Neutron activation processes simulation in an Elekta medical linear accelerator head

Area of Science:

• Medical Physics
• Nuclear Engineering
• Radiation Oncology

Background:

• Linear accelerators (LINACs) are crucial in radiation therapy.
• Understanding neutron production and activation within LINACs is vital for safety and component longevity.
• Giant Dipole Resonance (GDR) photoneutrons are a significant source of radiation within LINAC heads.

Purpose of the Study:

• To perform Monte Carlo estimation of giant-dipole-resonance (GDR) photoneutrons inside a LINAC head.
• To develop and validate a method for quantifying nuclear activation of accelerator components using MCNP6.
• To determine the origin and amount of nuclear activation within the Elekta Precise LINAC head.

Main Methods:

• Detailed modeling of LINAC head geometry and materials using manufacturer information.
• Simulation of primary photon interactions and subsequent photoneutron transport using MCNP6.
• Inclusion of (n, γ) reactions to simulate activation product formation.

Main Results:

• Successful simulation of photoneutron generation and transport within the LINAC head.
• Development of a quantitative method for assessing component activation.
• Identification of key contributors to nuclear activation within the accelerator head.

Conclusions:

• The MCNP6 code provides a robust method for estimating photoneutrons and quantifying nuclear activation in LINACs.
• The developed approach is effective for identifying the sources and levels of activation in accelerator components.
• This research contributes to improved safety and operational understanding of medical linear accelerators.