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Simplified model and measurement of specific absorption rate distribution in a culture flask within a transverse electromagnetic mode exposure system
Author(s) -
Pickard William F.,
Straube William L.,
Moros Eduardo G.,
Fan Xiaobing
Publication year - 1999
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/(sici)1521-186x(1999)20:3<183::aid-bem5>3.0.co;2-7
Subject(s) - specific absorption rate , bioelectromagnetics , absorption (acoustics) , computational physics , optics , scattering , thermal , transverse plane , biological system , field (mathematics) , diffusion , physics , mechanics , electromagnetic field , materials science , computer science , mathematics , meteorology , thermodynamics , telecommunications , pure mathematics , structural engineering , quantum mechanics , antenna (radio) , biology , engineering
In vitro experiments in bioelectromagnetics frequently require the determination of specific absorption rate (SAR) within a layer of cells on the bottom of a culture flask when the SAR has rapid spatial variation both horizontally within the cell layer and vertically in the medium bathing the cells. This problem has only recently been treated in the literature; and it is here approached differently for another irradiation system. It is shown that a simple two‐dimensional frequency‐domain guided‐wave treatment yields results qualitatively comparable to those of more computationally intensive three‐dimensional time‐domain free‐field scattering treatments. The problem of inferring local SARs from temperature‐vs.‐time curves is shown to be seriously confounded by thermal diffusion; and specific analytic and numerical results are presented to aid in understanding this effect. A novel experimental technique is introduced for measuring millikelvin temperature offsets with subsecond resolution, and illustrative experimental data are presented. Finally, present experimental and theoretical uncertainties are considered; and it is pessimistically asserted that, in a culture flask where spatial SAR variation is rapid, point SAR measurements by thermal methods may be in error by as much as ±3 dB. More reliable thermal determinations will require extreme care, challenging technological innovations, or both. Bioelectromagnetics 20:183–193, 1999. © 1999 Wiley‐Liss, Inc.