Original Research ARTICLE
Evaluation of an open source registration package for automatic contour propagation in online adaptive intensity-modulated proton therapy of prostate cancer
- 1Department of Radiology, Leiden University Medical Center, Netherlands
- 2Department of Radiation Oncology, Erasmus Medical Center Cancer Institute, Netherlands
- 3Faculty of Electrical Engineering, Mathematics & Computer Science, Delft University of Technology, Netherlands
- 4Department of Radiotherapy, Leiden University Medical Center, Netherlands
Objective: Our goal was to investigate the performance of an open source deformable image registration package, elastix, for fast and robust contour propagation in the context of online-adaptive intensity-modulated proton therapy (IMPT) for prostate cancer.
Methods: A planning and 7-10 repeat CT scans were available of 18 prostate cancer patients. Automatic contour propagation of repeat CT scans was performed using elastix and compared with manual delineations in terms of geometric accuracy and runtime. Dosimetric accuracy was quantified by generating IMPT plans using the propagated contours expanded with a 2 mm (prostate) and 3.5 mm margin (seminal vesicles and lymph nodes) and calculating dosimetric coverage based on the manual delineation. A coverage of V_95%>98% (at least 98% of the target volumes receive at least 95% of the prescribed dose) was considered clinically acceptable.
Results: Contour propagation runtime varied between 3 and 30 seconds for different registration settings. For the fastest setting, 83 in 93 (89.2%), 73 in 93 (78.5%), and 91 in 93 (97.9%) registrations yielded clinically acceptable dosimetric coverage of the prostate, seminal vesicles, and lymph nodes, respectively. For the prostate, seminal vesicles, and lymph nodes the Dice Similarity Coefficient (DSC) was 0.87 ±0.05, 0.63 ±0.18 and 0.89 ± 0.03 and the mean surface distance (MSD) was 1.4± 0.5 mm, 2.0 ± 1.2 mm and 1.5 ±0.4 mm, respectively.
Conclusion: With a dosimetric success rate of 78.5% to 97.9%, this software may facilitate online adaptive IMPT of prostate cancer using a fast, free and open implementation.
Keywords: Intensity modulated proton therapy, image registration, Open Source Software, prostate cancer, Elastix
Received: 01 May 2019;
Accepted: 08 Nov 2019.
Copyright: © 2019 QIAO, Jagt, Hoogeman, Lelieveldt and Staring. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Marius Staring, Department of Radiology, Leiden University Medical Center, Leiden, 2333, Netherlands, email@example.com