Light transport in tissue by 3D Monte Carlo: Influence of boundary voxelization

Binzoni, Tiziano; Leung, Terence S.; Giust, Remo; Rüfenacht, D; Gandjbakhche, Amir

doi:10.1016/j.cmpb.2007.10.008

Cited by 46 publications

(45 citation statements)

References 32 publications

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“…Here, we rely on a previously published implementation (Binzoni et al 2008a(Binzoni et al , 2008b, where we extended the original code with the laser-Doppler component. The algorithm was implemented on a cluster of 8 node PC (3 GHz, Intel, Pentium 4) allowing distributed calculations (Kirkby and Delpy 1997).…”

Section: Monte Carlo Methods and Generation Of The Power Spectrummentioning

confidence: 99%

“…It is important to emphasize that the behavior W r (r) in figure 10 does not indicate that the information content of the signal (the tissue blood flow) is dominated by tissue regions far from the detection point (>2 mm). In fact, we have previously demonstrated (Binzoni et al 2008a) that blood volume and/or velocity information mainly originates from a region situated just under the detection point in the case of an FFLDI source-detector geometry. This might also explains why FFLDI allows us to obtain a coherent image of the tissue blood perfusion occurring under the tissue surface.…”

Section: Physiological Interpretation Of the Zero-and First-order Mommentioning

confidence: 99%

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Full-field laser–Doppler imaging and its physiological significance for tissue blood perfusion

Binzoni¹,

Ville²

2008

Phys. Med. Biol.

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Using Monte Carlo simulations for a semi-infinite medium representing a skeletal muscle tissue, it is demonstrated that the zero-and first-order moments of the power spectrum for a representative pixel of a full-field laserDoppler imager behave differently from classical laser-Doppler flowmetry. In particular, the zero-order moment has a very low sensitivity to tissue blood volume changes, and it becomes completely insensitive if the probability for a photon to interact with a moving red blood cell is above 0.05. It is shown that the loss in sensitivity is due to the strong forward scatter of the propagating photons in biological tissues (i.e., anisotropy factor g = 0.9). The first-order moment is linearly related to the root mean square of the red blood cell velocity (the Brownian component), and there is also a positive relationship with tissue blood volume. The most common physiological interpretation of the first-order moment is as tissue blood volume times expectation of the blood velocity (in probabilistic terms). In this sense, the use of the first-order moment appears to be a reasonable approach for qualitative real-time blood flow monitoring, but it does not allow us to obtain information on blood velocity or volume independently. Finally, it is shown that the spatial and temporal resolution trade-off imposed by the CMOS detectors, used in full-field laser-Doppler hardware, may lead to measurements that vary oppositely with the underlying physiological quantities. Further improvements on detectors' sampling rate will overcome this limitation.

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Section: Monte Carlo Methods and Generation Of The Power Spectrummentioning

confidence: 99%

Section: Physiological Interpretation Of the Zero-and First-order Mommentioning

confidence: 99%

Full-field laser–Doppler imaging and its physiological significance for tissue blood perfusion

Binzoni¹,

Ville²

2008

Phys. Med. Biol.

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“…Mathematical models used to optimize selective photothermolysis in laser treatments have been widely published 8 , 12 . Monte Carlo simulations of light propagation in tissue are seen as the ‘gold standard’ to describe the transport of photons in biological turbid tissue (13) and have worked satisfactorily for some years, where each photon is followed through a propagation medium and its journey is directed by probability distributions of its interaction of scattering angles and absorption within the various tissue layers. In particular, Bjerring et al (14) showed the importance of the pulse shape of a pulsed dye laser (PDL) using mathematical and clinical evidence.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of the optimum pulse structure for safe and effective photo epilation using broadband pulsed light

Ash

Donne

Daniel

et al. 2012

J Applied Clin Med Phys

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The objective of this work is the investigation of intense pulsed light (IPL) photoepilation using Monte Carlo simulation to model the effect of the output dosimetry with millisecond exposure used by typical commercial IPL systems. The temporal pulse shape is an important parameter, which may affect the biological tissue response in terms of efficacy and adverse reactions. This study investigates the effect that IPL pulse structures, namely free discharge, square pulse, close, and spaced pulse stacking, has on hair removal. The relationship between radiant exposure distribution during the IPL pulse and chromophore heating is explored and modeled for hair follicles and the epidermis using a custom Monte Carlo computer simulation. Consistent square pulse and close pulse stacking delivery of radiant exposure across the IPL pulse is shown to generate the most efficient specific heating of the target chromophore, whilst sparing the epidermis, compared to free discharge and pulse stacking pulse delivery. Free discharge systems produced the highest epidermal temperature in the model. This study presents modeled thermal data of a hair follicle in situ, indicating that square pulse IPL technology may be the most efficient and the safest method for photoepilation. The investigation also suggests that the square pulse system design is the most efficient, as energy is not wasted during pulse exposure or lost through interpulse delay times of stacked pulses.PACS number: 87.10.Rt

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“…This is the only modification to the core of the MC code with respect to the 'classical' method. The MC code utilized in the present work has already been presented in Binzoni et al (2008aBinzoni et al ( , 2008b but any other code can be adapted in a similar way.…”

Section: Reorganizing Data Obtained From 'Classical' Monte Carlo Simumentioning

confidence: 99%

The photo-electric current in laser-Doppler flowmetry by Monte Carlo simulations

2009

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Monte Carlo (MC) simulations significantly contributed to a better understanding of laser-Doppler flowmetry (LDF). Here it is shown that the data obtained from standard MC simulations can be reinterpreted and used to extract more information such as the photo-electric current (i(t)). This is important because i(t) is the starting point for evaluating any existing or new algorithm to be used in LDF instrumentation. This circumvents the tedious procedure of generating a specific model (often approximated if possible at all) each time a different algorithm is considered. By a series of tutorial examples, the influence of various parameters is investigated, e.g. sampling rate, total acquisition time and dc filtering. These cases also demonstrate the fundamental role played by the photons' random phase in the shaping of the LDF signal. In particular, it is demonstrated by MC simulation that when the number of photon-moving red blood cell interactions is too low, then the Siegert relation that exists between the field and photo-electric current autocorrelation functions does not hold. This is an important point because the validity of the Siegert relation is implicitly admitted in the majority of the classical analytical models for the autocorrelation function in LDF (the classical MC approach does not allow one to study this problem). The proposed method and examples could stimulate new ideas and help the scientific community develop, test and validate new approaches in LDF.

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Light transport in tissue by 3D Monte Carlo: Influence of boundary voxelization

Cited by 46 publications

References 32 publications

Full-field laser–Doppler imaging and its physiological significance for tissue blood perfusion

Full-field laser–Doppler imaging and its physiological significance for tissue blood perfusion

Mathematical modeling of the optimum pulse structure for safe and effective photo epilation using broadband pulsed light

The photo-electric current in laser-Doppler flowmetry by Monte Carlo simulations

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