Characterization of Gamma Knife Perfexion™ source based on Monte Carlo simulation

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Dosimetry

Background:

• The Gamma Knife Perfexion™ utilizes Cobalt-60 sources for radiosurgery.
• Accurate characterization of these sources is crucial for treatment planning and dose delivery.
• Monte Carlo simulations provide a powerful tool for detailed source modeling.

Purpose of the Study:

• To characterize a single Cobalt-60 source capsule of the Gamma Knife Perfexion™ unit.
• To investigate the effect of source encapsulation on emitted gamma ray spectrum and fluence using BEAMnrc.
• To analyze the beam-hardening effect induced by source encapsulation.

Main Methods:

• Modeled the Gamma Knife Perfexion™ source capsule using BEAMnrc Monte Carlo code.
• Simulated a cylindrical Cobalt-60 source (1 mm diameter, 17 mm length).
• Calculated energy fluence with and without encapsulation, using specified electron and photon cutoff energies.

Main Results:

• Source encapsulation increased aggregate gamma ray particle counts by up to 92.36% and secondary gamma rays by up to 94.17%.
• Encapsulation attenuated gamma rays, altering the energy spectrum and increasing mean beam energy.
• A significant beam-hardening effect was observed due to source encapsulation.

Conclusions:

• Source encapsulation plays a critical role in modifying the spectral characteristics and fluence of Cobalt-60 Gamma Knife sources.
• The observed beam-hardening effect has implications for dose calculations and treatment planning in radiosurgery.
• BEAMnrc is a suitable tool for detailed characterization of medical radiation sources.