scholarly journals The specific absorption rate in different brain regions of rats exposed to electromagnetic plane waves

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hao-Yu Wang ◽  
Chun-Fang Li ◽  
Chao Yu ◽  
Ji Dong ◽  
Yong Zou ◽  
...  
Keyword(s):  
Brain Region ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Brain Regions ◽  
Dose Effect ◽  
Whole Body ◽  
Polarization Direction ◽  
Whole Brain ◽  
Specific Absorption ◽  
Effect Relationship

Abstract Accurate dosimetry of a specific brain region in rats exposed to an electromagnetic field (EMF) is essential for studies focusing on dose-effect relationship of the region. However, only dosimetry of whole brain or whole body were evaluated in most of previous studies. In this study, a numerical voxel rat model with 10 segmented brain regions was constructed. Then, the effects of frequency, incidence direction, and E-polarization direction of plane wave EMF on brain region averaged specific absorption rate (BRSAR) of rats were investigated. At last, the reliability of using whole-body averaged SAR (WBDSAR) and whole-brain averaged SAR (WBRSAR) as estimations of BRSAR were also evaluated. Our results demonstrated that the BRSAR depended on the frequency, incidence direction, and E-polarization direction of the EMF. Besides, the largest deviation could be up to 13.1 dB between BRSAR and WBDSAR and 9.59 dB between BRSAR and WBRSAR. The results suggested that to establish an accurate dose-effect relationship, the variance of the BRSAR induced by alteration of frequency, incidence direction, and E-polarization direction of EMF should be avoided or carefully evaluated. Furthermore, the use of WBDSAR and WBRSAR as estimations of BRSAR should be restricted to certain conditions such that the deviations are not too large.

Variation of whole body averaged phantom specific absorption rate (SAR) in seven different 1.5 T MR systems

2008 ◽  
Author(s):  
Wolfgang Kainz ◽  
Florian Fidler ◽  
Jean Bobgan ◽  
Gregor Schaefers ◽  
Roger Luechinger ◽  
...  
Keyword(s):  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Whole Body ◽  
Specific Absorption

scholarly journals Whole-Body Averaged Specific Absorption Rate Estimation Using a Personal, Distributed Exposimeter

2015 ◽  
Vol 14 ◽  
pp. 1534-1537 ◽  
Author(s):  
A. Thielens ◽  
P. Vanveerdeghem ◽  
S. Agneessens ◽  
P. Van Torre ◽  
G. Vermeeren ◽  
...  
Keyword(s):  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Whole Body ◽  
Specific Absorption ◽  
Rate Estimation

EVALUATION OF SPECIFIC ABSORPTION RATE IN THE FAR-FIELD, NEAR-TO-FAR FIELD AND NEAR-FIELD REGIONS FOR INTEGRATIVE RADIOFREQUENCY EXPOSURE ASSESSMENT

2020 ◽  
Vol 190 (4) ◽  
pp. 459-472 ◽  
Author(s):  
Ilaria Liorni ◽  
Myles Capstick ◽  
Luuk van Wel ◽  
Joe Wiart ◽  
Wout Joseph ◽  
...  
Keyword(s):  
Large Scale ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Numerical Study ◽  
Whole Body ◽  
Single Frequency ◽  
Far Field ◽  
Specific Absorption ◽  
Rf Systems ◽  
Body Tissues

Abstract The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and are frequently used simultaneously, leading to combined exposures for which almost no exposure evaluation exists. The aim and novelty of this study is to close this gap of knowledge by developing new methods to rapidly evaluate the SAR induced by RF systems in such scenarios at frequencies from 50 MHz to 5.5 GHz. To this aim, analytical methods for SAR estimation in several usage scenarios were derived through a large-scale numerical study. These include subject-specific characteristics, properties of the RF systems and provide an estimation of the SAR in the whole body, tissues and organs, and different brain regions.

Abstract 2803: Clinical Utility of Magnetic Resonance Imaging of Patients with Permanent Pacemakers and Implantable-Cardioverter Defibrillators at 1.5 Tesla

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Saman Nazarian ◽  
Rozann Hansford ◽  
Ariel Roguin ◽  
Menekhem M Zviman ◽  
Albert C Lardo ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Clinical Utility ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Whole Body ◽  
Resonance Imaging ◽  
Specific Absorption ◽  
Cardiac Devices ◽  
Mri Studies

Background: Magnetic resonance imaging (MRI) offers excellent soft tissue resolution and is the preferred imaging modality for diagnosis of musculoskeletal, neurological and many thoracic and abdominal conditions. While MRI is currently unavailable for millions of patients because of the presence of implantable cardiac devices, we and others have previously reported the safety of noncardiac and cardiac MRI at 1.5T using a protocol that incorporates device selection and programming and limits the estimated specific absorption rate of MRI sequences. In this study we report the clinical utility of MRI in implantable cardiac device recipients. Methods: One hundred and eighty six patients with devices shown to be MRI safe by in vitro phantom and in vivo animal testing underwent 228 MRI studies. Pacing mode was changed to “asynchronous” for pacemaker-dependent patients and to “demand” for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored. Efforts were made to limit the system-estimated whole-body average specific absorption rate to 2.0 W/kg (successful in >99% of sequences) while maintaining the diagnostic capability of MRI. Results: No episodes of inappropriate inhibition or activation of pacing were observed. There were no significant differences between baseline and immediate or long-term sensing amplitudes, lead impedances, or pacing thresholds. The diagnostic yield of alternative testing was 19% in 47 patients who underwent ultrasound, nuclear imaging or computed tomography prior to MRI. In contrast, diagnostic questions were answered in 95% of MRI studies. Conclusions: The diagnostic benefits of MRI significantly outweigh the theoretical risks in patients with implanted cardiac devices when appropriate safety measures are implemented.

scholarly journals Measurement Analysis of Specific Absorption Rate in Human Body Exposed to a Base Station Antenna by Using Finite Difference Time Domain Techniques

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Hla Myo Tun ◽  
Khin Kyu Kyu Win ◽  
Zaw Min Naing ◽  
Devasis Pradhan ◽  
Prasanna Kumar Sahu
Keyword(s):  
Finite Difference ◽  
Human Body ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Base Station ◽  
Whole Body ◽  
Specific Absorption ◽  
Difference Time

The system analysis of specific absorption rate (SAR) in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works. The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station. The paper investigates the electromagnetic wave absorption inside a human body. The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna (BSA) has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance (R) of human body from BSA is varied in the range of 0.1 m to 5.0 m. For the number of carrier frequency equal to one and R = 0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies. Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.

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