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Proceedings of SPIE

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https://www.readbyqxmd.com/read/28458443/renal-stone-characterization-using-high-resolution-imaging-mode-on-a-photon-counting-detector-ct-system
#1
A Ferrero, R Gutjahr, A Henning, S Kappler, A Halaweish, D Abdurakhimova, Z Peterson, J Montoya, S Leng, C McCollough
In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition...
March 9, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28515570/association-between-hemodynamic-modifications-and-clinical-outcome-of-intracranial-aneurysms-treated-using-flow-diverters
#2
Nikhil Paliwal, Robert J Damiano, Jason M Davies, Adnan H Siddiqui, Hui Meng
Treatment of intracranial aneurysms (IAs) has been revolutionized by the advent of endovascular Flow Diverters (FDs), which disrupt blood flow within the aneurysm to induce pro-thrombotic conditions, and serves as a scaffold for endothelial ingrowth and arterial remodeling. Despite good clinical success of FDs, complications like incomplete occlusion and post-treatment rupture leading to subarachnoid hemorrhage have been reported. In silico computational fluid dynamic analysis of the pre- and post-treated geometries of IA patients can shed light on the contrasting blood hemodynamics associated with different clinical outcomes...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28413240/detection-of-increased-vasa-vasorum-in-artery-walls-improving-ct-number-accuracy-using-image-deconvolution
#3
Kishore Rajendran, Shuai Leng, Steven M Jorgensen, Dilbar Abdurakhimova, Erik L Ritman, Cynthia H McCollough
Changes in arterial wall perfusion are an indicator of early atherosclerosis. This is characterized by an increased spatial density of vasa vasorum (VV), the micro-vessels that supply oxygen and nutrients to the arterial wall. Detection of increased VV during contrast-enhanced computed tomography (CT) imaging is limited due to contamination from blooming effect from the contrast-enhanced lumen. We report the application of an image deconvolution technique using a measured system point-spread function, on CT data obtained from a photon-counting CT system to reduce blooming and to improve the CT number accuracy of arterial wall, which enhances detection of increased VV...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28392615/ultra-high-spatial-resolution-multi-energy-ct-using-photon-counting-detector-technology
#4
S Leng, R Gutjahr, A Ferrero, S Kappler, A Henning, A Halaweish, W Zhou, J Montoya, C McCollough
Two ultra-high-resolution (UHR) imaging modes, each with two energy thresholds, were implemented on a research, whole-body photon-counting-detector (PCD) CT scanner, referred to as sharp and UHR, respectively. The UHR mode has a pixel size of 0.25 mm at iso-center for both energy thresholds, with a collimation of 32 × 0.25 mm. The sharp mode has a 0.25 mm pixel for the low-energy threshold and 0.5 mm for the high-energy threshold, with a collimation of 48 × 0.25 mm. Kidney stones with mixed mineral composition and lung nodules with different shapes were scanned using both modes, and with the standard imaging mode, referred to as macro mode (0...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28392614/a-virtual-clinical-trial-using-projection-based-nodule-insertion-to-determine-radiologist-reader-performance-in-lung-cancer-screening-ct
#5
Lifeng Yu, Qiyuan Hu, Chi Wan Koo, Edwin A Takahashi, David L Levin, Tucker F Johnson, Megan J Hora, Shane Dirks, Baiyu Chen, Kyle McMillan, Shuai Leng, J G Fletcher, Cynthia H McCollough
Task-based image quality assessment using model observers is promising to provide an efficient, quantitative, and objective approach to CT dose optimization. Before this approach can be reliably used in practice, its correlation with radiologist performance for the same clinical task needs to be established. Determining human observer performance for a well-defined clinical task, however, has always been a challenge due to the tremendous amount of efforts needed to collect a large number of positive cases. To overcome this challenge, we developed an accurate projection-based insertion technique...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28392613/lung-nodule-volume-quantification-and-shape-differentiation-with-an-ultra-high-resolution-technique-on-a-photon-counting-detector-ct-system
