Thermal Damage and Rate Processes in Biologic Tissues

Abstract

Heat is generated in laser irradiated tissues by absorption and transformation of the light energy into heat. Once generated within tissues, heat is heat no matter what original energy source is used to produce it. Heating of cells and biological tissues can produce reversible injury and dysfunction that can be repaired by innate cellular and host mechanisms. However, more severe, irreversible damage leads to death immediately (primary thermal effects) or after (delayed secondary effects) the heating event. Sometimes, the dividing line between reversible (repairable) and irreversible (lethal) damage in living, surviving tissues is not easily observed at the time of heating. Therefore, to determine accurately the extent of effective (killing) thermal treatment, the observer has to wait for all the moribund, injured cells to die and undergo post-mortem necrosis (two-four days) [1–6].