FUNDAMENTALS OF LASER-SURGERY

Laser light has unique properties that enable transmission of high amo unts of energy to a narrowly defined site. Biological effects may be t hermal, chemical, or mechanical. Medical procedures involve mainly the rmal tissue destruction by coagulation (>60 degrees C) or ablation (>3 00 degrees C). The effect is governed by tissue optical and thermal pr operties and laser variables; contact/non-contact, focus, output power (W), and exposure rime (s). The laser medium governs the wavelength e mitted. The carbon dioxide (CO2) laser light (10600 nm) requires trans mission through articulating arms with mirrors, whereas neodymium:yttr ium-aluminum-garnet (Nd:YAG) (1064 nm), and argon (488/515 nm) light c an be transmitted through flexible quartz fibres. CO2 lasers are used mainly for high precision tissue ablation; Nd:YAG lasers can coagulate or vaporise larger tissue areas and argon laser applications involve vascular destruction, based on selective absorption by haemoglobin. Re search has shifted towards a fundamental understanding of the interact ions of light with biological tissue, to allow treatment planning and to optimise laser procedures. Applications such as interstitial laser coagulation fur local destruction of solid rumours deserve further exp loration in general surgery.