Textbook of Lasers in Dermatology Koushik Lahiri, Abhishek De, Aarti Sarda
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Advent and Evolution of Lasers in DermatologyCHAPTER 1

AnuragTiwari
 
INTRODUCTION
Lasers are a relatively young technology which started as an analytical tool for physicists to look into the molecular structure but became one of the most sought after inventions. They were thought to be useful as weapons by some but failed. In medicine, lasers have been well accepted by doctors and patients for almost all the specialties.
 
HOW IT STARTED
In 1916, Einstein discussed the possibility of stimulating radiant energy based on Bohr's theory that atoms emitted energy in quanta when transitioning from excited states back to resting states.1 Stimulated emission received little attention from experimentalists during the 1920s and 1930s when atomic and molecular spectroscopy were of central interest to many physicists.2 Fabrikant defended his doctoral thesis The emission mechanism of a gas discharge, at the Lebedev Physical Institute in Moscow. It discussed experimental evidence for the existence of negative absorption (what was later called stimulated emission) and suggested experiments on light amplification.3
In early 1950s, physicists and electrical engineers began to collaborate with the research on monochromatic radiation of constant amplitude at very small wavelengths studying the microwave and radio frequency spectra of molecules. In this context, in 1953 and 1954, several physicists independently suggested the use of stimulated emission for microwave amplification, creating the acronym maser to stand for “microwave amplification by stimulated emission of radiation”.4
Townes, Basov, and Prokhorov received the Nobel Prize in Physics in 1964 for their “fundamental work in the field of quantum electronics which has led to the construction of oscillators and amplifiers based on the maser–laser principle.”5 In 1958, Townes and his brother-in-law Schawlow, professor at Stanford University, showed that masers could theoretically be made to operate in the optical and infrared regions.6 The same year, Makov et al. at the University of Michigan developed and built a solid state maser.7 They used crystalline corundum (ruby) in a large magnetic field and a strategy similar to that known as optical pumping, suggested by Bloembergen at Harvard University in 1956.8
Maiman, in 1960, presented the first functional optical ruby maser excited by a xenon flash lamp to produce a bright pulse of 693.7 nm, deep red light of about a 1 ms duration, and a power output of about a billion watt per pulse.9
Maiman's invention rapidly led to the development of multiple other optical masers, now called laser (light amplification by stimulated emission of radiation). In 1961, McClung and Hellwarth introduced the quality-switching (Q-switching) technique to shorten the pulse length to nanoseconds with the use of an electro-optical 2shutter that permitted the storage and subsequent release of a peak power up to gigawatts of energy.10,11
Treatment of skin diseases with light has long been known. Lupus vulgaris with the Finsen lamp in 1899, wound healing and rickets with artificial UV light sources after 1901, and psoriasis with the combination of light and tar in 1925.
Goldman, in 1961, founded the first biomedical laser laboratory at the University of Cincinnati.12 In 1963, Goldman and his coworkers published the first study on the effects of lasers on skin describing the selective destruction of pigmented structures of the skin including hair follicles with the beam of the ruby laser. They noted highly selective injury of pigmented structures (black hair) and no evident change in the white underlying skin.13,14 He expected the laser to bring substantial benefits to the treatment of skin cancer; because of the accessibility and color, laser surgery can be used extensively in the field of skin cancer.
In 1973, Goldman published promising effects on angiomas with the continuous-wave neodymium doped yttrium-aluminium-garnet (Nd:YAG) laser. His book Biomedical Aspects of the Laser, published in 1967, is a comprehensive overview over the possibilities, problems, and ideas of the use of the laser in medicine at that time, also emphasizing the need for protection from laser energy. In addition, he discussed ideas of using the laser as a diagnostic tool (transillumination) to detect foreign bodies, hard tumors, or bone defects, and recommended the use of laser in dentistry.
Photoexcision (the optical scalpel) was possible with continuous wave lasers all invented. First the carbon dioxide (CO2) laser, followed by the Nd:YAG laser and then the argon laser. The argon laser showed superior absorption by hemoglobin and was used for treating port wine stains and telangiectasia of the face and early rhinophyma.15
The early continuous wave lasers emitted an uninterrupted beam of light that was effective in destroying the desired target, but also damaged the healthy surrounding tissue. The result of this collateral damage was unacceptably high rates of scarring and pigmentary changes. The first attempt to minimize this nonspecific tissue injury involved making the continuous wave lasers discontinuous or quasi continuous by using a mechanical shutter to interrupt the beam of light.
In the treatment of vascular lesions, the development of the tunable yellow light dye laser with the absorption peak closer to oxyhemoglobin than the early argon lasers reduced the risk of side effects. In 1996, the erbium doped yttrium-aluminium-garnet laser with a very short wavelength of 2,940 nm allowed more superficial vaporization of tissue and was used together with CO2 lasers for skin resurfacing. Very recently, the new technical concept of fractional photothermolysis was introduced. It received Food and Drug Administration (FDA) approval in 2004 for skin resurfacing and in 2005, for the treatment of melisma.16
Goldman wrote in 1967 “There is every indication that Q-switched lasers will remain an important tool in the physicists' laboratories.”17
In 1980s, the pulsed ruby laser was commercialized in Japan for the treatment of tattoos and pigmented lesions, while being abandoned in Europe and the United States where tattoo removal was performed by CO2 laser vaporization.18 With the flashlamp-pumped pulsed dye laser in the early 1980s, Anderson and Parrish from Harvard Medical School in Boston developed the theory of selective photothermolysis that revolutionized the practice of cutaneous laser surgery.19
The authors recognized that the collateral thermal damage in the surrounding tissue of the target chromophore resulted from prolonged exposure to the laser's energy. By the appropriate manipulation of wavelength and pulse duration, and in dependence upon the chromophore's relaxation time, therapeutic destruction could be maximized while minimizing thermal damage to the surrounding tissue.20 More than 3 decades later, a nearly identical ruby laser to the one used by Goldman in 1963 became the first device approved by the FDA in 1989 for permanent removal of pigmented hair, and the Q-switched Nd:YAG received FDA approval as a treatment modality for tattoos in 1991.16,21
 
