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Imaging performance of an amorphous selenium flat-panel detector for digital fluoroscopy

2003; SPIE; Volume: 5030; Linguagem: Inglês

10.1117/12.480131

1996-756X

Dylan Hunt, O. Tousignant, Y. Demers, Luc Laperrière, J. A. Rowlands,

Radiation Detection and Scintillator Technologies

The imaging performance of a 34.5 x 34.5 cm 2 direct conversion flat-panel detector with a 1 mm thick amorphous selenium layer was measured over the fluoroscopic exposure range (0.56 - 10.8 μR/frame). The pixels measured 300 x 300 μm. Measurements of the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE) were made. By comparing the MTF to the sinc function the measured effective fill factor of the active matrix was determined to be almost 100%. The electronic noise of the active matrix was measured and found to be 3800 electrons. The DQE( f ) was found to be better than the expected sinc 2 function. This was due to the presence of a pre-sampling blur identified as charge trapping at an interface in the a -Se layers. At the highest exposure investigated, the DQE(0) was found to be less than the quantum efficiency and the difference was ascribed to a combination of the electronic noise, a small drop in sensitivity due to the charge trapping blur, and incomplete charge collection.