Advances in Radiation Oncology (Jul 2023)

Vestibulocochlear Delineation for Vestibular Schwannoma Treated With Radiation Therapy

  • Felipe Cicci Farinha Restini, MD,
  • Leticia Hernandes Brito, MD,
  • Fernanda Hayashida Yoshimoto, MD,
  • Ana Paula Alves Pereira, MD,
  • David Rodrigues Ferreira Neto, MD,
  • Vitor Cunha Gomes, BSc,
  • Beatriz Cunha Nascimento, BSc,
  • Anselmo Mancini, BSc,
  • Tatiana Midori Martins Telles Alves, BSc, MS,
  • Maria Thereza Mansur Starling, MD,
  • Guilherme Wilson Otaviano Garcia Chaves, MD,
  • Ula Lindoso Passos, MD, PhD,
  • Gustavo Nader Marta, MD, PhD,
  • Samir Abdallah Hanna, MD, PhD

Journal volume & issue
Vol. 8, no. 4
p. 101171

Abstract

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Purpose: To develop a specialist-based consensus of cochlear contouring to be used in patients undergoing stereotactic radiosurgery (SRS) treatment for vestibular schwannoma. Methods and Materials: Representative computed tomography (CT) and magnetic resonance imaging (MRI) were used for cochlear contouring. The semicircles, cochlea, vestibule, and internal acoustic meatus were delineated by 7 radiation oncology department physicians and reviewed by neuroradiologists. A total of 12 cases accrued from a single academic institution were studied for a similarity analysis by the Dice coefficient. Results: The suggested guideline is an easily reproductive tool that allows radiation oncologists to accurately contour the vestibulocochlear system to avoid toxicity due to inadequate dosimetry of organs at risk. This could be a useful tool even for non-vestibular schwannoma radiation therapy. The Dice coefficient suggests reproducible results as long as the following contouring recommendations are observed. Conclusions: The template for vestibulocochlear delineation may be useful for an adequate organs at risk definition. Future studies are required to find specific constraints for each segment of the vestibulocochlear system, and to mitigate interobserver variations.