Monte Carlo based modulated electron beam treatment planning using a few-leaf electron collimator--feasibility study

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Electron beam therapy offers potential for conformal dose distributions in superficial targets but lacks flexible collimation compared to photon IMRT.
• Existing electron-specific multileaf collimators are bulky and impractical for certain treatment sites like the head and neck.

Purpose of the Study:

• To investigate the treatment planning capabilities of a proposed 'few-leaf' electron collimator (FLEC) for radiation therapy.
• To assess the feasibility of using FLEC for delivering conformal dose distributions to superficial targets.

Main Methods:

• Developed a Monte Carlo model of the FLEC, comprising four motor-driven trimmer bars.
• Optimized dose distributions using a simulated annealing inverse planning algorithm with pre-generated dose kernels and dose-volume constraints.
• Evaluated the system using phantom setups and a realistic patient case.

Main Results:

• Demonstrated the ability to generate highly conformal dose distributions for superficial targets using the FLEC.
• The FLEC system allows shaping of irregular fields by combining rectangular fieldlets.
• Estimated treatment delivery times suggest a full fraction can be completed within 15 minutes.

Conclusions:

• The proposed few-leaf electron collimator (FLEC) is a viable accessory for standard radiotherapy equipment.
• FLEC facilitates the creation of conformal dose distributions, overcoming limitations of current electron therapy collimation.
• This technology shows promise for improving the efficiency and efficacy of electron beam radiotherapy, particularly for superficial tumors.