Medical Physics

CHLOE-PET, the ERC Starting Grant led by Dr. Gerard Ariño-Estrada, is entering a pivotal integration stage in the development of a new generation of time-of-flight PET detectors. The upper electronics modules have been built, while work continues on the lower crystal–photosensor assembly, the mechanical enclosure and thermal management. At the heart of the system is the FastIC PCB: a compact, fast signal-processing platform designed to capture the earliest detector signals and preserve the timing information that makes CHLOE possible (Figure 1). Together with BGO crystals and dual-ended SiPM readout, it enables CHLOE’s distinctive strategy of combining ultrafast Cherenkov light for timing with scintillation light for energy and position information.

CHLOE’s Cherenkov-detector research is also opening opportunities beyond PET. We have simulated a camera for Proton Range Verification (PRV) in proton—and potentially heavy-ion—therapy, based on prompt-gamma imaging (PGI) using exclusively Cherenkov light. Prompt gamma photons are produced almost instantaneously when therapeutic protons interact with tissue; detecting them can therefore provide a real-time indicator of the beam range and its distal fall-off near the Bragg-peak region. Compared with conventional scintillation-based prompt-gamma cameras, Cherenkov-only detection offers strong background discrimination, potential for high-rate operation and reduced reliance on energy-resolving readout. Figure 2 presents the simulation results: four test points are resolved comparably with a scintillation-based camera and a Cherenkov-only camera, opening a path toward two-dimensional PGI with Cherenkov detectors.