Program Information
Investigation of the Accuracy of Different Lung SBRT Plans Created in MultiPlan Treatment Planning System
M CEBE*, H MABHOUTI , P PACACI , E SERIN , E SANLI , S YILDIRIM , D ESITMEZ , N KUCUK , M DOYURAN , E KUCUKMORKOC , M CAGLAR , D CANOGLU , R RZAZADE , H ACAR , H CAGLAR OZKOK , Medipol University Hospital, Istanbul, istanbul
Presentations
SU-I-GPD-SPS-5 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: We aimed to investigate the dosimetric accuracy of different lung stereotactic body radiation therapy (SBRT) treatment plans created in MultiPlan Treatment Planning System (TPS).
Methods: In the study free breathing (FB), static and four dimensional computed tomography (4DCT) scans were performed on a movable phantom. Images generated from this scans were exported to MultiPlan TPS. Maximum intensity projection (MIP), average intensity projection (AIP) and minimum intensity projection (MinIP) composite images were generated in Eclipse TPS and generated composite images were exported to Multiplan TPS. Treatment plans were created for each phase of 4DCT scan, PTV10PHASE, PTVMIP, PTVAIP, PTVMinIP, PTVFB, and PTVSTATIC. For each plan, using Sequential Optimization non-coplanar treatment technique was performed using Monte Carlo dose calculation algorithm. After irradiation in CyberKnife M6 using X-sight Lung Tracking (XLT) system, doses measured by gafchromic films were compared with calculated doses using gamma index analysis.
Results: Mean beam-on time for plans based on PTV10PHASE, PTVMIP, PTVAIP, , PTVFB, and for phase plans was 18 minutes and 6 minutes for static plan. The gamma passing rate evaluated from EBT3 films were 97%, 80.1%, 83.9%, 94%, and 99.9% for PTV10PHASE, PTVMIP, PTVAIP, , PTVFB, and PTVSTATIC plans respectively and ranged between 90.4 - 100% (95.2 ± 4.8%) for phase plans. PTVMinIP plan couldnt be irradiated because of its improper volume for XLT system.
Conclusion: High gamma passing rate of phase plans and their reasonable treatment time implies that XLT can be considered as appropriate treatment technique for lung SBRT especially for patients who are not capable of holding their breath. PTV10PHASE plans can be considered as alternative treatment for CyberKnife systems while plans created based on composite images are not proper with XLT system. Despite of high gamma passing rate, FB plan is not appropriate for treatment because of 37% lower gross volume.
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