• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.703-708
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• 2022

A detector module measuring the depth of interaction(DOI) was designed to improve the spatial resolution of positron emission tomography(PET). The scintillation pixel array consists of two layers, and a light guide is inserted between the layers to make the light generated through the gamma-ray event different for each layer. There are four light guides, and one light guide is designed to be coupled to a 2 × 2 array of scintillation pixels. The light generated from the top layer is moved to the photosensor with a wider distribution through the light guide, and the light generated from the bottom layer is incident on the photosensor with a narrower distribution than the top layer. When a flood image is reconstructed based on the signals obtained from the photosensor by different distributions, scintillation pixels are imaged at different positions for each layer. To verify this, a DETECT2000 simulation tool that simulates the behavior of light in a scintillator was used. By designing a scintillation pixel array, a detector consisting of a light guide and a photosensor, a gamma ray event was generated in all scintillation pixels to obtain a flood imgae. As a result, it was confirmed that the top and bottom layers were imaged at different positions and completely separated. When this detector is applied to PET, it is considered that image quality can be improved through imporved spatial resolution.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.929-934
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• 2018

Studies for counting and detecting X-rays for the improvement of image quality and material analysis are active. In this work, the detector for X-ray photon counting was designed using Multi-pixel photon counter (MPPC) array and the detector characteristics were evaluated through simulation. Geant4 Application for Tomographic Emission (GATE) was used to obtain the position where the X-ray and the scintillation interacted, and this position was used as the light generation position of DETECT2000. 0.5 mm and 1 mm thick Gadolinium Aluminium Gallium Garnet (GAGG) scintillators were used and the light generated through a $4{\times}4$ array of MPPCs was acquired. The spatial resolution of the designed detector was evaluated by reconstructed image using the light signal acquired for each channel. We obtained images of more than 2 lp/mm in both 0.5 mm and 1 mm thick GAGG scintillation. When this detector is used in a X-ray system, a low-cost system capable of photon counting can be made.

• ETRI Journal
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• v.30 no.5
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• pp.747-749
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• 2008

We introduce a pixel-structured scintillator realized on a flexible polymeric substrate and demonstrate its feasibility as an X-ray converter when it is coupled to photosensitive elements. The sample was prepared by filling $Gd_2O_2S:Tb$ scintillation material into a square-pore-shape cavity array fabricated with polyethylene. For comparison, a sample with the conventional continuous geometry was also prepared. Although the pixelated geometry showed X-ray sensitivity of about 58% compared with the conventional geometry, the resolving power was improved by about 70% above a spatial frequency of 3 $mm^{-1}$. The spatial frequency at 10% of the modulation-transfer function was about 6 $mm^{-1}$.