#6
W Zhou, J Montoya, R Gutjahr, A Ferrero, A Halaweish, S Kappler, C McCollough, S Leng
A new ultra high-resolution (UHR) mode has been implemented on a whole body photon counting-detector (PCD) CT system. The UHR mode has a pixel size of 0.25 mm by 0.25 mm at the iso-center, while the conventional (macro) mode is limited to 0.5 mm by 0.5 mm. A set of synthetic lung nodules (two shapes, five sizes, and two radio-densities) was scanned using both the UHR and macro modes and reconstructed with 2 reconstruction kernels (4 sets of images in total). Linear regression analysis was performed to compare measured nodule volumes from CT images to reference volumes...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28479654/automated-ablation-of-dental-composite-using-an-ir-pulsed-laser-coupled-to-a-plume-emission-spectral-feedback-system
#7
Andrew T Jang, Kenneth H Chan, Daniel Fried
Dental composites are used as restorative materials for filling cavities, shaping, and covering teeth for esthetic purposes, and as adhesives. Dentists spend more time replacing existing restorations that fail than they do placing new restorations. Tooth colored restorations are difficult to differentiate from the surrounding tooth structure making them challenging to remove without damaging healthy tooth structure. Previous studies have demonstrated that CO2 lasers in conjunction with spectral feedback can be used to selectively remove composite from tooth surfaces...
January 28, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28450757/selective-removal-of-natural-caries-lesions-from-dentin-and-tooth-occlusal-surfaces-using-a-diode-pumped-er-yag-laser
#8
Jamison Jew, Kenneth H Chan, Cynthia L Darling, Daniel Fried
Selective removal of caries lesions with high precision is best accomplished using lasers operating at high pulse repetition rates utilizing small spot sizes. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped solid-state (DPSS) Er:YAG lasers have become available operating at high pulse repetition rates. Microradiography was used to determine the mineral content of the demineralized dentin of 200-μm thick sections with natural caries lesions prior to laser ablation...
January 28, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28450756/optical-changes-of-dentin-in-the-near-ir-as-a-function-of-mineral-content
#9
Rhett A Berg, Jacob C Simon, Daniel Fried, Cynthia L Darling
The optical properties of human dentin can change markedly due to aging, friction from opposing teeth, and acute trauma, resulting in the formation of transparent or sclerotic dentin with increased mineral density. The objective of this study was to determine the optical attenuation coefficient of human dentin tissues with different mineral densities in the near-infrared (NIR) spectral regions from 1300-2200 nm using NIR transillumination and optical coherence tomography (OCT). N=50 dentin samples of varying opacities were obtained by sectioning whole extracted teeth into ~ 150 μm transverse sections at the cemento-enamel junction or the apical root...
January 28, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28280284/the-fiber-optic-system-for-the-advanced-topographic-laser-altimeter-system-atlas-instrument
#10
Melanie N Ott, Joe Thomes, Eleanya Onuma, Robert Switzer, Richard Chuska, Diana Blair, Erich Frese, Marc Matyseck
The Advanced Topographic Laser Altimeter System (ATLAS) Instrument has been in integration and testing over the past 18 months in preparation for the Ice, Cloud and Land Elevation Satellite - 2 (ICESat-2) Mission, scheduled to launch in 2017. ICESat-2 is the follow on to ICESat which launched in 2003 and operated until 2009. ATLAS will measure the elevation of ice sheets, glaciers and sea ice or the "cryosphere" (as well as terrain) to provide data for assessing the earth's global climate changes. Where ICESat's instrument, the Geo-Science Laser Altimeter (GLAS) used a single beam measured with a 70 m spot on the ground and a distance between spots of 170 m, ATLAS will measure a spot size of 10 m with a spacing of 70 cm using six beams to measure terrain height changes as small as 4 mm...
