Which scintillator is used in a time-of-flight PET scanner?

The correct answer is LYSO, which stands for Lutetium Yttrium Oxyorthosilicate. LYSO is a scintillator that is particularly well-suited for use in time-of-flight (TOF) positron emission tomography (PET) scanners due to its excellent detection efficiency and fast scintillation response.

In time-of-flight PET, the precise timing of the detection of annihilation photons is crucial because it allows the scanner to pinpoint the location of the positron emitters with greater accuracy. LYSO has a high light output and a short decay time compared to other scintillators, which enables it to produce a rapid response to incoming gamma photons. This rapid response is vital for the time resolution required in TOF applications, as it directly affects the ability to measure the time difference between the detection of the two photons emitted during the annihilation event.

Additionally, LYSO has a relatively high density and effective atomic number, which enhances its stopping power for gamma photons, making it proficient in converting gamma energy into detectable light. This contributes to better spatial resolution and overall image quality in PET scanning, particularly when rapid timing is needed.

While BaF2, GSO, and BGO are all scintill