Over the past half century, lasers have been used in ophthalmology, oncology, plastic surgery and many other areas of medicine and biomedical research.
The possibility of using light to treat diseases has been known for thousands of years. The ancient Greeks and Egyptians used solar radiation in therapy, and the two ideas were even linked in mythology - the Greek god Apollo was the god of the sun and healing.
It was only after the invention of the coherent radiation source more than 50 years ago that the potential of using light in medicine was really revealed.
Due to their special properties, lasers are much more efficient than radiation from the sun or other sources. Each quantum generator operates in a very narrow wavelength range and emits coherent light. Also, lasers in medicine allow you to create high powers. The beam of energy can be concentrated in a very small point, due to which its high density is achieved. These properties have led to the fact that today lasers are used in many areas of medical diagnostics, therapy and surgery.
Skin and eye treatment
The use of lasers in medicine began with ophthalmology and dermatology. QuantumThe generator was opened in 1960. And a year later, Leon Goldman demonstrated how the ruby red laser could be used in medicine to remove capillary dysplasia, a type of birthmark, and melanoma.
This application is based on the ability of coherent radiation sources to operate at a certain wavelength. Coherent radiation sources are now widely used to remove tumors, tattoos, hair and moles.
Lasers of various types and wavelengths are used in dermatology, due to the different types of lesions being cured and the main absorbing substance inside them. The wavelength also depends on the patient's skin type.
Today, one cannot practice dermatology or ophthalmology without having lasers, as they have become the main tools for treating patients. The use of quantum generators for vision correction and a wide range of ophthalmic applications grew after Charles Campbell became the first physician to use a red laser in medicine in 1961 to treat a patient with a retinal detachment.
Later, for this purpose, ophthalmologists began to use argon sources of coherent radiation in the green part of the spectrum. Here, the properties of the eye itself, especially its lens, were used to focus the beam in the area of retinal detachment. The highly concentrated power of the device literally welds her.
Patients with some forms of macular degeneration can benefit from laser surgery – laser photocoagulation and photodynamic therapy. In the first procedure, the beam of coherentradiation is used to seal blood vessels and slow down their pathological growth under the macula.
Similar studies were done in the 1940s with sunlight, but doctors needed the unique properties of quantum generators to complete them successfully. The next use of the argon laser was to stop internal bleeding. Selective absorption of green light by hemoglobin, a pigment in red blood cells, has been used to block bleeding blood vessels. To treat cancer, they destroy the blood vessels that enter the tumor and supply it with nutrients.
This cannot be achieved using sunlight. Medicine is very conservative, as it should be, but sources of coherent radiation have gained acceptance in various fields. Lasers in medicine have replaced many traditional instruments.
Ophthalmology and dermatology have also benefited from excimer sources of coherent UV radiation. They have become widely used for corneal reshaping (LASIK) for vision correction. Lasers in aesthetic medicine are used to remove blemishes and wrinkles.
Profitable cosmetic surgery
Such technological developments are inevitably popular with commercial investors, as they have huge potential for profit. Analytical company Medtech Insight in 2011 estimated the size of the market for laser beauty equipment at more than 1 billion US dollars. Indeed, despitedeclining overall demand for medical systems during the global downturn, quantum generator-based cosmetic surgeries continue to enjoy strong demand in the United States, the dominant market for laser systems.
Visualization and diagnostics
Lasers in medicine play an important role in the early detection of cancer, as well as many other diseases. For example, in Tel Aviv, a group of scientists became interested in IR spectroscopy using infrared sources of coherent radiation. The reason for this is that cancer and he althy tissue may have different infrared permeability. One of the promising applications of this method is the detection of melanomas. In skin cancer, early diagnosis is very important for patient survival. Currently, melanoma detection is done by eye, so it remains to rely on the skill of the doctor.
In Israel, every person can go for a free melanoma screening once a year. A few years ago, studies were conducted in one of the major medical centers, as a result of which it became possible to clearly observe the difference in the infrared range between potential, but not dangerous signs, and real melanoma.
Katzir, the organizer of the first SPIE conference on biomedical optics in 1984, and his group in Tel Aviv also developed optical fibers that are transparent to infrared wavelengths, allowing the method to be extended to internal diagnostics. In addition, it can be a quick and painless alternative to a cervical smear ingynecology.
