Cyberknife Synchrony® Solunum Takip Sisteminin Polimer Jel Dozimetre ile Üç Boyutlu Performans Analizi
Şahin, Meryem Cansu
xmlui.mirage2.itemSummaryView.MetaDataShow full item record
ŞAHİN, M. C. Three Dimensional Performance Analysis Of Cyberknife Synchrony® Respiratory Tracking System Using Polymer Gel Dosimeter. Hacettepe University Institute of Health Sciences, Thesis in Radiotherapy Physics Program, Ankara, 2017. Tumor movement is a challenging issue for the precise delivery of radiation for thoracic tumors. The Synchrony respiratory motion tracking system (RMTS) of Cyberknife® robotic radiosurgery unit synchronizes radiation beam delivery with the respiration induced tumor motion. This study aims to investigate the performance of Synchrony RMTS for different movement widths using polymer gel dosimetry. To the best of our knowledge this is the first study to make the three dimensional performance analysis of Synchrony RMTS. The MultiPlan® treatment planning system (TPS) of Cyberknife® was used to deliver 4 Gy to a tumor of 1X1X1 cm3. BrainLab Gating lung phantom was used to simulate lung movements with three different amplitudes (1 cm, 2 cm and 3 cm). Three fiducials were inserted to the phantom for tracking. Radiochromic film and polymer gel dosimetry were used and measurements were compared with the dose distributions acquired from the TPS. The dose information of irradiated gel were read out using 1.5 T magnetic resonance imaging. The gamma index values were analysed using the Ashland FilmQA Pro 3.0 software for film dosimeters and Polygevero software for gel dosimeters using the 3mm/3% criteria. PolyGevero gamma index value of ≤1 is accepted as a passing criteria according to the literature. The mean 3 mm 3% gamma index values of film dosimetry were 92.6±1.94%, 91.0±4.00%, 90.3±2.04% for tumor motions of 1 cm, 2 cm and 3 cm, respectively (p<0.001). For polymer gel dosimetry, the mean gamma index values calculated over almost three million points were 0.56±0.10, 0.60±0.24 and 0.65±0.30 for tumor motions of 1 cm, 2 cm and 3 cm, respectively (p<0.001). Although the difference was statistically significant for 3 different amplitudes, the performance of the system was within the acceptance limits. Three dimensional performance analysis showed that Cyberknife Synchrony® RMTS is successful in tumor tracking regardless of the amplitude of movement.