Development of a relocatable frame technique for gamma knife radiosurgery. Technical note

Area of Science:

• Neurosurgery
• Radiation Oncology
• Medical Imaging

Background:

• Stereotactic frames are crucial for Gamma Knife radiosurgery but limit treatments to a single session due to fixation.
• Fractionated treatments and flexible timing require the ability to remove and reapply the stereotactic frame accurately.

Purpose of the Study:

• To investigate techniques for stereotactic frame fixation and position verification after removal and reapplication.
• To assess the feasibility of fractionated Gamma Knife radiosurgery by enabling accurate frame repositioning.

Main Methods:

• A novel fixation technique using four surgical screws and aluminum pins was developed.
• Phantom tests involved repeated frame removal and reapplication, with target coordinates verified using an angiographic localizer.
• Radiotherapy simulator projections were used to detect frame movement, comparing their efficacy to bubble skull measurements.

Main Results:

• The proposed technique allows frame reapplication with a mean error of 0.3 mm and a maximum error of 0.7 mm.
• Radiotherapy simulator verification detected frame movements as small as 1 mm.
• Bubble skull measurements proved unreliable for detecting frame repositioning errors.

Conclusions:

• The developed frame fixation technique facilitates accurate reapplication (±0.7 mm), supporting fractionated radiosurgery.
• Radiotherapy simulators are effective for verifying correct frame placement and detecting minimal frame movement.
• Bubble measurements are inadequate for ensuring accurate stereotactic frame repositioning.