Detection sensitivity of optical property-based radiation detection for PET: refraction index modulation

Optical properties modulation based ionization radiation detection method was used as a potential method for the TOF-PET detection, which is with the potential to improve the coincidence timing performance of current PET to picosecond. In this article, we present our simulation works on optical properties modulation based method and demonstrate the feasibility of the optical method for the future PET applications. We first simulate (using Monte Carlo simulation) the energy deposition track of 511 keV photons in the detector crystal, and use Matlab to convert it to the number of ionized charges generated. Then, we (using finite element calculation tools) simulate the distribution of carrier density and electric field modulation caused by ionized charges. Finally, we calculated the change in optical refractive index (n) caused by Pockels effect modulation. Cadmium Telluride (CdTe) was chosen as the detector for the simulation work. Based on our simulation conditions, a 511 keV photon depositing 350 keV energy, the induced optical photon-refraction modulation is around 4.9E-04 (in CdTe), 4.1E-04 refractive index measurement has been achieved by modern optics method. Therefore, the feasibility of the optical properties modulation method has been demonstrated.