Analyse des Stellenwertes einer lasergestützten Abtastung der Thoraxexkursion zur Atemtriggerung bei der Hochpräzisionsbestrahlung atembeweglicher Tumore.

By the intensive application of new technologies radiotherapy could achieve big progress in the treatment of cancer. Nowadays the highest target exactness can be reached in the craniel area. The combination of fixation facilities and exact stereotactical systems for the localisation of the tumour create ideal conditions on radiotherapeutic interventions in this area. High doses can be installed in the craniel tumor volume and the surrounding fabric ist best possible spared by a precipitously dropping dose gradient. A transference of the good results of the craniel stereotactical radiotherapy on extracraniel destination volumes is an object of intensive efforts in numerous medical centres. Nevertheless, this is possible only in the principle. On the one hand the fixation possibilities are strongly limited in the area of the body trunk, on the other hand, the natural breath movement of the target structures requires large safe distances in the definition of the PTV. This fact leads to a high load of the healthy fabric by radiotherapy treatments in the thorakal area and limits the appliable dose. Here the breath-hold techniques offer a temporary immobilization during radiotherapeutic treatment and allow an opitmal repositioning of thoracal tumors. These techniques allow a reduction of the PTV, the dose in the target volume and the local controlling rates can be raised. Indeed, the breath-hold procedures introduced up to now have very restricted application possibilities. Often her application fails because of the insufficient compliance of the patient or because of the contraindication for marker implantations in the tumour. To be able to introduce breath-hold systems with broader application spectrum, a new way was walked. A laser sensor which allows a scanning of the thoracic excursion without touch was integrated into a breath-hold system. First attempts for the qualitative judgement of the new technology proved a good practise suitability and a low mistake susceptibility of the measuring procedure. Three different anatomical sensoring positions were examined (lat. thorax, sternum, abdomen). Attaching the sensor above the lateral thorax and above the sternum was best suitable. Here the divergence of the laser measurement and the spirometric authoritative measurement (= the precision of tumor-repositioning) amounted to only 4.2% (sensor position: lateral thorax) or to 2.9% (sensor position: sternum). Conclusions: a breath-hold system based on laser measurement of thoracic excursion could be created and tested. Interesting possibilities arise from the results of the attempts for a future clinical application of this measuring procedure.