Laser has become an unavoidable tool in modern medicine and provides healthcare professionals with exceptional levels of precision and control. The medical sector harnesses the unique properties of focused light beams at specific wavelengths and opens up a diverse range of medical applications that enhance diagnostic accuracy, enable minimally invasive procedures, and contribute to improved patient outcomes. Lasers play an important role in various medical disciplines, showcasing their impact on surgeries, diagnostics, dermatology, ophthalmology, and beyond. The integration of lasers into medical practices not only illustrates technological advancement but also represents significant progress towards more effective and patient-friendly healthcare solutions.
The major applications of laser in medicine include:
The use of light in treating illness has been known for thousands of years. The ancient Greeks and Egyptians used sunlight for therapy, and they even linked it to their god Apollo, who was designated responsible for both light and healing. However, the potential of light in medicine was revealed only after the invention of lasers 50 years ago.
The invention of the laser in 1960 by Theodore Maiman opened the path for exploration into its potential applications in medicine. The unique characteristics of lasers, including directivity, impulse capability for short pulses, and monochromaticity made it more significant.
Early medical uses of lasers emerged in 1961 when Dr. Charles J. Campbell successfully employed a ruby laser to eliminate an angiomatous retinal tumor with a single pulse. Dr. Leon Goldman, in 1963, utilized the ruby laser for treating pigmented skin cells. The argon-ionized laser, with a preferred wavelength of 488 nm - 514 nm, became the choice for retinal detachment treatment. Kumar Patel and colleagues developed the carbon dioxide laser in the early 1960s for not only medical purposes but also found applications in welding and drilling. The integration of optical fiber since 1970 broadened laser applications, particularly in endocavitary procedures through endoscopic channels.
In the 1970s, the argon laser found use in gastroenterology and pneumology. Dr. Peter Kiefhaber pioneered endoscopic argon laser photocoagulation for gastrointestinal bleeding. Additionally, he played an important role in introducing the Nd:YAG laser for controlling gastrointestinal bleeding. Urology saw the introduction of lasers by Dr. Hofstetter in 1976. The late 1970s witnessed the emergence of photodynamic therapy, facilitated by laser dye.
From the early 1980s, lasers became indispensable tools in ophthalmology, gastroenterology, and facial and aesthetic surgery. In 1981, the American Society for Laser Medicine and Surgery was founded by Goldman, Dr. Ellet Drake, and others, marking the specialization of certain medical branches with lasers. The Francophone Society of Medical Lasers, founded in the same year, served a similar purpose under the leadership of Maurice Bruhat. The end of the 20th century witnessed the establishment of laser medicine centers, initially in the OECD and later more broadly in the 21st century. The historic Lindbergh Operation in 2001, involving surgeons in New York and doctors and a patient in Strasbourg, utilized lasers among other technologies.
Major lasers used in medicine include:
Outcome of Laser-Tissue Interactions
Laser radiation interacts with biological tissue, and the outcomes are dependent upon the laser beam's energy, exposure duration, and wavelength. The possible interaction outcomes are:
When a human body interacts with laser, the light transfer photon energy through absorption. These body tissues heated by lasers between 50°C and 100°C, undergoes disordering of protein and bio-molecule through photocoagulation. During surgery, laser-induced photocoagulation causes tissues to shrink as water is expelled at these temperatures. The heated region undergoes color changes and loses mechanical integrity. Cells in the photocoagulated area die and render the tissue non-functional and easily removable. This laser-induced photocoagulation process finds application in tumor destruction, treating eye conditions like diabetes-induced retinal disorders, and achieving bloodless incisions or excisions in laser surgery.
When intense laser power densities are applied, tissues heat beyond 100°C that leads to water boiling and evaporation. As 70% of body tissue comprises water, this phenomenon, known as photo-vaporization, transforms the tissue into a gas. Photo-vaporization allows for complete tissue removal and make it suitable for skin rejuvenation, resurfacing, and bloodless incisions or excisions in laser surgery. The rapid elevation of tissue temperature to over 100°C for photo-vaporization necessitates the application of high power density in a pulsed mode. In general, power density up to 10W/cm2 results in tissue heating, while 10 - 100W/cm2 induces photocoagulation. Power density exceeding 100W/cm2 is necessary for photo-vaporization.
Notably, a laser can be utilized for photo-vaporization in focused mode and photocoagulation in defocused mode. Excimer lasers, especially in the ultraviolet range, possess the ability to break chemical bonds without substantial tissue heating and result in photochemical ablation. This type of ablation yields clean-cut incisions with a limited thermal interaction zone.
Different lasers and processes cater to various applications. Pulsed infrared lasers, for instance, are ideal for skin rejuvenation, employing selective absorption for photo-vaporization. In hair removal, the melanin pigment in hair and follicles is best targeted using the ruby laser. Pulsed dye lasers, operating in the yellow region, are effective for removing port-wine stains by absorbing in the presence of hemoglobin in blood vessels. Lasers for ophthalmological purposes include argon and excimer lasers. Visible lasers, like the green argon laser, are popular for retina operations, taking advantage of transparency to the cornea and crystalline lens.
Effects of Laser-Tissue Interactions
The interaction of laser beams with biological tissues produces various effects, each with distinct applications and implications in medical treatments. From thermal and mechanical effects to tissue-welding and photochemical reactions, lasers have become integral in surgical and therapeutic interventions. The laser's interaction with various tissues gives rise to one or more of the following effects:
Advantages of Using Lasers in Medical Applications:
The application of lasers in medicine has ushered in a new era of advanced diagnostics, precision surgery, and therapeutic interventions. Here are some key advantages of using lasers in medical applications:
Disadvantages of Using Lasers in Medical Applications:
While lasers bring many benefits to medical applications, there are also certain disadvantages and challenges associated with their use. Some of the disadvantages include:
Click here to know more about the Effects of Laser Radiation on Human Body.
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