Intracranial motion during frameless Gamma-Knife stereotactic radiosurgery

Area of Science:

• Neurosurgery
• Radiation Oncology
• Medical Physics

Background:

• Frameless Gamma Knife radiosurgery (GKRS) offers precise radiation delivery but is susceptible to intracranial displacement.
• The Gamma Knife Icon system uses high-definition motion management (HDMM) to track nasal tip motion as a surrogate for intracranial motion.
• Limited data exists on intrafraction motion incidence and influencing factors in frameless GKRS.

Purpose of the Study:

• To evaluate patient and treatment-related factors affecting intrafraction motion during frameless GKRS.
• To assess the impact of anxiolytics and other variables on intracranial displacement.

Main Methods:

• Retrospective analysis of 89 frameless GKRS treatments on brain tumor patients using the Gamma Knife Icon.
• Data collected included patient demographics, mask type, anxiolytic use, treatment time, and physics clearance.
• Logistic regression analyzed average and maximum displacement (mm) in relation to various factors.

Main Results:

• Median average and maximum displacement were 0.60 mm and 1.22 mm, respectively.
• Higher ECOG status, male gender, and malignant tumors correlated with increased average displacement.
• Anxiolytic use, older age (>65), and shorter treatment times were associated with reduced motion.

Conclusions:

• This study identifies key factors influencing intrafraction motion in mask-based frameless GKRS.
• Higher ECOG, male gender, longer treatment times, and malignant tumors increase displacement.
• Anxiolytics effectively mitigate motion, highlighting their importance for radiosurgery teams.