@misc{oai:repo.qst.go.jp:00068811,
 author = {Inadama, Naoko and Tsuda, Tomoaki and Murayama, Hideo and Yamaya, Taiga and Yoshida, Eiji and Shibuya, Kengo and Tanada, Shuji and Kitamura, Keishi and 稲玉 直子 and 津田 倫明 and 村山 秀雄 and 山谷 泰賀 and 吉田 英治 and 澁谷 憲悟 and 棚田 修二 and 北村 圭司},
 month = {Jun},
 note = {Objectives: jPET-RD a small animal PET scanner which is under development at our institute. Its capability of 4-layer DOI encoding in the detector allows closer detector setting to a subject for keeping large axial view that is greatly advantageous in terms of high sensitivity but, at the same time, causes significant parallax error in non-DOI detector systems. At the present stage, we developed an experimental system which replicates detector geometry in the jPET-RD. With a pair of prototype jPET-RD detectors, we measured spatial resolution in the system to show the effects of the 4-layer DOI encoding on uniformity in the resolution.
Methods: The jPET-RD detector is designed to have a 256ch flat panel position sensitive PMT (FP-PMT) and 4096 Lu2(1-x)Y2xSiO5 (LYSO) crystal elements, which arranged in four layers of 32 x 32 arrays. Each crystal size is 1.46 mm x 1.46 mm x 4.5 mm. 6 detectors form one detector ring of 8.8 cm diameter. The prototype detector we developed has full 32 x 4 crystal elements in transaxial and depth but 8 crystal alignments in axial direction. A 68Ge-68Ga line source of 1.65 mm in diameter is first placed at the center of the field of view (FOV) and coincidence events are measured at all detector pair positions on the experimental system. Signals from FP-PMT anodes are reduced to 8 signals by a resistor-chain in each prototype detector and provided to the coincidence circuit of the system. Measurements are performed with the source positions of every 0.5 cm steps from the center till 4.0 cm off-center. Point spread functions (PSFs) are measured as FWHM of the image reconstructed by filtered backprojection.
Results: PSFs at the center and at the 4.0 cm off-center source positions were measured to be 2.2 mm and 2.5 mm in FWHM, respectively. The average of all 9 source positions was 2.5 mm. Without DOI information, these spatial resolutions degraded to 2.6 mm (center), 5.0 mm (4.0 cm off-center) and 3.3 mm (average). Intrinsic spatial resolutions of 1.46 mm (center) and 1.88 mm (4.0 cm off-center) with DOI information are estimated by deconvoluting the source distribution, with the assumption that the source distribution is a Gaussian function of 1.65 mm FWHM.
Conclusions: Almost uniform spatial resolution from the center to the top face of detectors was obtained by the jPET-RD experimental system., 第５３回米国核医学会},
 title = {Preliminary Resolution Evaluation of jPET-RD: a 4-layer DOI-PET Scanner for Small Animals},
 year = {2006}
}