Conference Paper

High resolution large formatted CMOS flat panel sensors for X-ray

Hamamatsu Photonics, Japan
DOI: 10.1109/NSSMIC.2003.1352297 Conference: Nuclear Science Symposium Conference Record, 2003 IEEE, Volume: 3
Source: IEEE Xplore


This paper describes world largest monolithic CMOS flat panel sensor (FPS) and high speed amplifier with columnar CsI scintillator directly deposited onto the active area. These elements have been employed as a compact digital camera module for dynamic X-ray imaging will be used in digital mammography and scientific image measurement. The FPS has a diagonal size of 11 inches and 4,416 × 3,520 pixel array (15,544,320 pixels), which features a high resolution of 10 lp/mm with single pixel drive. The key material of the FPS is monocrystalline silicon optimized for use in digital radiography. The sensor utilizes a direct deposited scintillator layer made from high resolution, high luminance CsI crystals grown into a needle structure onto a large formatted photodiode array for indirect detection of X-ray images. The CsI scintillation spectrum well matches the spectral response range of the photodiode. The CsI has the advantages of high sensitivity and high resolution compared to GOS phosphors screen. These image sensors are manufactured in a 0.15μ 12 inches CMOS process allowing a high fill factor of 76% for 50μ pixel. Only one chip is taken from one 12 inches wafer in order to realize a seamless active area. The monolithic amplifier blocks have 4,416 channels of charge amplifiers with internal CDS (correlated double sampling) circuit has an optimal design yielding a high gain of 0.26 μV per electron and a data transfer speed of 17.8 Mbytes per second in sufficient low noise. This paper discusses the system design, dynamic range, resolution, detective quantum efficiency (DQE) and imaging performance using ACR mammography phantom.

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    01/2008; 25(1).
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    ABSTRACT: We evaluated X-ray image performance for several scintillators and a CMOS APS imager by both diagnostic radiography and mammography conditions. Commercially available scintillators such as Lanex screen, needle structured CsI (Tl), and fiber optic structured CsI (Tl) were coupled with a CMOS APS imager. The X-ray machines used in this study were fixed tube voltage of 80 kVp and variable tube current over 0.33 mA using LISTEMtrade for diagnostic radiography, and fixed tube voltage of 28 kVp and variable tube current over 16 mA using Alpha-STtrade for mammography. We used the RadEye1trade CMOS APS imager having an active area of 25 mm by 50 mm with the pixel size of 48 m.
    IEEE Transactions on Nuclear Science 07/2008; 55(3-55):1327 - 1332. DOI:10.1109/TNS.2008.922214 · 1.28 Impact Factor
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    ABSTRACT: Contrast enhancement by refraction was used to visualize tumours in the rabbit lung. VX2 tumour cells were intravenously injected into a rabbit. After 14 days the rabbit was euthanized and the lungs were imaged. Refraction-enhanced X-ray images were obtained with a sample-to-detector distance of 2.65-6m. The beamline BL20B2 at the SPring-8 synchrotron radiation facility was used for the experiment, with a monochromatic X-ray beam with an energy of 33.2 keV. In the case of projection images, it was found that refraction did not help visualization of small tumours: the nodules did not show up with sharply defined edges. In tomography, tumours with a size of 1-10mm were clearly visualized, together with blood vessels with a diameter down to 0.4mm. These results show that refraction-enhanced imaging may be useful in human lung tomography to find small tumours.
    European journal of radiology 07/2008; 68(3 Suppl):S54-7. DOI:10.1016/j.ejrad.2008.04.030 · 2.37 Impact Factor
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