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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
The active medium need not be a gas. Examples of lasers with solid active media are diode lasers, used in various medical applications, compact disc players, and supermarket scanner devices. Glasses such as neodymium-yttrium-aluminum-garnet (abbreviated Nd:YAG and pronounced “neodymium yag”), erbium:YAG, and holmium:YAG are used to make especially versatile, high-power lasers. The Nd:YAG laser can be operated at one of three wavelengths: the infrared (1064 nm), and – with a special optical element called a frequency-doubling crystal – green (532 nm), and ultraviolet (355 nm) wavelengths.
Laser Photocoagulation Principles
Published in John P. Papp, Endoscopie Control of Gastrointestinal Hemorrhage, 2019
Several methods for raising the energy of atoms in preparation for a “stimulating experience” have been devised. The two most common are illustrated in Figure 6a and 6b. In Figure 6a, atoms are forced to carry an electric current by undergoing ionization and becoming electrical charge carriers. As they accelerate under the influence of an applied electric field, their energy increases. When they collide with other atoms, they can cause orbital electrons to jump up in energy. If the energy jump is to the proper level, laser action can then proceed. This type of energy excitation is easily accomplished in a gaseous laser such as the argon laser. In Figure 6b, the lasing material is excited by an external source of light of very high (similar to the most powerful used in photography). This type of excitation is useful for solid laser materials such as the Nd: YAG laser. Normal YAG material is a gemstone quality crystal which, without the presence of Nd impurity, is water-white and widely used as a fake diamond material.
Adult Anaesthesia
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Daphne A. Varveris, Neil G. Smart
The neodymium-doped yttrium-aluminium-garnet (Nd:Yag) laser was introduced in the 1980s and penetrates tissue more deeply than the CO2 laser. It can also be delivered by means of a flexible fibre-optic light cable that can be used in conjunction with a fibre-optic bronchoscope to treat lesions in the trachea and bronchi. The potassium titanyl phosphate (KTP) laser is a variant of the Nd:Yag, in which the laser beam is passed through a potassium titanyl phosphate crystal.
Evaluation of the safety and efficacy of long pulsed Nd: YAG laser in the treatment of vascular lesions in vivo
Published in Journal of Cosmetic and Laser Therapy, 2022
Yun-Hee Rhee, Han-Yong Ryu, Jin-Chul Ahn, Phil-Sang Chung
The wavelength used needs to have sufficient penetration depth for the target vasculature. Longer wavelengths yield deeper penetration, but also require higher fluences for efficacy. The pulse duration for laser treatment of vascular lesions depends on the target vessel diameter (1,3–5). However, the clinical application of lasers in vascular lesions does not have specific guidelines and only depends on the empirical data of physicians. Hence, we conducted a study in vivo and investigated the ablating effects of the long pulsed yttrium-aluminum-garnet laser (Nd:YAG) on vascular lesions without skin damage. We performed laser treatment to various diameter of blood vessels with 7.5–12 J/cm2 at 532 nm and 100–140 J/cm2 at 1064 nm and observed the changes in microvascular blood flow using a Doppler image scanner and investigated the skin damage and hemorrhage by hematoxylin and eosin staining.
Intense pulsed light treatment for Becker’s nevus
Published in Journal of Dermatological Treatment, 2021
Pin-Ru Wu, Lan-Jun Liu, Yi-Xin Zhang, Ying Liu, Xiao-Xi Lin, Gang Ma
Ablative lasers including Er:YAG laser and CO2 laser have also been utilized to treat BN. The ablative Er:YAG laser, which targets tissue water and removes the entire epidermis and varying thickness of the dermis, was reported to be effective in treating BN. Comparison of one treatment session of Er:YAG to three treatment sessions of Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) found superiority of Er:YAG in improving hyperpigmentation (8). But patients experience a high incidence of significant adverse effects, such as persistent erythema, scars, and pigmentary changes (8). Ablative fractional CO2 laser in conjunction with topical bleaching cream was shown to have a modest effect on hyperpigmentation in some patients with BN after a single treatment (17). However, post-inflammatory hyperpigmentation and relatively negative patient-reported outcomes still preclude it from being a standard therapy (17). Non-ablative fractional resurfacing with the 1550 nm Erbium-doped fiber laser has shown promise with greater than 75% clearance in pigment (18,19). However, the hypertrichotic component of the BN was expectedly unaffected that needed further laser hair removal (19). Thus, IPL is considered to be superior to ablative and fractional lasers in that hypertrichosis and hyperpigmentation are simultaneously treated.
Recall erythema phenomenon following Er:YAG laser treatment: two case studies and literature review
Published in Journal of Cosmetic and Laser Therapy, 2018
Margit L. W. Juhász, Melissa Kanchanapoomi Levin, Ellen S. Marmur
Recall erythema is a phenomenon in which an area previously treated with laser therapy is subjected to a trigger causing reproducible erythema in the treatment zone after complete resolution of postoperative erythema. Radiation recall dermatitis occurs when an area treated with radiation is subjected to an activating factor, most commonly antibiotics and chemotherapeutics, causing erythema in the distribution of radiation treatment. Recall dermatitis following laser treatment is extremely rare and cases have been reported in the setting of hair removal using a diode neodymium-doped yttrium aluminum garnet (Nd:YAG) laser after non-ionic contrast media injection for computed tomography or docetaxel-induced. While recall radiation is uncommon, it is important for laser surgeons to recognize and manage this condition appropriately. In this case series, we report two cases of recall radiation following exposure to either hot water or ultraviolet radiation in the setting of prior treatment with erbium-doped yttrium aluminum garnet (Er:YAG) resurfacing laser. To the authors’ knowledge, this is the first reported case series of recall radiation with Er:YAG resurfacing laser.