Low level laser therapy is used as a treatment of several conditions, including inflammatory processes and wound healing. Possible changes in mechanical properties of cells, caused by illumination, are investigated with optical magnetic twisting cytometry (OMTC), which is a technique used to evaluate mechanical properties in cell culture. Ferromagnetic micro beads are bound to cell cytoskeleton, the beads are magnetized vertically and a horizontal twisting magnetic field is applied causing a torque that moves the beads and deforms the cell, the beads rotate and displace. Based on the lateral displacement of the beads, elastic shear and loss moduli are obtained. Samples of human bronchial epithelial cell culture were divided in two groups: one was illuminated with a 660 nm red laser, 30 mW power, 0.75 W/cm2 irradiance, during different time intervals, and the other one, the control group, was not illuminated. The values of the mechanical constants of the cells of the control group showed a tendency of increasing with the time out of the incubator. On the other hand, the illuminated group showed constancy on the behavior of both moduli, keeping the normal conditions of the cell culture. Those results indicate that illumination can induce cells to homeostasis, and OMTC is sensitive to observe departures from the steady conditions. Hence, OMTC is an important technique which can be used to aggregate knowledge on the light effect in cell cytoskeleton and even on the low level laser therapy mechanisms in inflammatory processes and/or wound healing.
Over the last few years, low-level light therapy (LLLT) has shown an incredible suitability for a wide range of applications for central nervous system (CNS) related diseases. In this therapeutic modality light dosimetry is extremely critical so the study of light propagation through the CNS organs is of great importance. To better understand how light intensity is delivered to the most relevant neural sites we evaluated optical transmission through slices of rat brain point by point. We experimented red (λ = 660 nm) and near infrared (λ = 808 nm) diode laser light analyzing the light penetration and distribution in the whole brain. A fresh Wistar rat (Rattus novergicus) brain was cut in sagittal slices and illuminated with a broad light beam. A high-resolution digital camera was employed to acquire data of transmitted light. Spatial profiles of the light transmitted through the sample were obtained from the images. Peaks and valleys in the profiles show sites where light was less or more attenuated. The peak intensities provide information about total attenuation and the peak widths are correlated to the scattering coefficient at that individual portion of the sample. The outcomes of this study provide remarkable information for LLLT dose-dependent studies involving CNS and highlight the importance of LLLT dosimetry in CNS organs for large range of applications in animal and human diseases.
Low level laser therapy (LLLT) is used in several applications, including the reduction of inflammatory processes. It might be used to prevent the systemic inflammatory response syndrome (SIRS), which some patients develop after cardiopulmonary bypass (CPB) surgery. The objectives of this study were to investigate light distribution inside blood, in order to implement the LLLT during CPB, and, through this study, to determine the best wavelength and the best way to perform the treatment. The blood, diluted to the same conditions of CPB procedure was contained inside a cuvette and an optical fiber was used to collect the scattered light. Two wavelengths were used: 632.8 nm and 820 nm. Light distribution in blood inside CPB tubes was also evaluated. Compared to the 820 nm light, the 632.8 nm light is scattered further away from the laser beam, turning it possible that a bigger volume of blood be treated. The blood should be illuminated through the smallest diameter CPB tube, using at least four distinct points around it, in only one cross section, because the blood is kept passing through the tube all the time and the whole volume will be illuminated.
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.