Transcript Presentation

Saratov State University
Department of Optics &
Biophotonics
Optical properties of parietal
peritoneum in the spectral range
350-2500 nm
Marina D. Kozintseva1, Alexey N. Bashkatov1,
Elina A. Genina1, Vyacheslav I. Kochubey1, Sergey
Yu. Gorodkov2, Dmitry A. Morozov3, Valery V.
Tuchin1
1
Department of Optics and Biophotonics of N.G. Chernyshevsky
Saratov State University, Saratov, Russia
2 Saratov State Medical University named after V.I. Razumovsky
3 Moscow State Scientific-Research Institute of Pediatrics and
Children Surgery
Motivation:
Saratov State University
Department of Optics &
Biophotonics

The wide application of optical methods in modern medicine
in the areas of diagnostics, therapy and surgery has stimulated
the investigation of optical properties of various biological
tissues.

The knowledge of tissue optical properties is necessary for the
development of the novel optical technologies of
photodynamic and photothermal therapy, optical tomography,
optical biopsy, and etc. Numerous investigations related to
determination of tissue optical properties are available
however the optical properties of many tissues have not been
studied in a wide wavelength range.
Goal of the study is to investigate the optical properties of
parietal peritoneum in the wavelength range 350-2500 nm
Saratov State University
Department of Optics &
Biophotonics
Materials and Methods:



For this study 13 samples of the parietal peritoneum mucous membrane , 10
samples of the parietal peritoneum muscle membrane and 14 samples of the
entire parietal peritoneum (mucous membrane + muscle membrane) have
been used. The samples keep in saline during 3-4 hour until
spectrophotometric measurements at temperature 4-5°C. All the tissue
samples has been cut into pieces with the area about 8.4  0.99 cm2. For
mechanical support, the tissue samples have been sandwiched between two
glass slides. The average thickness of the samples was 0.77  0.2 mm for
parietal peritoneum mucous membrane, 2.3  0.8 mm for parietal
peritoneum muscle membrane and 3.13  0.15 mm for entire parietal
peritoneum (mucous membrane + muscle membrane).
Measurement of the diffuse reflectance, total and collimated transmittance
have been performed using a commercially available spectrophotometer
PerkinElmer LAMBDA 950 in the spectral range 350-2500 nm.
All measurements were performed at room temperature (about 20°C)
For estimation of absorption and scattering coefficients, and anisotropy
factor of the tissue the inverse Monte Carlo method was used.
Saratov State University
Department of Optics &
Biophotonics
Experimental setup
The geometry of the measurements in A)
transmittance mode, B) reflectance mode.
1 - the incident beam (diameter 1-10 mm);
2 - the tissue sample; 3 - the entrance port
(square 2516 mm); 4 - the transmitted (or
diffuse reflected) radiation; 5 - the
integrating sphere (inner diameter is 150
mm); 6 - the exit port (diameter 28 mm)
The geometry of the collimated
transmittance measurements.
Diameter of the incident beam is 2
mm.
Saratov State University
Department of Optics &
Biophotonics
Inverse Monte Carlo
The computer program package for determination of absorption and scattering
tissue properties has been developed. This inverse Monte Carlo method based on
the solution of direct problem by Monte Carlo simulation and minimization of
the target function
F  a , s , g    Rdexp  Rdcalc  a , s , g    Tcexp  Tccalc  a , s , g    Tt exp  Tt calc  a , s , g  
2
2
with the boundary condition 0  g  0.98
To minimize the target function the Simplex method described in detail by Press
et al (Press W.H., et al. Numerical recipes in C: the art of scientific computing /
Cambridge: Cambridge University Press, 1992.) has been used. Iteration
procedure repeats until experimental and calculated data are matched within a
defined error limit (<0.1%). Here Rdexp, Ttexp, Tcexp, Rdcalc, Ttcalc, Tccalc are
measured and calculated values of diffuse reflectance and total and collimated
transmittance, respectively.
2
Saratov State University
Department of Optics &
Biophotonics
Inverse Monte Carlo
This method includes inverse adding-doubling (IAD) method developed by Prahl et al (Prahl S.A., et al. // Appl.
Opt., 1993, Vol. 32(4), P. 559-568) and inverse Monte Carlo simulations. The IAD method is widely used in tissue
optics for processing the experimental data of spectrophotometry with integrating spheres. This method allows one
to determine the absorption and the reduced scattering coefficients of a turbid media from the measured values of
the total transmittance and the diffuse reflectance. In these calculations the anisotropy factor can be fixed as 0.9,
since this value is typical for tissues in the visible and NIR spectral ranges.
Based on the obtained values of the tissue absorption and reduced scattering coefficients the inverse Monte Carlo
calculations have been performed. The inverse method includes direct problem, i.e. Monte Carlo simulation, which
takes into account the geometric and optical conditions (sample geometry, sphere parameters, refractive index
mismatch, etc.), and solution of inverse problem, i.e. minimization of target function by an iteration method. In this
study, we used Monte Carlo algorithm developed by L. Wang et al (Wang L., et al. // Computer Methods and
Programs in Biomedicine, Vol. 47, P. 131-146, 1995). The stochastic numerical MC method is widely used to model
optical radiation propagation in complex randomly inhomogeneous highly scattering and absorbing media such as
biological tissues.
Usually the inverse Monte Carlo technique requires very extensive calculations since all sample optical parameters
(absorption and scattering coefficients and anisotropy factor) unknown. To avoid the long time calculations as a
guest values we used values of absorption and reduced scattering coefficients obtained from calculations performed
by IAD method. For final determination of the tissue absorption and scattering coefficients, and the tissue
anisotropy factor minimization of the target function has been performed.
Saratov State University
Department of Optics &
Biophotonics
Inverse Monte Carlo
The flow-chart of the inverse Monte Carlo method
Saratov State University
Department of Optics &
Biophotonics
Results:
80
Reduced scattering coefficient, 1/cm
Absorbtion coefficient, 1/сm
50
40
1938 nm
30
20
425 nm
1450 nm
1740 nm
555 nm
1194 nm
10
60
40
20
0
0
500
1000
1500
2000
2500
Wavelenght, nm
The absorption spectrum of the
parietal peritoneum mucous
membrane
IS, IMC, data averaged for 13
samples
0
500
1000
1500
2000
2500
Wavelenght, nm
The reduced scattering coefficient
spectrum of the parietal
peritoneum mucous membrane
IS, IMC, data averaged for 13
samples
Saratov State University
Department of Optics &
Biophotonics
Results:
1,0
400
0,8
Anisotropy factor
Scattering coefficient, 1/cm
500
300
200
0,6
0,4
100
0,2
0
500
1000
1500
2000
2500
Wavelenght, nm
The scattering coefficient
spectrum of the parietal
peritoneum mucous membrane
IS, IMC, data averaged for 13
samples
500
1000
1500
2000
2500
Wavelenght, nm
The wavelength dependence of
scattering anisotropy factor of the
parietal peritoneum mucous
membrane
IS, IMC, data averaged for 13
samples
Saratov State University
Department of Optics &
Biophotonics
Results:
12
16
Reduced scattering coefficient, 1/cm
Absorbtion coefficient, 1/сm
1950 нм
10
8
6
4
430 нм
555 нм
1450 нм
980 нм
1183 нм
2
14
12
10
8
6
4
2
0
0
500
1000
1500
2000
2500
Wavelenght, nm
The absorption spectrum of the
parietal peritoneum muscle
membrane
IS, IMC, data averaged for 10
samples
500
1000
1500
2000
2500
Wavelenght, nm
The reduced scattering coefficient
spectrum of the parietal
peritoneum muscle membrane
IS, IMC, data averaged for 10
samples
Saratov State University
Department of Optics &
Biophotonics
Results:
35
2343 нм
2451 нм
8
1935 нм
6
1450 нм
425 нм
1194 нм
555 нм
4
1740 нм
970 нм
2
0
Reduced scattering coefficient, 1/cm
Absorbtion coefficient, 1/сm
10
30
25
20
15
10
5
0
500
1000
1500
2000
2500
Wavelenght, nm
The absorption spectrum of the
entire parietal peritoneum
(mucous membrane + muscle
membrane)
IS, IMC, data averaged for 14
samples
500
1000
1500
2000
2500
Wavelenght, nm
The reduced scattering coefficient
spectrum of the entire parietal
peritoneum (mucous membrane +
muscle membrane)
IS, IMC, data averaged for 14
samples
Saratov State University
Department of Optics &
Biophotonics
Results:
3,5
Depth of penetration, mm
3,0
2,5
2,0
1,5
1,0
0,5
0
500
1000
1500
2000
2500
Wavelenght, nm
The depth of penetration spectrum of the entire parietal peritoneum
(mucous membrane + muscle membrane)
IS, IMC, data averaged for 14 samples
Saratov State University
Department of Optics &
Biophotonics
Results:

From the last figure we can se, that the penetration
depth of the probe radiation is depend on its
wavelength. The maximum effect is seen in the spectral
range of 700 – 900 nm, where the depth of penetration
of the probe radiation is approximately 3 mm, that
corresponds to the total depth of mucous membrane of
parietal peritoneum and muscle membrane parietal
peritoneum. In the spectral range from 900 nm and
more in the absorption band of water with increasing
wavelength we can see the decreasing of the depth of
penetration of the probe radiation up to 0.6 mm.
Acknowledgements:
The work was carried out under the
partial support from the Russian
Foundation for Basic Research (grant 1302-91176); RF Governmental contract
14.B37.21.0728; project № 1.4.09; 224014
Photonics4life-FP7-ICT-2007-2;
RF
President’s grant 1177.2012.2 “Scientific
Schools”