Image quality of scintillator-based x-ray electronic imagers

Moy, Jean-Pierre

doi:10.1117/12.317016

Cited by 17 publications

(11 citation statements)

References 3 publications

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“…It is interesting to note that while providing high MiT (66 to 35 %) in the radiologically most useful frequency range (1 to 2 lp/mm), the CsI scintillator acts as a sampling filter in front ofthe a-Si pixels by actually cutting the frequencies above the Nyquist frequency (3.5lp/mm). As described in ref [2], this has a major benefit in filtering the high frequency components ofthe X-ray quantum noise which would be aliased into the useflul low frequencies if no filtering was applied (i.e. if the MTF was too high at and above Nyquist frequency).…”

Section: Detector To System Interfacesmentioning

confidence: 99%

“…The CsI material is ideally suited to General Radiography application because it provides both high absorption in the 40 to 150 kVp range, and high X-ray to photon conversion factor [2]. In order to be coupled to the a-Si array in a sealed watertight encapsulation, the scintillator is deposited onto a thin Aluminum substrate, which will also act as a light reflector and sealing material when assembled to the panel.…”

Section: Cesium Iodide Scintillatormentioning

confidence: 99%

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New CsI/a-Si 17" x 17" x-ray flat-panel detector provides superior detectivity and immediate direct digital output for general radiography systems

Chaussat¹,

Chabbal²,

Ducourant³

et al. 1998

SPIE Proceedings

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A new 17" x 17" immediate direct digital flat panel detector has been developed to fit the needs of General Radiography. After reviewing a few key aspects of the General Radiography needs (X-ray energy range and associated measurement conditions, system integration and system operation), we describe the new detector Cesium Iodide I Amorphous Silicon based technology, and give measurement results (MTF, DQE, stability). We compare the new detector performance to existing technologies (film I screen combination, storage phosphor devices) and also to other flat panel solutions (Selenium). We conclude that the CsI I a-Si technology is now the best suited one in order to fit the needs of General Radiography, this means all kinds of examinations (chest, abdomen, bones, extremities. ..) which have been up to now done using films.

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Section: Detector To System Interfacesmentioning

confidence: 99%

Section: Cesium Iodide Scintillatormentioning

confidence: 99%

New CsI/a-Si 17" x 17" x-ray flat-panel detector provides superior detectivity and immediate direct digital output for general radiography systems

Chaussat¹,

Chabbal²,

Ducourant³

et al. 1998

SPIE Proceedings

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“…Based on existing documentation, the packing density of structured CsI is ϳ75%. 12 The nominal thicknesses of the samples used in our experiments were 150, 300, 450, and 600 m. Both HL and HR types were obtained for 150 m thick samples. The CsI layers were deposited on fiber optic faceplates ͑FOP͒, and are referred to as fiber optic scintillator ͑FOS͒ plates.…”

Section: X-ray Absorption and Determination Of Mass Loadingmentioning

confidence: 99%

X‐ray imaging performance of structured cesium iodide scintillators

2004

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Columnar structured cesium iodide (CsI) scintillators doped with Thallium (Tl) have been used extensively for indirect x-ray imaging detectors. The purpose of this paper is to develop a methodology for systematic investigation of the inherent imaging performance of CsI as a function of thickness and design type. The results will facilitate the optimization of CsI layer design for different x-ray imaging applications, and allow validation of physical models developed for the light channeling process in columnar CsI layers. CsI samples of different types and thicknesses were obtained from the same manufacturer. They were optimized either for light output (HL) or image resolution (HR), and the thickness ranged between 150 and 600 microns. During experimental measurements, the CsI samples were placed in direct contact with a high resolution CMOS optical sensor with a pixel pitch of 48 microns. The modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) of the detector with different CsI configurations were measured experimentally. The aperture function of the CMOS sensor was determined separately in order to estimate the MTF of CsI alone. We also measured the pulse height distribution of the light output from both the HL and HR CsI at different x-ray energies, from which the x-ray quantum efficiency, Swank factor and x-ray conversion gain were determined. Our results showed that the MTF at 5 cycles/mm for the HR type was 50% higher than for the HL. However, the HR layer produces approximately 36% less light output. The Swank factor below K-edge was 0.91 and 0.93 for the HR and HL types, respectively, thus their DQE(0) were essentially identical. The presampling MTF decreased as a function of thickness L. The universal MTF, i.e., MTF plotted as a function of the product of spatial frequency f and CsI thickness L, increased as a function of L. This indicates that the light channeling process in CsI improved the MTF of thicker layers more significantly than for the thinner ones.

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“…Hence, a MTF which does not reach the limit given by the sinc-function acts as a built-in low-pass filter. This is the case for the most frequently used scintillators such as CsI and Gd 2 O 2 S. The advantage is that aliasing and therefore back-folding of noise from the frequency region beyond the Nyquist frequency is partially suppressed-an important aspect to reach high DQE values at high spatial frequencies [28].…”

Section: Modulation Transfer Functionmentioning

confidence: 99%

Flat detectors and their clinical applications

Spahn

2005

Eur Radiol

108

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Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications.

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Image quality of scintillator-based x-ray electronic imagers

Cited by 17 publications

References 3 publications

New CsI/a-Si 17" x 17" x-ray flat-panel detector provides superior detectivity and immediate direct digital output for general radiography systems

New CsI/a-Si 17" x 17" x-ray flat-panel detector provides superior detectivity and immediate direct digital output for general radiography systems

X‐ray imaging performance of structured cesium iodide scintillators

Flat detectors and their clinical applications

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