Cherenkov detectors are an indispensable tool in a number of particle physics experiments, in particular in flavor physics. For the next generation of particle physics experiments, novel methods will be employed where single photons have to be detected with an excellent time precision. Several novel very fast light sensors with single photon detection abilities have been developed for this purpose, including micro-channel plate PMTs, hybrid avalanche photo-diodes (HAPD), and solid state sensors (SiPMs). It turned out that these sensors can also be used in Cherenkov light based detection of annihilation gamma rays in time-of-flight positron emission tomography (TOF-PET). In the seminar we will discuss advances in instrumentation and their implications in high precision medical imaging, allowing a construction of full-body scanners. Finally, we will review results of tests with a TOF-PET prototype and possible ways on how to proceed.