ESTRO 2022 - Abstract Book

S1325

Abstract book

ESTRO 2022

Conclusion The PTW 1600 SRS assembly seems adequate to verify SRS plans, as discrepancies in gamma passing rates obtained respect to the film-based measurements were generally within 5%. The O4D method, however, revealed bad results (pass rates < 90%), as compared to the film-based measurements.

PO-1544 The role of dose rate and gantry speed variations in PRO and PO algorithms for rapidarc delivery

V. Sundaram 1 , G. Rao 2 , M. Bhattacharjee 1 , J. Joseph 3 , B. Balaji 4 , D.B. Patil 5

1 Meherbai Tata Memorial Hospital, Department of Radiation Oncology, Jamshedpur, India; 2 Meherbai Tata Memorial Hospital, Department of Radiation Oncology, Jamshepur, India; 3 All India Institute of Medical Sciences, Department of Radiation Oncology, Jodhpur, India; 4 KLES Belgaum Cancer Hospital, Department of Radiation Oncology, Belgaum, India; 5 State Cancer Institute, IGIMS, Department of Radiation Oncology, Patna, India Purpose or Objective The study was performed to assess and compare the performance of two different RapidArc TM optimization algorithms such as PRO and PO by changing the Gantry speed and Dose Rate technical parameters. Additionally, the study aimed to assess the plan quality, agreement between plan delivery and TPS calculation, technical delivery performance using with trajectory log files. Materials and Methods Total five patients selected for this study from each site: Brain, Head and Neck, Hodgkin’s Lymphoma, Advanced Right Lung, Ca cervix. The RapidArc TM plans were generated using Varian Eclipse TPS v15.6 PRO and PO algorithms with maximum range of Dose Rates (DR) from 100 to 600 MU/min, minimum 0.5 and maximum Gantry Speed (GS) fixed at 6.0 deg/sec. The reference plans were created for all patients by PO algorithm with GS 6.0 deg/sec and DR 600 MU/min, other plans were re-optimized using same dose constraints and objectives, for each patient 24 plans were generated and total 120 plans were created. Pretreatment gamma verification were performed using Portal dosimetry and ArcCheck to assess deliverability and accuracy. Plan quality scores were analyzed using target and OAR’s values. Trajectory log files from Truebeam LINAC controllers were collected and analyzed to verify delivery performance.