Interlaced x-ray microplanar beams: a radiosurgery approach with clinical potential

Area of Science:

• Radiation Oncology
• Neuroscience
• Medical Physics

Background:

• Microbeam radiation therapy (MRT) uses thin, precisely spaced microplanar x-ray beams.
• Conventional MRT spares normal tissues, particularly the central nervous system (CNS), and targets tumors.
• Synchrotron sources are required for thin microbeams, limiting clinical applications.

Purpose of the Study:

• To investigate the tolerance of the CNS to thicker microbeams.
• To develop and evaluate an interlaced microbeam geometry for improved clinical feasibility.
• To assess the efficacy and safety of interlaced microbeams for treating brain abnormalities.

Main Methods:

• Rats received transaxial spinal cord or brain irradiation with thicker microbeams (0.68 mm) at various doses and spacings.
• An interlaced geometry was employed, combining two arrays at a 90-degree angle.
• Monte Carlo simulations were used to calculate dose falloff at the target edge.

Main Results:

• Rats tolerated thicker microbeams to the spinal cord and brain without observable adverse effects.
• Interlaced microbeams delivered localized 90-150 Gy doses to the rat brain.
• Focal damage occurred within the target at 120-150 Gy, with no damage elsewhere at 120 Gy.
• A sharp dose falloff (30 microm) was calculated for interlaced microbeams, significantly less than conventional methods.

Conclusions:

• Thicker microbeams are tolerated by the CNS, expanding potential clinical applications.
• Interlaced microbeam geometry offers a practical approach for delivering high-dose radiation to target volumes.
• This technique shows potential for treating CNS tumors and other abnormalities with reduced damage to surrounding healthy tissue.