![]() ![]() Metal artifact reduction was achieved in VMIs synthesized. The results demonstrated the feasibility of DE-CBCT imaging using the proposed approach. The ability of the CNT x-ray source to generate the output needed to compensate the reduction of photon flux due to attenuation from the spectral filters and to maintain the CT imaging time was evaluated. A significant reduction of the metal artifacts was observed in the VMI images synthesized at high energies compared to those from the same object imaged by the clinical dental CBCT scanner. The results were compared to the reconstructed images from a single energy clinical dental CBCT scanner (CS9300, Carestream Dental, Atlanta, GA). The VMIs were synthesized using an image-domain basis materials decomposition method with energy ranging from 30 to 150keV. An anthropomorphic head phantom (RANDO, Nuclear Associates, Hicksville, NY) with metal beads was imaged using the testbed and the images were reconstructed using an iterative volumetric CT reconstruction algorithm. The calculated post-object air kerma rate of the HE beam was 31.7% of the LE beam. The HE filter attenuated the x-ray photons more than the LE filter. Two distinct polychromatic x-ray spectra with the mean photon energies of 66.7keV and 86.3keV were produced at a fixed 120kVp x-ray tube voltage by using Al+Au and Al+Sn foils as the respective LE and HE filters attached to the exist window of the x-ray source. A testbed with a CNT field emission x-ray source (NuRay Technology, Chang Zhou, China), a flat panel detector (Teledyne, Waterloo, Canada), and a rotating object stage was used for this feasibility study. The objectives of this study were to investigate the feasibility of developing a low-cost dual energy CBCT (DE-CBCT) by retrofitting a regular CBCT scanner with a carbon nanotube (CNT) x-ray source with dual focal spots and corresponding low-energy (LE) and high-energy (HE) spectral filters. Although several techniques exist for DECT imaging, they in general come with significantly increased equipment cost and not available in dental clinics. ![]() Virtual monoenergetic images (VMIs) synthesized from dual energy CT (DECT) datasets are known to reduce metal artifacts. The presence of strong metal artifacts is however a major concern of using CBCT especially in dentistry due to the presence of highly attenuating dental restorations, fixed appliances, and implants. Cone beam computed tomography (CBCT) is now widely used in dentistry and growing areas of medical imaging.Affiliation: School of Medicine, Department of Radiology.Affiliation: School of Medicine, UNC/NCSU Joint Department of Biomedical Engineering.Affiliation: College of Arts and Sciences, Department of Applied Physical Sciences.Affiliation: College of Arts and Sciences, Department of Physics and Astronomy. ![]() The proposed definition offers a nascent ascriptive characterization of VCs along five dimensions of participants, purpose, platforms, protocols and persona – together constituting the 5 Ps of VCs. Definitions from seminal research studies in these domains are subsequently synthesized to propose an interdisciplinary socio-technical definition of VCs. These include: computer mediated communication community informatics knowledge management and internet marketing. Following this review, the chapter provides a summary of four interdisciplinary literature domains that have significantly contributed to the body of knowledge on VCs. Key issues and theoretical orientations from four research streams are discussed, namely: sociological/psychological technological business/management and economic perspectives. Firstly, the chapter offers a brief synopsis of research fields that form the basis of socio-technical research on VCs. The objective of this chapter is to offer a holistic perspective of virtual communities (VCs) by outlining their underlying concepts and fundamental properties. ![]()
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