Volumetric modulated arc therapy of head-and-neck cancer on a fast-rotating O-ring linac: Plan quality and delivery time comparison with a C-arm linac

Steven Michiels; Kenneth Poels; Wouter Crijns; Laurence Delombaerde; Robin De Roover; Bianca Vanstraelen; Karin Haustermans; Sandra Nuyts; Tom Depuydt

doi:10.1016/j.radonc.2018.04.021

Volumetric modulated arc therapy of head-and-neck cancer on a fast-rotating O-ring linac: Plan quality and delivery time comparison with a C-arm linac

Radiother Oncol. 2018 Sep;128(3):479-484. doi: 10.1016/j.radonc.2018.04.021. Epub 2018 May 5.

Authors

Steven Michiels¹, Kenneth Poels², Wouter Crijns², Laurence Delombaerde³, Robin De Roover³, Bianca Vanstraelen², Karin Haustermans⁴, Sandra Nuyts⁴, Tom Depuydt⁵

Affiliations

¹ Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven - University of Leuven, Belgium. Electronic address: michiels.steven@kuleuven.be.
² Department of Radiation Oncology, University Hospitals Leuven, Belgium.
³ Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven - University of Leuven, Belgium.
⁴ Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven - University of Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
⁵ Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven - University of Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium. Electronic address: tom.depuydt@kuleuven.be.

PMID: 29739713
DOI: 10.1016/j.radonc.2018.04.021

Abstract

Background and purpose: Linac improvements in gantry speed, leaf speed and dose rate may increase the time-efficiency of volumetric modulated arc therapy (VMAT) delivery. The plan quality achievable with faster VMAT however remains to be investigated. In this study, a fast-rotating O-ring linac with fast-moving leaves is compared with a C-arm linac in terms of plan quality and delivery time for VMAT of head-and-neck cancer (HNC).

Material and methods: For 30 patients with HNC, treatment planning was performed using dual-arc (HA2) and triple-arc (HA3) VMAT on a Halcyon fast-rotating O-ring linac and using dual-arc VMAT on a TrueBeam C-arm linac (TB2). Target coverage metrics and complication probabilities were compared. Plan delivery was verified using 3%/3 mm gamma-index analysis of helical diode array measurements. Volumetric image acquisition and plan delivery times were compared.

Results: All studied VMAT-techniques fulfilled the target coverage objectives. D_2% to the boost volume was higher for HA2 (median 103.7%, 1st-3rd quartile [103.5%;104.0%]) and HA3 (103.2% [103.0%;103.7%)] than for TB2 (102.6% [102.3%;103.0%)], resulting in an increased boost target dose heterogeneity for HA2 and HA3. Complication probabilities were comparable between HA2 and TB2, while HA3 showed a xerostomia probability reduction (0.8% [0.2%;1.8%]) and dysphagia probability reduction (1.0% [0.2%;1.8%]) compared with TB2. Gamma-index agreement scores were never below 93.0% for HA2, HA3 and TB2. Volumetric imaging and plan delivery time was shorter for HA2 (1 m 24 s ± 1 s) and HA3 (1 m 54 s ± 1 s) than for TB2 (2 m 47 s ± 1 s).

Conclusion: For VMAT of HNC, the fast-rotating O-ring linac at least maintains the plan quality of two arcs on a C-arm linac while reducing the image acquisition and plan delivery time.

Keywords: FFF; Fast-rotating O-ring linac; Head-and-neck cancer; Plan quality; Treatment time; VMAT.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Head and Neck Neoplasms / radiotherapy*
Humans
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Intensity-Modulated / methods*