Affiliations: Department of Laser Medicine, Chinese PLA General
Hospital, Beijing 100853, China | Department of Oncology, The First Affiliated Hospital
of Chinese PLA General Hospital, Beijing 100037, China | Department of Automatic Control, Beijing Institute of
Technology, Beijing 100081, China
Abstract: Intravascular low level laser therapy (ILLLT) has been applied in
the treatment of many diseases for about twenty years. However, much
fundamental work has not been done on its dosimetry. The study was designed to
compare the difference of light distribution during ILLLT between using flat
end fiber and optical fiber coupled with cylindrical light diffuser. Light
distribution of He-Ne laser was processed by Monte Carlo model. The laser
output was 5 mW. The diameter of both optical fibers was 400 μ. Four tissue optical parameters were chosen for simulation. The
results showed that optical parameters of blood are important to determine the
distribution of laser energy. The highest power density could increase to over
5000 mW/cm^{2} using flat end fiber. And the laser energy
was absorbed by the blood cells in very small area before the tip of flat end
fiber. But when using optical fiber coupled with cylindrical light diffuser,
the highest power density was about 100 mW/cm^{2}. More
volume of blood cells could be irradiated by laser light. In summary, optical
fiber coupled with cylindrical light diffuser is superior to flat end fiber at
the aspect of increasing the volume of irradiated blood and decreasing unwanted
damage to blood cells during intravascular low level laser therapy.
