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Title: Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

Abstract

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. Inmore » 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.« less

Authors:
 [1];  [2];  [3];  [4];  [3];  [1];  [5];  [4];  [5];  [1];  [6];  [7];  [8];  [3];  [8];
  1. Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany)
  2. (China)
  3. Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany)
  4. (Germany)
  5. Saphir Radiosurgery Center Northern Germany, Güstrow (Germany)
  6. (Denmark)
  7. Department for Radiation Oncology, University Medicine Rostock, Rostock (Germany)
  8. Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany)
Publication Date:
OSTI Identifier:
22649874
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 97; Journal Issue: 4; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ANGULAR CORRELATION; ERRORS; LIVER; NEOPLASMS; RADIATION DOSE DISTRIBUTIONS; RADIOTHERAPY; RESPIRATION; SAFETY MARGINS

Citation Formats

Chan, Mark, Tuen Mun Hospital, Hong Kong, Grehn, Melanie, Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck, Cremers, Florian, Siebert, Frank-Andre, Wurster, Stefan, Department for Radiation Oncology, University Medicine Greifswald, Greifswald, Huttenlocher, Stefan, Dunst, Jürgen, Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen, Hildebrandt, Guido, Schweikard, Achim, Rades, Dirk, Ernst, Floris, and and others. Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases. United States: N. p., 2017. Web. doi:10.1016/J.IJROBP.2016.11.041.
Chan, Mark, Tuen Mun Hospital, Hong Kong, Grehn, Melanie, Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck, Cremers, Florian, Siebert, Frank-Andre, Wurster, Stefan, Department for Radiation Oncology, University Medicine Greifswald, Greifswald, Huttenlocher, Stefan, Dunst, Jürgen, Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen, Hildebrandt, Guido, Schweikard, Achim, Rades, Dirk, Ernst, Floris, & and others. Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases. United States. doi:10.1016/J.IJROBP.2016.11.041.
Chan, Mark, Tuen Mun Hospital, Hong Kong, Grehn, Melanie, Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck, Cremers, Florian, Siebert, Frank-Andre, Wurster, Stefan, Department for Radiation Oncology, University Medicine Greifswald, Greifswald, Huttenlocher, Stefan, Dunst, Jürgen, Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen, Hildebrandt, Guido, Schweikard, Achim, Rades, Dirk, Ernst, Floris, and and others. Wed . "Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases". United States. doi:10.1016/J.IJROBP.2016.11.041.
@article{osti_22649874,
title = {Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases},
author = {Chan, Mark and Tuen Mun Hospital, Hong Kong and Grehn, Melanie and Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck and Cremers, Florian and Siebert, Frank-Andre and Wurster, Stefan and Department for Radiation Oncology, University Medicine Greifswald, Greifswald and Huttenlocher, Stefan and Dunst, Jürgen and Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen and Hildebrandt, Guido and Schweikard, Achim and Rades, Dirk and Ernst, Floris and and others},
abstractNote = {Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.},
doi = {10.1016/J.IJROBP.2016.11.041},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 4,
volume = 97,
place = {United States},
year = {Wed Mar 15 00:00:00 EDT 2017},
month = {Wed Mar 15 00:00:00 EDT 2017}
}