Blue semiconductor laser in medicine has found application in fluorescence diagnostics.
Systems based on quantum generators are also beginning to replace X-rays, which have traditionally been used in mammography. X-rays present physicians with a difficult dilemma: they need high intensity to reliably detect cancers, but the increase in radiation itself increases the risk of cancer. As an alternative, the possibility of using very fast laser pulses to image the chest and other parts of the body, such as the brain, is being studied.
OCT for eyes and more
Lasers in biology and medicine have been used in optical coherence tomography (OCT), which has caused a wave of enthusiasm. This imaging technique uses the properties of a quantum generator and can provide very clear (on the order of a micron), cross-sectional and three-dimensional images of biological tissue in real time. OCT is already used in ophthalmology, and can, for example, allow an ophthalmologist to see a cross section of the cornea to diagnose retinal diseases and glaucoma. Today, the technique is beginning to be used in other areas of medicine as well.
One of the biggest fields emerging from OCT is fiber optic imaging of the arteries. Optical coherence tomography can be used to evaluate a ruptured unstable plaque.
Microscopy of living organisms
Lasers in science, technology, medicine also playa key role in many types of microscopy. A large number of developments have been made in this area, the purpose of which is to visualize what is happening inside the patient's body without the use of a scalpel.
The hardest part about removing cancer is the need to constantly use a microscope so that the surgeon can make sure everything is done correctly. The ability to do live and real-time microscopy is a significant advance.
A new application of lasers in engineering and medicine is the near-field scanning of optical microscopy, which can produce images with a resolution much higher than that of standard microscopes. This method is based on optical fibers with notches at the ends, the dimensions of which are smaller than the wavelength of light. This enabled subwavelength imaging and laid the foundation for imaging biological cells. The use of this technology in IR lasers will allow a better understanding of Alzheimer's disease, cancer and other changes in cells.
PDT and other treatments
Developments in the field of optical fibers help expand the possibilities of using lasers in other areas. In addition to the fact that they allow diagnostics inside the body, the energy of coherent radiation can be transferred to where it is needed. It can be used in treatment. Fiber lasers are becoming much more advanced. They will radically change the medicine of the future.
Field of photomedicine using photosensitive chemicalsubstances that interact with the body in a particular way can use quantum generators to both diagnose and treat patients. In photodynamic therapy (PDT), for example, a laser and a photosensitive drug can restore vision to patients with the "wet" form of age-related macular degeneration, the leading cause of blindness in people over the age of 50.
In oncology, certain porphyrins accumulate in cancer cells and fluoresce when illuminated at a certain wavelength, indicating the location of the tumor. If these same compounds are then illuminated with a different wavelength, they become toxic and kill damaged cells.
The red gas helium-neon laser is used in medicine in the treatment of osteoporosis, psoriasis, trophic ulcers, etc., since this frequency is well absorbed by hemoglobin and enzymes. Radiation slows down inflammation, prevents hyperemia and swelling, and improves blood circulation.
Personalized treatment
Genetics and epigenetics are two other areas where lasers can be used.
In the future, everything will happen at the nanoscale, which will allow us to do medicine at the scale of the cell. Lasers that can generate femtosecond pulses and tune to specific wavelengths are ideal partners for medical professionals.
This will open the door to personalized treatment based on the patient's individual genome.
Leon Goldman - the founderlaser medicine
Speaking about the use of quantum generators in the treatment of people, one cannot fail to mention Leon Goldman. He is known as the "father" of laser medicine.
Already a year after inventing the coherent radiation source, Goldman became the first researcher to use it to treat skin disease. The technique that the scientist applied paved the way for the subsequent development of laser dermatology.
His research in the mid-1960s led to the use of the ruby quantum generator in retinal surgery and discoveries such as the ability of coherent radiation to simultaneously cut skin and seal blood vessels, limiting bleeding.
Goldman, a dermatologist at the University of Cincinnati for most of his career, founded the American Society for Lasers in Medicine and Surgery and helped lay the foundation for laser safety. Died 1997
Miniaturization
The first 2-micron quantum generators were the size of a double bed and were cooled with liquid nitrogen. Today there are palm-sized diode lasers and even smaller fiber lasers. Changes like these pave the way for new applications and developments. The medicine of the future will have tiny lasers for brain surgery.
