First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

Area of Science:

• Medical Physics
• Nuclear Instrumentation
• Radiotherapy Physics

Background:

• Particle therapy generates positron emitters during irradiation.
• Positron Emission Tomography (PET) can image activity correlated with radiation dose.
• In-beam PET offers real-time quality assurance for dose delivery.

Purpose of the Study:

• To present a novel dedicated PET system for in-beam measurements.
• To evaluate the system's performance during proton therapy.
• To assess the impact of including beam-on data on range verification accuracy.

Main Methods:

• Developed a PET system with two detector heads (10x10 cm each) using LYSO crystals.
• Implemented a modular acquisition system with a 3 ns coincidence window for high count rates.
• Tested the system during proton irradiation at the CATANA facility using PMMA phantoms.

Main Results:

• The in-beam PET system sustained high single count rates with low random coincidences (<25%).
• Including beam-on data significantly improved the accuracy and precision of range measurements.
• Beam-on data alone achieved sub-millimeter precision (better than 1 mm) with ≥5 Gy dose.

Conclusions:

• The developed in-beam PET system enables real-time monitoring during particle therapy.
• Acquiring data during irradiation (beam-on) is superior to post-irradiation measurements for range verification.
• This technology enhances quality assurance in proton therapy by providing precise dose delivery feedback.