Laser fluence for permanent damage of cutaneous blood vessels.
Treatment of vascular disorders may be improved by a more thorough understanding of laser-blood vessel interaction. In this study, the probability of permanent damage to a given type and size of blood vessel was determined as a function of fluence at the top (superficial edge) of the vessel lumen. A 532 nm wavelength, 10 ms pulse duration, 3 mm spot size laser was used to perform approximately 250 irradiations of subdermal blood vessels in the hamster dorsal skin flap preparation. The radiant exposure required for a 50% probability of permanent damage was calculated using a probit analysis of experimental results. Threshold radiant exposure increased with larger blood vessel diameters and was greater for arterioles than venules. Monte Carlo modeling of a typical blood vessel geometry revealed that fluence at the top of the blood vessel lumen was amplified by a factor of approximately 2.4 over tissue surface radiant exposure, due to light scattering in the tissue and internal reflection at the skin-air interfaces.
Barton
J K
JK
Biomedical Engineering Program, University of Arizona, Tucson 85721-0104, USA. barton@u.arizona.edu
Vargas
G
G
Pfefer
T J
TJ
Welch
A J
AJ
D000818:Animals; D001160:Arterioles / Q000293:injuries / Q000528:radiation effects; D006224:Cricetinae; D004307:Dose-Response Relationship, Radiation; D007834:Lasers / Q000009:adverse effects*; D009010:Monte Carlo Method; D012867:Skin / Q000098:blood supply*; D014699:Venules / Q000293:injuries / Q000528:radiation effects