Magnetic repulsion of linear accelerator contaminates

Area of Science:

• Medical Physics
• Radiation Oncology
• Materials Science

Background:

• Electron contamination in clinical linear accelerators increases skin dose.
• Reducing this contamination is crucial for improving patient safety and treatment outcomes.
• Neodymium Iron Boron (NdFeB) magnets offer unique properties for potential clinical application.

Purpose of the Study:

• To evaluate the efficacy of NdFeB magnets in reducing electron contamination.
• To assess the impact of these magnets on central axis entrance surface dose.
• To determine the clinical usability of such a magnetic device.

Main Methods:

• NdFeB rare earth permanent magnets were attached to the accessory mount of a clinical linear accelerator.
• Measurements of central axis entrance surface dose were performed with and without the magnetic device.
• Experiments were conducted for different field sizes and with a perspex block tray.

Main Results:

• The magnetic device reduced central axis entrance surface dose by 11% for a 20 x 30 cm field size (from 32% to 21% of maximum dose).
• A further reduction of 14% was observed for a 20 x 20 cm field size with a 6 mm perspex block tray (from 32% to 18% of maximum dose).
• The magnetic device was found to be lightweight and clinically usable.

Conclusions:

• NdFeB magnets effectively reduce electron contamination in clinical linear accelerators.
• The magnetic device significantly decreases central axis entrance surface dose, enhancing skin sparing.
• The lightweight and practical nature of the magnetic device supports its clinical implementation in radiation therapy.