Heating of tissue by near-field exposure to a dipole: a model analysis.

IEEE transactions on bio-medical engineering · 1999 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 6352

Study snapshot

PublicationIEEE transactions on bio-medical engineering · 1999

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

We report a numerical study of the induced electric fields and specific absorption rate (SAR) produced by microwave radiation from a half-wavelength dipole near tissue models, and the resulting transient and steady-state temperature rises. Several models were explored, including a uniform semi-infinite plane of tissue, uniform sphere, a phantom model of the head filled with tissue-equivalent material, a numerical model of the head with uniform dielectric properties (obtained from a digitized computed tomography image), and a numerical model of the head with different dielectric properties corresponding to various tissues. The electromagnetic calculations were performed for half-wave dipoles radiating at 900 and 1900 MHz at various distances from the model, using the finite-difference-time-domain (FDTD) method. The resulting temperature rises were estimated by finite element solution of the bioheat equation. The calculated SAR values agree well with an empirical correlation due to Kuster. If the limiting hazard of such exposures is associated with excessive temperature increase, present exposure limits are very conservative and guidelines that are easier to implement might provide adequate protection.

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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 directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureRF

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Numerical modeling (FDTD EM calculations plus bioheat equation) estimated induced electric fields, SAR, and resulting transient and steady-state temperature rises for half-wave dipoles at 900 and 1900 MHz near multiple tissue/head models. Calculated SAR values agreed well with an empirical correlation due to Kuster. The authors state that if hazard is limited by excessive temperature increase, present exposure limits are very conservative and simpler guidelines might still provide adequate protection.

Outcomes measured

induced electric fields
specific absorption rate (SAR)
transient temperature rise
steady-state temperature rise

Limitations

Numerical/modeling study rather than measurements in humans or animals
Exposure conditions limited to half-wave dipoles at 900 and 1900 MHz and modeled geometries/distances
Assumes hazard is associated with temperature increase (as framed in the abstract)

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "half-wavelength dipole (near-field)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "induced electric fields",
    "specific absorption rate (SAR)",
    "transient temperature rise",
    "steady-state temperature rise"
  ],
  "main_findings": "Numerical modeling (FDTD EM calculations plus bioheat equation) estimated induced electric fields, SAR, and resulting transient and steady-state temperature rises for half-wave dipoles at 900 and 1900 MHz near multiple tissue/head models. Calculated SAR values agreed well with an empirical correlation due to Kuster. The authors state that if hazard is limited by excessive temperature increase, present exposure limits are very conservative and simpler guidelines might still provide adequate protection.",
  "effect_direction": "unclear",
  "limitations": [
    "Numerical/modeling study rather than measurements in humans or animals",
    "Exposure conditions limited to half-wave dipoles at 900 and 1900 MHz and modeled geometries/distances",
    "Assumes hazard is associated with temperature increase (as framed in the abstract)"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "near-field exposure",
    "dipole",
    "microwave radiation",
    "RF",
    "900 MHz",
    "1900 MHz",
    "FDTD",
    "bioheat equation",
    "SAR",
    "temperature rise",
    "head phantom",
    "tissue models"
  ],
  "suggested_hubs": []
}

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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: 10.1109/10.775400
PubMed: 10431455

Read the original paper →

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