A novel 2D binary collimator for IMRT dose delivery: dosimetric characterization using Monte Carlo simulations.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Current radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), face challenges in dose delivery speed, particularly in rotational delivery.
• Efficient and precise beam shaping is crucial for optimizing dose distribution and minimizing radiation exposure to healthy tissues.

Purpose of the Study:

• To introduce and present the technical concept of a novel two-dimensional binary multileaf collimator (2D-bMLC).
• To conduct a comprehensive dosimetric evaluation of the 2D-bMLC using Monte Carlo simulations.
• To assess the potential of the 2D-bMLC for fast dose delivery in rotational IMRT.

Main Methods:

• Development of a Monte Carlo model for an exemplary 30x30 element 2D-bMLC.
• Characterization of linac phase space using a virtual source model of a flattening filter-free 7 MV linear accelerator.
• Calculation of primary radiation efficiency and collimator leakage.

Main Results:

• The 2D-bMLC achieved a primary radiation efficiency of 43% for an open field configuration.
• Calculated leakage for the closed collimator was below 0.5%.
• Geometric bixel widths increased predictably towards the collimator edges, with a slight tongue-and-groove effect observed between abutting elements.

Conclusions:

• The established dosimetric model of the 2D-bMLC demonstrates promising results for its intended application.
• The 2D-bMLC concept is suitable for fast rotational IMRT treatments.
• Further investigation with real patient plans is warranted to confirm clinical benefits.