Authors: Damodar Pokhrel, PhD^†,∗, Richard Mallory, BS^†, Matthew Bush, MD, PhD^‡, William St. Clair, MD, PhD^†, Mark E. Bernard, MD^†

^† Department of Radiation Medicine, University of Kentucky, Lexington KY, 40536, USA
^‡ Department of Otolaryngology - Head and Neck Surgery, University of Kentucky, Lexington KY, 40536, USA

Abstract:
This study aims to report on the clinical validation and feasibility of utilizing a novel fully automated treatment planning and delivery system, HyperArc VMAT stereotactic radiosurgery (SRS) for glomus jugulare tumors (GJT). Independent dose verification of the HyperArc module via the MD Anderson’s SRS head phantom irradiation and credentialing results showed compliance with the SRS treatment requirements per IROC MD Anderson’s standard. Following the Alliance clinical trial, AAPM, RTOG protocols, and QUANTEC requirements, utilizing selected three-partial arc geometry of HyperArc module on TrueBeam Linac with 6MV-FFF beam, GJT SRS plans were generated for nine previously treated Gamma Knife (GK) radiosurgery patients using advanced Acuros-based algorithm to account for tissue inhomogeneity corrections and frameless immobilization with Q-fix mask and Encompass device insert. HyperArc VMAT produced highly conformal SRS dose distributions to GJT, a steep dose gradient around the GJT, and spared adjacent critical organs including the spinal cord (< 3.0 Gy). Due to faster patient setup and less MLC modulation through the target (average beam-on time, 6.2 minutes), the HyperArc VMAT plan can deliver a single high-dose of 18 Gy to the GJT in less than 15 minutes overall treatment time, significantly im- proving patient comfort and clinic workflow. Pretreatment portal dosimetry quality assurance results and independent dose verification via Monte Carlo-based physics second check met our clinical SRS protocol’s requirements for treatment. Due to the highly conformal dose distribution, rapid dose fall-off, excellent sparing of adjacent critical organs, and highly precise and accurate treatment, clinical implementation of frameless HyperArc VMAT for GJT patients who may not have access to nor tolerate frame-based GK SRS treatment are underway.

As of January 1, 2022, ARRT requires CE Credits for Directed Journal Readings to be based on the word count for each article. So, the number of CE Credits for each DJR article will vary for ARRT. For this article, the ARRT CE Credit will be 1 Credit. The MDCB CE Credits will remain at 2.5 Credits.

ARRT CQR Credit Distribution
Radiation Therapy - 2017
Procedures
Prescription and Dose Calculation = 0.25 credits
Treatments = 0.25 credits
Radiation Therapy - 2022
Procedures    
Prescription and Dose Calculation = 0.25 credits
Treatments = 0.25 credits