Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) annihilation photon pair coincidence time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit of around 100 ps. On the other hand, modulation mechanisms of a material's optical properties as exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to study whether ionizing radiation can also produce fast modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately 5x10^-6 is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the radiation source flux rate and average photon energy.

Date Published: 3 October 2016
PDF: 12 pages
Proc. SPIE 9969, Radiation Detectors: Systems and Applications XVII, 99690G (3 October 2016); doi: 10.1117/12.2241608

Published in SPIE Proceedings Vol. 9969:
Radiation Detectors: Systems and Applications XVII
Gary P. Grim; H. Bradford Barber; Lars R. Furenlid, Editor(s)