Candela AlexTriVantage, Operator'S Manual

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1-2 Confidential 8501-00-1800, Revision 05
Candela Corporation AlexTriVantage Laser System
Overview
This chapter provides a a brief introduction to the Candela AlexTriVantage Laser system.
This chapter provides information on the application for which the system was designed, and
a brief description of the laser system's major components and their function.
Laser Treatment of Skin Pigmentation Abnormalities
The Candela AlexTriVantage Laser system is a flashlamp excited, Q-switched Alexandrite
laser designed for the treatment of tattoos, benign cutaneous pigmented lesions, Nevus of
Ota and lesions like Nevus of Ota. Blue, green and black pigments respond best to treatment,
whereas other pigments show more variable response and test spots are recommended.
With the 755 nm nominal wavelength, laser irradiation is selectively absorbed by the targeted
pigment with minimal effect on the surrounding tissue. This is accomplished by careful
selection of the wavelength that yields maximum absorption by the target and minimum
absorption by surrounding skin structures. In addition, the laser pulse duration is controlled to
be equal to or shorter than the thermal relaxation time of the target, to minimize heat transfer
to surrounding tissues. This principle was first described by Anderson and Parrish.
Tattoo pigments vary in composition depending on the color of the tattoo and its origin
(amateur, professional, or traumatic). Ideally, the wavelength selected for eradication of the
tattoo should be highly absorbed by the tattoo pigment and only minimally absorbed by other
chromophores in the skin. Absorption of radiation by most pigments in amateur and
professional tattoos is strong in the near-infrared region of the spectrum. Melanin has a very
broad absorption band throughout the ultra-violet, visible, and near-infrared regions of the
spectrum, with absorption of light greatest in the ultraviolet, and least in the near-infrared.
Other chromophores in the skin, such as hemoglobin and oxyhemoglobin, have little to no
absorption of light within the selected wavelength.
The 755 nm nominal wavelength of the AlexTriVantage Laser has been carefully selected to
utilize the difference in absorption for the treatment of dark tattoo pigments. Treatment of
tattoos can therefore be performed with minimal adverse effects on normal skin structures.
The laser pulse duration should be shorter than the thermal relaxation time of the target
absorbing the laser radiation to confine the thermal damage and spare surrounding skin
structures. The relaxation time of a target is determined by its size. In the case of tattoos, the
targets are the solid pigment particles of the tattoo inks or dyes. The thermal relaxation time
of these micron size absorbers is approximately one microsecond (Margolis, et al), and,
according to selective photothermolysis theory, pulse durations as long as several hundred
nanoseconds should be effective. However, experiments show that a greater effect is
obtained by fragmenting the absorber into smaller particles so that phagocytes can more
effectively dispose of the fragmented particulates after laser exposure. This fragmentation is
accomplished by using pulse durations shorter than the upper limit predicted by selective
photothermolysis theory. The shorter pulses instantaneously raise the temperature of
pigmented structures to a very high level and cause fragmentation and further
decomposition, a desirable effect in the treatment of tattoos.