Non-coplanar trajectories to improve organ at risk sparing in volumetric modulated arc therapy for primary brain tumors.

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BEDFORD (SMYTH) Non-coplanar trajectories to improve organ at risk - Radiotherapy and Oncology.pdf (3.37 MB)

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ICR Authors

Bamber, Jeffrey
 Mandeville, Henry
 Bedford, James

Authors

Smyth, G
Evans, PM
Bamber, JC
Mandeville, HC
Welsh, LC
Saran, FH
Bedford, JL

Document Type

Journal Article

Date

2016-10-01

Date Accepted

2016-07-19

Abstract

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.

Citation

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 2016, 121 (1), pp. 124 - 131

DOI

10.1016/j.radonc.2016.07.014

URI

https://repository.icr.ac.uk/handle/internal/64

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Source Title

Publisher

ELSEVIER IRELAND LTD

ISSN

0167-8140

eISSN

1879-0887

Collections

Radiotherapy and Imaging

Research Team

Paediatric and Adolescent Radiotherapy
Radiotherapy treatment planning
Ultrasound & Optical Imaging

Notes