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23.7. LASER SURGERY Advantages of the CO The application of lasers to veteri 2-lasers. nary surgery is based on the absorption of laser radiation by the tissue. Absorption causes heating and destruction of the cells via thermal, hydrodynamical or photochemical mechanisms. The CO (l0.6 11m) is currently used in all fields of surgery due 2-laser to its unique properties. The advantages of CO as a surgical 2-lasers instrument are: I) a reduction in operating time by eliminating the need to ligate most of the bleeding points; 2) a reduction of the amount of necrotic tissue and haematoma formation and, therefore, a lower infection rate; 3) the tendency of the laser beam to sterilize the wound as it cuts; 4) faster wound healing due to a combination of the first three factors; and 5) the blood vessels are sealed during cancer surgery which helps prevent the spread of the malignant cells. Mechanisms of Laser Action. The thermal therapeutic effect of the CO is caused by a denaturation and inactivation of pro 2-laser teins. Convection (movement due to mass transport) and conduction (movement without mass transport) are the primary means of heat transfer within the tissue. The intensity of CO can 2-lasers be varied from levels that cause little heating to the destruction of the tissue through evaporation. The hydrodynamical mechanism of CO irradiation is re 2-laser lated to the strong absorption by water in the living tissue (generally -80% water), intense heating, and the destruction of the tissue by hydrodynamic shock waves through the explosive evaporation of the tissue. The temperature at the focal point of the laser beam is about 100°C. The photochemical action of the laser irradiation means that the radiation energy is expended through the degradation of chemical bonds that cause the destruction of the tissue through volatilization. The mechanism can also be realized using pulsed ultraviolet laser radiation. CO 2-laser Surgery. CO 2-laser beams are strongly absorbed by living tissue, i.e., -95% of the radiant energy is absorbed by a thin layer of cells -200 urn thick with the energy being transformed into heat. The cutting efficiency of a CO is pro 2-laser portional to the wavelength. A flexible optical. system can focus 180 laser radiation onto a -1 mm diameter spot. Examples of highly effective uses of CO surgery in veterinary medicine include 2-laser the castration of farm animals and the amputation of poultry wings. Disadvantages of the CO as a surgical scalpel are the 2-laser lack of mechanical contact with the tissue, thermal damage to the edges of the skin at incisions, and restricted manoeuvrability. Laser Microsurgery. The high intensities (l08 - 10 9 Wfcm 2 ) and the wide variety of wavelengths available make laser surgery an attractive tool for microsurgery. Using a laser in conjunction with a microscope allows focusing the laser beam on a very small spot (i.e., -111m in diameter), such as that needed for precise surgical procedures. As a consequence, it is possible to destroy specific subcellular organelles, single cells or groups of cells. For example, laser microsurgery can be used for operating on the aero-digestive tract (mouth, throat and nose), the ears, and brain haemorrhages. VOCABULARY English Ukrainian English Ukrainian Active medium AKTHBHe Interference IHTep¢epeHI~iH cepenonmue Acupuncture Axyrrynxrypa Interference IHTep¢epeHI.dH microscope HHH MiKPocKon Analyzer AHaJIi3aTop Iris Paiinyzcna 060JIOHKa Antirickets Anripaxi- Keratopathy Keparonaris action THqHa .L\iH Aqueous Bayrpiunrsoouua pinana polarized light pH30BaHe CBiTJIO Linearly JIiHiHHo nOJIH humor Atonic ATOHiqHHH Magnifica tion 36iJIbllIeHHH dermatitis .L\epMaTHT Bandwidth IllHpHHa Malignant 3JIoHKicHa cMyrH tumor nYXJIHHa Bipolar cells Einonspni Melanogenesis MeJIaHoreHe3 KJIiTHHH Blind spot OnTHqHHH Monochromaticitv THqHicTb Monoxpoxa- .L\HCK Brightness 51cKpaBicTb Optical OnTHqHa activity aKTHBHicTb BronchopneumoninHeBMoHiH resonator pesouarop EpOHXO Optical OnTHqHHH 181
Continuation of Vocabulary Carcinoma KaplJ,HHOMa Photoelectric oTOeJIeKTpWIeffect HHH ediexr Coherency Korepearuicrs Photosensiti oToceHcH6iJIization sanis Compound CKJIa~OBHH Photosynthetically active HO aKTHBHe BH oTocHHTeTH-q: microscope MiKpocKon radiation npoMiHIOBaHHlI Cones KOJI6o'IKH PJ:!ytochrome iTOxpoM Constructive ni~CHJIeHHlI Polarimeter nOJIlIpHMeTp interference cBiTJIa xepea iHTep
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Yuriy I. Posudin PHYSICS WITH FUNDA
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Air Air Air Water Water Water Water
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Chapter 5. MECHANOBIOLOGY ..... .11
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Continuation of Vocabulary Averaged
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VOCABULARY Enzlish Ukrainian Englis
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N J and N 2 represent the number of
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