Collins, D.J.

den Otter, Lydia

Kaza, E

Kierkels, Roel G J

Knopf, Antje

Langendijk, J.A.

Leach, M.O.

Meijers, Arturs

English

Background and purpose: The treatment of moving targets with scanned proton beams is challenging. For motion mitigation, an Active Breathing Coordinator (ABC) can be used to assist with breath-holding. We evaluated the robustness of scanned proton therapy against anatomical uncertainties when treating lung patients during ABC controlled breath-hold. Materials and methods: Four subsequent MRIs of five healthy volunteers were acquired under ABC controlled breath-hold during two simulated treatment fractions. Deformation vector fields between these MRIs were used to deform CTs of three non-small-cell lung cancer patients. Per patient eight cases with different tumour sizes and locations were modeled. Intensity-modulated proton plans were created and split into sub-plans of 20 seconds duration (assumed breath-hold duration), and recalculated on the deformed CTs. Results: Dosimetric evaluation showed &lt;2% target coverage loss (V95% [%]) for 19/24 cases. Simulated tumours in the caudal regions showed a loss of V95% up to 6.1%. Organs at risk doses differed little compared to the planned doses (V5Gy [%] &lt;1% for the heart and the lungs minus GTV, &lt;1.4 Gy difference in D0.1cc [Gy]) to the spinal cord and esophagus). Conclusions: When treating under ABC controlled breath-hold, robustly optimized IMPT plans lack robustness to caudally located lung tumours. For most other cases anatomical variations between repeated ABC breath-holds have limited dosimetric consequences

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   University of GroningenReproducibility of the lung anatomy under Active Breathing Coordinator control: Dosimetricconsequences for scanned proton treatments.den Otter, Lydia; Kierkels, Roel G J; Kaza, E; Meijers, Arturs; Leach, M.O.; Collins, D.J.;Langendijk, J.A.; Knopf, AntjeIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Publication date:2017Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):den Otter, L., Kierkels, R. G. J., Kaza, E., Meijers, A., Leach, M. O., Collins, D. J., Langendijk, J. A., &Knopf, A. (2017). Reproducibility of the lung anatomy under Active Breathing Coordinator control:Dosimetric consequences for scanned proton treatments.. Poster session presented at 4D Treatment(Planning)Workshop, Vienna, Austria.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 05-06-2022Pencil beam scanning (PBS) is a highly conformal technology to treat cancer. The time structure of PBS makes the treatment of moving tumours challenging due to the interplay effect. For motion mitigation, an Active Breathing Coordinator (ABC) can be used to assist with breath-holding. As the treatment is delivered over several fractions with delivery times extending a feasible breath-hold duration, high reproducibility of ABC breath-holding is required. We evaluated the robustness of scanned proton therapy against anatomical reproducibility uncertainties when treating lung patients during ABC controlled breath-hold.    Reproducibility of the lung anatomy under Active Breathing Coordinator control: Dosimetric consequences for scanned proton treatments Lydia A. den Otter1, Roel G.J. Kierkels1, Allia Kaza2, Arturs Meijers1, Martin O. Leach2, David J. Collins2, Johannes A. Langendijk1, Antje C. Knopf1 1: Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, The Netherlands 2: CR-UK Cancer Imaging Centre, The Institute of Cancer Research and The Royal Marsden Hospital, London, UK. PURPOSE RESULTS INTRODUCTION To investigate dosimetric robustness of scanned proton treatment to the anatomical reproducibility uncertainties in the lung under ABC. CONCLUSION When treating under ABC controlled breath-hold, robustly optimized IMPT plans lack robustness to caudally located lung tumours. For most other cases anatomical variations between repeated ABC breath-holds have limited dosimetric consequences. References: E. Kaza, A. Dunlop, R. Panek, D.J. Collins, M. Orton, R. Symonds-Tayler, D. McQuaid, E. Scurr, V. Hansen and M.O.  Leach (2017), “Lung volume reproducibility under ABC control and self-sustained breath-holding”. J Appl Clin Med Phys, 18:154–162. doi:10.1002/acm2.12034  l.a.den.otter@umcg.nl MATERIALS & METHODS Four subsequent MRIs of three healthy volunteers were acquired under ABC controlled breath-hold during two simulated treatment fractions. Deformation vector fields between these MRIs representing the different breath-holds were used to deform CT scans of three non-small-cell lung cancer patients that matched visually (Figure 1). Per patient eight cases with different tumour sizes and locations were modeled (Figure 1). Intensity-modulated proton plans were created and split into sub-plans of 20 seconds duration (assumed breath-hold duration). The plans were recalculated on the deformed CTs that represent different breath-hold geometries to simulate the effect of the reproducibility of breath-holding during treatment on the dose distributions.   Dosimetric evaluation of the recalculated treatment plans showed <2% V95% target coverage loss for 19/24 cases (Figure 2). Simulated tumours in the caudal regions showed a loss of V95% up to 6.1%. Organs at risk doses differed little compared to the planned doses (V5Gy<1% for the heart and the lungs, D0.1cc<1.4 Gy to the spinal cord and esophagus). For one sample case (Figure 3), the planned and recalculated dose distribution is shown. The loss of CTV coverage is depicted by the dose heterogeneities shown in Figure 3(b).     Figure 2. The V95% loss of coverage and the V105% of the CTV for each simulation and all patients. The tolerance thresholds (yellow lines) were set to 2% loss of target coverage and 1% V105% coverage. Figure 1. Fused views of the three patient/volunteer matches. 3D views of simulated tumour locations and sizes for patient number 2. A: left lower lobe, 4.5 cm diameter. B: left lower lobe, 6.5 cm diameter. C: left upper lobe, 4.5 cm diameter. D: left upper lobe, 6.5 cm diameter. E: right lower lobe, 4.5 cm diameter. F: right lower lobe, 6.5 cm diameter. G: right middle lobe, 4.5 cm diameter. H: right upper lobe, 4.5 cm dia-meter. Red coloured: heart. Blue coloured: lungs. Brown coloured: simulated tumour. Figure 3. (a) Transversal view overlaid with the planned 3D dose distribution for a patient with a simulated tumour in the right lower lobe (7 cm CTV). (b) Transversal view of the dose distribution after re-calculation under realistic breath-hold conditions (scenario B). (c) Dose volume histogram of the planned dose (solid lines) compared to the re-calculated dose (dotted lines). 

Reproducibility of the lung anatomy under Active Breathing Coordinator control: Dosimetric consequences for scanned proton treatments.

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Reproducibility of the lung anatomy under Active Breathing Coordinator control: Dosimetric consequences for scanned proton treatments.

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