A pressure controlled low-level laser probe to enhance photon density in soft tissue

Abstract

Noninvasive low-level laser devices have been introduced for therapeutic purpose in medicine. However, low-level laser cannot deliver enough photon density to expect positive therapeutic results in deep tissue layer due to light scattering property in tissue. In order to overcome the limitation, this study was aimed to develop a negative pressure applied low-level laser probe to enhance laser transmission and, therefore, photon density in soft tissue. In order to evaluate clinical feasibility of developed laser probe, ex-vivo experiments were performed with porcine skin samples and laser transmissions were quantitatively measured as a function of tissue compression. The laser probe has an air suction hole to apply negative pressure to skin, a transparent plastic body to observe tissue deformation, and a small metallic optical fiber guide to support the optical fiber when negative pressure was applied. By applying negative pressure to the laser probe, the porcine skin under the fiber guide is compressed down and, low-level laser is emitted into the skin. Diffusion images of laser in the skin samples were acquired with a CCD camera and analyzed. Compared to the intensity without compression, the peak intensity of laser beam profiles increased about 2~2.5 times and FWHM (Full Width at Half Maximum) decreased about 1.67~2.85 times. In addition, the peak intensity was linearly increased as a function of compression. In conclusion, we verified the enhancement of laser transmission and therefore, photon density in tissue by applying negative pressure to the developed low-level laser probe and its potential for clinical usefulness.