Speaker
Dr
P. Lecoq
Description
Abstract: Charged particles traversing a medium at a speed exceeding the speed of light in this medium will emit Cerenkov radiation. In biological soft tissues the contents of water ranges from 70% in the brain to 90% in lungs. With the index of refraction of water (1.33) the Cerenkov energy threshold is 260 KeV. Scintillating crystals used as radiation detectors in SPECT and PET scanners have a much higher index of refraction and therefore a lower Cerenkov energy threshold:
Crystal Refraction index Cerenkov energy threshold (KeV)
NaI :Tl 1.85 96
CsI:Tl 1.80 104
LSO:Ce 1.82 101
LaBr3:Ce 1.88 92
LuAP:Ce 1.95 84
This talk will illustrate how the Cerenkov emission produced by b+ or b- radioisotopes in the human body can be used as a new imaging modality. But it will also discuss under which condition the Cerenkov photons emitted by the recoil electrons during the g conversion process in the detecting medium can be exploited to improve the timing resolution of PET scanners.
