# Dose-Painting Linear Accelerator Radiosurgery of Glomus Jugulare With Dosimetric Comparison to Gamma Knife

## TL;DR

This study compares two radiosurgery methods for treating glomus jugulare tumors, showing that HyperArc offers faster treatment and better tumor coverage while protecting the facial nerve.

## Contribution

The study introduces HyperArc as a faster and more effective alternative to Gamma Knife for stereotactic radiosurgery of glomus jugulare tumors.

## Key findings

- HyperArc treatments took an average of 29 minutes versus 180 minutes for Gamma Knife.
- HyperArc achieved 95-100% tumor coverage while limiting facial nerve dose to <13 Gy.
- Gamma Knife replanned treatments achieved 92-99% tumor coverage with longer treatment times.

## Abstract

Objectives

In this study, we outline our rationale for delivering a dose of ≥15 Gy in stereotactic radiosurgery (SRS) of glomus jugulare tumor (GJT) while ensuring the avoidance of complications associated with doses >13 Gy to the facial nerve. To avoid such complications, we initially utilized the Gamma Knife Perfexion (GK) system (Elekta Instrument AB, Stockholm, Sweden) at our institution but encountered challenges related to lengthy treatment times and difficulty in sculpting doses to minimize doses to spare the facial nerve. As a potential solution, we propose the use of HyperArc (Varian Medical Systems, Palo Alto, CA), a newly developed automated delivery platform for linear accelerator (LINAC)-based SRS. HyperArc offers the potential for faster treatment and more complex shaping of the radiotherapy dose with multiple arcs and multi-leaf collimators.

Methods

We retrospectively reviewed nine cases of patients with GJT treated with HyperArc. Patients’ demographic and treatment data were collected. Additionally, simulated GK treatment plans were created and compared with HyperArc plans to assess time savings, PTV coverage, and plan quality.

Results

One male and eight female patients, with a mean age of 63.9 years, were included. Treatments were delivered on average in 29 minutes, achieving 95-100% of the tumor while limiting the facial nerve to <13 Gy. Treatments replanned using our GK system could achieve only 92-99% tumor coverage while respecting facial nerve constraints, with average treatment times of 180 minutes. Comparable plan quality parameters were attained with both modalities.

Conclusions

The HyperArc system provides a qualitatively satisfactory and rapid treatment delivery of a highly sculpted radiotherapy dose to maximize tumor coverage and minimize facial nerve complications.