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Open Access Research article

Using an oblique incident laser beam to measure the optical properties of stomach mucosa/submucosa tissue

Hua Jiang Wei1, Da Xing1*, Bo Hua He2, Huai Min Gu1, Guo Yong Wu3 and Xue Mei Chen4

Author Affiliations

1 MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631, Guangdong Province, PR China

2 Department of Surgery, the First Affiliated Hospital, Guangdong College of Pharmacy, Guangzhou 510224, Guangdong Province, PR China

3 Department of Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, PR China

4 Department of Ophthalmology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, Guangdong Province, PR China

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BMC Gastroenterology 2009, 9:64  doi:10.1186/1471-230X-9-64

Published: 28 August 2009

Abstract

Background

The purpose of the study is to determine the optical properties and their differences for normal human stomach mucosa/submucosa tissue in the cardiac orifice in vitro at 635, 730, 808, 890 and 980 nm wavelengths of laser.

Methods

The measurements were performed using a CCD detector, and the optical properties were assessed from the measurements using the spatially resolved reflectance, and nonlinear fitting of diffusion equation.

Results

The results of measurement showed that the absorption coefficients, the reduced scattering coefficients, the optical penetration depths, the diffusion coefficients, the diffuse reflectance and the shifts of diffuse reflectance of tissue samples at five different wavelengths vary with a change of wavelength. The maximum absorption coefficient for tissue samples is 0.265 mm-1 at 980 nm, and the minimum absorption coefficient is 0.0332 mm-1 at 730 nm, and the maximum difference in the absorption coefficients is 698% between 730 and 980 nm, and the minimum difference is 1.61% between 635 and 808 nm. The maximum reduced scattering coefficient for tissue samples is 1.19 mm-1 at 635 nm, and the minimum reduced scattering coefficient is 0.521 mm-1 at 980 nm, and the maximum difference in the reduced scattering coefficients is 128% between 635 and 980 nm, and the minimum difference is 1.15% between 890 and 980 nm. The maximum optical penetration depth for tissue samples is 3.57 mm at 808 nm, and the minimum optical penetration depth is 1.43 mm at 980 nm. The maximum diffusion constant for tissue samples is 0.608 mm at 890 nm, and the minimum diffusion constant is 0.278 mm at 635 nm. The maximum diffuse reflectance is 3.57 mm-1 at 808 nm, and the minimum diffuse reflectance is 1.43 mm-1 at 980 nm. The maximum shift Δx of diffuse reflectance is 1.11 mm-1 at 890 nm, and the minimum shift Δx of diffuse reflectance is 0.507 mm-1 at 635 nm.

Conclusion

The absorption coefficients, the reduced scattering coefficients, the optical penetration depths, the diffusion coefficients, the diffuse reflectance and the shifts of diffuse reflectance of tissue samples at 635, 730, 808, 890 and 980 nm wavelengths vary with a change of wavelength. There were significant differences in the optical properties for tissue samples at five different wavelengths (P < 0.01).