TITLE
Performance of 256ch Flat Panel PS-PMT with Small Crystals for a DOI PET Detector
AUTHORS
Naoko Inadama, Hideo Murayama, Mitsuo Watanabe, Tomohide Omura, Takaji Yamashita, Hideyuki Kawai, Narimichi Orita, and Tomoaki Tsuda
SOURCE
IEEE TRANSACTIONS ON NUCLEAR SCIENCE 52 (1): 15-20 Part 1, FEB 2005
(DOI: 10.1109/TNS.2004.843148)

IEEE-TNS

ABSTRACT
A 256 channel flat panel position, sensitive photomultiplier tube (256ch FP-PMT) was evaluated for application to a depth of interaction (DOI) PET detector composed of small crystal elements. The 256ch FP-PMT has 52 x 52 mm opening area with 89% useful area. Its 256 anodes are placed at a 3.04 mm interval. To estimate the FP-PMT performance, light spread functions of anodes at central and peripheral regions of a prototype 256ch FP-PMT were measured with a Gd2SiO5 (GSO) crystal sized 1.42 x 1.42 x 4.5 mm. The crystal cross section area is about one quarter of one anode area of the FP-PMT. It was found that light spread functions of peripheral anodes were similar to the functions of central anodes and also the functions measured with a 2.9 x 2.9 x 7.5 mm GSO crystal which has almost the same dimensions of cross-section as the anode area. Transit time fluctuation among the 256ch FP-PMT anodes was estimated by measuring time resolutions of a LuYSiO5 (LYSO) crystal at some central and peripheral positions. The LYSO crystal has the same dimensions as the smaller GSO crystal. BaF2 was used for a reference detector. The obtained distributions show about the same time resolution between the central and peripheral positions and the full width at half maximum is (366 +/- 15) ps. The transit time fluctuation is 106 ps. Two-dimensional position histograms of a 32 x 32 GSO crystal array and two layers of 9 x 9 GSO crystal arrays are obtained by uniform gamma-ray irradiation. The crystal dimensions are 1.42 x 1.42 x 4.5 mm so that the 32 x 32 array covers all the useful area and indicates variation of crystal identification performance over the useful area. The 9 x 9 x 2 array is coupled to peripheral region. The resultant histograms confirm that a 256ch FP-PMT has enough capability for identifying crystals of this size even on the periphery and in DOI arrangement.

Fig.6

Fig. 6. Two-dimensional position histogram of a 32 x 32 GSO crystal array coupled to a 256ch FP-PMT. The crystal element dimensions are 1.42 x 1.42 x 4.5 mm3.
KEYWORDS
multi-anode photomultiplier tube (PMT); position sensitive detector; scintillation detector; small animal positron emission tomography (PET)