Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients

Kimberley S. Koetsier*, Michelle Oud, Erik de Klerck, Erik F. Hensen, Marco van Vulpen, Anne van Linge, Peter Paul van Benthem, Cleo Slagter, Steven J.M. Habraken, Mischa S. Hoogeman, A. Méndez Romero

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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To investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas. 

Materials and Methods: 

Clinically delivered photon radiosurgery treatment plans were compared to five cochlear-optimized plans: one photon and four proton plans (total of 120). A 1x12 Gy dose was prescribed. Photon plans were generated with Precision (Cyberknife, Accuray) with no PTV margin for set-up errors. Proton plans were generated using an in-house automated multi-criterial planning system with three or nine-beam arrangements, and applying 0 or 3 mm robustness for set-up errors during plan optimization and evaluation (and 3 % range robustness). The sample size was calculated based on a reduction of cochlear Dmean > 1.5 Gy(RBE) from the clinical plans, and resulted in 24 patients. 


Compared to the clinical photon plans, a reduction of cochlear Dmean > 1.5 Gy(RBE) could be achieved in 11/24 cochlear-optimized photon plans, 4/24 and 6/24 cochlear-optimized proton plans without set-up robustness for three and nine-beam arrangement, respectively, and in 0/24 proton plans with set-up robustness. The cochlea could best be spared in cases with a distance between tumor and cochlea. Using nine proton beams resulted in a reduced dose to most organs at risk. 


Cochlear dose reduction is possible in vestibular schwannoma radiosurgery while maintaining tumor coverage, especially when the tumor is not adjacent to the cochlea. With current set-up robustness, proton therapy is capable of providing lower dose to organs at risk located distant to the tumor, but not for organs adjacent to it. Consequently, photon plans provided better cochlear sparing than proton plans.

Original languageEnglish
Article number100689
JournalClinical and Translational Radiation Oncology
Early online date6 Oct 2023
Publication statusPublished - Nov 2023

Bibliographical note

Funding Information:
The primary author received a travel stipend and salary partly funded by 1) the Surcharge for Top Consortia for Knowledge and Innovation (TKIs) from the Ministry of Economic Affairs and Climate and the HollandPTC consortium – Erasmus Medical Center, Rotterdam, HollandPTC, Delft, Leiden University Medical Center (LUMC), Leiden, and Delft University of Technology, Delft, the Netherlands, and 2) Varian, a Siemens Healthineers company.

Publisher Copyright:
© 2023 The Authors


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