[Monte Carlo simulation of a dynamic multileaf collimator:implementation and applications].

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Modeling

Context:

• Accurate simulation of linear accelerator (LINAC) heads is crucial for precise radiation therapy planning.
• The BEAM Monte Carlo code is a standard tool for simulating radiation beams, but requires specific modules for advanced components like multileaf collimators (MLCs) and backup jaws.
• Existing LINAC head models often use simplified geometries for collimating devices.

Purpose:

• To develop and validate a Monte Carlo model for simulating the accelerator heads of two identical linear accelerators equipped with multileaf collimators (MLCs) and backup jaws featuring curved leaf-ends.
• To assess the accuracy of the simulation by comparing calculated depth dose curves with measured data.
• To investigate the dosimetric impact of curved leaf-ends in MLCs and backup jaws.

Summary:

• A detailed Monte Carlo model of linear accelerator heads was created using the BEAM code, incorporating a novel module for backup jaws and the standard MLCQ module for MLCs with curved leaf-ends.
• The simulation accurately reproduced measured depth dose curves in water, with discrepancies less than 2%.
• The study found that the use of curved leaf-ends in both MLCs and backup jaws results in a higher shoulder in the y-profile compared to straight-ended designs.

Impact:

• Provides a validated computational tool for accurate simulation of complex linear accelerator head geometries.
• Offers insights into the beam shaping capabilities of modern MLCs and jaws, aiding in treatment planning optimization.
• Contributes to the understanding of dose distribution characteristics in radiation therapy, potentially improving treatment efficacy and reducing off-target dose.