Due to technological progress, there is a constant reduction in costs. Just as lasers have become commonplace in home appliances, they have begun to play a key role in hospital equipment.
If earlier lasers in medicine were very large andcomplex, today's production from optical fiber has significantly reduced the cost, and the transition to the nanoscale will reduce costs even more.
Other uses
Urologists can treat urethral stricture, benign warts, urinary stones, bladder contracture and prostate enlargement with lasers.
The use of the laser in medicine has enabled neurosurgeons to make precise incisions and endoscopic examinations of the brain and spinal cord.
Veterinarians use lasers for endoscopic procedures, tumor coagulation, incisions and photodynamic therapy.
Dentists use coherent radiation for hole making, gum surgery, antibacterial procedures, dental desensitization and oro-facial diagnostics.
Laser tweezers
Biomedical researchers around the world use optical tweezers, cell sorters, and many other tools. Laser tweezers promise better and faster cancer diagnosis and have been used to capture viruses, bacteria, small metal particles and DNA strands.
In optical tweezers, a beam of coherent radiation is used to hold and rotate microscopic objects, similar to how metal or plastic tweezers can pick up small and fragile objects. Individual molecules can be manipulated by attaching them to micron-sized slides or polystyrene beads. When the beam hits the ball, itcurves and has a slight impact, pushing the ball straight into the center of the beam.
This creates an "optical trap" that is able to trap a small particle in a beam of light.
Laser in medicine: pros and cons
The energy of coherent radiation, the intensity of which can be modulated, is used to cut, destroy or change the cellular or extracellular structure of biological tissues. In addition, the use of lasers in medicine, in short, reduces the risk of infection and stimulates healing. The use of quantum generators in surgery increases the accuracy of dissection, however, they are dangerous for pregnant women and there are contraindications for the use of photosensitizing drugs.
The complex structure of tissues does not allow for an unambiguous interpretation of the results of classical biological analyzes. Lasers in medicine (photo) are an effective tool for the destruction of cancer cells. However, powerful sources of coherent radiation act indiscriminately and destroy not only the affected, but also the surrounding tissues. This property is an important tool in the microdissection technique used to perform molecular analysis at a site of interest with the ability to selectively destroy excess cells. The goal of this technology is to overcome the heterogeneity present in all biological tissues in order to facilitate their study in a well-defined population. In this sense, laser microdissection has made a significant contribution to the development of research, to understandingphysiological mechanisms that today can be clearly demonstrated at the level of a population and even a single cell.
The functionality of tissue engineering today has become a major factor in the development of biology. What happens if actin fibers are cut during division? Will a Drosophila embryo be stable if the cell is destroyed during folding? What are the parameters involved in the meristem zone of a plant? All these issues can be solved with lasers.
Nanomedicine
Recently, many nanostructures have emerged with properties suitable for a range of biological applications. The most important of them are:
- quantum dots are tiny nanometer-sized light-emitting particles used in highly sensitive cellular imaging;
- magnetic nanoparticles that have found application in medical practice;
- polymer particles for encapsulated therapeutic molecules;
- metal nanoparticles.
The development of nanotechnology and the use of lasers in medicine, in short, has revolutionized the way drugs are administered. Suspensions of nanoparticles containing drugs can increase the therapeutic index of many compounds (increase solubility and efficacy, reduce toxicity) by selectively affecting affected tissues and cells. They deliver the active ingredient and also regulate the release of the active ingredient in response to external stimulation. Nanotheranostics is furtheran experimental approach that allows the dual use of nanoparticles, drug compound, therapy and diagnostic imaging tools, opening the way to personalized treatment.
The use of lasers in medicine and biology for microdissection and photoablation made it possible to understand the physiological mechanisms of disease development at different levels. The results will help determine the best methods of diagnosis and treatment for each patient. The development of nanotechnology in close connection with advances in imaging will also be indispensable. Nanomedicine is a promising new form of treatment for certain types of cancer, infectious diseases or diagnostics.
