Abstract Book

S1020

ESTRO 37

Material and Methods The prostate model was trained using 35 prostate patients previously treated with 74 Gy in 37 fractions. Plans were created using 2 arcs volumetric modulated arc therapy. The final model was validated on a set of 10 patients. RP plans were created by a single optimization without planner intervention during optimization. Differences between RP plans and manual optimization plans created by planners for the same patients were analyzed in terms of D 95% , and D 2% to planning target volume (PTV), mean dose to rectum, bladder, intestine and femoral heads and V 40Gy to rectum and bladder, number of monitor units. Results RP and MO values for PTV D 95% were significantly similar (p<0.05 for all); for D 2% RP plans were better than MO plans (values were lower). RP plans mean dose to rectum, bladder, intestine and femoral heads were comparable to MO values; RP plans V 40Gy to rectum and bladder were lower than in MO plans (p<0.05). MU values were for RP plans: 662±67MU and MO plans: 603±128MU (p<0.05). Conclusion The automated RP based plans created by a single optimization resulted fully consistent with the manually optimized set. In all cases the RP data fulfilled the clinical acceptability requirements of VMAT plans for patient with prostate cancer. Our simple model could reduce optimization time, independently of planner's skill and knowledge. EP-1885 Evaluation of Pinnacle automated VMAT planning for complex pelvic treatments S. Cilla 1 , A. Ianiro 1 , G. Macchia 2 , G. Siepe 3 , R. Vanini 4 , M. Buwenge 3 , S. Cammelli 3 , V. Valentini 5 , A. Morganti 3 , F. Deodato 2 1 Fondazione di Ricerca e Cura "Giovanni Paolo II"- Università Cattolica del Sacro Cuore, Medical Physics Unit, Campobasso, Italy 2 Fondazione di Ricerca e Cura "Giovanni Paolo II"- Università Cattolica del Sacro Cuore, Radiation Oncology Unit, Campobasso, Italy 3 Department of Experimental- Diagnostic and Specialty Medicine - DIMES- University of Bologna- S. Orsola- Malpighi Hospital, Radiation Oncology Department, Bologna, Italy 4 Department of Experimental- Diagnostic and Specialty Medicine - DIMES- University of Bologna- S. Orsola- Malpighi Hospital, Medical Physics Unit, Bologna, Italy 5 Policlinico Universitario "A. Gemelli"- Università Cattolica del Sacro Cuore, Radiation Oncology Department, Roma, Italy Purpose or Objective Treatment plans for high-risk prostate cancer are highly complex due to large irregular shaped pelvic target volumes, to multiple dose prescription levels and to several organs at risk (OARs) close to the target. The quality of these plans is highly inter-planner dependent. We aimed to assess the performance of the Auto-Planning module present in the Pinnacle TPS (version 16.0), comparing automatically generated VMAT plans (AP) with the historically clinically accepted manually-generated ones (MP) for high-risk prostate cancer patients. Material and Methods Twelve consecutive patients treated with VMAT-SIB for high-risk prostate cancer were re-planned with the Auto- Planning engine. The PTV1 included the prostate and the seminal vesicles; the PTV2 included the obturator, internal and external iliac, and presacral lymph nodes. The rectum, bladder, small bowel and femoral heads were delineated as main OARs. The two target volumes were simultaneously irradiated over 25 daily fractions at 65.0 Gy (2.6 Gy/fraction) and 45.0 Gy (1.8 Gy/fraction) to the PTV1 and PTV2, respectively. All manually (MP)

the Sun Nuclear ArcCHECK system was used to investigate deliverability. Next, the Autoplan treatment technique was tested on a patient group of 9 patients and compared to the clinically used manual IMRT plans. Dose parameters and DVH curves of both plans were used for quantitative and qualitative comparison. Results For Autoplan 40 iterations were used, as this was found to be sufficient and time efficient. For the advanced settings a tuning balance of 10% and a dose fall-off margin of 1.5 cm were selected, the cold spot ROIs was switched on and the hot-spot maximum was set to 107%. A treatment time of 90 s per beam was selected. The automatically generated VMAT plans resulted in a comparable or lower dose to the OARs compared to the IMRT plans. The distributions of the mean dose to OARs are shown in Figure 1.

A standardized Autoplan treatment technique can offer a one-click solution for all patients in the study, at least competitive to the manual IMRT plans. ArcCheck measurements passed using our criteria. Conclusion A class-solution for H&N patients was developed with Pinnacle Autoplan. This resulted in more consistent treatment plans with better OAR sparing while using much less planner time. The study has led to clinical implementation of VMAT using Autoplan. EP-1884 Automated treatment planning of volumetric arc therapy for patient with prostate cancer M. Olminska 1 , A. Skrobala 1,2 , B. Pawalowski 1 , T. Piotrowski 1,2 1 Greater Poland Cancer Centre, Department of Medical Physics, Poznan, Poland 2 Poznan University of Medical Sciences, Department of Electroradiology, Poznan, Poland Purpose or Objective The study aimed to evaluate whether plans optimized manually (MO plans) by planners were comparable to RapidPlan based plans (RP plans) created by a single optimization in volumetric modulated arc therapy (VMAT) for patients with prostate cancer.