First proton minibeam radiation therapy treatment plan evaluation

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Proton minibeam radiation therapy (pMBRT) utilizes spatial dose fractionation, showing promise in preclinical models for enhanced tumor control and reduced side effects compared to standard irradiation.
• Recent advancements in pMBRT implementation on clinical systems necessitate theoretical evaluation for patient treatment applications.

Purpose of the Study:

• To conduct a first theoretical investigation into the clinical potential of proton minibeam radiation therapy (pMBRT).
• To evaluate two clinically relevant patient treatment plans (high-grade glioma and meningioma) using a dedicated dose engine.

Main Methods:

• Development of a dedicated dose engine for pMBRT simulations.
• Comparison of pMBRT plans with standard proton therapy plans using commercial software (ECLIPSE-Varian Medical systems) and Monte Carlo simulations.
• Utilized a multislit brass collimator to shape planar minibeams (0.4 mm wide slits, 4 or 6 mm center-to-center distance).

Main Results:

• Achieved spread-out Bragg peaks and homogeneous dose distributions (±7% variation) within target volumes for both glioma and meningioma plans.
• Evaluated Peak-to-Valley Dose Ratios (PVDR) between 9.2 and 12.8 at 20 mm depth.
• Observed slightly better target homogeneity with standard proton therapy but similar dose-volume histograms for deep organs-at-risk and lower average dose for shallow organs with pMBRT.

Conclusions:

• pMBRT demonstrates potential for treating radioresistant tumors, offering advantages for shallow organs-at-risk.
• The theoretical evaluation supports further clinical research and design for future pMBRT applications.
• This novel dose delivery method warrants continued investigation for its clinical translation.