Numerical developments for short-pulsed Near Infra-Red laser spectroscopy. Part II: inverse treatment

Boulanger, Joan; Charette, André B.

doi:10.1016/j.jqsrt.2004.05.062

Cited by 46 publications

(19 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(6)) must be minimized under some constraints given by the radiative transfer equations for both the collimated and induced radiation. Those derivations are detailed in [19] and are not repeated here. After some algebra, gradients are explicitly given by…”

Section: Inversion Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Investigation on the reflection at the boundaries for reconstruction laser-based imaging

Boulanger

Liu

Charette

2007

Journal of Quantitative Spectroscopy and Radiative Transfer

Self Cite

View full text Add to dashboard Cite

Optical tomography is acknowledged as an economic and harmless probing technique for medical applications. Recent research tends to show that the use of long term photons, which have travelled a long time in the whole sample to be probed, carry more information in the image reconstruction process. Numerical simulations based on short-pulsed laser beam interaction with non-homogeneous matter are presented. The aim is to emphasize the effect of reflective boundary conditions since reflection enforces photons to stay for a longer period of time in the phantom. It is found that the quality of reconstruction is better when the boundaries are reflecting. Crown

show abstract

Section: Inversion Methodsmentioning

confidence: 99%

“…The next section is dedicated to the presentation of the algorithm. The last section presents reconstructions as in [19] and the accuracy of the reconstruction is studied with respect to the new boundary conditions.…”

Section: Incident Directionmentioning

confidence: 99%

Investigation on the reflection at the boundaries for reconstruction laser-based imaging

Boulanger

Liu

Charette

2007

Journal of Quantitative Spectroscopy and Radiative Transfer

Self Cite

View full text Add to dashboard Cite

show abstract

“…Second, in the case of some particular set-ups, such as inverse imaging, absorption and scattering may be recovered, providing not only structural but functional imaging such as identification of tissues or physiological changes due to pathology, e.g. [4,5]. Some applications of this new imaging method are presently in use and concern the monitoring of cerebral blood and tissue oxygenation [6].…”

Section: Introductionmentioning

confidence: 99%

“…The underlying principle of these techniques is to separate the photons which have followed a straight line in order to apply on them back-projection methods. The merits of direct imaging is the recovery of internal structure with the use of relatively simple theoretical and numerical techniques, while inverse imaging necessitates a complete field of measurements and a numerical definition of the problem (geometry, boundaries, meshing and light transport model) in order to allow the implementation of an inverse algorithm [4,5]. However as stated above, direct imaging is limited by the intense scattering in the thickness of the material, while inverse problems are able to take advantage of this by accessing the information embedded in the diffuse photons; it provides only structural images and needs to work only in straight transmission.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Direct imaging of turbid media using long-time back-scattered photons, a numerical study

Boulanger

Akel²,

Charette³

et al. 2006

International Journal of Thermal Sciences

Self Cite

View full text Add to dashboard Cite

Direct imaging is a convenient way to obtain information on the interior of a semi-transparent turbid material by non-invasive probing using laser beams. The major difficulty is linked to scattering which scrambles the directional information coming from the laser beam. It is found in this paper that the long-term multiple-scattered reflected photons may provide structural information on the inside of a material, which offers an interesting alternative to using information only from un-scattered or least-scattered photons as obtained from current direct imaging set-ups for thin media.Based on some observations on a non-homogeneous three layered 1-D slab irradiated by a laser pulse, a direct probing methodology making use of the long-term back-scattered photons is illustrated to recover inclusions positions in a turbid 2-D medium. First, the numerical model is presented. Second, an extended parametrical study is conducted on 1-D homogeneous and non-homogeneous slabs with different laser pulse durations. It is found that the reflected asymptotic logarithmic slope carries information about the presence of the inclusion and that short laser pulses are not necessary since only the decaying parts of the remanent optical signature is important. Longer laser pulses allow a higher level of energy injection and signal to noise ratio. Third, those observations are used for the probing of a 2-D non-homogeneous phantom.

show abstract

Radiative transfer of luminescence light in biological tissue

Klose

2009

Light Scattering Reviews 4

View full text Add to dashboard Cite

We present the first algorithm for solving the equation of radiative transfer (ERT) in the frequency domain (FD) on three-dimensional block-structured Cartesian grids (BSG). This algorithm allows for accurate modeling of light propagation in media of arbitrary shape with air-tissue refractive index mismatch at the boundary at increased speed compared to currently available structured grid algorithms. To accurately model arbitrarily shaped geometries the algorithm generates BSGs that are finely discretized only near physical boundaries and therefore less dense than fine grids. We discretize the FD-ERT using a combination of the upwind-step method and the discrete ordinates (S N) approximation. The source iteration technique is used to obtain the solution. We implement a first order interpolation scheme when traversing between coarse and fine grid regions. Effects of geometry and optical parameters on algorithm performance are evaluated using numerical phantoms (circular, cylindrical, and arbitrary shape) and varying the absorption and scattering coefficients, modulation frequency, and refractive index. The solution on a 3-level BSG is obtained up to 4.2 times faster than the solution on a single fine grid, with minimal increase in numerical error (less than 5%).

show abstract

Numerical developments for short-pulsed Near Infra-Red laser spectroscopy. Part II: inverse treatment

Cited by 46 publications

References 17 publications

Investigation on the reflection at the boundaries for reconstruction laser-based imaging

Investigation on the reflection at the boundaries for reconstruction laser-based imaging

Direct imaging of turbid media using long-time back-scattered photons, a numerical study

Radiative transfer of luminescence light in biological tissue

Contact Info

Product

Resources

About