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Lasers in Medicine: Healing with Light
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
These infrared lasers take advantage of the presence of water in the skin to provide an ability to remove skin and body tissues in general. However, the absorption specificity of lasers operating in the visible has opened new possibilities in dermatology not available with conventional techniques. In particular, lasers can eradicate certain blemishes otherwise resistant to removal. This is especially true of port-wine stains, a type of birthmark often covering extensive regions of the body. The fine mesh of blood capillaries that makes up the port-wine stain is not dangerous, but people may wish to have them removed for cosmetic reasons (Figure 3.1a). A favored treatment for removing port-wine stains is the use of a pulsed dye laser operating at a yellow wavelength of 585 nm. This corresponds to a peak in the absorption of hemoglobin (Figure 3.25), giving good destruction of the blood vessels, and fading the port-wine stains by 80% to 90%. The more transparent surrounding skin absorbs much less of the laser light, and hence there is no scarring. The same laser can also be used for treating unsightly superficial capillaries on the legs, often called spider veins.
Photoacoustic Depth Determination and Imaging of Port Wine Stain Birthmarks
Published in Lihong V. Wang, Photoacoustic Imaging and Spectroscopy, 2017
John A. Viator, Roy G.M. Kolkman, Wiendelt Steenbergen
Port wine stain (PWS) birthmarks are a form of nevus flammeus and are characterized by pink to purple colored skin, usually occurring on the head and neck, though they may be found on other parts of the body as well [1–3]. Other forms of nevus flammeus such as stork bite, found on the nape of the neck, are present at birth and resolve themselves in infancy. PWS, however, persist into adulthood, usually darken in color, and may turn from macular into papular lesions. In some cases, the lesions affect underlying bone structure causing changes not only in the color, but the shape of a person’s features.
Numerical investigation of multi-pulsed cryogen spray cooling for skin cold protection in laser lipolysis
Published in Numerical Heat Transfer, Part A: Applications, 2020
Hui Xin, Bin Chen, Zhifu Zhou, Dong Li, Jiameng Tian
Existing simulations on MCS in laser surgery have focused on the treatment of port wine stain (PWS), which is a congenital vascular malformation existing in the dermis [23]. During laser PWS simulation, the skin can be simplified as a multilayer homogeneous model [18], discrete blood vessel model [24], or porous medium model [23]. To overcome the insufficient cold protection of a single cryogen spray for darkly pigmented skin type (e.g., V–VI types [25]), Aguilar et al. [26] developed a four-layer homogenous model to calculate the heat diffusion and light distribution. The findings showed that multiple cryogen spurts and multiple laser pulses (MCS-MLP) can produce expected destruction to PWS and provide sufficient epidermal cold protection of the types V–VI skin. Large diameter vessels can be partially coagulated and subsequently recanalized because laser energy may be absorbed by melanin. Jia et al. [27] presented a novel therapy of intermittent multiple cryogen spurts with multiple two-wavelength laser pulses (MCS-MTWLP). The numerical simulation indicated that MCS-MTWLP can achieve the photocoagulation of large-diameter vessels and provide sufficient epidermal cold protection compared with single cryogen spurt and single laser pulse. Chen et al. [28] simulated energy deposition and temperature distribution of 1064 nm (1210 nm) laser in biological tissues and observed that 1064 nm (1210 nm) laser radiation can effectively destroy adipocytes.