A Basic Study on the Use of Semiconductor Laser of Penetrative Sensitivity on Living Tissue

Abstract

The penetrative sensitivity of Ga-Al-As semi-conductor laser (790nm, 60mW, continuous wave) in living tissue were evaluated the amount and the distribution of the laser beam on the penetrative side were quantified. Tissues used in this study consist of mandi bular cortical bone derived from human or ox, masseter muscle and fat tissue from ox, white meat of chicken and human venous blood which were all collected on the same day of mesurement. Five samples of each tissue were investigated in fresh status the transmittance and the attenuance of each sample were calculated, and finally following results were indicated.1. Contact irradiation was more effective for the reduction of energy loss on tissue surface than incontact method.2. Percent transmittance of either human or ox mandibular cortical bone in 1.0mm thickness reached approximately 50%. The distribution of the beam power on the penetrative side showed remarkable scattering and some absorption through the same sample.3. The transmittance of masseter muscle and fat tissue from ox close to cortical bone but chicken white meat showed high transmittance of 75% in 1.0mm thickness. In the analysis of the distribution of energy on penetrative side of these three soft tissues, resemble patterns produced under the mixed effects of absorption and scattering were observed.4. Human venous blood indicated low level of the transmittance as compared with other tissues. According to the results of analysis on power distribution, the laser beam seemed to be attenuated by absorption rather than by scattering.5. Attenuation of the laser beam in accordance with the thickness was similar to the graph which was led to Kubelka-Munk's formula for the attenuation of scattering light.