Optimal beam size for light delivery to absorption-enhanced tumors buried in biological tissues and effect of multiple-beam delivery: a Monte Carlo study

Abstract

Optimal laser light delivery into turbid biological tissues was studied by using Monte Carlo simulations based on the delta-scattering technique. The goal was to deliver efficiently the maximum amount of optical power into buried tumors being treated while avoiding potential damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding normal tissue because of selective uptake of the absorption-enhancement dye. The power delivering efficiency to buried tumors was investigated for various diameters of the laser beam. An optimal beam diameter was estimated to achieve the maximum product of the power coupling efficiency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single-beam delivery and multiple-beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumor could be achieved.

Photon penetration depth in human brain for light stimulation and treatment: A realistic Monte Carlo simulation study

“…Compared to the recent developed analytical approximation method, 5 Monte Carlo method is more°e xible and reliable, especially for nonin¯nite medium. There are several widely used Monte Carlo simulation techniques o®ered in our¯eld, such as the one for layered tissue model (MCML), 6 the one for medical image depicted tissue model (tMCimg), 7 the one for mathematical geometry depicted tissue model (MCLS), 8 and the one for 3D voxelized media (MCVM). 9 Although these methods have been accepted in biomedical¯eld in accurate light propagation computation, the MCML and MCLS are only applicable layered tissue model or the model depicted with cube, sphere, or cylinder.…”

“…8,10,11,15 There was only one Monte Carlo study on light penetration depth on realistic head model, 13 which uses a MRI head model in which precision is not high enough. A more realistic and precised head model was recommended to model light propagation.…”

Optical focusing through biological tissue and tissue-mimicking phantoms up to 9.6 centimeters thick with digital optical phase conjugation

“…Second, the laser power is finite such that the beam diameter cannot be too large, because the sources at the rim will not couple well to the target location. Therefore, there exists an optimal beam diameter that can efficiently deliver light to the target location 12 . Figure 2.…”

Fast 3-D dark-field reflection-mode photoacoustic microscopy in vivo with a 30-MHz ultrasound linear array

“…However, a large dark-field area may reduce the optical fluence reaching the targeted area. The optimal illumination radius was estimated to be 7 mm using the concept of effective attenuation coefficient, 13 the exponential decay rate of fluence far from the source, with typical tissue parameters. Consequently, leaving a ϳ1-mm width right below the array elements as the dark field gives approximately the best performance.…”