Sensor-controlled laser processes for medical applications

The connection of such key technologies as laser and sensor technology opens a broad field of applications especially in medicine. The development of sensor-controlled medical laser systems represents a quantum leap in precision and safety in medical practice. This makes the treatment or surgery more gentle and safer for both physician and patient. This paper presents the possibilities and the potential of sensor-based laser procedures in medical practice. It starts with medical laser technology and sensor systems that are already used in medical diagnostics and therapy. A concrete example from laser surgery illustrates the advantages of laser ablation for an osteotomy of the mandible and a sensor and control concept for tissue-specific bone ablation. An Er:YAG laser system was combined with a process control and qualified for layer-specific ablation of hard tissue. Layer-specific ablation of tissue is especially important when, as in the laser osteotomy of the mandible (lower jaw), vulnerable structures, as e.g. nerves (mandibular nerve), run underneath the to-be-ablated tissue that may not be damaged. The closed loop control system developed for laser osteotomy is based on the evaluation of process emissions that occur during the laser ablation and are recorded with several sensors. Thereby optical and acoustic process emissons are used for achieving switching-off criteria for the laser system before damaging the nerve. Tests were performed on dissected bone specimens from the rabbit's femur and minipig's jaw. After laser application the bone specimens were evaluated macroscopically, radiologically, histologically and by micro computed tomography.