ESTRO 2023 - Abstract Book

S1341

Digital Posters

ESTRO 2023

collimator combinations and clinical used constraints. Resulting treatment times, PTV coverage, and conformality index (CI) of this automated plan (AP) were analyzed. Results For all treatment plans, a suitable collimator combination could be detected with a 2D-coverage of over 98% in over 85% of the evaluated beam angles. In none of the treatment plans the selected collimators corresponded to the collimators used in clinical routine (cf. Table 1).

The newly optimized treatment plans revealed a median treatment time of 31 minutes (AP) compared with 34 minutes in CP . The PTV coverage decreased from median 99.2% (CP) to 98.2% (AP) and the CI increased from in median 1.17 (CP) to 1.18 (AP) (cf. Figure 1).

Conclusion This planning study demonstrates automatic collimator determination as a first step for complete automation of CyberKnife treatment planning. While no reproduction of collimators used in clinical routine was possible, the planning study showed a comparable median PTV coverage with shorter treatment times. However, for specific treatments with critical adjacent OARs, the automated treatment plan failed to reproduce the clinical coverage within 2%. Whereas the defined settings within this evaluation were set for fast treatment times, a change of allowed collimator overlap leads to higher conformality with greater treatment times. Therefore integrating this parameter as a function of adjacent OARs needs to be evaluated in further studies.

PO-1644 Robustness of nodal outlining software for breast radiotherapy

A. McBride 1 , R. Elt 1 , C. Bennett 1

1 The Clatterbridge Cancer Centre, Physics, Liverpool, United Kingdom

Purpose or Objective