Rescaling pMBRT plans for uniform target dose.

Area of Science:

• Medical Physics
• Radiation Oncology
• Particle Therapy

Background:

• Proton minibeam radiation therapy (pMBRT) offers improved tumor control and reduced healthy tissue damage.
• Mechanical collimators are used in pMBRT for dose shaping but introduce dose inhomogeneities.
• Uniform dose delivery is crucial for pMBRT evaluation and comparison with conventional radiotherapy.

Purpose of the Study:

• To develop and validate a combined transverse and longitudinal rescaling method to enhance dose uniformity in pMBRT.
• To address dose inhomogeneities caused by mechanical collimators in pMBRT.
• To achieve clinically acceptable dose uniformity within the planning target volume.

Main Methods:

• Utilized Geant4 Monte Carlo simulations to quantify dose profiles for various energy layers.
• Developed a rescaling algorithm adjusting spot weights based on proton energy and lateral position.
• Applied combined transverse and longitudinal rescaling factors to correct collimator-induced dose inhomogeneities.

Main Results:

• Individual transverse or longitudinal rescaling alone did not meet clinical standards for dose uniformity.
• The combined rescaling method achieved a uniform dose distribution within the planning target volume.
• The final dose distribution was within the clinically acceptable range of 95%-107%.

Conclusions:

• Combined transverse and longitudinal rescaling is essential for achieving uniform dose coverage in pMBRT.
• The developed method significantly improves dose homogeneity in pMBRT.
• Optimized pMBRT dose uniformity facilitates clinical evaluation and comparison.