3.1 Lasers in biology and medicine

Minet, Olaf; Dörschel, K.; Müller, G.

doi:10.1007/10877768_11

Cited by 4 publications

(7 citation statements)

References 155 publications

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“…Parameters used to characterize tissue optical properties include the light scattering (μ s ) and absorption coefficients (μ a ), which refer to the average number of absorption and scattering events per unit length of a photon propagating through a medium. 2 Enamel is a composite material with chemical and structural gradients varying as a function of depth. 3 As a result, light propagation in enamel can be described by the same physical processes as in soft biological tissues (i.e., highly scattering turbid media).…”

Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of the kinetics of human enamel simulated caries using photothermal radiometry and modulated luminescence

2011

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Photothermal radiometry and modulated luminescence (PTR-LUM) is an emerging nondestructive methodology applied toward the characterization and quantification of dental caries. We evaluate the efficacy of PTR-LUM in vitro to detect, monitor, and quantify human enamel caries. Artificial caries are created in extracted human molars (n = 15) using an acidified gel system (pH 4.5) for 10 or 40 days. PTR-LUM frequency scans (1 Hz-1 kHz) are performed before and during demineralization. Transverse microradiography (TMR) analysis, the current gold standard, follows at treatment conclusion to determine the mineral loss and depth of the artificially demineralized lesions. A theoretical model is applied to PTR experimental data to evaluate the changes in optothermophysical properties of demineralized enamel as a function of time. Higher optical scattering coefficients and poorer thermophysical properties are characteristic of the growing demineralized lesions, as verified by TMR, where the generated microporosities of the subsurface lesion confine the thermal-wave centroid. Enhanced optical scattering coefficients of demineralized lesions result in poorer luminescence yield due to scattering of both incident and converted luminescent photons. PTR-LUM sensitivity to changes in tooth mineralization coupled with opto-thermophysical property extraction illustrates the technique's potential for nondestructive quantification of enamel caries.

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Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of the kinetics of human enamel simulated caries using photothermal radiometry and modulated luminescence

2011

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“…Here, the nontrivial choice of (s ij ), s > 0 enables us to get final states close to the corresponding initial values u 0 , see (6) and (12). Naturally, planar images are represented by bounded rectangular domains Ω ⊂ R 2 .…”

Section: Simulation Resultsmentioning

confidence: 98%

“…The crucial point for any quantitative predictions on the outcome of diagnostic and therapeutic use of lasers in the human body is the knowledge of light distribution in biological tissues. Monte Carlo simulations (MCS) have been used until now for quite different scientific investigations in this field, see [6]. If information shall be gained by means of light from the interior of the body, there is a serious difference com- pared to x-ray and nuclear magnetic resonance methods.…”

Section: Introductionmentioning

confidence: 99%

The analysis of laser light scattering during rheumatoid arthritis by image segmentation

et al. 2007

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Optical imaging in biomedicine is governed by the light absorption and scattering interaction on microscopic and macroscopic constituents in the medium. Therefore, light scattering characteristics of human tissue correlates with the stage of some diseases. In the near infrared range the scattering event with the coefficient approximately two orders of magnitude greater than absorption plays a dominant role. The potential of an experimental laser diode based setup for the transillumination of rheumatoid finger joints and the pattern of the stray light detection are demonstrated. For evaluating the scattering light images a new non-local image segmentation method is presented. Regarding a noisy picture as a multicomponent mixture of gray scaled particles, this method minimizes a non-convex free energy functional under the constraint of mass conservation of the components. Contrary to constructing equilibrium distributions as steady states of an adequate evolution equation, a direct descent method for the free energy is used to separate the components of the image.Segmentation of scattering laser light images from healthy and rheumatoid finger joints

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“…1). A -capsula articularis, B -cartilage, C -synovia, D -thickened synovia with pannus formation, E -shaggy synovialis, F -inflammatory cells try, fluorescence applications up to Optical Biopsy and Optical Molecular Imaging, tissue oxygenation, modelling multi-layer and complex geometries considering variance reduction methods, too [4,5]. These are valuable examples for recent applications of MCS in biomedicine, which is the discipline of natural sciences where biophysics meets medicine.…”

Section: Introductionmentioning

confidence: 99%

Deconvolution of laser based images for monitoring rheumatoid arthritis

2005

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Optical imaging in biomedicine is governed by the light absorption and scattering interaction on microscopic and macroscopic constituents in the medium. Therefore, light scattering characteristics of human tissue correlate with the stage of some diseases. In the near infrared range the scattering event with the coefficient approximately two orders of magnitude greater than absorption plays a dominant role. When measuring the optical parameters variations were discovered that correlate with the rheumatoid arthritis of a small joint. The potential of an experimental setup for transillumination of the finger joint with a laser diode and the pattern of the stray light detection are demonstrated. The scattering caused by skin contains no useful information and it can be removed by a deconvolution technique to enhance the diagnostic value of this non-invasive optical method. Monte Carlo simulations ensure both the construction of the corresponding point spread function and the theoretical verification of the stray light picture in rather complex geometry.

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3.1 Lasers in biology and medicine

Cited by 4 publications

References 155 publications

Quantitative evaluation of the kinetics of human enamel simulated caries using photothermal radiometry and modulated luminescence

Quantitative evaluation of the kinetics of human enamel simulated caries using photothermal radiometry and modulated luminescence

The analysis of laser light scattering during rheumatoid arthritis by image segmentation

Deconvolution of laser based images for monitoring rheumatoid arthritis

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