Variability analysis of SAR from 20 MHz to 2.4 GHz for different adult and child models using finite-difference time-domain

Conil, Emmanuelle; Hadjem, Abdelhamid; Lacroux, Fabrice; Wong, M.F.; Wiart, Joe

doi:10.1088/0031-9155/53/6/001

Cited by 153 publications

(106 citation statements)

References 20 publications

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“…Since local SAR 10g is more dependent on local geometry than the global average, these values are subject to greater uncertainty, especially when attempting to represent a population using a small number of models. It is difficult to assess this uncertainty; a 30% estimate is given in the mobile communications literature 28 (in the GHz range); however, the lower frequencies used in MRI will lead to deviations closer to 10% 29. Our own SAR 10g estimate for an adult model at 3 T was very close to the scanner's prediction (10.1 W kg −1 compared with 10 W kg −1 ), though this may be coincidental given that the model used by the scanner's own software is unknown.…”

Section: Discussionmentioning

confidence: 99%

Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

et al. 2015

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MRI is finding increased clinical use in neonatal populations; the extent to which electromagnetic models used for quantification of specific absorption rate (SAR) by commercial MRI scanners accurately reflect this alternative scenario is unclear. This study investigates how SAR predictions relating to adults can be related to neonates under differing conditions when imaged using 1.5 T and 3 T MRI scanners. Electromagnetic simulations were produced in neonatal subjects of different sizes and positions within a generic MRI body transmit device operating at both 64 MHz and 128 MHz, corresponding to 1.5 T and 3 T MRI scanners, respectively. An adult model was also simulated, as was a spherical salt‐water phantom, which was also used in a calorimetry experiment. The SAR in neonatal subjects was found to be less than that experienced in an adult in all scenarios; however, the overestimation factor was variable. For example a 3 T body scan resulting in local 10 g SAR of 10.1 W kg−1 in an adult would deposit 2.6 W kg−1 in a neonate: an approximately fourfold difference. The SAR experienced by neonatal subjects undergoing MRI is lower than that in adults in equivalent situations. If the safety of such procedures is assessed using adult‐appropriate models then the result is a conservative estimate. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

et al. 2015

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“…Such biological effects may be more significant for children, because it has been argued that different head shapes and thinner skulls may make them more susceptible to RF energy [Kheifets et al, 2005;Wiart et al, 2005;Conil et al, 2008]. RF exposure from a mobile phone handset has been associated with slightly shorter reaction times in children [Preece et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

Mobile telephone use is associated with changes in cognitive function in young adolescents

Abramson

Benke

Dimitriadis

et al. 2009

Bioelectromagnetics

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As part of the Mobile Radiofrequency Phone Exposed Users' Study (MoRPhEUS), a cross-sectional epidemiological study examined cognitive function in secondary school students. We recruited 317, 7th grade students (144 boys, 173 girls, median age 13 years) from 20 schools around Melbourne, Australia. Participants completed an exposure questionnaire based on the Interphone study, a computerised cognitive test battery, and the Stroop colour-word test. The principal exposure metric was the total number of reported mobile phone voice calls per week. Linear regression models were fitted to cognitive test response times and accuracies. Age, gender, ethnicity, socio-economic status and handedness were fitted as covariates and standard errors were adjusted for clustering by school. The accuracy of working memory was poorer, reaction time for a simple learning task shorter, associative learning response time shorter and accuracy poorer in children reporting more mobile phone voice calls. There were no significant relationships between exposure and signal detection, movement monitoring or estimation. The completion time for Stroop word naming tasks was longer for those reporting more mobile phone voice calls. The findings were similar for total short message service (SMS, also known as text) messages per week, suggesting these cognitive changes were unlikely due to radiofrequency (RF) exposure. Overall, mobile phone use was associated with faster and less accurate responding to higher level cognitive tasks. These behaviours may have been learned through frequent use of a mobile phone.

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“…24 Thinner skin and skull, and large head compared to body in children when matched with adults led to higher SAR values after exposure to EMF. Conil et al 25 reported mean resonance frequency as 60 MHz in adults, while 80, 100 and 120 MHz, respectively, in 12, 8 and 5 years old models. Children may be more sensitive to EMF exposure than adults; however, all the side effects of EMF and protection principles have not been fully clarified today.…”

Section: Discussionmentioning

confidence: 97%

Effects of long-term pre- and post-natal exposure to 2.45 GHz wireless devices on developing male rat kidney

et al. 2016

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Purpose The aim of the present study was to investigate oxidative stress and apoptosis in kidney tissues of male Wistar rats that pre-and postnatally exposed to wireless electromagnetic field (EMF) with an internet frequency of 2.45 GHz for a long time. Methods The study was conducted in three groups of rats which were pre-natal, post-natal. and sham exposed groups. Oxidative stress markers and histological evaluation of kidney tissues were studied. Results Renal tissue malondialdehyde (MDA) and total oxidant (TOS) levels of pre-natal group were high and total antioxidant (TAS) and superoxide dismutase (SOD) levels were low. Spot urine NAG/ creatinine ratio was significantly higher in pre-and post-natal groups (p50.001). Tubular injury was detected in most of the specimens in post-natal groups. Immunohistochemical analysis showed low-intensity staining with Bax in cortex, high-intensity staining with Bcl-2 in cortical and medullar areas of pre-natal group (p values, 0.000, 0.002, 0.000, respectively) when compared with sham group. Bcl2/Bax staining intensity ratios of medullar and cortical area was higher in pre-natal group than sham group (p ¼ 0.018, p ¼ 0.011). Conclusion Based on this study, it is thought that chronic pre-and post-natal period exposure to wireless internet frequency of EMF may cause chronic kidney damages; staying away from EMF source in especially pregnancy and early childhood period may reduce negative effects of exposure on kidney.ARTICLE HISTORY

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Variability analysis of SAR from 20 MHz to 2.4 GHz for different adult and child models using finite-difference time-domain

Cited by 153 publications

References 20 publications

Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

Mobile telephone use is associated with changes in cognitive function in young adolescents

Effects of long-term pre- and post-natal exposure to 2.45 GHz wireless devices on developing male rat kidney

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