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ABSTRACT
The effects of uncertainties of laser exposure time, phase lag times, blood perfusion coefficient, scattering coefficient, and diffuse reflectance of light on the thermal damage of living biological tissue by laser irradiation are investigated using a sample-based stochastic model. The variabilities of input and output parameters are quantified using the coefficient of variance (COV) and interquartile range (IQR), respectively. The IQR analysis concluded that phase lag times for temperature gradient and heat flux, laser exposure time, and blood perfusion rate have more significant influences on the maximum temperature and maximum thermal damage of the living biological tissue induced by laser irradiation than the diffuse reflectance of light and scattering coefficient.
Nomenclature
| A | = | frequency factor [s−1] |
| E | = | energy of activation of denaturation reaction [J/mol] |
| G | = | coupling factor between blood and tissue [W/(m3 K)] |
| h | = | heat transfer coefficient [W/(m2 K)] |
| k | = | thermal conductivity [W/(m K)] |
| q | = | heat flux vector [W/m2] |
| Rd | = | diffuse reflectance of light |
| R | = | universal gas constant [J/(mol K)] |
| r | = | position vector [m] |
| QL | = | heat source due to hyperthermia therapy [W/m3] |
| t | = | time [s] |
| T | = | average temperature [K] |
| w | = | blood perfusion rate [m3/m3 tissue] |
| α | = | thermal diffusivity [m2/s] |
| ε | = | porosity |
| ρ | = | density [kg/m3] |
| σ | = | standard deviation |
| µ | = | mean |
| τq | = | phase lag time of the heat flux [s] |
| τT | = | phase lag of the temperature gradient [s] |
| τL | = | laser exposure time |
| φin | = | incident laser irradiance |
| μa | = | absorption coefficient [cm−1] |
| μs | = | scattering coefficient [cm−1] |
| ϕ(x) | = | local light irradiance |
| δ | = | effective penetration depth |
| g | = | scattering anisotropy |
| Ω | = | damage parameter |
| (δx)w | = | distance between W and P (two grid points) |
| (δx)e | = | distance between P and E (two grid points) |
| Subscripts | = | |
| s | = | solid matrix (tissue) |
| b | = | blood vessel |
Nomenclature
| A | = | frequency factor [s−1] |
| E | = | energy of activation of denaturation reaction [J/mol] |
| G | = | coupling factor between blood and tissue [W/(m3 K)] |
| h | = | heat transfer coefficient [W/(m2 K)] |
| k | = | thermal conductivity [W/(m K)] |
| q | = | heat flux vector [W/m2] |
| Rd | = | diffuse reflectance of light |
| R | = | universal gas constant [J/(mol K)] |
| r | = | position vector [m] |
| QL | = | heat source due to hyperthermia therapy [W/m3] |
| t | = | time [s] |
| T | = | average temperature [K] |
| w | = | blood perfusion rate [m3/m3 tissue] |
| α | = | thermal diffusivity [m2/s] |
| ε | = | porosity |
| ρ | = | density [kg/m3] |
| σ | = | standard deviation |
| µ | = | mean |
| τq | = | phase lag time of the heat flux [s] |
| τT | = | phase lag of the temperature gradient [s] |
| τL | = | laser exposure time |
| φin | = | incident laser irradiance |
| μa | = | absorption coefficient [cm−1] |
| μs | = | scattering coefficient [cm−1] |
| ϕ(x) | = | local light irradiance |
| δ | = | effective penetration depth |
| g | = | scattering anisotropy |
| Ω | = | damage parameter |
| (δx)w | = | distance between W and P (two grid points) |
| (δx)e | = | distance between P and E (two grid points) |
| Subscripts | = | |
| s | = | solid matrix (tissue) |
| b | = | blood vessel |