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Detective quantum efficiency of photon-counting x-ray detectors.
Tanguay, Jesse,Yun, Seungman,Kim, Ho Kyung,Cunningham, Ian A The American Association of Physicists in Medicine 2015 Medical physics Vol.42 No.1
<P>Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning.</P>
The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses.
Tanguay, Jesse,Yun, Seungman,Kim, Ho Kyung,Cunningham, Ian A The American Association of Physicists in Medicine 2013 Medical physics Vol.40 No.4
<P>Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems.</P>
Yun, Seungman,Tanguay, Jesse,Kim, Ho Kyung,Cunningham, Ian A The American Association of Physicists in Medicine 2013 Medical physics Vol.40 No.4
<P>Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper describes an extension of the CSA approach to incorporate coherent and incoherent interactions, important for low-Z detectors such as silicon and selenium.</P>
The role of chorion on toxicity of silver nanoparticles in the embryonic zebrafish assay
김기태,Robert L. Tanguay 환경독성보건학회 2014 환경독성보건학회지 Vol.29 No.-
Objectives This study was designed to investigate how the size- and surface coating-dependenttoxicity of silver nanoparticles (AgNPs) is influenced by the presence and absenceof the chorion in an embryonic zebrafish assay. Methods Normal and dechorinated embryos were exposed to four different AgNPs, 20or 110 nm in size, with polypyrrolidone (PVP) or citrate surface coatings in a standardzebrafish embryo medium (EM). This was then compared to a 62.5 μM calcium chloride(CaCl2) solution where agglomeration was controlled. Results Embryonic toxicity in the absence of the chorion was greater than in its presence. The smaller 20 nm AgNPs were more toxic than the larger 110 nm AgNPs, regardlessof the chorion and test media. However, surface coating affected toxicity, since PVPcoatedAgNPs were more toxic than citrate-coated AgNPs; this was strongly affected bythe presence of the chorion in both EM and CaCl2. Conclusions Our results demonstrate the permeability function of the chorion on thesize- and surface coating-dependent toxicity of AgNPs. Thereafter, careful experimentshould be conducted to assess nanoparticle toxicity in zebrafish embryos.
Analytic Model of Energy-Absorption Response Functions in Compound X-ray Detector Materials
Seungman Yun,Ho Kyung Kim,Hanbean Youn,Tanguay, Jesse,Cunningham, Ian A. IEEE 2013 IEEE transactions on medical imaging Vol.32 No.10
<P>The absorbed energy distribution (AED) in X-ray imaging detectors is an important factor that affects both energy resolution and image quality through the Swank factor and detective quantum efficiency. In the diagnostic energy range (20-140 keV), escape of characteristic photons following photoelectric absorption and Compton scatter photons are primary sources of absorbed-energy dispersion in X-ray detectors. In this paper, we describe the development of an analytic model of the AED in compound X-ray detector materials, based on the cascaded-systems approach, that includes the effects of escape and reabsorption of characteristic and Compton-scatter photons. We derive analytic expressions for both semi-infinite slab and pixel geometries and validate our approach by Monte Carlo simulations. The analytic model provides the energy-dependent X-ray response function of arbitrary compound materials without time-consuming Monte Carlo simulations. We believe this model will be useful for correcting spectral distortion artifacts commonly observed in photon-counting applications and optimal design and development of novel X-ray detectors.</P>
The role of chorion on toxicity of silver nanoparticles in the embryonic zebrafish assay
Ki-Tae Kim,Robert L. Tanguay 환경독성보건학회 2014 환경독성보건학회지 Vol.29 No.-
Objectives : This study was designed to investigate how the size- and surface coating-dependent toxicity of silver nanoparticles (AgNPs) is influenced by the presence and absence of the chorion in an embryonic zebrafish assay. Methods : Normal and dechorinated embryos were exposed to four different AgNPs, 20 or 110 nm in size, with polypyrrolidone (PVP) or citrate surface coatings in a standard zebrafish embryo medium (EM). This was then compared to a 62.5 μM calcium chloride (CaCl₂) solution where agglomeration was controlled. Results : Embryonic toxicity in the absence of the chorion was greater than in its presence. The smaller 20 nm AgNPs were more toxic than the larger 110 nm AgNPs, regardless of the chorion and test media. However, surface coating affected toxicity, since PVPcoated AgNPs were more toxic than citrate-coated AgNPs; this was strongly affected by the presence of the chorion in both EM and CaCl₂. Conclusions : Our results demonstrate the permeability function of the chorion on the size- and surface coating-dependent toxicity of AgNPs. Thereafter, careful experiment should be conducted to assess nanoparticle toxicity in zebrafish embryos.