Light distribution in the erythrocyte under laser irradiation: a finite-difference time-domain calculation.
In medical applications of low power laser irradiations, safety is one of the most concerning problems since the light focused by the biological object itself may cause damage of living organisms. The light distributions in an erythrocyte with the shape of native biconcave, oblate spheroid, or disk sphere under the irradiation of a plane light of 632.8 nm were studied with a numerical calculation method of finite-difference time domain. The focusing effect by either the biconcave erythrocyte, oblate spheroid, or disk sphere erythrocyte was found to be so remarkable that the light intensities at the focused areas close to the erythrocyte membrane were about 10 times higher than that of the incident light when the light irradiated along the erythrocyte plane. This focusing effect became weak and even disappeared when the irradiation direction deviated from the erythrocyte plane for more than an angle of 15 degrees. Because the highest light intensity in the erythrocyte can be about one order of magnitude higher than that of the incident light, this factor should be taken into account for laser safety in medical applications.
Wang
Xiao-Qian
XQ
Surface Physics Laboratory, Department of Physics, Fudan University, Shanghai 200433, China.
Yu
Ji-Tong
JT
Wang
Pei-Nan
PN
Chen
Ji-Yao
JY
D000818:Animals; D003198:Computer Simulation; D004912:Erythrocytes / Q000502:physiology* / Q000528:radiation effects*; D020342:Finite Element Analysis; D006801:Humans; D007834:Lasers; D008027:Light; D008955:Models, Cardiovascular; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation