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Current Directions in Biomedical Engineering

Joint Journal of the German Society for Biomedical Engineering in VDE and the Austrian and Swiss Societies for Biomedical Engineering

Editor-in-Chief: Dössel, Olaf

Editorial Board: Augat, Peter / Buzug, Thorsten M. / Haueisen, Jens / Jockenhoevel, Stefan / Knaup-Gregori, Petra / Kraft, Marc / Lenarz, Thomas / Leonhardt, Steffen / Malberg, Hagen / Penzel, Thomas / Plank, Gernot / Radermacher, Klaus M. / Schkommodau, Erik / Stieglitz, Thomas / Urban, Gerald A.


CiteScore 2018: 0.47

Source Normalized Impact per Paper (SNIP) 2018: 0.377

Open Access
Online
ISSN
2364-5504
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Treatment planning for MLC based robotic radiosurgery for brain metastases: plan comparison with circular fields and suggestions for planning strategies

Daniela Schmitt
  • Corresponding author
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Rami El Shafie
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Sebastian Klüter
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Nathalie Arians
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Kai Schubert
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Stefan Rieken
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Jürgen Debus
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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/ Angela Paul
  • Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany and National Center for Radiation Research in Oncology (NCRO) and Heidelberg Institute for Radiation Oncology (HIRO)
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Published Online: 2017-09-07 | DOI: https://doi.org/10.1515/cdbme-2017-0032

Abstract

To evaluate the possible range of application of the new InCise2 MLC for the CyberKnife M6 system in brain radiosurgery, a plan comparison was made for 10 brain metastases sized between 1.5 and 9cm3 in 10 patients treated in a single fraction each. The target volumes consist of a PTV derived by expanding the GTV by 1mm and were chosen to have diversity in the cohort regarding regularity of shape, location and the structures needed to be blocked for beam transmission in the vicinity. For each case, two treatment plans were optimized: one using the MLC and one using the IRIS-collimator providing variable circular fields. Plan re-quirements were: dose prescription to the 70% isodose line (18 or 20Gy), 100% GTV coverage, ≥98% PTV coverage, undisturbed central high dose region (95% of maximum dose) and a conformity index as low as possible. Plan com-parison parameters were: conformity index (CI), high-dose gradient index (GIH), low-dose gradient index (GIL), total number of monitor units (MU) and expected treatment time (TT). For all cases, clinically acceptable plans could be gen-erated with the following results (mean±SD) for CI, GIH, GIL, MU and TT, respectively for the MLC plans: 1.09±0.03, 2.77±0.26, 2.61±0.08, 4514±830MU and 27±5min and for the IRIS plans: 1.05±0.01, 3.00±0.35, 2.46±0.08, 8557±1335MU and 42±7min. In summary, the MLC plans were on average less conformal and had a shallower dose gradient in the low dose region, but a steeper dose gradient in the high dose region. This is accompanied by a smaller vol-ume receiving 10Gy. A plan by plan comparison shows that usage of the MLC can spare about one half of the MUs and one third of treatment time. From these experiences and results suggestions for MLC planning strategy can be de-duced.

Keywords: Treatment planning; stereotactic radiotherapy; radiosurgery; robotic guided radiation therapy; multi leaf collimator; plan comparison

About the article

Published Online: 2017-09-07


Citation Information: Current Directions in Biomedical Engineering, Volume 3, Issue 2, Pages 151–154, ISSN (Online) 2364-5504, DOI: https://doi.org/10.1515/cdbme-2017-0032.

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©2017 Daniela Schmitt et al., published by De Gruyter, Berlin/Boston. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. BY-NC-ND 4.0

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