Effective attenuation coefficient and penetration depth of 630 nm laser light in polyvinyl alcohol slime glue phantoms simulating the human brain tumour

Abstract

The effectiveness of optical methods such as photodynamic therapy (PDT) depends on the amount of light distribution within the tissue to aid their potential for early cancer detection in a quantitative and non-invasive manner. Knowledge of the effective attenuation coefficient and penetration depth for the laser light is crucial to ensuring that the tumour tissue receives adequate optical energy. This study investigated the effective attenuation coefficient and penetration depth of He–Ne 630 nm red laser light in polyvinyl alcohol slime glue phantoms simulating human brain tumour tissues. The effective attenuation coefficient (µeff) and penetration depth (δ) were deduced from the absorption coefficient (µa), scattering coefficient (µs), and anisotropy factor (g) obtained from the Henyey–Greenstein (H–G) function by collimated laser beam measurements. We found that the effective attenuation coefficient and penetration depth were 0.25 ± 0.02 mm−1 and 4.00 mm, respectively, in the simulated phantoms. These values were in reasonable agreement with values reported for malignant human brain tumour tissues in the literature. The constructed phantoms would be an excellent tool for the continued evaluation of PDT as an essential therapeutic procedure in cancer management.

Keywords

• biomedical physics
• slime phantoms
• effective attenuation coefficient
• penetration depth
• he–ne laser.