August 28, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27807391/arterial-wall-perfusion-measured-with-photon-counting-spectral-x-ray-ct
#11
Steven M Jorgensen, Mark J Korinek, Andrew J Vercnocke, Jill L Anderson, Ahmed Halaweish, Shuai Leng, Cynthia H McCollough, Erik L Ritman
Early atherosclerosis changes perfusion of the arterial wall due to localized proliferation of the vasa vasorum. When contrast agent passes through the artery, some enters the vasa vasorum and increases radiopacity of the arterial wall. Technical challenges to detecting changes in vasa vasorum density include the thin arterial wall, partial volume averaging at the arterial lumen/wall interface and calcification within the wall. We used a photon-counting spectral CT scanner to study carotid arteries of anesthetized pigs and micro-CT of these arteries to quantify vasa vasorum density...
August 28, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27795606/evaluation-of-a-photon-counting-medipix3rx-czt-spectral-x-ray-detector
#12
Steven M Jorgensen, Andrew J Vercnocke, David S Rundle, Philip H Butler, Cynthia H McCollough, Erik L Ritman
We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current...
August 28, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27746582/optical-manipulation-of-a-single-human-virus-for-study-of-viral-cell-interactions
#13
Ximiao Hou, Michael C DeSantis, Chunjuan Tian, Wei Cheng
Although Ashkin and Dziedzic first demonstrated optical trapping of individual tobacco mosaic viruses in suspension as early as 1987, this pioneering work has not been followed up only until recently. Using human immunodeficiency virus type 1 (HIV-1) as a model virus, we have recently demonstrated that a single HIV-1 virion can be stabled trapped, manipulated and measured in physiological media with high precision. The capability to optically trap a single virion in suspension not only allows us to determine, for the first time, the refractive index of a single virus with high precision, but also quantitate the heterogeneity among individual virions with single-molecule resolution, the results of which shed light on the molecular mechanisms of virion infectivity...
August 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27942095/bridging-the-gap-between-sample-collection-and-laboratory-analysis-using-dried-blood-spots-to-identify-human-exposure-to-chemical-agents
#14
Elizabeth I Hamelin, Thomas A Blake, Jonas W Perez, Brian S Crow, Rebecca L Shaner, Rebecca M Coleman, Rudolph C Johnson
Public health response to large scale chemical emergencies presents logistical challenges for sample collection, transport, and analysis. Diagnostic methods used to identify and determine exposure to chemical warfare agents, toxins, and poisons traditionally involve blood collection by phlebotomists, cold transport of biomedical samples, and costly sample preparation techniques. Use of dried blood spots, which consist of dried blood on an FDA-approved substrate, can increase analyte stability, decrease infection hazard for those handling samples, greatly reduce the cost of shipping/storing samples by removing the need for refrigeration and cold chain transportation, and be self-prepared by potentially exposed individuals using a simple finger prick and blood spot compatible paper...
May 13, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27761058/silicon-technologies-for-arrays-of-single-photon-avalanche-diodes
#15
Angelo Gulinatti, Francesco Ceccarelli, Ivan Rech, Massimo Ghioni
In order to fulfill the requirements of many applications, we recently developed a new technology aimed at combining the advantages of traditional thin and thick silicon Single Photon Avalanche Diodes (SPAD). In particular we demonstrated single-pixel detectors with a remarkable improvement in the Photon Detection Efficiency in the red/near-infrared spectrum (e.g. 40% at 800nm) while maintaining a timing jitter better than 100ps. In this paper we discuss the limitations of such Red-Enhanced (RE) technology from the point of view of the fabrication of small arrays of SPAD and we propose modifications to the structure aimed at overcoming these issues...
