Biophysical fundamentals, technical prerequisites, and safety aspects for the application of the neodymium-YAG laser in urology.

The relationship between the physical parameters of the biological objects and the parameters of the laser radiation is important when considering the interaction between laser radiation and biological molecules. A consideration of the dependence of absorption and scattering in the tissue on wavelength alone permits a simple explanation of the various thermal effects of the various laser systems used in surgery. The thermal properties of tissue may be assumed to be the same as those of water. As an example of a medical neodymium-YAG laser instrument the mediLas system is presented with different application instruments that are necessary for an efficient use of the laser. The prerequisite for the use of high-power laser in surgery is complete safety not only for the patient when determining the right irradiation dose, but also for the doctor and his staff.