ESTRO 2021 Abstract Book

S360

ESTRO 2021

shows treated ECHO plans for different disease sites. PTV sizes varied greatly with median 77 cc (range 1.5 - 988). The median time to produce one ECHO plan was 29 minutes (range 7 - 168) mainly depending on the PTV size. For prostate plans, all plans were clinically accepted after single run. For paraspinal/metastatic tumor SBRT plans, 76% of ECHO plans required only one run.

Conclusion An automated and clinical-criteria-driven optimal planning has been established in our institution. ECHO now produces a majority of SBRT plans for paraspinal and other metastatic tumors in our clinic. We are rapidly expanding ECHO for prostate, non-small-cell lung cancer and other disease sites. ECHO improved consistency of plan quality for treatment planning and enabled expedited treatment including same day SBRT treatment in our clinic. OC-0473 Pre-clinical validation of a novel TPS for fully-automated multi-criterial treatment planning R. Bijman 1 , A.W. Sharfo 2 , L. Rossi 2 , S. Breedveld 2 , B. Heijmen 2 1 Erasmusmc, Radiotherapy, Rotterdam, The Netherlands; 2 ErasmusMC, Radiotherapy, Rotterdam, The Netherlands Purpose or Objective Recently, Elekta AB (Stockholm, Sweden) has developed a novel system for fully-automated multi-criterial treatment planning, here designated NovelATP. The aim of the system is to generate for each patient a single treatment plan that is Pareto-optimal and clinically favourable, without any manual interference such as Pareto navigation. In this study we performed a pre-clinical validation of NovelATP. To this purpose, for 4 patient groups, NovelATP plans were compared to plans generated with our in-house autoplanning solution (InHouseATP). InHouseATP has consistently shown superiority compared to manual planning in many previous validation studies for a broad range of tumor sites (including the sites studied here). Apart from dosimetric plan quality, also calculation time, total MU, delivery time and delivery accuracy were compared. Materials and Methods For in total 194 patients, NovelATP and InHouseATP plans were compared. Included patients were 1) conventional prostate cancer (101 pts, ‘Prostate Conventional’), 2) prostate SBRT (20 pts, ‘Prostate SBRT’), 3) bilateral head-and-neck cancer (50 pts, ‘Head-and-Neck’) and 4) rectal cancer treated at a Unity MR-Linac (23 pts, ‘Rectum MRL’). VMAT plans were generated for 1), 2) and 3) while IMRT was used for 4), as VMAT was not available. To provide the ‘best possible’ competing autoplans, in line with the clinical protocols, maximum attention was paid to configuration of both systems. Then, NovelATP and InHouseATP plans were automatically generated for the study patients. Plans were dosimetrically evaluated and pairwise compared based on clinically used PTV and OAR plan parameters, conformality and dose bath. Delivery accuracy was assessed using a PTW 2D-Array seven29 TM and OctaviusTM phantom (PTW, Freiburg, Germany). Comparisons with predictions were performed with VeriSoft version 7 (PTW, Freiburg, Germany) with 5% cut-off, 3% global maximum dose and 3 mm distance-to-agreement criteria used in the gamma-analyses. Results Dosimetrical differences between NovelATP and InHouseATP were on average small, sometimes in favour of NovelATP, sometimes in favour of InHouseATP, and if statistically significant, mostly not clinically relevant (Figure 1). For individual patients, differences were sometimes considered relevant, but again no overall advantage for one of the systems. Calculation times for NovelATP plans were between 29 and 151 min, depending on treatment site, with no overall differences with the InHouseATP plans. Slight disadvantages were observed for NovelATP in total MU, delivery time and gamma pass-rate (Table 1).