CONCLUSION
The history is never complete; it is written with every passing moment. Lasers have become an integral part of any dermatology setup. The author is thankful all the physicists and physicians who founded and followed up on this technology.
REFERENCES
  1. Einstein A. Zur Quantentheorie derStrahlung. Physikalische Gesellschaft Zürich. 1916;18:47–62. (The same paper was published on 15 March 1917, Physikalische Zeitschrift. 1917;18:121-8).
  1. Townes CH. Production of coherent radiation by atoms and molecules: Nobel Lecture [Online]. 1964. Available from: http://nobelprize.org/nobel_prizes/physics/laureates/1964/townes-lecture.pdf [Accessed 30 October 2010].
  1. Lukishova SG, Valentin A Fabrikant. Negative absorption, his 1951 patent application for amplification of electromagnetic radiation (ultraviolet, visible, infrared and radio spectral regions) and his experiments. J Eur Optical Soc. 2010;5:10045s.3
  1. Townes CH. Early history of quantum electronics. J Modern Optics. 2005;52:1637-45.
  1. Edlén B. (1964). Nobel prize award ceremony speech. [Online] Available from: http://nobelprize.org/nobel_prizes/physics/laureates/1964/press.html. [Accessed 30 Oct 2010].
  1. Schawlow AL, Townes CH. Infrared and optical masers. Phys Rev. 1958;112:1940-9.
  1. Makov G, Kikuchi C, Lambe J, Terhune RW. Maser action in ruby. Phys Rev. 1958;109:1399-1400.
  1. Bloembergen N. Proposal for a new type solid state maser. Phys Rev. 1956;104:324-7.
  1. Maiman TH. Stimulated optical radiation in ruby. Nature. 1960;187:493.
  1. Hellwarth RW. Theory of the pulsation of fluorescent light from ruby. Phys Rev Lett. 1961;6:9-11.
  1. Hellwarth RW, McClung FJ. Giant pulsations from ruby. Appl Phys. 1962;33:838-41 and Bull Am Phys Soc. 1962;6:414.
  1. Coras B, Landthaler M, Leon Goldman. In: Loeser C, Plewig G, editors. Pantheon der Dermatologie–Herausragende historische Persönlich-keiten. Springer;  Heidelberg:  2008. pp 357-61.
  1. Goldman L, Blaney DJ, Kindel DJ Jr, Franke EK. Effect of the laser beam on the skin. Preliminary report. J Invest Dermatol. 1963;40:121-2.
  1. Goldman L, Blaney DJ, Kindel DJ Jr, Richfield D, Franke EK. Pathology of the effect of the laser beam on the skin. Nature. 1963;197:912-4.
  1. Goldman L. Historical perspective: personal reflections. In: Arndt KA, Noe JM, Rosen S. Cutaneous Laser Therapy: Principles and Methods. Wiley;  New York:  1983. p. 7.
  1. Houk LD, Humphreys T. Masers to magic bullets: an updated history of lasers in dermatology. Clin Dermatol. 2007:25;434-42.
  1. Goldmann L. Biomedical Aspects of the Laser: The Introduction of Laser Applications into Biology and Medicine. Springer;  Berlin:  1967.
  1. Bailin PL, Ratz JL, Levine HL. Removal of tattoos by CO2 laser. J Dermatol Surg Oncol. 1980;6:997-1001.
  1. Anderson RR, Parrish JA. Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation. Science. 1983:220: 524-7.
  1. Parrish JA, Anderson RR, Harrist T, Paul B, Murphy GF. Selective thermal effects with pulsed irradiation from lasers: from organ to organelle. J Invest Dermatol. 1983;80(suppl):75s-80s.
  1. Anderson RR. Dermatologic history of the ruby laser: the long story of short pulses. Arch Dermatol. 2003;139:70-4.