A Pilot Research for Real-Time Specific Patient Quality Assurance Using the Hybrid Optimized Vmat Phantom (Hovp) in Volume Modulated Arc Therapy / 의학물리

ABSTRACT

The purpose of this was to investigate the measurement of fluence dose map for the specific patient quality assurance. The measurement of fluence map was performed using 2D matrixx detector. The absorbed dose was measured by a glass detector, Gafchromic film and ion chamber in Hybrid Optimized VMAT Phantom (HOVP). For 2D Matrixx, the results of comparison were average passing rate 85.22%+/-1.7 (RT_Target), 89.96%+/-2.15 (LT_Target) and 95.14%+/-1.18 (G4). The dose difference was 11.72%+/-0.531, -11.47%+/-0.991, 7.81%+/-0.857, -4.14%+/-0.761 at the G1, G2, G3, G4. In HOVP, the results of comparison for film were average passing rate (3%, 3 mm) 93.64%+/-3.87, 90.82%+/-0.99. We were measured an absolute dose in steep gradient area G1, G2, G3, G4 using the glass detector. The difference between the measurement and calculation are 8.3% (G1), -5.4% (G2), 6.1% (G3), 7.2% (G4). The using an Ion-chamber were an average relative dose error -1.02%+/-0.222 (Rt_target), 0.96%+/-0.294 (Lt_target). Though we need a more study using a transmission detector. However, a measurement of real-time fluence map will be predicting a dose for real-time specific patient quality assurance in volume modulated arc therapy.