[Clinical experience in image-guided ultra-conformal hypofractionated radiotherapy in case of metastatic diseases at the University of Pécs].

With the development of radiation therapy technology, the utilization of more accurate patient fixation, inclusion of PET/CT image fusion into treatment planning, 3D image-guided radiotherapy, and intensity-modulated dynamic arc irradiation, the application of hypofractionated stereotactic radiotherapy can be extended to specified extracranial target volumes, and so even to the treatment of various metastases. Between October 2012 and August 2014 in our institute we performed extracranial, hypofractionated, image-többguided radiotherapy with RapidArc system for six cases, and 3D conformal multifield technique for one patient with Novalis TX system in case of different few-numbered and slow-growing metastases. For the precise definition of the target volumes we employed PET/CT during the treatment planning procedure. Octreotid scan was applied in one carcinoid tumour patient. Considering the localisation of the metastases and the predictable motion of the organs, we applied 5 to 20 mm safety margin during the contouring procedure. The average treatment volume was 312 cm3. With 2.5-3 Gy fraction doses we delivered 39-45 Gy total dose, and the treatment duration was 2.5 to 3 weeks. The image guidance was carried out via ExacTrac, and kV-Cone Beam CT equipment based on an online protocol, therefore localisation differences were corrected before every single treatment. The patients tolerated the treatments well without major (Gr>2) side effects. Total or near total regression of the metastases was observed at subsequent control examinations in all cases (the median follow-up time was 5 months). According to our first experience, extracranial, imageguided hypofractionated radiotherapy is well-tolerated by patients and can be effectively applied in the treatment of slow-growing and few-numbered metastases.