Simulation-Based X-Ray Spectrum Optimization for Dose Enhancement in X-Ray-Induced Photodynamic Therapy with...

Area of Science:

• Medical Physics
• Radiotherapy
• Nanomedicine

Background:

• X-ray-induced photodynamic therapy (X-PDT) uses nanoprobes for deep-tumor treatment.
• Optimal X-ray energy selection is a critical challenge for X-PDT efficacy.
• Maximizing dose enhancement requires systematic energy optimization.

Purpose of the Study:

• To identify the optimal X-ray energy for X-PDT.
• To evaluate nanoprobe-mediated dose enhancement across clinical X-ray energies.
• To correlate simulation data with experimental tumor growth inhibition.

Main Methods:

• Developed a Geant4 Monte Carlo model to simulate absorbed dose in tumor phantoms.
• Simulated dose with and without X-PDT nanoprobes across X-ray energies (20-160 kVp).
• Calculated Dose Enhancement Ratio (DER) and correlated simulated dose with in vivo tumor growth inhibition (TGI).

Main Results:

• Absorbed dose peaks at shallow depths (<1.0 mm).
• 60 kVp X-ray energy yielded the highest peak dose and maximum DER.
• Simulated dose with nanoprobes showed stronger correlation with experimental TGI, validating the model.

Conclusions:

• An optimal X-ray excitation energy maximizes X-PDT therapeutic effects.
• Monte Carlo simulation can optimize X-PDT treatment protocols.
• Accurate X-PDT simulation requires integration with biological modeling.