A Monte Carlo feasibility study on quantitative laser-driven proton radiography.

Area of Science:

• Medical Physics
• High-Energy Physics
• Biomedical Imaging

Background:

• Laser-accelerated proton bunches offer unique properties for radiological and biomedical applications.
• Accurate on-site imaging is crucial for precise biological target positioning in these applications.
• Proton radiography, utilizing laser-driven proton bunches, is a potential imaging modality.

Purpose of the Study:

• To assess the feasibility and potential of laser-driven proton radiography for imaging small objects (millimeter to centimeter scale).
• To evaluate the accuracy of water equivalent thickness (WET) reconstruction and spatial resolution.
• To investigate the imaging dose requirements for this technique.

Main Methods:

• A Monte Carlo (MC) simulation was performed to model a proton radiography setup.
• The setup included a time-of-flight spectrometer and a pixelated silicon detector.
• Water equivalent thickness was calculated using reconstructed proton energy distributions and an MC-generated look-up table.

Main Results:

• Reconstructed WET for a 1mm thin object was within 1.5% of ground truth values with a dose of 43mGy (using protons up to 20 MeV).
• Spatial resolution of 2.5 lp/mm was achieved with a 5mm object-detector gap.
• The current imaging dose limits application to radio-resistant targets, but dose reduction strategies were discussed.

Conclusions:

• Laser-driven proton radiography is a feasible technique for imaging small objects with high accuracy.
• Further optimization is required to reduce the imaging dose for broader biomedical applications.
• The study highlights the potential of this technology for precise target localization in various fields.