknown orientation with respect to the sound beam. A mathematical analysis demonstrates that the normalized returned voltage spectrum from this model is independent of the planes orientation. Hence, the total attenuation can be estimated by comparing the location of the spectral peak in the reflection from the fetus to the location of the spectral peak in a reflection obtained from a rigid plane in a water bath. The independence of the attenuation estimate and plane orientation is then demonstrated experimentally using a Plexiglas plate, a rat's skull, and a tissue-mimicking phantom

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 250)

This bibliography lists 265 reports, articles and other documents introduced into the NASA scientific and technical information system in September 1983

SAFETY AND PERFORMANCE CONSIDERATIONS FOR INTERACTIONS BETWEEN ELECTROMAGNETIC FIELDS AND BIOLOGICAL TISSUE: APPLICATIONS TO HIGH FIELD HUMAN MAGNETIC RESONANCE IMAGING AND TISSUE-IMPLANTED DEVICES

The principal advantage of magnetic resonance imaging (MRI) at high field is the increase in signal to noise ratio (SNR), however, high field imaging also leads to an increased Larmor (operating) frequency, thus the wavelength in tissue can become comparable to the size of the load and/or the coil. The performance of the radiofrequency (RF) coil, as a result, becomes increasingly dependent on its electromagnetic interactions with the load, human body or head.Invasive brain machine interface (BMI) technology uses implanted microelectrodes to capture the action potentials of many individual neurons, especially those that code for movement or its intent. Traditionally, stimulating nerves or brain tissue involves cumbersome wiring to power/communicate with the chip. To avoid the limit of the BMI's mobility and freedom, RF powered wireless implementation of a BMI chip has been proposed to widely extend BMI applications. It is essential to perform an analysis of electromagnetic power deposition throughout the human head to determine the amount of power available to BMI devices.In this dissertation, a complete electromagnetic computational (full wave) analysis, the finite difference time domain (FDTD) method, is applied to calculate the interaction between the radio frequency (RF) magnetic field and the subjects during ultra high field MRI exams and wireless BMI operations. The interactions between the high frequency RF fields with the human head and the body models severely affect the performances of MRI and BMI operations, and they also cause heating safety concerns to the tissues exposed to the RF radiation. Through precisely numerical calculations, we accomplished in this dissertation 1) an improved optimization scheme using variable phase and variable amplitude excitation to improve the performance of RF transverse electromagnetic (TEM) coils in MRI with safety concerns; and 2) evaluations of the performance and safety for a prototype of the wireless invasive BMI. Temperature changes caused by RF power deposition are calculated in both MRI and BMI applications

Anniversary Paper: Evolution of ultrasound physics and the role of medical physicists and the AAPM and its journal in that evolution

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134810/1/mp2048.pd

Excessive whole-body exposure to 28 GHz quasi-millimeter wave induces thermoregulation accompanied by a change in skin blood flow proportion in rats

IntroductionLimited information is available on the biological effects of whole-body exposure to quasi-millimeter waves (qMMW). The aim of the present study was to determine the intensity of exposure to increase body temperature and investigate whether thermoregulation, including changes in skin blood flow, is induced in rats under whole-body exposure to qMMW.MethodsThe backs of conscious rats were extensively exposed to 28 GHz qMMW at absorbed power densities of 0, 122, and 237 W/m2 for 40 minutes. Temperature changes in three regions (dorsal and tail skin, and rectum) and blood flow in the dorsal and tail skin were measured simultaneously using fiber-optic probes.ResultsIntensity-dependent temperature increases were observed in the dorsal skin and the rectum. In addition, skin blood flow was altered in the tail but not in the dorsum, accompanied by an increase in rectal temperature and resulting in an increase in tail skin temperature.DiscussionThese findings suggest that whole-body exposure to qMMW drives thermoregulation to transport and dissipate heat generated on the exposed body surface. Despite the large differences in size and physiology between humans and rats, our findings may be helpful for discussing the operational health-effect thresholds in the standardization of international exposure guidelines

The doctoral research abstract. Vol:9 2016 / Institute of Graduate Studies, UiTM

FOREWORD: Seventy three doctoral graduands will be receiving their scroll today signifying their achievements in completing their PhD journey. The novelty of their research is shared with you through The Doctoral Abstracts on this auspicious occasion, UiTM 84th Convocation. We are indeed proud that another 73 scholarly contributions to the world of knowledge and innovation have taken place through their doctoral research ranging from Science and Technology, Business and Administration, and Social Science and Humanities. As we rejoice and celebrate your achievement, we would like to acknowledge dearly departed Dr Halimi Zakaria’s scholarly contribution entitled “Impact of Antecedent Factors on Collaborative Technologies Usage among Academic Researchers in Malaysian Research Universities”. He has left behind his discovery to be used by other researchers in their quest of pursuing research in the same area, a discovery that his family can be proud of. Graduands, earning your PhD is not the end of discovering new ideas, invention or innovation but rather the start of discovering something new. Enjoy every moment of its discovery and embrace that life is full of mystery and treasure that is waiting for you to unfold. As you unfold life’s mystery, remember you have a friend to count on, and that friend is UiTM. Congratulations for completing this academic journey. Keep UiTM close to your heart and be our ambassador wherever you go. / Prof Emeritus Dato’ Dr Hassan Said Vice Chancellor Universiti Teknologi MAR