Dosimetric accuracy of dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) for primary brain tumours.
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Date
2019-04-05ICR Author
Author
Smyth, G
Evans, PM
Bamber, JC
Mandeville, HC
Rollo Moore, A
Welsh, LC
Saran, FH
Bedford, JL
Type
Journal Article
Metadata
Show full item recordAbstract
Radiotherapy treatment plans using dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) reduce the dose to organs at risk (OARs) compared to coplanar VMAT, while maintaining the dose to the planning target volume (PTV). This paper seeks to validate this finding with measurements. DCR-VMAT treatment plans were produced for five patients with primary brain tumours and delivered using a commercial linear accelerator (linac). Dosimetric accuracy was assessed using point dose and radiochromic film measurements. Linac-recorded mechanical errors were assessed by extracting deviations from log files for multi-leaf collimator (MLC), couch, and gantry positions every 20 ms. Dose distributions, reconstructed from every fifth log file sample, were calculated and used to determine deviations from the treatment plans. Median (range) treatment delivery times were 125 s (123-133 s) for DCR-VMAT, compared to 78 s (64-130 s) for coplanar VMAT. Absolute point doses were 0.8% (0.6%-1.7%) higher than prediction. For coronal and sagittal films, respectively, 99.2% (96.7%-100%) and 98.1% (92.9%-99.0%) of pixels above a 20% low dose threshold reported gamma <1 for 3% and 3 mm criteria. Log file analysis showed similar gantry rotation root-mean-square error (RMSE) for VMAT and DCR-VMAT. Couch rotation RMSE for DCR-VMAT was 0.091° (0.086-0.102°). For delivered dose reconstructions, 100% of pixels above a 5% low dose threshold reported gamma <1 for 2% and 2 mm criteria in all cases. DCR-VMAT, for the primary brain tumour cases studied, can be delivered accurately using a commercial linac.
Collections
Subject
Humans
Brain Neoplasms
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Algorithms
Rotation
Particle Accelerators
Radiotherapy, Intensity-Modulated
Patient Positioning
Organs at Risk
Research team
Paediatric and Adolescent Radiotherapy
Radiotherapy treatment planning
Ultrasound & Optical Imaging
Language
eng
Date accepted
2019-02-26
License start date
2019-04-05
Citation
Physics in medicine and biology, 2019, 64 (8), pp. 08NT01 - ?
Publisher
IOP PUBLISHING LTD