Article

Feasibility of Pencil Beam Scanned Intensity Modulated Proton Therapy in Breath-hold for Locally Advanced Non-Small Cell Lung Cancer

International Journal of Radiation Oncology • Biology • Physics, Elsevier, ISSN 1879-355X

Volume 99, 5, 2017

DOI:10.1016/j.ijrobp.2017.08.023, Dimensions: pub.1091340877, PMID: 28964587,

Affiliations

Organisations

  1. (1) Rigshospitalet, grid.475435.4, Capital Region
  2. (2) University of Copenhagen, grid.5254.6, KU
  3. (3) Paul Scherrer Institute, grid.5991.4
  4. (4) University Hospital of Zurich, grid.412004.3
  5. (5) ETH Zurich, grid.5801.c

Countries

Denmark

Switzerland

Continents

Europe

Description

PURPOSE: We evaluated the feasibility of treating patients with locally advanced non-small cell lung cancer (NSCLC) with pencil beam scanned intensity modulated proton therapy (IMPT) in breath-hold. METHODS AND MATERIALS: Fifteen NSCLC patients who had previously received 66 Gy in 33 fractions with image guided photon radiation therapy were included in the present simulation study. In addition to a planning breath-hold computed tomography (CT) scan before the treatment start, a median of 6 (range 3-9) breath-hold CT scans per patient were acquired prospectively throughout the radiation therapy course. Three-field IMPT plans were constructed using the planning breath-hold CT scan, and the four-dimensional dose distributions were simulated, with consideration of both patient intra- and interfraction motion, in addition to dynamic treatment delivery. RESULTS: The median clinical target volume receiving 95% of the prescribed dose was 99.8% and 99.7% for the planned and simulated dose distributions, respectively. For 3 patients (20%), the dose degradation was >5%, and plan adjustment was needed. Dose degradation correlated significantly with the change in water-equivalent path lengths (P<.01) in terms of the percentage of voxels with 3-mm or more undershoot on repeat CT scans. The dose to the organs at risk was similar for the planned and simulated dose distributions. Three or fewer breath-holds per field would be required for 12 of the 15 patients, which was clinically feasible. CONCLUSIONS: For 9 of 15 NSCLC patients, IMPT in breath-hold was both dosimetrically robust and feasible to deliver regarding the treatment time. Three patients would have required plan adaption to meet the dosimetric criteria. The change in water-equivalent path length is an indicator of plan robustness and should be considered for the selection of patients for whom the plan would require adaptation.

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University of Copenhagen

Danish Open Access Indicator

2017: Unused

Research area: Science & Technology

Danish Bibliometrics Indicator

2017: Level 1

Research area: Science & Technology

Dimensions Citation Indicators

Times Cited: 12

Field Citation Ratio (FCR): 3.79

Relative Citation ratio (RCR): 1.41