Thermal Analysis Complementary to Standardized Experimental Dosimetry of SAR in Human Head

2019 · Mixed · Low evidence

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MixedLow evidencePaper 1784

Study snapshot

Publicationmanual · 2019

Study typeengineering

Reported directionMixed

Evidence ratingLow

Abstract

Thermal Analysis Complementary to Standardized Experimental Dosimetry of SAR in Human Head Ilie-Săndoiu AM, Morega M, Morega AM. Thermal Analysis Complementary to Standardized Experimental Dosimetry of SAR in Human Head. 2019 11th International Symposium on Advanced Topics in Electrical Engineering (ATEE). 28-20 March 2019. DOI: 10.1109/ATEE.2019.8724859 Abstract Cellular phones (CPs) intensive, long-term usage may raise concerns regarding collateral effects such as hyperthermia through direct exposure to electromagnetic field, and direct thermal contact to the outer ear.Among other methods used to evaluate the thermal menace posed by CPs, the physical experiments, conducted on equivalent phantoms play an important role. Replacing the head content with biologically- equivalent fluid is considered to provide for satisfactory experimental conditions with the aim to assess realistic "specific energy absorption rate" (SAR) levels and the pending thermal load. Moreover, numerical experiments may complement physical experiments, strengthening the predictive consistency of this already standardized lab approach.A numerical model of the human head and radiation source is designed and validated in compliance with experimental electromagnetic dosimetry standards with the aim of extending and processing useful information from limited experimental output. The current study goes further by exploring the heat absorption from the CP used nearby the head, making use of numerical simulation of the coupled electromagnetic and thermal problems, applied on models with varying degrees of realism. The analysis presented here concentrates on the assessment of cumulative contributions - energy absorption through SAR and direct contact with the heated CP device - on raising the temperature. Conclusions Present work shows some results from a numerical study performed on a phantom-like head model, the SAM head, described by international standards that are used for the certification of mobile phone devices [6], [7]. This benchmark numerical model was initially developed and validated through experiment for SAR dosimetry [8], but its applicability is extended here for heating estimates. A combined thermal dosimetry analysis is performed, taking two heating sources into account, i.e. the well-documented temperature rise from radiofrequency power absorption and additional warming from direct contact of the ear with the casing of the phone (heated by power dissipation inside the device). The results show a highly non-uniform distribution of the temperature inside the target volume, as much as a slight increase of the local temperature on the hot spots, due to the additional ear surface warming. One could see that all the analysis was performed on a very simplified numerical model, if compared against true anatomy and functionality of the human head (i.e. non-homogeneous anatomical structure with specific physical properties and energy transfer under the influence of subtle physiology mechanisms - metabolism, blood perfusion); realistic conditions could bring substantial differences. However, the cumulative effect of the heating sources is a reality; it depends on the emitted power and complexity of the phone and operation conditions and it is commonly sensed during long conversations because it creates discomfort to the phone user. This aspect needs to be considered more carefully in the assessment of bio-thermal effects and human protection. ieeexplore.ieee.org

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionmixed

PopulationNot supplied

Sample sizeNot supplied

ExposureRF · long-term usage (general context); numerical simulations of phone used nearby the head

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

A coupled electromagnetic-thermal numerical simulation based on a standardized SAM head phantom model assessed cumulative heating from RF power absorption (SAR-related) and direct contact with a heated phone casing. The study reports a highly non-uniform temperature distribution and a slight increase of local temperature at hot spots due to additional ear surface warming from phone contact.

Outcomes measured

SAR dosimetry in human head phantom model (SAM head)
Temperature distribution/temperature rise in head/ear region from RF absorption
Additional warming from direct contact with heated phone casing
Non-uniform temperature distribution and local hot spots

Limitations

Analysis performed on a very simplified numerical model compared with true anatomy (homogeneous phantom-like model)
Physiological mechanisms (e.g., metabolism, blood perfusion) not represented; realistic conditions could differ
Emitted power/phone complexity/operation conditions not specified in the abstract

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "mobile phone",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "long-term usage (general context); numerical simulations of phone used nearby the head"
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "SAR dosimetry in human head phantom model (SAM head)",
    "Temperature distribution/temperature rise in head/ear region from RF absorption",
    "Additional warming from direct contact with heated phone casing",
    "Non-uniform temperature distribution and local hot spots"
  ],
  "main_findings": "A coupled electromagnetic-thermal numerical simulation based on a standardized SAM head phantom model assessed cumulative heating from RF power absorption (SAR-related) and direct contact with a heated phone casing. The study reports a highly non-uniform temperature distribution and a slight increase of local temperature at hot spots due to additional ear surface warming from phone contact.",
  "effect_direction": "mixed",
  "limitations": [
    "Analysis performed on a very simplified numerical model compared with true anatomy (homogeneous phantom-like model)",
    "Physiological mechanisms (e.g., metabolism, blood perfusion) not represented; realistic conditions could differ",
    "Emitted power/phone complexity/operation conditions not specified in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "specific absorption rate",
    "SAR",
    "thermal dosimetry",
    "human head",
    "SAM phantom",
    "mobile phone",
    "radiofrequency",
    "coupled electromagnetic-thermal simulation",
    "ear heating",
    "hot spots"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.32,
      "reason": "Uses standardized SAM head phantom and SAR certification context relevant to exposure limits/standards."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1109/atee.2019.8724859
PubMed: Not supplied

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