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T-matrix computations of light scattering by red blood cells

Nilsson, Annika M. K.; Alsholm, Peter; Karlsson, Anders LU and Andersson-Engels, Stefan LU (1998) In Technical Report LUTEDX/(TEAT-7068)/1-24/(1998) TEAT-7068.
Abstract
The electromagnetic far field, as well as near field, originating from light

interaction with a red blood cell (RBC) volume equivalent spheroid, were

analyzed utilizing T-matrix theory. This method is a powerful tool which enables

the influence of cell shape on the angular distribution of scattered light

to be studied. General observations were that the three-dimensional shape,

as well as optical thickness apparent to the incident field, affect the forward

scattering. The back scattering was influenced by the shape of the surface

facing the incident beam. Furthermore, sphering as well as elongation of an

oblate shaped RBC into a volume equivalent sphere or prolate... (More)
The electromagnetic far field, as well as near field, originating from light

interaction with a red blood cell (RBC) volume equivalent spheroid, were

analyzed utilizing T-matrix theory. This method is a powerful tool which enables

the influence of cell shape on the angular distribution of scattered light

to be studied. General observations were that the three-dimensional shape,

as well as optical thickness apparent to the incident field, affect the forward

scattering. The back scattering was influenced by the shape of the surface

facing the incident beam. Furthermore, sphering as well as elongation of an

oblate shaped RBC into a volume equivalent sphere or prolate shaped spheroid,

respectively, were theoretically modeled in order to imitate physiological

phenomena caused, e.g., by sphering agents, heat or increased shear stress

of flowing blood. Both sphering and elongation were shown to decrease the

intensity of the forward directed scattering, thus yielding lower g-factors. The

sphering made the scattering pattern independent of the azimuthal scattering

angle φs, while the elongation induced more apparent φs-dependent patterns.

The light scattering by an RBC volume equivalent spheroid, was thus found

to be highly influenced by the shape of the scattering object. A near-field

radius, rnf, was evaluated as the distance to which the maximum intensity of

the total near field had decreased to 2.5 times that of the incident field. It

was estimated to 2-24.5 times the maximum radius of the scattering spheroid,

corresponding to 12-69 µm. When the absorption properties of a red

blood cell were incorporated in the computations, the near-field radius was

only slightly reduced by 0.2-0.6 times the maximum radius. As the near-field

radius was shown to be larger than a simple estimation of the distance between

the RBCs in whole blood, the assumption of independent scattering,

frequently employed in optical measurements on whole blood, seems inappropriate.

This also indicates that results obtained from diluted blood, cannot

be extrapolated to whole blood, by multiplying with a simple concentration

factor. (Less)
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organization
publishing date
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Book/Report
publication status
published
subject
in
Technical Report LUTEDX/(TEAT-7068)/1-24/(1998)
volume
TEAT-7068
pages
24 pages
publisher
[Publisher information missing]
external identifiers
  • Scopus:0001724232
language
English
LU publication?
yes
id
fea0e30b-ca92-45ea-822c-1ca040fcb650 (old id 530473)
date added to LUP
2007-09-12 10:37:03
date last changed
2016-10-30 04:44:09
@misc{fea0e30b-ca92-45ea-822c-1ca040fcb650,
  abstract     = {The electromagnetic far field, as well as near field, originating from light<br/><br>
interaction with a red blood cell (RBC) volume equivalent spheroid, were<br/><br>
analyzed utilizing T-matrix theory. This method is a powerful tool which enables<br/><br>
the influence of cell shape on the angular distribution of scattered light<br/><br>
to be studied. General observations were that the three-dimensional shape,<br/><br>
as well as optical thickness apparent to the incident field, affect the forward<br/><br>
scattering. The back scattering was influenced by the shape of the surface<br/><br>
facing the incident beam. Furthermore, sphering as well as elongation of an<br/><br>
oblate shaped RBC into a volume equivalent sphere or prolate shaped spheroid,<br/><br>
respectively, were theoretically modeled in order to imitate physiological<br/><br>
phenomena caused, e.g., by sphering agents, heat or increased shear stress<br/><br>
of flowing blood. Both sphering and elongation were shown to decrease the<br/><br>
intensity of the forward directed scattering, thus yielding lower g-factors. The<br/><br>
sphering made the scattering pattern independent of the azimuthal scattering<br/><br>
angle φs, while the elongation induced more apparent φs-dependent patterns.<br/><br>
The light scattering by an RBC volume equivalent spheroid, was thus found<br/><br>
to be highly influenced by the shape of the scattering object. A near-field<br/><br>
radius, rnf, was evaluated as the distance to which the maximum intensity of<br/><br>
the total near field had decreased to 2.5 times that of the incident field. It<br/><br>
was estimated to 2-24.5 times the maximum radius of the scattering spheroid,<br/><br>
corresponding to 12-69 µm. When the absorption properties of a red<br/><br>
blood cell were incorporated in the computations, the near-field radius was<br/><br>
only slightly reduced by 0.2-0.6 times the maximum radius. As the near-field<br/><br>
radius was shown to be larger than a simple estimation of the distance between<br/><br>
the RBCs in whole blood, the assumption of independent scattering,<br/><br>
frequently employed in optical measurements on whole blood, seems inappropriate.<br/><br>
This also indicates that results obtained from diluted blood, cannot<br/><br>
be extrapolated to whole blood, by multiplying with a simple concentration<br/><br>
factor.},
  author       = {Nilsson, Annika M. K. and Alsholm, Peter and Karlsson, Anders and Andersson-Engels, Stefan},
  language     = {eng},
  pages        = {24},
  publisher    = {ARRAY(0x977fa08)},
  series       = {Technical Report LUTEDX/(TEAT-7068)/1-24/(1998)},
  title        = {T-matrix computations of light scattering by red blood cells},
  volume       = {TEAT-7068},
  year         = {1998},
}