Tuning spatially fractionated radiotherapy dose profiles using the moiré effect

Area of Science:

• Medical Physics
• Radiation Oncology
• Biophysics

Background:

• Spatially Fractionated Radiotherapy (SFRT) shows promise for reduced side effects and better local control in cancer treatment.
• Proton minibeam radiotherapy (pMBRT) offers potential for superior normal tissue sparing compared to conventional proton therapy.
• Effective beam generation is crucial for pMBRT's clinical application, requiring adjustable dose profiles.

Purpose of the Study:

• To investigate a dual collimator system (DCS) utilizing the moiré effect for generating pMBRT dose profiles.
• To demonstrate the flexibility in modifying dose distribution center-to-center distance (CTC) using a DCS.
• To explore the DCS's potential for simple and effective pMBRT beam generation.

Main Methods:

• Geant4 Monte Carlo simulations were employed to model the dose profiles generated by a DCS.
• The impact of DCS angle variations on CTC was analyzed, ranging from 10 to 50 degrees.
• The influence of multi-slit collimator (MSC) parameters on dose profiles was investigated.

Main Results:

• Varying the DCS angle from 10 to 50 degrees allowed CTC adjustment from 11.8 mm to 2.4 mm.
• MSC physical parameters significantly influenced the spatially fractionated dose profile, including CTC, throughput, and spacing.
• The DCS demonstrated capacity for dynamic alteration of irradiation profiles and potential for improved normal tissue sparing.

Conclusions:

• The dual collimator system is an efficient and adaptable tool for refining pMBRT techniques.
• Precise control over irradiation profiles can be achieved, facilitating tailored dose adjustments for clinical scenarios.
• The DCS shows versatility for various SFRT modalities and beam types (X-rays, electrons).