Lexicographic optimization-based planning for stereotactic radiosurgery of brain metastases

Sara Trivellato; Paolo Caricato; Roberto Pellegrini; Martina Camilla Daniotti; Sofia Bianchi; Bianca Bordigoni; Stefano Carminati; Valeria Faccenda; Denis Panizza; Gianluca Montanari; Stefano Arcangeli; Elena De Ponti

doi:10.1016/j.radonc.2024.110308

Lexicographic optimization-based planning for stereotactic radiosurgery of brain metastases

Radiother Oncol. 2024 Jul:196:110308. doi: 10.1016/j.radonc.2024.110308. Epub 2024 Apr 25.

Affiliations

¹ Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy.
² Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy; Department of Physics, University of Milan, Milan, Italy; Medical Physics Department, Veneto Institute of Oncology IOV-IRCCS, Padova, Italy.
³ Medical Affairs, Elekta AB, Stockholm, Sweden.
⁴ Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy; Department of Physics, University of Milan, Milan, Italy.
⁵ School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy; Radiation Oncology Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy.
⁶ Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy; School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy.
⁷ School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy; Radiation Oncology Department, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. Electronic address: stefano.arcangeli@unimib.it.

PMID: 38677330
DOI: 10.1016/j.radonc.2024.110308

Abstract

Aim: To validate a fully-automated lexicographic optimization-planning system (mCycle, Elekta) for single-(SL) and multiple-(ML, up to 4 metastases) lesions in intracranial stereotactic radiosurgery (SRS, 21 Gy, single fraction).

Methods: A pre-determined priority list, Wish-List (WL), represents a dialogue between planner and clinician, establishing strict constraints and pursuing objectives. In order to satisfy the clinical protocol without manual intervention, four patients were required to tweak and fine-tune each WL (SLp, MLp) for coplanar arcs. Thirty-five testing plans (20 SLp, 15 MLp) were automatically re-planned (mCP). Automatic and manual plans were compared including dose constraints, conformality, modulation complexity score (MCS), delivery time, and local gamma analysis (2%/2 mm). To ensure plan clinical acceptability, two radiation oncologists conducted an independent blind plan choice.

Results: Each WL-tuning took 3 days. Estimated median manual plans and mCP calculation time were 8 and 3 h, respectively. Significant increases in SLp and MLp target coverage and conformity were registered. mCP showed a not significant and clinically acceptable higher median brain V₁₂_Gy. SLp registered a -5.8% MU decrease with comparable median delivery time (MP 2.0 min, mCP 1.9 min) while MLp showed a +9.8% MU increase and longer delivery time (MP 3.5 min, mCP 4.4 min). mCP MCS resulted significantly higher without affecting gamma passing rates. At blind choice, mCP were preferred in the majority of cases.

Conclusions: Lexicographic optimization produced acceptable SRS plans with coplanar arcs significantly reducing the overall planning time in cases with up to 4 brain metastases. These planning improvements suggest further investigations by setting high-quality non-coplanar arc plans as a reference.

Keywords: Automated planning; Brain metastases; Coplanar arcs; Lexicographic optimization; Linac-based stereotactic radiosurgery; Plan quality.

MeSH terms

Brain Neoplasms* / diagnostic imaging
Brain Neoplasms* / radiotherapy
Brain Neoplasms* / secondary
Brain Neoplasms* / surgery
Humans
Radiosurgery* / methods
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted* / methods