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The Twentieth Century and Beyond
Published in Scott M. Jackson, Skin Disease and the History of Dermatology, 2023
The next major advancement in twentieth-century dermatologic technology is the laser. “Laser” is an acronym that stands for Light Amplification by Stimulated Emission of Radiation. The scientific history of lasers begins with the work of Max Planck (1858–1947) and Albert Einstein (1879–1955). In 1900, Planck discovered the relationship between energy and frequency in radiation, concluding that energy is emitted or absorbed in discrete chunks called quanta. Einstein applied Planck's idea to light, discovering the photon and formulating the Quantum Theory of Light in 1905. Einstein introduced the concept of stimulated emission about ten years later: a photon of a specific frequency can interact with an excited electron, and new photons are generated that have the same properties (frequency, polarization, direction) as the original photon. Einstein's concept was first applied to microwave radiation, and “masers” were developed in the 1950s. Late in that decade, the same idea was applied to visible light and infrared radiation. Experiments by Charles Townes (1915–2015), Arthur Schawlow (1921–1999), and Gordon Gould (1920–2005) led up to the invention of the laser in 1960.
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 word laser, used to denote a wide variety of specialized sources of light, is actually an acronym for light amplification by stimulated emission of radiation – a definition we will explore shortly. You may consider lasers exotic and dangerous, but in fact, you routinely encounter them in everyday life. For example, supermarket price scanners utilize tiny red lasers for reading the bar code information from packaging. DVDs have their audio and video information encoded in a pattern of tiny reflective and nonreflective patches etched on their surfaces. DVD players use a laser beam to detect this pattern, which is converted back into sound and pictures by electronic circuitry. The laser printers used with computers utilize lasers to “write” an image of the page to be printed on a light-sensitive surface, to which ink then adheres, and then is transferred to paper. Pen-sized lasers often are used as pointers for giving presentations, and laser light shows are a popular entertainment at music concerts and science museums.
Laser Photocoagulation Principles
Published in John P. Papp, Endoscopie Control of Gastrointestinal Hemorrhage, 2019
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. In a simplified model, the atom (no longer an indivisible natural entity) consists of electrons circling about a dense nucleus of protons and neutrons. As the electrons gain speed, and hence energy, they increase the size of their orbit. If they gain enough speed, they will leave the nuclear core altogether which then becomes “ionized”. One of the fundamental tenants of the quantum theory of nature (and hence atoms) is that electrons will in general not be able to increase their orbital energies in a continuous fashion, but rather in “jumps” or “quanta”. These characteristic energy jumps are the very parameter that spectroscopic chemists utilize to label atoms based on the wavelengths which they absorb. According to Planck,8 the relationship between the wavelength of light and its energy per photon is given as:
Lasers for the treatment of psoriasis: a systematic review
Published in Expert Review of Clinical Immunology, 2023
Kristine Heidemeyer, Mustafa Kulac, Andrea Sechi, Simone Cazzaniga, Luigi Naldi
Laser (Light Amplification by Stimulated Emission of Radiation), producing high energy monochromatic collimated coherent light, had first been used in dermatology in 1963 [7]. When the principle of selective photothermolysis had been introduced in 1980, laser therapy was further refined with the possibility of targeted destruction of a specific chromophore/structure with minimal damage of the surrounding tissue [7]. Pulsed dye lasers are mainly used for treatment of vascular lesions as port wine stains. Due to their effect on vascularization, the effect on inflammatory skin diseases has been later investigated and described [8]. In 1992, laser therapy had been suggested for the first time for the treatment of psoriasis [9]. Laser-assisted drug delivery is a method to increase bioavailability and therefore efficacy of topical dermatologic treatments by disturbance of the epidermal skin barrier with fractional ablative or fractional non-ablative devices [10]. Recently, its use in the treatment of psoriasis has been investigated.
Laser and radiofrequency ablations for benign and malignant thyroid tumors
Published in International Journal of Hyperthermia, 2019
Giovanni Mauri, Nicolò Gennaro, Min Kyoung Lee, Jung Hwan Baek
Laser (an acronym for ‘light amplification by stimulated emission of radiation’) is a highly coherent, collimated and monochromatic energy that can be precisely delivered into small targets from a primary source or through optical fibers that allows a great variability in length and shape of applicators [9]. Common primary sources are laser diode or neodymium–yttrium aluminum garnet, which produce optical wavelengths of 820 nm or 1064 nm. When laser light hits the target, a local increase of temperature occurs, causing permanent damages such as coagulative necrosis (46–100 °C) and tissue carbonization/vaporization (100–110 °C). The grade and rapidity of tissue damage depend on many factors, including the amount of energy released, the application time, the vascularization and the water content of the tissue [10]. Laser ablation in the neck is usually performed under ultrasound (US) guidance, which allows a real-time monitoring of the procedure.
Laser ablation and topical drug delivery: a review of recent advances
Published in Expert Opinion on Drug Delivery, 2019
Chien-Yu Hsiao, Shih-Chun Yang, Ahmed Alalaiwe, Jia-You Fang
The term laser is an abbreviation of light amplification by stimulated emission of radiation. Laser is a modality producing an intense beam of coherent monochromatic radiation by photon emission stimulation from excited molecules or atoms. The first laser device was developed in 1955 by Dr. Theodore Maiman at Hughes Research Laboratories [7]. The first experience of employing laser for medicinal practice was the use of a ruby laser in tattoo removal by Dr. Leon Goldman [8]. Over the last few decades, lasers have largely been used in dermatology for treating wrinkling, photoaging, hyperpigmentation, actinic keratosis, and scars. The laser is also useful to treat cancers in the presence of photothermal effect. For instance, the near infrared laser in combination with photothermal agents can be applied to deliver anticancer drugs for tumor inhibition [9–11]. The concept of laser-assisted drug transport is based on the reversible ablation or disruption of skin by irradiation to increase skin absorption of the drugs and allow deeper penetration. The first approval of laser-assisted skin delivery was reported by Jacques et al. in 1987 [12]. In that paper, an excimer laser (193 nm) was used to ablate SC from in vitro human skin. The laser fluence at 70 mJ/cm2 produced a 124-fold enhancement of tritiated water permeation, which is similar to that obtained after SC stripping or epidermal removal by mild heat treatment. Since then, some research groups put their efforts into studying drug absorption enhancement by a variety of laser modalities.