Non-coplanar trajectories to improve organ at risk sparing in volumetric modulated arc therapy for primary brain tumors.
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Date
2016-10-01ICR Author
Author
Smyth, G
Evans, PM
Bamber, JC
Mandeville, HC
Welsh, LC
Saran, FH
Bedford, JL
Type
Journal Article
Metadata
Show full item recordAbstract
BACKGROUND AND PURPOSE: To evaluate non-coplanar volumetric modulated arc radiotherapy (VMAT) trajectories for organ at risk (OAR) sparing in primary brain tumor radiotherapy. MATERIALS AND METHODS: Fifteen patients were planned using coplanar VMAT and compared against non-coplanar VMAT plans for three trajectory optimization techniques. A geometric heuristic technique (GH) combined beam scoring and Dijkstra's algorithm to minimize the importance-weighted sum of OAR volumes irradiated. Fluence optimization was used to perform a local search around coplanar and GH trajectories, producing fluence-based local search (FBLS) and FBLS+GH trajectories respectively. RESULTS: GH, FBLS, and FBLS+GH trajectories reduced doses to the contralateral globe, optic nerve, hippocampus, temporal lobe, and cochlea. However, FBLS increased dose to the ipsilateral lens, optic nerve and globe. Compared to GH, FBLS+GH increased dose to the ipsilateral temporal lobe and hippocampus, contralateral optics, and the brainstem and body. GH and FBLS+GH trajectories reduced bilateral hippocampi normal tissue complication probability (p=0.028 and p=0.043, respectively). All techniques reduced PTV conformity; GH and FBLS+GH trajectories reduced homogeneity but less so for FBLS+GH. CONCLUSIONS: The geometric heuristic technique best spared OARs and reduced normal tissue complication probability, however incorporating fluence information into non-coplanar trajectory optimization maintained PTV homogeneity.
Collections
Subject
Humans
Brain Neoplasms
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Probability
Algorithms
Models, Biological
Radiotherapy, Intensity-Modulated
Organs at Risk
Research team
Paediatric and Adolescent Radiotherapy
Radiotherapy treatment planning
Ultrasound & Optical Imaging
Language
eng
Date accepted
2016-07-19
License start date
2016-10
Citation
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 2016, 121 (1), pp. 124 - 131
Publisher
ELSEVIER IRELAND LTD