ESTRO 2022 - Abstract Book

S105

Abstract book

ESTRO 2022

The 24 participating centers can include a selection of 10 IMRT/VMAT patients treated in their practice (240 patients in total). There were no restrictions regarding delivery units or clinical TPS and no limitation in tumor location, extension, treatment machine, prescribed dose and fractionation. Autoplanning was performed with an optimizer implemented in a commercial TPS. A single algorithm configuration was used for all participating centers. For each patient, the autoplan was generated for the clinically applied delivery machine. Autoplans were compared to clinical plans by clinician blind scoring, and by dosimetrical comparisons for PTV and OARs. In the blind scoring, the clinical plan and the autoplan were simultaneously loaded and the treating clinician could score High, Medium or Low impact advantage for one of the plans, or Parity. Results So far 175 patients have been included from 18 centers; 116 (66%) with left-sided breast cancer and 59 with right-sided. 40 patients (23%) also had a boost dose. Supraclavicular nodes, internal mammary nodes and axillary nodes were treated in 54 patients (31%), 12 patients (7%) and 7 patients (4%), respectively. Delivered doses were between 40.05 Gy and 50 Gy (from 15 to 25 fractions), with concomitant boost doses of 55-60 Gy. All C-arm linacs and Tomotherapy were used for delivery. All clinical plans were generated manually, and all major commercial TPS were represented. For 82/175 patients (47%), the treating clinicians preferred the autoplan, while the clinical plan was favoured in 75 (43%) cases. For 18 (10%) the clinicians scored Parity. See Fig. 1 for details. Statistically significant differences (p<0.05) in favor of autoplans were found for PTV coverage and conformity, while D 0,03cc and Homogeneity index were favorable to Manual (Figure 2a). For OARs , following differences were found to be statistically significative: contralateral breast average and D 0.03cc were reduced by 23% and 23,6% respectively; for heart, average dose and V 8Gy were reduced by 19.6% and 3.8%; for ipsilateral lung, all dosimetric parameters (V 16Gy , V 8Gy , V 4Gy and Average) were favorable to autoplans (2,7%, 2,6%, 2.8% and 11,6%)

Conclusion Even with the large variation in included patients, delivery machines, treatment techniques and clinical TPSs, and no institution-specific configurations of the autoplanning algorithm, in 57% of the 175 patients from 18 centers, clinicians scored higher or equal quality for autoplans compared to manually generated clinical plans. Dose- volume parameters were mainly in favor of autoplans. This study points at an opportunity to substantially reduce treatment planning workload for breast cancer.

OC-0129 Adaptive Dose Painting vs standard IMRT in a randomized phase II trial: a dosimetric analysis.

T. Vercauteren 1 , A. De Bruycker 1 , F. Duprez 1 , J. Daisne 2 , A.M.L. Olteanu 1 , S. Deheneffe 2 , D. Berwouts 1 , W. De Neve 1 , I. Madani 3 , L. Paelinck 1 , B. Speleers 3 , I. Goethals 4 , W. De Gersem 1 1 Ghent University Hospital, Radiation Oncology, Ghent, Belgium; 2 CHU-UCL, Radiation Oncology, Namur, Belgium; 3 Ghent University, Radiation Oncology, Ghent, Belgium; 4 Ghent University Hospital, Nuclear Medicine, Ghent, Belgium

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