Background: The methods used for evaluating wound dimensions, especially the chronic ones, are invasive and inaccurate. The fringe projection technique with phase shift is a non-invasive, accurate and low-cost optical method. Objective: The aim is to validate the technique through the determination of dimensions of objects of known topography and with different geometries and colors to simulate the wounds and tones of skin color. Taking into account the influence of skin wound optical factors, the technique will be used to evaluate actual patients’ wound dimensions and to study its limitations in this application. Methods: Four sinusoidal fringe patterns, displaced ¼ of period each, were projected onto the objects surface. The object dimensions were obtained from the unwrapped phase map through the observation of the fringe deformations caused by the object topography and using phase shift analysis. An object with simple geometry was used for dimensional calibration and the topographic dimensions of the others were determined from it. After observing the compatibility with the data and validating the method, it was used for measuring the dimensions of real patients’ wounds. Results and Conclusions: The discrepancies between actual topography and dimensions determined with Fringe Projection Technique and for the known object were lower than 0.50 cm. The method was successful in obtaining the topography of real patient’s wounds. Objects and wounds with sharp topographies or causing shadow or reflection are difficult to be evaluated with this technique.
Due to the great number of new clinical applications of Low-Level-Laser-Therapy (LLLT), the development of precise,
stable and low cost solid phantoms of skin, fat, muscle and bone becomes extremely important. The aim is to find the
best combination of matrix, absorber and scatterers, which simulate skin, fat, muscle and bone tissues to build LLLT
phantoms. Eight cylindrical phantoms simulating various human fingers were constructed and tested. Matrixes of
polyester resins and paraffin were used with various concentrations of dyes and scatterers (Al2O3 nanoparticles) to adjust
the optical parameters. A CCD camera was used to obtain transmission and scattering images of the phantoms, and of
swine tissues and volunteer's fingers illuminated by lasers (diode 635 and 820 nm, and HeNe, 633 nm). The light fluence
transmitted through the sample form Gaussian shaped profiles. Light scattered at 90 degrees shows an intensity profile
with a steep growth followed by an exponential attenuation. The comparison of these two kinds of profiles for phantoms
and swine tissue was used to evaluate the concentrations that better simulate different kinds of tissues. The outcomes of
this study point to a reliable tool to aid clinicians with LLLT dosimetry.
MCML1.2.2-2000 code was used to simulate light distribution in LipovenosR 10% (Lp) layers with various
thicknesses illuminated by red laser. Light fluence distribution at the layer bottom and fluence profile along a
plane distant 5.5 mm from the laser beam were calculated. The results show that the light transmitted to the
bottom of the sample has a Gaussian distribution with widths that increase linearly with the thickness. Also,
the maximum light intensity and the total fluence transmitted across the sample have exponential decay
behavior with thickness. An experiment has been carried out, acquiring, with a CCD camera, pictures of light
transmitted and scattered at 90° from a cuvette containing different quantities of Lp, illuminated from the top
with He-Ne laser. The experimental results show that the maximum intensity of transmitted light has an
asymptotic exponential behavior with the sample thickness, very similar to the simulation. Gaussian curves
fitted to the experimental results have widths similar to the simulated ones. The simulated light profile at
5.5 mm from the incidence plane is very similar to the variation of scattered light intensity with depth. We
conclude that images of illuminated tissue combined with MCS can contribute with evaluation of light
distribution inside tissue.
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