A torus source and its application for non-primary radiation evaluation.

Area of Science:

• Medical Physics
• Radiation Oncology
• Particle Accelerator Technology

Background:

• Non-primary radiation from proton therapy can increase secondary malignancy risk in long-term survivors.
• Evaluating non-primary radiation dose levels against IEC standards is crucial for proton therapy system quality.
• Proton therapy systems, unlike photon therapy, have multiple subsystems that can generate non-primary radiation.

Purpose of the Study:

• To develop a systematic method for evaluating non-primary radiation dose levels from proton therapy systems.
• To assess the radiation safety of the P-Cure synchrotron-based proton therapy system.
• To introduce a novel torus source model for accurate beam loss and non-primary dose evaluation.

Main Methods:

• Monte Carlo (MC) simulations using FLUKA code to model 7 radiation sources in the P-Cure system.
• Development and application of a new torus source model to define off-orbit particle bombardment.
• Calculation of non-primary doses in different regions (15-50 cm and 50-200 cm) relative to the planned dose.

Main Results:

• Non-primary doses from all modeled sources were significantly lower than IEC requirements.
• The P-Cure synchrotron-based proton therapy system demonstrated a clean and patient-friendly radiation profile.
• The study concluded that inner shielding concrete between the accelerator and patient is unnecessary for this system.

Conclusions:

• The developed MC procedure and torus source model provide a feasible method for evaluating non-primary radiation in synchrotron-based proton therapy.
• The findings confirm the P-Cure system's compliance with IEC standards, ensuring patient safety.
• The torus source model has broad applicability for dose evaluation in various accelerator components like bending magnets.