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Author Dueck, Jenny ♦ Knopf, Antje-Christin ♦ Lomax, Antony ♦ Albertini, Francesca ♦ Persson, Gitte F. ♦ Josipovic, Mirjana ♦ Aznar, Marianne ♦ Weber, Damien C. ♦ Munck af Rosenschöld, Per
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIOLOGY AND NUCLEAR MEDICINE ♦ COMPUTERIZED TOMOGRAPHY ♦ FEASIBILITY STUDIES ♦ LUNGS ♦ NEOPLASMS ♦ PROTON BEAMS ♦ RADIATION HAZARDS ♦ RADIOTHERAPY
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 V{sub 95%} (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 V{sub 95%} 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 V{sub 95%} (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 V{sub 95%} 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.
ISSN 03603016
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-05-01
Publisher Place United States
Journal International Journal of Radiation Oncology, Biology and Physics
Volume Number 95
Issue Number 1


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