Computation of Temperature Elevation in a Fetus Exposed to Ambient Heat and Radio Frequency Fields

Hirata, Akimasa; Laakso, Ilkka; Ishii, Yuri; Nomura, Tomoki; Chan, Kwok Hung

doi:10.1080/10407782.2013.869075

Cited by 4 publications

(4 citation statements)

References 29 publications

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“…In this section, study on thermal effects due to RF EMF exposures on human body are presented and threshold levels are defined to protect from EMFs. Exposures to RF EMFs cause generation of heat in human body, therefore it is essential to keep the safe levels in order to overcome heat-induced adverse health impairments [68], [69]. To avoid significant temperature increase in human body, temperature thresholds are defined in terms of ''temperature rise'' instead of ''absolute temperature''.…”

Section: Thermal Effects Of Rf Emfmentioning

confidence: 99%

Implications of mmWave Radiation on Human Health: State of the Art Threshold Levels

Dilli

2021

IEEE Access

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millimeter (mmWave) frequencies are covering from 30GHz to 300GHz in the electromagnetic spectrum and their uses in various applications like next-generation wireless communication systems (massive 5G telecommunications network), medical devices, airport security and automatic collision avoidance systems are growing vastly in the near future. Therefore, it is important to study the effects of mmWave radiation (non-ionization radiation) on biological systems and biophysical mechanisms. This paper focus on thorough review of nascent literature about current understandings of biological effects and epidemiological studies due to mmWave radiation in human beings. It presents latest guidelines with quantitative electromagnetic field thresholds by considering the realistic exposure scenarios of ''general public'' and ''occupational'' who undergo through wireless communication sources in their daily life. It also gives necessary safety measures to be taken while using the emerging mmWave technologies for future generation wireless communication networks.

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Section: Thermal Effects Of Rf Emfmentioning

confidence: 99%

Implications of mmWave Radiation on Human Health: State of the Art Threshold Levels

Dilli

2021

IEEE Access

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“…They assumed the same blood temperature in mother and fetus, starting from 37 • C and increasing over time with RF exposure. In contrast, Hirata et al 46 modeled the fetal and maternal blood temperatures as separate (0.5 • C difference initially) and time dependent. Then the heat exchange between the mother and the fetus was modeled by the heat exchange between the maternal and fetal blood circulating in the placenta.…”

Section: Discussionmentioning

confidence: 99%

Local SAR management strategies to use two‐channel RF shimming for fetal MRI at 3 T

Yetisir,

Abaci Turk,

Adalsteinsson

et al. 2023

Magnetic Resonance in Med

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PurposeThis study evaluates the imaging performance of two‐channel RF‐shimming for fetal MRI at 3 T using four different local specific absorption rate (SAR) management strategies.MethodsDue to the ambiguity of safe local SAR levels for fetal MRI, local SAR limits for RF shimming were determined based on either each individual's own SAR levels in standard imaging mode (CP mode) or the maximum SAR level observed across seven pregnant body models in CP mode. Local SAR was constrained either indirectly by further constraining the whole‐body SAR (wbSAR) or directly by using subject‐specific local SAR models. Each strategy was evaluated by the improvement of the transmit field efficiency (average |B1+|) and nonuniformity (|B1+| variation) inside the fetus compared with CP mode for the same wbSAR.ResultsConstraining wbSAR when using RF shimming decreases B1+ efficiency inside the fetus compared with CP mode (by 12%–30% on average), making it inefficient for SAR management. Using subject‐specific models with SAR limits based on each individual's own CP mode SAR value, B1+ efficiency and nonuniformity are improved on average by 6% and 13% across seven pregnant models. In contrast, using SAR limits based on maximum CP mode SAR values across seven models, B1+ efficiency and nonuniformity are improved by 13% and 25%, compared with the best achievable improvement without SAR constraints: 15% and 26%.ConclusionTwo‐channel RF‐shimming can safely and significantly improve the transmit field inside the fetus when subject‐specific models are used with local SAR limits based on maximum CP mode SAR levels in the pregnant population.

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“…The parameter χ denotes the coefficient related to the decline of sweating; ∆TS,dec and ∆TH,dec denote the threshold as per aging-related deterioration in the thermal sensitivity of the skin and hypothalamus [45], [59], [60]. To discuss the assessment of heatstroke for the elderly, the following four types of sweating were considered: (i) a healthy adult patient, (ii) a patient aged >65 years, (iii) a patient aged >75 years, and (iv) a patient without sweating (most severe case).…”

Section: ) Thermoregulatory Response Modelingmentioning

confidence: 99%

Computed and Measured Core Temperature of Patients With Heatstroke Transported From Their Homes via Ambulance

et al. 2022

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The number of patients experiencing heat-related illnesses has gradually increased due to global warming. Owing to an aging society, 50% of patients with heat-related illnesses in Japan are elderly. Core temperature is one key parameter for health care; however, its monitoring is virtually impossible. Internet of Things (IoT) devices for healthcare have been proposed; however, the vital parameters to be monitored remain controversial. Here, we assessed the core temperature of elderly patients who were transported to hospitals by ambulance from their homes. The patients' core temperatures were recorded by the Fire Department of Nagoya City in the summers of 2019 and 2020. The time course of the core temperature of each patient was then replicated using the integrated computational techniques through multiphysics analysis and thermoregulation under ambient condition data. According to the statistics, most elderly patients who were transported from their homes had a high core temperature. The measured core temperature in 31.4% of the patients was higher than the computed core temperature even assuming that there was no sweating. Assuming that the sweating function works well, the total amount of water loss was insufficient to have caused dehydration in a single day. These results suggest that successive heat stress during the preceding days should be considered to recreate the computed core temperature to match the measurement. These results were consistent with the previous finding that some elderly suffered from heatstroke successively over a few days. In the IoT-based monitoring system development, it would be informative for monitoring core temperature during the preceding days.

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Computation of Temperature Elevation in a Fetus Exposed to Ambient Heat and Radio Frequency Fields

Cited by 4 publications

References 29 publications

Implications of mmWave Radiation on Human Health: State of the Art Threshold Levels

Implications of mmWave Radiation on Human Health: State of the Art Threshold Levels

Local SAR management strategies to use two‐channel RF shimming for fetal MRI at 3 T

Computed and Measured Core Temperature of Patients With Heatstroke Transported From Their Homes via Ambulance

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