Proton minibeam radiation therapy: Experimental dosimetry evaluation

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Techniques

Background:

• Proton minibeam radiation therapy (pMBRT) combines proton therapy's physical benefits with spatial fractionation for normal tissue preservation.
• Current radiotherapy techniques face challenges in maximizing tumor dose while minimizing damage to surrounding healthy tissues.

Purpose of the Study:

• To demonstrate the technical feasibility of implementing proton minibeam radiation therapy (pMBRT).
• To conduct dosimetry measurements for proton minibeams at Institut Curie - Proton Therapy Center.

Main Methods:

• Generated proton minibeams (400 and 700 μm width) using a multislit collimator.
• Performed absolute and relative dosimetry using ionization chambers and radiochromic films in a phantom.
• Evaluated depth dose curves, lateral profiles, peak-to-valley dose ratios (PVDR), and beam widths.

Main Results:

• Maintained transverse dose peaks and valleys, with PVDR decreasing with depth.
• Observed homogeneous dose profiles beyond 6.7 cm due to Coulomb scattering.
• Achieved comprehensive dosimetric data for small proton field sizes, crucial for biological experiments.

Conclusions:

• pMBRT presents a promising strategy for reducing radiotherapy side effects.
• Experimental data confirm the feasibility of pMBRT, potentially enabling high tumor doses with normal tissue sparing.
• Further biological experiments are necessary to validate the clinical potential of pMBRT.