Scattered neutron dose equivalent from an active scanning proton beam delivery system

Area of Science:

• Medical Physics
• Radiation Oncology
• Particle Therapy

Background:

• Proton therapy utilizes active scanning beam delivery systems.
• Secondary neutron production is a concern in proton therapy.
• Quantifying neutron dose is crucial for patient safety.

Purpose of the Study:

• To investigate neutron production from a novel active scanning proton beam delivery system.
• To determine the neutron dose equivalent at various angles and beam parameters.
• To assess the potential for mitigating secondary neutron dose.

Main Methods:

• Neutron dose equivalent measurements using a rem detector (≤10 MeV).
• Measurements conducted at 0, 45, and 90 degrees relative to the beam axis.
• Evaluations performed across proton beam energies (127-208 MeV) and scanned field sizes (25-144 cm²).

Main Results:

• Maximum neutron dose equivalent observed was 0.43 mSv/(proton treatment Gy).
• Highest dose recorded at 90 degrees for 208.4 MeV and 144 cm² field size.
• Neutron production is dependent on beam energy and field size.

Conclusions:

• The novel active scanning system produces measurable secondary neutron doses.
• Optimizing treatment nozzle parameters and employing shielding can mitigate neutron dose.
• Further research can refine strategies for minimizing neutron exposure in proton therapy.