Accurate time estimation utilizing (semi-)prompt photons can benefit Time-of-Flight Positron Emission Tomography. However, we are limited to fewer detected photons with current state-of-the-art ultra-fast detectors, ultimately resulting in the pursuit of every single photon.
In the lab, this quest starts with light production (Cherenkov photons, quantum confinement luminescence etc), continues with the efficient light transport to the photodetector (high refractive index materials, photonic crystals, novel readout designs) over the photodetector (SPTR, PDE, correlated noise) and finishes with signal processing (low noise, high bandwidth electronics, fast ASIC, power consumption) and digitization. Finally, the measured data can be reconstructed to images using the appropriate TOF system response matrix. However, even the best time resolution does not achieve the desired image quality if quantities such as sensitivity, energy resolution, or depth-of-interaction are overlooked.
This contribution provides an extensive review of recent developments in fast timing with (semi-)prompt photons, emphasizing the whole radiation detector chain. In addition, we discuss system integration aspects, limits and paths for future detector improvements toward and below 100 ps CTR with PET-sized geometries.