TITLE
Preliminary resolution performance of the prototype system for a 4-layer DOI-PET scanner: jPET-D4
AUTHORS
Taiga Yamaya, Naoki Hagiwara, Takashi Obi, Tomoaki Tsuda, Keishi Kitamura, Tomoyuki Hasegawa, Hideaki Haneishi, Naoko Inadama, Eiji Yoshida, and Hideo Murayama
SOURCE
IEEE TRANSACTIONS ON NUCLEAR SCIENCE 53 (3): 1123-1128 Part 2, JUN 2006
(DOI: 10.1109/TNS.2006.871901)

IEEE-TNS

ABSTRACT
We are developing a high-performance brain PET scanner, jPET-D4, which provides 4-layer depth-of-interaction (DOI) information. The scanner is designed to achieve not only high spatial resolution but also high scanner sensitivity with the DOI information obtained from multi-layered thin crystals. The scanner has 5 rings of 24 detector blocks each, and each block consists of 1024 GSO crystals of 2.9 mm x 2.9 mm x 7.5 mm, which are arranged in 4 layers of 16 x 16 arrays. At this stage, a pair of detector blocks and a coincidence circuit have been assembled into an experimental prototype gantry. In this paper, as a preliminary experiment, we investigated the performance of the jPET-D4's spatial resolution using the prototype system. First, spatial resolution was measured from a filtered backprojection reconstructed image. To avoid systematic error and reduce computational cost in image reconstruction, we applied the DOI compression (DOIC) method followed by maximum likelihood expectation maximization that we had previously proposed. Trade-off characteristics between background noise and resolution were investigated because improved spatial resolution is possible only when enhanced noise is avoided. Experimental results showed that the jPET-D4 achieves better than 3mm spatial resolution over the field-of-view.

Fig.3

Fig. 2. Experimental setup of the prototype system for the line source measurement.
KEYWORDS
depth-of-interaction (DOI), maximum likelihood expectation maximization (ML-EM), positron emission tomography (PET), statistical image reconstruction, position sensitive photomultiplier tube (PS-PMT)