Use of lasers in surgery and medicine
Use of lasers in surgery and medicine:
LASER stands for Light Amplification by Stimulated Emission of Radiation. Without going into the physics of stimulation of radition, it is sufficient to know that a laser is a beam of monochromatic, coherent light with a high energy, which can be finely focussed. Lasers operate in two modes: the pulsed mode and the continuous wave mode. For continuous wave operation, the Helium, Neon, Argon, Krypton or Carbon-dioxide lasers are used. For plused operation, Ruby and Neodymium glass is used. Each type differs in wavelength of light emitted and peak power output.
Lasers are used in many types of surgery as well as in medical treatment. Different tissues of the body absorb different wavelengths; hence different lasers are used for different applications.
Ruby Laser: Ruby is a Aluminum trioxide with 0.05% of Aluminum atoms replaced by Chromium atoms. The Ruby laser emits a red light of 6943 A, with a pulse width of 1us and energy of 10^6 watts. It is used in the treatment of retinal detachment. By using the laser beam, the retina is welded to the choroids because of the intense heat produced. The laser beam travels through the cornea, pupil, lense, vitreous humour and strikes the choroids leating it at the spot. The intense heat welds the retina.
Argon Laser: The argon wavelength is in the blue-green range of visible light. It can be transmitted through clear fluids without conversion into heat. It can pass through glass fibers and hence the light can be directed through the optical fiber to any desired region. It is highly absorbed by the red color. Hence, blood vessels haemoglobin can absorb the light energy and conver it to heat, resulting in photocoagulation of the blood protein.
Argon lasers are used in microsurgery, neurosurgery and in a veriety of applications in gastrointestinal endoscopy, dermatology and gynaecology. It is used to treat a range of lesions.
Carbondioxide Laser: This laser distroys tissues by vaporising cells. Tissue which contains 80%-90% water, when exposed to the laser, is destroyed by steam formation within the cell. The destroyed area is localised and shows no combustion since the intracellular temperatures never exceed 100° C. There is minimal damage to the surrounding areas.
Carbondioxide laser is extensively used in surgery. Lasers have now become the preferred surgical instruments for many diseases of the nose, oral cavity, trachea, larynx and pharynx. It is used in the treatment of cervical and vaginal neoplasia.
For laser surgery, the field of operation must be dry. Inflammable gases like oxygen or anaesthetic gases should be taken care of to prevent accidental fires, which may be caused if a laser beam is reflected and gets focussed on the gas.