April 17, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27695157/the-effects-of-compressive-sensing-on-extracted-features-from-tri-axial-swallowing-accelerometry-signals
#16
Ervin Sejdić, Faezeh Movahedi, Zhenwei Zhang, Atsuko Kurosu, James L Coyle
Acquiring swallowing accelerometry signals using a comprehensive sensing scheme may be a desirable approach for monitoring swallowing safety for longer periods of time. However, it needs to be insured that signal characteristics can be recovered accurately from compressed samples. In this paper, we considered this issue by examining the effects of the number of acquired compressed samples on the calculated swallowing accelerometry signal features. We used tri-axial swallowing accelerometry signals acquired from seventeen stroke patients (106 swallows in total)...
April 17, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27313332/igf-1-receptor-targeted-nanoparticles-for-image-guided-therapy-of-stroma-rich-and-drug-resistant-human-cancer
#17
Hongyu Zhou, Weiping Qian, Fatih M Uckun, Zhiyang Zhou, Liya Wang, Andrew Wang, Hui Mao, Lily Yang
Low drug delivery efficiency and drug resistance from highly heterogeneous cancer cells and tumor microenvironment represent major challenges in clinical oncology. Growth factor receptor, IGF-1R, is overexpressed in both human tumor cells and tumor associated stromal cells. The level of IGF-1R expression is further up-regulated in drug resistant tumor cells. We have developed IGF-1R targeted magnetic iron oxide nanoparticles (IONPs) carrying multiple anticancer drugs into human tumors. This IGF-1R targeted theranostic nanoparticle delivery system has an iron core for non-invasive MR imaging, amphiphilic polymer coating to ensure the biocompatibility as well as for drug loading and conjugation of recombinant human IGF-1 as targeting molecules...
April 17, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27453623/national-institute-of-standards-and-technology-measurement-service-of-the-optical-properties-of-biomedical-phantoms-current-status
#18
Paul Lemaillet, Catherine C Cooksey, Zachary H Levine, Adam L Pintar, Jeeseong Hwang, David W Allen
The National Institute of Standards and Technology (NIST) has maintained scales for reflectance and transmittance over several decades. The scales are primarily intended for regular transmittance, mirrors, and solid surface scattering diffusers. The rapidly growing area of optical medical imaging needs a scale for volume scattering of diffuse materials that are used to mimic the optical properties of tissue. Such materials are used as phantoms to evaluate and validate instruments under development intended for clinical use...
March 24, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27199501/segmentation-and-labeling-of-the-ventricular-system-in-normal-pressure-hydrocephalus-using-patch-based-tissue-classification-and-multi-atlas-labeling
#19
Lotta M Ellingsen, Snehashis Roy, Aaron Carass, Ari M Blitz, Dzung L Pham, Jerry L Prince
Normal pressure hydrocephalus (NPH) affects older adults and is thought to be caused by obstruction of the normal flow of cerebrospinal fluid (CSF). NPH typically presents with cognitive impairment, gait dysfunction, and urinary incontinence, and may account for more than five percent of all cases of dementia. Unlike most other causes of dementia, NPH can potentially be treated and the neurological dysfunction reversed by shunt surgery or endoscopic third ventriculostomy (ETV), which drain excess CSF. However, a major diagnostic challenge remains to robustly identify shunt-responsive NPH patients from patients with enlarged ventricles due to other neurodegenerative diseases...
March 21, 2016: Proceedings of SPIE
https://www.readbyqxmd.com/read/27053825/pdt-dose-dosimeter-for-pleural-photodynamic-therapy
#20
Michele M Kim, Arash Darafsheh, Mahmoud Ahmad, Jarod C Finlay, Timothy C Zhu
PDT dose is the product of the photosensitizer concentration and the light fluence in the target tissue. For improved dosimetry during plural photodynamic therapy (PDT), a PDT dose dosimeter was developed to measure both the light fluence and the photosensitizer concentration simultaneously in the same treatment location. Light fluence and spectral data were rigorously compared to other methods of measurement (e.g. photodiode, multi-fiber spectroscopy contact probe) to assess the accuracy of the measurements as well as their uncertainty...
March 17, 2016: Proceedings of SPIE
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