A method for calculating the dose due to capture gamma rays in accelerator mazes

Area of Science:

• Medical Physics
• Radiation Oncology
• Accelerator Technology

Background:

• High-energy medical accelerators produce significant radiation, including capture gamma rays.
• Shielding design for accelerator facilities requires accurate dose assessment.
• Maze structures are critical for radiation attenuation but complex to model.

Purpose of the Study:

• To describe an empirical technique for calculating capture gamma ray dose in medical accelerator mazes.
• To determine tenth-value lengths for photon dose components in accelerator mazes.
• To relate maze dose components to accelerator and room parameters.

Main Methods:

• Empirical measurement of total photon dose along the maze centerline.
• Graphical analysis to separate capture gamma dose and low-energy photon dose.
• Measurement on four medical accelerators (16.8-22.0 MV).

Main Results:

• Tenth-value lengths for capture gamma and low-energy photon dose components were determined.
• Capture gamma dose and low-energy photon dose were correlated with room surface area, isocenter-to-maze distance, and neutron head leakage.
• The technique provides a practical method for dose assessment in accelerator mazes.

Conclusions:

• The described empirical technique effectively quantifies capture gamma ray dose in medical accelerator mazes.
• Understanding dose components and their relationship to facility parameters aids in optimizing radiation shielding.
• This method supports safer design and operation of high-energy medical accelerator facilities.