Modeling of pixelated and continuous crystals for high-resolution small-animal PET imaging

por Sascha Moehrs (Functional Imaging and Instrumentation Group, Department of Physics, Universitá degli Studi di Pisa)

lunes 3 dic. 2007 12:00 → 13:00 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

Small-animal imaging is becoming a more and more important tool for preclinical studies. As a consequence many different, dedicated designs for high resolution small-animal PET scanners have been proposed. Within our group the YAP-(S)PET scanner, which is based on pixelated YAP:Ce crystals, has been designed and has now been commercialized. For a new generation of such a scanner, we envision to use a similar design, i.e. rotating planar detector heads. However, in order to improve the spatial resolution, we will use continuous crystals which are coupled to the recently developed Silicon Photomultipliers (SiPM). Within this seminar I am going to talk about the modeling of pixelated as well as continuous crystals. Building a sophisticated model of the detector is particularly important to make design decisions as well as for iterative image reconstruction algorithms. In the case of pixelated crystals, I will concentrate on a multi-ray method, which incorporates accurate analytical (geometric) considerations as well as the crystal depth. At the same time, the method has the potential to model seamlessly other physical aspects such as crystal scatter and positron range. Thus, it can be considered as an alternative to purely Monte-Carlo based methods. For continuous crystals, however, I am going to present a Monte-Carlo based approach to set up a system model. An emphasis is set on the recovery of the performance close to the edges of the crystal using a log-likelihood estimation and statistical moments to reduce the data.