Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor

K. Sato; F. Nariyuki; H. Nomura; A. Takasu; S. Fukui; M. Nakatsu; Y. Okada; T. Nabeta; Y. Hosoi

doi:10.1117/12.877752

16 March 2011 Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor

K. Sato, F. Nariyuki, H. Nomura, A. Takasu, S. Fukui, M. Nakatsu, Y. Okada, T. Nabeta, Y. Hosoi

Author Affiliations +

Proceedings Volume 7961, Medical Imaging 2011: Physics of Medical Imaging; 79614I (2011) https://doi.org/10.1117/12.877752
Event: SPIE Medical Imaging, 2011, Lake Buena Vista (Orlando), Florida, United States

Abstract

In this study, we characterized the image quality of two types of indirect-conversion flat-panel detectors: an X-ray incident-side photo-detection system (IS) and an X-ray penetration-side photo-detection system (PS). These detectors consist of a Gd₂O₂S:Tb (GOS) scintillator coupled with a photodiode thin film transistor (PD-TFT) array on a glass substrate. The detectors have different X-ray incident directions, glass substrates, and scintillators. We also characterized the effects of layered scintillator structures on the image quality by using a single-layered scintillator containing large phosphor grains and a double-layered scintillator consisting of a layer of large phosphor grains and a layer of small phosphor grains. The IS system consistently demonstrated a higher MTF than the PS system for a scintillator of the same thickness. Moreover, the IS system showed a higher DQE than the PS system when a thick scintillator was used. While the double-layered scintillators were useful for improving the MTF in both systems, a thick single-layered scintillator was preferable for obtaining a high DQE when the IS system was applied. These results indicate that an IS system can efficiently utilize the light emitted from the phosphor at the far side of the PD without the occurrence of blurring. The use of IS systems makes it possible to increase the thickness of the scintillator layer for improving the sensitivity without reducing the MTF, which increases the DQE. The DQE of the IS system was 1.2 times that of the PS system, despite the absorption of X-rays at the glass substrate before entering the phosphor.

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K. Sato, F. Nariyuki, H. Nomura, A. Takasu, S. Fukui, M. Nakatsu, Y. Okada, T. Nabeta, and Y. Hosoi "Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor", Proc. SPIE 7961, Medical Imaging 2011: Physics of Medical Imaging, 79614I (16 March 2011); https://doi.org/10.1117/12.877752

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