Portal de Periódicos da CAPES

Development of a Dual-Sided Readout DOI-PET Module Using Large-Area Monolithic MPPC-Arrays

2013; Institute of Electrical and Electronics Engineers; Volume: 60; Issue: 1 Linguagem: Inglês

10.1109/tns.2012.2233215

1558-1578

Aya Kishimoto, J. Kataoka, Takuya Kato, Takamasa Miura, Takeshi Nakamori, Kei Kamada, Shigeyuki Nakamura, Kenichi Sato, Yoshitaka Ishikawa, K. Yamamura, N. Kawabata, Seiichi Yamamoto,

Nuclear Physics and Applications

We are proposing a novel design for a module with depth of interaction (DOI) capability for gamma rays by measuring the pulse-height ratio of double-sided Multi-Pixel Photon Counters (MPPCs) coupled at both ends of a scintillation crystal block. Thanks to newly developed monolithic MPPC arrays consisting of 4 × 4 channels with a three-side buttable package, the module is very thin and compact, thereby enabling less dead space between each module when arranged into a fully designed gantry. To demonstrate our concept of a DOI measuring technique, we first made a 1-D crystal array consisting of five Ce-doped Gd 3 Al 2 Ga 3 O 12 (Ce:GAGG) cubic crystals measuring 3×3×3 mm 3 in size, separated by a layer of air approximately 10 μm-thick. When the light signals output from both ends are read with the 3×3 mm 2 MPPCs, the position of each crystal is clearly distinguished. The same measurements were also made using Ce-doped (Lu,Y) 2 (SiO 4 )O (Ce:LYSO), achieving a similarly good separation. We then fabricated thin Ce:GAGG 2-D crystal arrays consisting of two types: [A] 4 × 4 matrix of 3×3×3 mm 3 pixels, and [B] 10 × 10 matrix of 0.8×0.8×5 mm 3 pixels, with each pixel divided by a BaSO 4 reflector 0.2 mm-thick. Then four arrays are laid on top of each other facing the DOI direction through a layer of air 10 μm-thick. We demonstrated that the 3-D position of each Ce:GAGG pixel is clearly distinguished in both the 2-D and DOI directions for type A and B when illuminated by 662 keV gamma rays. Average energy resolutions of 9.8 ± 0.8% and 11.8 ± 1.3% were obtained for types A and B, respectively. These results suggest that our proposed method is simple and offers promise in achieving both excellent spatial and energy resolutions for future medical imaging, particularly in positron emission tomography (PET).