Electron dose optimisation based on tumour thickness and shape for photon multi-leaf collimated megavoltage electrons

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Modulated Electron Radiation Treatment (MERT) requires precise dose delivery.
• Tumor thickness is a critical factor in radiation therapy planning.
• Current MERT techniques may lack optimization for varying tumor depths.

Purpose of the Study:

• To develop and validate an optimization method for MERT that accounts for tumor thickness.
• To improve dose coverage and minimize dose spread within the tumor.
• To establish a robust planning technique for MERT.

Main Methods:

• Developed an optimization method incorporating tumor bed matrix and depth data.
• Utilized EGSnrc-based Monte Carlo codes (BEAMnrc, DOSXYZnrc) for accelerator modeling and dose scoring.
• Applied least squares cost function minimization for sub-beam energy and intensity modulation.

Main Results:

• Successfully modeled electron beam segments and sub-beams for MERT.
• Investigated intensity-modulated electron sub-beams for parotid lesion irradiation.
• Generated weight factors for beam intensity modulation to optimize dose delivery.

Conclusions:

• The developed optimization method provides a robust technique for planning MERT.
• The method yields dose-covering results with optimal dose spread within the tumor.
• This approach aligns with established literature findings for MERT effectiveness.