ESTRO 2021 Abstract Book

S259

ESTRO 2021

OC-0357 The MArkerless Lung target Tracking CHallenge (MATCH) M. Mueller 1 , P. Poulsen 2 , W. Verbakel 3 , R. Berbeco 4 , D. Ferguson 4 , L. Wang 5 , L. Ren 6 , S. Mori 7 , J. Roeske 8 , P. Zhang 9 , P. Keall 1 1 The University of Sydney, ACRF Image X Institute, Sydney, Australia; 2 Aarhus University, Department of Oncology, Aarhus, Denmark; 3 Amsterdam University Medical Center, Department of Radiation Oncology, Amsterdam, The Netherlands; 4 Harvard Medical School, Department of Radiation Oncology, Boston, USA; 5 Stanford Medical School, Department of Radiation Physics, Stanford, USA; 6 Duke University, Department of Radiation Oncology, Durham, USA; 7 National Institute of Radiological Sciences, Department of Medical Physics, Chiba, Japan; 8 Loyola University Medical Center, Department of Medical Physics, Chicago, USA; 9 Memorial Sloan Kettering Cancer Center, Department of Medical Physics, New York, USA Purpose or Objective Several commercial and academic markerless lung target tracking (MLTT) approaches have been developed to further improve patient safety during lung cancer stereotactic ablative body radiotherapy (SABR). However, these approaches have yet to be benchmarked using a common measurement methodology. This knowledge gap motivated the Markerless Lung Target Tracking Challenge (MATCH). Materials and Methods MATCH was an American-Association-of-Physicists-in-Medicine (AAPM) sponsored Grand Challenge. The participants aimed to localise lung targets accurately in a retrospective in-silico study and prospective experimental study. Common materials for both studies were an anthropomorphic thorax phantom including three lung targets, and a lung SABR planning protocol. The phantom was moved rigidly with patient-measured lung target motion traces, which also acted as ground truth. In the in-silico study a dataset of a simulated volumetric modulated arc therapy treatment with fluoroscopic kV-imaging on a conventional linac was provided to the participants. In the experimental study the participants received a phantom experiment setup and used their own MLTT approach to localise the moving target during a simulated SABR treatment for five provided motion traces. The challenge was open to any participant, and participants could complete either one or both parts of the challenge. A total of 30 institutions registered and 16 result submissions were received. Five pre-clinical MLTT approaches were analysed in-silico and eleven MLTT systems were benchmarked experimentally: 2x Accuray CyberKnife, 2x Accuray Radixact, 1x BrainLab Vero, 1x Catalyst Sentinel, 5x preclinical MLTT on a conventional linear accelerator. MLTT approaches were ranked based on the percentage of the tracking errors being within 2mm of the ground truth. The winning participants were selected based on the initial submission and the presented results include a correction for study design-related errors in individual procedures for each MLTT approach.

Results In the in-silico study the percentage of the tracking error being smaller than 2mm ranged from 91% to 47%. For the experimental study, the values ranged from 98% to 62%. All clinical MLTT approaches achieved sub- millimetre lung target tracking accuracy and precision.