[12p-M103-1~11] 2.2 Detection systems

▼ [12p-M103-2] Four-layer DOI PET detector with 1 mm crystal pitch

〇(P)HanGyu Kang¹, Sodai Takyu¹, Fujino Obata¹, Fumihiko Nishikido¹, Eiji Yoshida¹, Taiga Yamaya¹ (1.NIRS-QST)

Keywords:Positron emission tomography (PET), Depth of interaction (DOI), Silicon photomultiplier (SiPM)

Depth of interaction (DOI) information can minimize the parallax error at the peripheral field of view of a positron emission tomography (PET). In the previous study, we developed a four-layer DOI PET detector with 1.5 mm crystal pitch. The aim of this study is to develop a four-layer DOI PET detector with 1 mm crystal pitch to improve the spatial resolution. The proposed four-layer DOI PET detector consists of an 8 × 8 LYSO crystal array (1 × 1 × 5 mm³) stacked in four-layer which yielded a total thickness of 20 mm, an acrylic light guide (13 × 13 × 1 mm³), and 4 × 4 SiPM array (Hamamatsu, S13361-3050NE-04, Japan) with a pixel pitch of 3.2 mm. In order to encode the DOI information into 2D flood histogram, a combination of enhanced specular reflector (ESR) and room temperature vulcanizing (RTV) rubber was used (Fig. 1). The sixteen SiPM output signals were multiplexed into four positional signals (A, B, C, and D) using charge division circuit, and the multiplexed signals were digitized using CAMAC DAQ (Fig. 2). A Na-22 point source was used to irradiate 511 keV gamma photon to the LYSO crystal array. The energy resolution was measured to be 30.8% (Fig. 3). All the LYSO crystals could be identified in 2D flood histogram except at the corner region (Fig. 4). In conclusion, a single-ended readout four-layer DOI PET detector with 1.1 mm LYSO crystal pitch was developed. In future, the corner crystal identification will be optimized.