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Induced currents>
Induced Current Abstracts
We give here the abstracts and bibliographical details of some
of the key papers in the area of numerical calculations of induced
currents in the body.
| Phys Med Biol. 2005 Mar 21;50(6):1047-70.
Epub 2005 Feb 23.
Development of the female voxel phantom, NAOMI, and
its application to calculations of induced current densities
and electric fields from applied low frequency magnetic and
electric fields.
Dimbylow P.
National Radiological Protection Board, Chilton, Didcot,
Oxon, OX11 0RQ, UK.
This paper outlines the development of a 2 mm resolution
voxel model, NAOMI (aNAtOMIcal model), designed to be representative
of the average adult female. The primary medical imaging data
were derived from a high-resolution MRI scan of a 1.65 m tall,
23 year old female subject with a mass of 58 kg. The model
was rescaled to a height of 1.63 m and a mass of 60 kg, the
dimensions of the International Commission on Radiological
Protection reference adult female. There are 41 tissue types
in the model. The application of NAOMI to the calculations
of induced current densities and electric fields from applied
low frequency magnetic and electric fields is described. Comparisons
are made with values from the male voxel model, NORMAN. The
calculations were extended from 50 Hz up to 10 MHz. External
field reference levels are compared with the ICNIRP guidelines.
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| Phys Med Biol. 2002 Apr 21;47(8):1391-8.
Modelling fields induced in humans by 50/60 Hz magnetic
fields: reliability of the results and effects of model variations.
Caputa K, Dimbylow PJ, Dawson TW, Stuchly MA.
Department of Electrical and Computer Engineering, University
of Victoria, BC, Canada
This paper presents a comparison of anatomically realistic
human models and numerical codes in the dosimetry of power
frequency magnetic fields. The groups at the University of
Victoria and the National Radiological Protection Board have
calculated the induced electric fields in both their 'UVic
and 'NORMAN' models using independently developed codes. A
detailed evaluation has been performed for a uniform magnetic
field at 60 Hz. Comparisons of all dosimetric metrics computed
in each particular model agree within 2% or less. Since in
situ measurements cannot be performed in humans, and achievable
accuracy of measurements in models and animals is not likely
to be better than 10-15%, the comparisons presented should
provide confidence limits on computational dosimetry. An evaluation
of the effect of model size, shape and resolution has also
been performed and further illuminated the reasons for differences
in induced electric fields for various human body models. |
| Phys Med Biol. 2000 Apr;45(4):1013-22.
Current densities in a 2 mm resolution anatomically
realistic model of the body induced by low frequency electric
fields.
Dimbylow PJ.
National Radiological Protection Board, Didcot, Oxon, UK.
Current density distributions in a fine resolution (2 mm) anatomically
realistic voxel model of the human body have been calculated
for uniform, low frequency vertically aligned electric fields
for a body grounded and isolated from 50 Hz to 10 MHz. The
voxel phantom NORMAN is used which has a height of 1.76 m
and a mass of 73 kg. There are 8.3 million voxels in the body
differentiated into 37 tissue types. Both finite-difference
potential and time-domain methods were used. Results are presented
for the current density averaged over 1 cm2 in muscle, heart,
brain and retina. Electric field values required to reach
the NRPB and ICNIRP basic restrictions on current density
are derived and compared with the external field guidelines
from these standards. |
| Phys Med Biol. 1998 Feb;43(2):221-30.
Induced current densities from low-frequency magnetic
fields in a 2 mm resolution, anatomically realistic model
of the body.
Dimbylow PJ.
National Radiological Protection Board, Didcot, Oxon, UK.
This paper presents calculations of current density in a
fine-resolution (2 mm) anatomically realistic voxel model
of the human body for uniform magnetic fields incident from
the front, side and top of the body for frequencies from 50
Hz to 10 MHz. The voxel phantom, NORMAN, has a height of 1.76
m and a mass of 73 kg. There are 8.3 million voxels in the
body differentiated into 37 tissue types. Both the impedance
method and the scalar potential finite difference method were
used to provide mutual corroboration. Results are presented
for the current density averaged over 1 cm2 in muscle, heart,
brain and retina. |
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