CHEMONO: a Cherenkov-Only Monolithic Detector for PGI in Proton Range Verification

Area of Science:

• Medical Physics
• Nuclear Instrumentation
• Radiation Detection

Background:

• Proton range verification (PRV) is crucial in proton therapy but remains a clinical challenge.
• Prompt-gamma imaging (PGI) using scintillation detectors is a leading PRV method.
• Existing PGI detectors require scintillation crystals coupled to photodetectors.

Purpose of the Study:

• To develop and evaluate monolithic pure Cherenkov emitter crystals for PRV.
• To demonstrate the spatial resolution capabilities of Cherenkov detectors for PGI.
• To assess the potential of this new detector concept as an alternative to current PGI systems.

Main Methods:

• A detector composed of a PbF2 Cherenkov crystal coupled to an 8x8 SiPM array was constructed.
• A row-column readout system was implemented, triggered by column sums.
• Three event reconstruction algorithms (CoG, RTP, NN) were tested for spatial resolution analysis.

Main Results:

• The Cherenkov detector demonstrated spatial resolution capabilities for the first time.
• The neural network (NN) algorithm achieved the best average spatial resolution of 3.7±0.9 mm FWHM.
• CoG and RTP algorithms showed consistent positional shifts, with average resolutions between 4-7 mm.

Conclusions:

• Monolithic pure Cherenkov emitters show promise for multi-MeV gamma imaging in PRV.
• This detector concept offers potential advantages including high count rate capability, background rejection, and lower cost.
• Cherenkov detectors represent a viable alternative for collimated PGI in proton therapy applications.