Jenny Dueck1, Antje-Christin Knopf2, Antony Lomax3, Francesca Albertini4, Gitte F Persson5, Mirjana Josipovic6, Marianne Aznar7, Damien C Weber8, Per Munck Af Rosenschöld6. 1. Section of Radiotherapy, Department of Oncology, Rigshospitalet, Copenhagen, Denmark; Center for Proton Therapy, Paul Scherrer Institut, Villigen PSI, Switzerland; Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark. Electronic address: jenny.dueck@psi.ch. 2. Joint Department of Physics at the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, London, UK. 3. Center for Proton Therapy, Paul Scherrer Institut, Villigen PSI, Switzerland; Department of Physics, ETH Zürich, Zürich, Switzerland. 4. Center for Proton Therapy, Paul Scherrer Institut, Villigen PSI, Switzerland. 5. Department of Oncology, Rigshospitalet, Copenhagen, Denmark. 6. Section of Radiotherapy, Department of Oncology, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark. 7. Section of Radiotherapy, Department of Oncology, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. 8. Center for Proton Therapy, Paul Scherrer Institut, Villigen PSI, Switzerland; University of Zürich, Zürich, Switzerland.
Abstract
PURPOSE: The safe clinical implementation of pencil beam scanning (PBS) proton therapy for lung tumors is complicated by the delivery uncertainties caused by breathing motion. The purpose of this feasibility study was to investigate whether a voluntary breath-hold technique could limit the delivery uncertainties resulting from interfractional motion. METHODS AND MATERIALS: Data from 15 patients with peripheral lung tumors previously treated with stereotactic radiation therapy were included in this study. The patients had 1 computed tomographic (CT) scan in voluntary breath-hold acquired before treatment and 3 scans during the treatment course. PBS proton treatment plans with 2 fields (2F) and 3 fields (3F), respectively, were calculated based on the planning CT scan and subsequently recalculated on the 3 repeated CT scans. Recalculated plans were considered robust if the V95% (volume receiving ≥95% of the prescribed dose) of the gross target volume (GTV) was within 5% of what was expected from the planning CT data throughout the simulated treatment. RESULTS: A total of 14/15 simulated treatments for both 2F and 3F met the robustness criteria. Reduced V95% was associated with baseline shifts (2F, P=.056; 3F, P=.008) and tumor size (2F, P=.025; 3F, P=.025). Smaller tumors with large baseline shifts were also at risk for reduced V95% (interaction term baseline/size: 2F, P=.005; 3F, P=.002). CONCLUSIONS: The breath-hold approach is a realistic clinical option for treating lung tumors with PBS proton therapy. Potential risk factors for reduced V95% are small targets in combination with large baseline shifts. On the basis of these results, the baseline shift of the tumor should be monitored (eg, through image guided therapy), and appropriate measures should be taken accordingly. The intrafractional motion needs to be investigated to confirm that the breath-hold approach is robust.
PURPOSE: The safe clinical implementation of pencil beam scanning (PBS) proton therapy for lung tumors is complicated by the delivery uncertainties caused by breathing motion. The purpose of this feasibility study was to investigate whether a voluntary breath-hold technique could limit the delivery uncertainties resulting from interfractional motion. METHODS AND MATERIALS: Data from 15 patients with peripheral lung tumors previously treated with stereotactic radiation therapy were included in this study. The patients had 1 computed tomographic (CT) scan in voluntary breath-hold acquired before treatment and 3 scans during the treatment course. PBS proton treatment plans with 2 fields (2F) and 3 fields (3F), respectively, were calculated based on the planning CT scan and subsequently recalculated on the 3 repeated CT scans. Recalculated plans were considered robust if the V95% (volume receiving ≥95% of the prescribed dose) of the gross target volume (GTV) was within 5% of what was expected from the planning CT data throughout the simulated treatment. RESULTS: A total of 14/15 simulated treatments for both 2F and 3F met the robustness criteria. Reduced V95% was associated with baseline shifts (2F, P=.056; 3F, P=.008) and tumor size (2F, P=.025; 3F, P=.025). Smaller tumors with large baseline shifts were also at risk for reduced V95% (interaction term baseline/size: 2F, P=.005; 3F, P=.002). CONCLUSIONS: The breath-hold approach is a realistic clinical option for treating lung tumors with PBS proton therapy. Potential risk factors for reduced V95% are small targets in combination with large baseline shifts. On the basis of these results, the baseline shift of the tumor should be monitored (eg, through image guided therapy), and appropriate measures should be taken accordingly. The intrafractional motion needs to be investigated to confirm that the breath-hold approach is robust.
Authors: Chenbin Liu; Steven E Schild; Joe Y Chang; Zhongxing Liao; Shawn Korte; Jiajian Shen; Xiaoning Ding; Yanle Hu; Yixiu Kang; Sameer R Keole; Terence T Sio; William W Wong; Narayan Sahoo; Martin Bues; Wei Liu Journal: Int J Radiat Oncol Biol Phys Date: 2018-02-14 Impact factor: 7.038
Authors: Michelle Lis; Wayne Newhauser; Marco Donetti; Moritz Wolf; Timo Steinsberger; Athena Paz; Marco Durante; Christian Graeff Journal: Front Oncol Date: 2021-03-19 Impact factor: 6.244