In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillatorbased CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd 2 O 2 S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm 2 active area and a 48 µm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE). KEYWORDS: X-ray detectors; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators); Scintillators and scintillating fibres and light guides; X-ray radiography and digital radiography (DR)

Color filter process for CMOS image sensor process is divided into micro-lens and color layer steps. And the structure of color layers is made by building up photo resist(PR). Then, color is distinguished by color pattern of image sensor after light induced transmits through the pattern built. So negative PR is generally used for the structural characteristic in color filter process. Negative PR needs high-dose which results in deactivation effect by oxygen radical. In this paper, the experiment was developed by reducing oxygen radical and the process in order to pattern by reduced dose was acquired