Experimental measurement of a high resolution CMOS detector coupled to CsI scintillators under X-ray radiation

Michail, C.; Valais, I.; Seferis, I.; Kalyvas, N.; Fountos, G.; Kandarakis, I.

doi:10.1016/j.radmeas.2015.02.007

Cited by 39 publications

(23 citation statements)

References 61 publications

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“…The modulation transfer function (MTF) was used to characterize the resolution properties of an X-ray imaging system, describing the variation of contrast with spatial frequency [18][19][20]. The MTF was measured by means of a PTW Freiburg tungsten edge test device.…”

Section: Modulation Transfer Function (Mtf)mentioning

confidence: 99%

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: Modulation Transfer Function (Mtf)mentioning

confidence: 99%

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

et al. 2016

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“…The last years, research for small-sized sensors, such as nano-phosphors and quantum dots (QDs) is in the spotlight providing noteworthy advances in these fields [1][2][3][4][5][6][7]. A challenge in the production processes of these nano-sensors is the aggregation of the nanoparticles in the polymer matrix, which can reduce fluorescence [8].…”

Section: Introductionmentioning

confidence: 99%

Polymer Based Thin Film Screen Preparation Technique

Valais

Michail

Fountzoula

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Phosphor screens, mainly prepared by electrophoresis, demonstrate brightness equal to the standard sedimentation on glass or quartz substrate process and are capable of very high resolution. Nevertheless, they are very fragile, the shape of the screen is limited to the substrate shape and in order to achieve adequate surface density for application in medical imaging, a significant quantity of the phosphor will be lost. Fluorescent films prepared by the dispersion of phosphor particles into a polymer matrix could solve the above disadvantages. The aim of this study is to enhance the stability of phosphor screens via the incorporation of phosphor particles into a PMMA (PolyMethyl MethAcrylate) matrix. PMMA is widely used as a plastic optical fiber, it shows almost nearly no dispersion effects and it is transparent in the whole visible spectral range. Different concentrations of PMMA in MMA (Methyl Methacrylate) were examined and a 37.5 % w /w solution was used for the preparation of the thin polymer film, since optical quality characteristics were found to depend on PMMA in MMA concentration. Scanning Electron Microscopy (SEM) images of the polymer screens demonstrated high packing density and uniform distribution of the phosphor particles. This method could be potentially used for phosphor screen preparation of any size and shape.

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“…The scintillating screens needs to fulfill characteristics, such as high density and high atomic number, to ensure efficient stopping power of ionizing radiation, but also high luminescence efficiency and low afterglow to ensure good energy resolution. The most traditionally used commercial scintillating materials are thallium doped cesium iodide (CsI:Tl), due to its good spatial resolution properties arising from columnar structure and terbium-doped gadolinium oxysulphide (Gd 2 O 2 S:Tb) due to its high X-ray absorption and light conversion efficiency [1][2][3][4]. Furthermore many scintillators have been investigated for X-ray imaging applications, such as Gd 2 O 2 S:Eu, Gd 2 O 2 S:Pr,Ce,F, Lu 2 O 3 :Eu, Gd 2 O 2 S:Pr employed in granular phosphors screens, and LuPO 4 :Eu semitransparent thin films [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

X-ray imaging resolution of phosphor screens prepared with different grains size and shape of granular Lu₂O₃:Eu

Seferis

Michail

Zeler

et al. 2017

J. Phys.: Conf. Ser.

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Experimental measurement of a high resolution CMOS detector coupled to CsI scintillators under X-ray radiation

Cited by 39 publications

References 61 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

Polymer Based Thin Film Screen Preparation Technique

X-ray imaging resolution of phosphor screens prepared with different grains size and shape of granular Lu₂O₃:Eu

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Experimental measurement of a high resolution CMOS detector coupled to CsI scintillators under X-ray radiation

Cited by 39 publications

References 61 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

Polymer Based Thin Film Screen Preparation Technique

X-ray imaging resolution of phosphor screens prepared with different grains size and shape of granular Lu2O3:Eu

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X-ray imaging resolution of phosphor screens prepared with different grains size and shape of granular Lu₂O₃:Eu