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Povzetek. Sirjenje nepolarizirane svetlobe po bioloskih tkivih pogosto formuliramo v okviru enacbe sevalnega prenosa energije. Ta za vecino uporabnih geometrij ni analiticno resljiva, zato jo najpogosteje resujemo numericno v okviru simulacij Monte Carlo. Tovrstno metodologijo je mogoce uspesno uporabiti v stevilnih eksperimentalnih postavitvah, ki vkljucujejo tudi prostorsko razlocene meritve povratno sipane svetlobe (reflektance) z opticno vlaknenimi sondami. V okviru te studije smo podrobneje proucili vpliv omejenega simulacijskega volumna na cas in natancnost izracunov prostorsko razlocene reflektance zajete z linearno razporeditvijo opticnih vlaken v sondi. Rezultati kazejo, da je napaka pri izracunih reflektance s simulacijami Monte Carlo pri uporabi omejenega simulacijskega volumna najvecja za vzorce z nizkim absorpcijskim in reduciranim sipalnim koeficientom. Nasprotno, rezultati kazejo, da je napaka le malo odvisna od faktorja anizotropije sipalne fazne funkcije. Z zmanjsanjem simulacijskega volumna je mogoce izracune reflektance pohitriti tudi do dvakrat, a le pri vzorcih z nizkim absorpcijskim ([asymp] 1 cm-1) in do zmernim reduciranim sipalnim koeficientom ([asymp] 30 cm-1). Poleg stevilnih bioloskih tkiv se s tovrstnimi opticnimi lastnostmi pogosto srecujemo pri opticnih fantomih za vrednotenje in umerjanje reflektance izracunane s simulacijami Monte Carlo.
Kljucne besede: reflektancna spektroskopija, absorpcija, sipanje, Monte Carlo simulacije, napaka, hitrost izracunov, opticne sonde
The impact of a reduced simulation volume on the accuracy and computational time of the Monte Carlo reflectance simulations
Light propagation in biological tissues formulated within the framework of the radiative transport equation is frequently simulated by stochastic Monte Carlo simulations. Such methodology is used in numerous experimental settings including spatially resolved reflectance measurements conducted by optical fiber probes. In this paper, we analyse the impact of the simulation volume on the computational time and relative error of the Monte Carlo simulated reflectance for an optical fiber probe with a linear fiber layout. The results show, that the largest relative reflectance error for a reduced simulation volume is observed for samples with low absorption and reduced scattering coefficients and for larger source detector separations. A subsequent analysis revealed that the reflectance error does not significantly depend on the anisotropy factor of the scattering phase function. A twofold reduction in the computational time of the Monte Carlo simulations can be attained without significantly affecting the accuracy of the computed reflectance for the given experimental setting. However, the computational time is...