Red Diode Laser in the Treatment of Epidermal Diseases in PDT

The process of laser absorption in the skin during laser irradiation was a critical point in medical application treatments. Delivery the correct amount of laser light is a critical element in photodynamic therapy (PDT). More amounts of laser light able to affect tissues in the skin and small amount not able to enhance PDT procedure in skin. The knowledge of the skin tone laser dependent distribution of 635 nm radiation and its penetration depth in skin is a very important precondition for the investigation of advantage laser induced effect in (PDT) in epidermis diseases (psoriasis). The aim of this work was to estimate an optimum effect of diode laser (635 nm) on the treatment of epidermis diseases in different color skin. Furthermore, it is to improve safety of laser in PDT in epidermis diseases treatment. Advanced system analytical program (ASAP) which is a new approach in investigating the PDT, dependent on optical properties of different skin color was used in present work. A two layered Realistic Skin Model (RSM); stratum corneum and epidermal with red laser (635 nm, 10 mW) were used for irradiative transfer to study fluence and absorbance in different penetration for various human skin colors. Several skin tones very fair, fair, light, medium and dark are used to irradiative transfer. This investigation involved the principles of laser tissue interaction when the skin optically injected by a red laser diode. The results demonstrated that the power characteristic of a laser diode (635 nm) can affect the treatment of epidermal disease in various color skins. Power absorption of the various human skins were recorded and analyzed in order to find the influence of the melanin in PDT treatment in epidermal disease. A two layered RSM show that the change in penetration depth in epidermal layer of the color skin has a larger effect on the distribution of absorbed laser in the skin; this is due to the variation of the melanin concentration for each color.

Authors:

• Farhad H. Mustafa
• Mohamad S. Jaafar
• Asaad H. Ismail
• Ahamad F. Omar
• Zahra A. Timimi
• Hend A. A. Houssein

Keywords:

• Photodynamic therapy
• Realistic skin model
• Laser
• Light penetration
• simulation
• Optical properties of skin
• Melanin.

References:

[1] Keoth, L., et al. and Paul, N., Topical photodynamic therapy at low
fluence rates-theory and practice (2001) (Cambridge: Elservier).
[2] Thomas, S., Dosimetric concepts for PDT(2008) (Buffalo: Elsevier),
pp.217-223.
[3] Asta, J., Petras, Juzenas.and Li-Wei, M., Effectiveness of different light
sources for 5-aminolevulinic acid photodynamic therapy (2004)
(London: Laser in medical science), pp.139-149.
[4] SSteven, L., Role of tissue optics and pulse duration on the tissue effects
during high power laser radiation (1993) (Texas: Applied
Physics),pp.2447-2454.
[5] BBashkato, A., Genina, E., Kochubey, V. and Tuchin, V., Optical
properties of human skin subcutaneous and mucous tissues in the
wavelength range from 400 to 2000 nm (2005) (Saratov: Journal of
physics D: Applied Physics), pp. 2543-2555.
[6] Kolarova, H., Ditrichova, D., and Wagner, J., Penetration of laser light
into the skin in vitro (1999) (Czech Republic: Lasers in surgery and
medicine), pp. 231-235.
[7] Joachim, W., Razvigor D., and Enzo, B., Ethnic groups and sensitive
skin: two examples of special population in dermatology (2008) (USA:
Elsevier), pp. e249-e261.
[8] Norvang, L., Milner, T., Nelson, M., Berns, L. and Svaasand, L., Skin
pigmentation characterized by visible reflectance measurements (1997)
(California: Laser in medical science), pp. 99-112.
[9] Alper, M., Kavak, A., and Yesildal, N., Measurement of epidermal
thickness in a patient with psoriasis by computer-supported image
analysis (2004) (Duzce: Braz J Med Biol Res), pp.111-117.
[10] LLisa, C. and Tatyana, R., Laser - tissue interactions (2006)
(Philadelphia: Elsevier), pp.2-7.