Modeling quantum and structure noise of phosphors used in medical X-ray imaging detectors

Kalivas, N.; Costaridou, Lena; Kandarakis, I.; Cavouras, D.; Nomicos, C.; Panayiotakis, G.

doi:10.1016/s0168-9002(02)01088-4

Cited by 33 publications

(15 citation statements)

References 35 publications

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“…The latter sedimented much faster due to the large particles, while the former, being nanocrystalline, sedimented very slowly. And this is the uniformity of a screen which affects the low frequencies noise properties mainly [26,27]. Indeed, according to Tamatani et al [28], nanosized spherical particles, like in our LuPO 4 :Eu, offer much more uniform packing, improved compactness and thus, higher effective density than in the case of the coarse, micron-sized phosphor.…”

Section: Discussionmentioning

confidence: 97%

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

et al. 2016

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In the present work, we demonstrate the fabrication technique of highly translucent layers of nanoparticulated (*50 nm) LuPO 4 :Eu phosphor, present their basic luminescent properties and give results of their performance in a planar imaging system coupled to a CMOS photodetector. For comparison, the imaging performance of an opaque Gd 2 O 2 S:Eu phosphor screen prepared by sedimentation is also shown. The X-ray detection parameters as well as the luminescence efficiency of the investigated films were discussed. Results show that the in-line transmittance at *600-700 nm, in the range of the phosphor luminescence, varies with respect to the thickness of the films from 40 to 50 % for a film of 67 lm thick to 4-12 % when the thickness increases to 460 lm. Yet, X-ray detection parameters get enhanced as the thickness of the films increases. Those results affect the luminescence efficiency curves of the films under poly-energetic X-ray radiation of various tube energies. The normalized noise power spectrum values were found similar for LuPO 4 :Eu films and a phosphor screen made using commercial Gd 2 O 2 S:Eu powder. The detective quantum efficiency of our films is clearly lower compared to the Gd 2 O 2 S:Eu screen from 2 to 10 cycles mm -1 frequency range while the modulation transfer function is lower from 0 to 5.5 cycles mm -1 frequency range. The acquired data allow to predict that high-temperature sintering of our films under pressure may help to improve their imaging quality, since such a processing should increase the luminescence efficiency without significant growth of the grains and thus without sacrificing their translucent character.

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Section: Discussionmentioning

confidence: 97%

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

et al. 2016

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“…In the space domain, noise was assessed by the measurement of a single index parameter, such as the coefficient of variation (CV), defined in terms of standard deviation ( σ ) and the mean pixel value (MPV). In the spatial frequency domain, noise was assessed via the noise power spectrum (NPS) [23–30]. σ and CV of image pixels were calculated in a region of interest (ROI) of 100 pixels [31] as

\begin{matrix} CV = (\frac{σ}{MPV}) . \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Figure of Image Quality and Information Capacity in Digital Mammography

Michail

Kalyvas

Valais

et al. 2014

BioMed Research International

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Objectives. In this work, a simple technique to assess the image quality characteristics of the postprocessed image is developed and an easy to use figure of image quality (FIQ) is introduced. This FIQ characterizes images in terms of resolution and noise. In addition information capacity, defined within the context of Shannon's information theory, was used as an overall image quality index. Materials and Methods. A digital mammographic image was postprocessed with three digital filters. Resolution and noise were calculated via the Modulation Transfer Function (MTF), the coefficient of variation, and the figure of image quality. In addition, frequency dependent parameters such as the noise power spectrum (NPS) and noise equivalent quanta (NEQ) were estimated and used to assess information capacity. Results. FIQs for the “raw image” data and the image processed with the “sharpen edges” filter were found 907.3 and 1906.1, correspondingly. The information capacity values were 60.86 × 103 and 78.96 × 103 bits/mm2. Conclusion. It was found that, after the application of the postprocessing techniques (even commercial nondedicated software) on the raw digital mammograms, MTF, NPS, and NEQ are improved for medium to high spatial frequencies leading to resolving smaller structures in the final image.

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“…Further refinements can be introduced to take into account more complex interactions, like in the case of cascading models [16], [17], but to the detriment of the simplicity 0018-9499/$25.00 © 2007 IEEE Fig. 1.…”

Section: Influence Of the Substrate Materials And Thickness On Scrmentioning

confidence: 99%

Simulation Study of the Role Played by Intensifying or Support Layers in Scintillation Screens

Pistrui-Maximean

Freud

Létang

et al. 2007

IEEE Trans. Nucl. Sci.

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The advantage of using reinforcing substrate layers with phosphor screens is that they increase the phosphor sensitivity and filter the scattered radiation, while providing a mechanical support for the phosphor layer. A simulation model based on the Monte Carlo code Geant4 was developed to study the influence of the substrate properties (material, thickness) on the phosphor screen spatial response. The optimal substrate/phosphor combinations have been determined at given sensitivity of the screen. Of all studied cases at medium energy (300 keV), a configuration with slight improvement in the screen spatial response has been found. Moreover, the results show that, without degrading the performances of the screen, the phosphor thickness may be significantly reduced (by 35% in the case of a 0.05 mm Pb substrate). Besides, PolyEthylene Terephthalate (PET) makes a good mechanical support (of up to minimum 4 mm in thickness) for the phosphor layer. The simulation methodology permitted to study the role played by the X-ray and electron processes inside the substrate layer.

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Modeling quantum and structure noise of phosphors used in medical X-ray imaging detectors

Cited by 33 publications

References 35 publications

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications

Figure of Image Quality and Information Capacity in Digital Mammography

Simulation Study of the Role Played by Intensifying or Support Layers in Scintillation Screens

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