An Investigation of the SAR Distribution in Bone Marrow with Possible Non-Thermal Effects | Chapter 1 | Advances and Trends in Physical Science Research Vol. 2
The power absorption due to EMF radiation is
calculated, in bone and bone marrow. The EMF employed in various communication
and technological applications indicate undeniable effect on humans both as
public and occupational environments. These EMF effects arouse from electronic
devices such as, cellular phones and their networks, wi-fi routers, microwave
transmitters, antennae, etc. besides the upcoming 5G generation and their
extended applications. EMF exposure effects are estimated by either animal
experimentation or phantom model assessments. Moreover computer modelling,
either stochastic or deterministic, besides epidemiological studies are taken
into account as well. A deterministic mathematical model is constructed and
applied, using the reported frequency dependent electromagnetic properties, for
bone and bone marrow. The specific absorption rate (SAR), in both anatomic
structures, is computed according to the present mathematical model, is
represented spatially in the bone-marrow-bone layers under study. The effect of
exposure to electric field of strengths ranging from 1V/m to 1kV/m is investigated
for a wide frequency spectrum in each layer of the proposed model. The frequency dependence of the SAR, through
these layers, is illustrated for frequencies ranging from 1kHz to1GHz. The
thermal and non-thermal power densities are calculated for an extended
frequency range from (10MHz-100GHz).The present results are in agreement with
international safety standards for applied field strengths of maximum value;
10V/m for bone and 100V/m for bone marrow. Furthermore, the present model shows
that oblique incidence results in higher SAR values than with normal incidence,
highly evident for low frequency, especially for the frequency 1kHz. Higher
absorption rates are exhibited by frequencies around 10MHz than those exhibited
by frequencies in the range 1GHz to10GHz.
The model, developed by this study, provides a possibility for
establishment of some features or changes in the assessed biological
parameters, which couldn’t be established by other methods applied. The author
suggests introducing standardization for the non-thermal power and giving its
assessment considerable attention by the international organizations.
Aim: Deterministic evaluation of the microwave
power density distribution and absorption, in long bone and bone marrow, due to
far field exposure.
Study Design: A mathematical model is constructed and
applied to a bone –bone marrow-bone section to simulate EMF propagation and
hence absorption in each layer.
Place and
Duration of Study: Department of Engineering Math. And Physics Dept.,
Fac. Of Engineering, Cairo University.
Methodology: The author
employs a bone-marrow-bone model to investigate the effect of incident EMF. The
equations governing the total electric and magnetic field distributions in each
layer are deduced, considering its biological electromagnetic properties. The
model is simulated by a computer program using Maple V. The computed values of
real and imaginary components of power density in bone and bone marrow are
graphically represented versus frequency. The exposure to electric field of
strength ranging from 1V/m to 1kV/m is investigated using the proposed method.
The frequency dependence of the power density, both dissipated and stored,
through the bone-marrow-bone layers is illustrated for a frequency range of 1kHz-10GHz.
Results:
Electromagnetic radiation of 1MHz-10MHz induce absorbed power within the safety
limits for all applied field strengths. The 1GHz incident radiation induces SAR
values higher than permissible ranges for field strengths above 400V/m whereas
the same occurs for a low frequency range at 100V/m. Moreover, the present
results are in agreement with international safety standards for applied filed
strengths till 10V/m for bone and till 100V/m for bone marrow, covering the
applied frequencies (1 kHz -1 GHz). Except for exposure to electric field of
strength higher than 100V/m, the SAR acquired by the bone marrow is within the
safety levels. These results also show that the non-thermal power densities are
more effective for the UHF range 100MHz-100GHz.
Conclusion: The results
obtained are in agreement with international safety standards for filed
strengths of maximum value 10V/m for bone and 100V/m for bone marrow. Oblique
incidence results in higher SAR values than normal incidence, especially for
low frequency (1kHz). Non-thermal effects should be given further consideration
especially for UHF ranges.
Biography of author(s)
Dr. Mona Amin El-Naggar
Department of Engineering Physics and
Mathematics, Faculty of Engineering, Cairo University, Cairo, Egypt.
Read full article: http://bp.bookpi.org/index.php/bpi/catalog/view/25/59/147-1
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