A reusable and universal size polyethylene terephthalate glycol head fixation device for Gamma Knife Radiosurgery: a prospective comparative cohort study

Accurate cranial fixation is fundamental to the precision and safety of Gamma Knife Radiosurgery (GKRS). Traditional invasive frames, while reliable, limit patient comfort and adaptability for multi-session procedures. This study introduces and validates a reusable, 3D-printed head fixation frame made from polyethylene terephthalate glycol (PETG), engineered to provide mechanical stability and compatibility with the Leksell Gamma Knife Icon®. The PETG frame was modelled in SolidWorks® and analysed mechanically using ANSYS® 2022 to evaluate deformation, stress distribution, and safety factors under tightening forces from 50 N to 160 N. Phantom dosimetry was performed with a CC13 + F ionisation chamber to determine dose attenuation. Clinical validation included 15 patients undergoing hypofractionated GKRS. Cone-beam CT (CBCT) and High-Definition Motion Management (HDMM) were used for alignment and motion monitoring. Statistical comparison of motion parameters was performed using one-way ANOVA. Finite element analysis revealed a maximum von Mises stress of 10.36 MPa, well below PETG’s yield strength (53 MPa). Phantom testing showed a mean dose attenuation of 3.8%, confirming negligible influence on radiation accuracy. Clinical analysis demonstrated an average patient motion of 0.44 ± 0.22 mm, with only 40% of cases showing transient deviations beyond 1.5 mm. ANOVA indicated a significant difference in motion distribution among sessions (p = 0.041). Patients rated the frame as comfortable and non-intimidating, with no major skin reactions. The PETG frame offers a reusable, non-invasive, and cost-effective immobilization alternative for GKRS. Its proven mechanical reliability, radiological transparency, and compatibility with CBCT and HDMM systems establish it as a sustainable advancement in modern radiosurgical head fixation technology.