Improvement of the sensitivity and spatial resolution of pixelated CsI:Tl scintillator with reflective coating

Kyung, Bo; Bae, Jinho; Lee, Chaehun; Jeon, Hosang; Kim, Hyunduk; Chang, Sung-Ho; Kang, Bo Sun; Cho, Gyuseong

doi:10.1016/j.nima.2009.03.145

Cited by 14 publications

(9 citation statements)

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“…Pixelated scintillators can be fabricated by (a) patterning a pre-deposited CsI:Tl film (Nagarkar et al 2003), (b) thermal evaporation CsI:Tl on a pre-patterned pixelated substrate (Cha et al 2008(Cha et al , 2009 or (c) filling scintillating phosphors in pixelated molds (2D wells) (Simon et al 2008). It has been reported by different groups that pixelated scintillators improve the MTF and DQE at high spatial frequencies (Cha et al 2009, Kim et al 2008b, Cha et al 2008, Simon et al 2008, Nagarkar et al 2003. In this work, the impact of scintillator pixelation on the 3D imaging performance is evaluted.…”

Section: Impact Of Pixelated Scintillatormentioning

confidence: 99%

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

et al. 2017

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Abstract. High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g. ±30°) improves the low spatial frequency (below 5 mm -1 ) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used.Theoretical analysis suggests that a pixelated scintillator in combination with the 50 μm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film A c c e p t e d M a n u s c r i p t transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.Keywords: CMOS active pixel sensor, x-ray detector, digital breast tomosynthesis, three-dimensional, cascaded system analysis, pixelated scintillator, detective quantum efficiency IntroductionHigh performance x-ray detectors based on the complementary metal-oxide-semiconductor ( Up to now, most studies focus on CMOS APS detector evaluation by measuring the one-dimensional (1D) or 2D modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) using a single x-ray projection at the zero-degree incident angle (perpendicular to the detector). Nevertheless, since DBT is a quasi-three-dimensional (3D) imaging technology, the DBT image quality is influenced by the system geometry and reconstruction algorithms (Sechopoulos 2013a(Sechopoulos , 2013b. Therefore, the 3D imaging performance should be evaluated for the CMOS APS detectors. However, it is difficult to empirically investigate the 3D image quality. To deal with this issue, the 3D cascaded system analysis for CMOS APS detectors was developed and is presented in this study.Cascaded system analysis can accurately model the signal and noise propagation and blurring within ...

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Section: Impact Of Pixelated Scintillatormentioning

confidence: 99%

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

et al. 2017

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“…[ 14–16 ] Moreover, a delicate packaging process is required because of the hygroscopic nature and rapid degradation of these materials under ambient conditions. [ 17,18 ] Hence, it is essential to search for new scintillators with low growth temperature, low cost, high sensitivity, along with high chemical and environmental stability. [ 19–21 ]…”

Section: Introductionmentioning

confidence: 99%

Organic Semiconductor Single Crystals for X‐ray Imaging

Chen

Sun

Ou³

et al. 2021

Advanced Materials

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Low‐dose, high‐resolution X‐ray imaging is vital for medical diagnostics and material/device analyses. Current X‐ray imagers are dominated by expensive inorganic materials via high‐temperature solid processes (up to 1700 °C, e.g., CsI:Tl) with heavy metal elements. It is essential to search for new materials as X‐ray imagers with low growth temperature, low cost, high sensitivity, along with high chemical and environmental stability. Here, 9,10‐diphenylanthracene (9,10‐DPA) single crystals are used as a representative model, which are grown via low‐temperature solution processes, exhibiting intense X‐ray radioluminescence with ultrahigh photon‐conversion efficiency, ultrafast response and high sensitivity. The resolution of devices based on organic crystals exceeds 20.00 lp mm−1. Meanwhile the crystals exhibit high cycle performance under X‐ray irradiation and environmental stability. This study demonstrates that organic semiconductors have potential use in low‐cost, high‐sensitivity and low‐dose X‐ray imaging systems.

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“…The two effusion-cell sources were placed on each side of a vacuum chamber and operated at different temperatures according to the desired composition ratio of Tl to CsI inside the scintillator. Conditions such as deposition rate, chamber vacuum pressure, heat treatment temperature, and Tl doping concentration affect the microstructures and scintillation properties of CsI:Tl films [11][12]. CsI:Tl scintillator was deposited onto the substrate in a vacuum chamber at 150°C and 10 -3 Torr at low deposition rate (< 3 µm/min) and Tl doping concentration (0.1 mol%) with substrate plate rotation.…”

Section: Deposition Of Csi:tl Filmsmentioning

confidence: 99%

A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

Kim¹,

Kim²,

Kwon³

et al. 2014

Journal of the Optical Society of Korea

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Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide (TiO 2 ) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a TiO 2 reflective layer showed the best properties.

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Improvement of the sensitivity and spatial resolution of pixelated CsI:Tl scintillator with reflective coating

Cited by 14 publications

References 13 publications

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Organic Semiconductor Single Crystals for X‐ray Imaging

A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

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Improvement of the sensitivity and spatial resolution of pixelated CsI:Tl scintillator with reflective coating

Cited by 14 publications

References 13 publications

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Organic Semiconductor Single Crystals for X‐ray Imaging

A TiO2-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

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A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors