The Experts below are selected from a list of 439707 Experts worldwide ranked by ideXlab platform
Hans Dj Huisman - One of the best experts on this subject based on the ideXlab platform.
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The use of Hand-Held XRF for investigating the composition and corrosion of Roman copper-alloyed Artefacts
Heritage Science, 2013Co-Authors: Ricardo Fernandes, Hans Dj HuismanAbstract:The study of archaeological Artefacts using deployed in situ analytical instruments presents some obvious advantages. Including, obtaining an immediate feedback that can be used to redefine in real-time fieldwork strategies. Ideally analytical field instruments should also have characteristics that limit damage to the studied Artefact. Here, we present a case study on the use of a Hand Held XRF (HH XRF) device employed to define the composition of copper-alloyed Artefacts retrieved from the Roman military site of Fectio in the vicinity of Vechten (The Netherlands). The goals of the study were to establish Artefact preservation status, to investigate Artefact elemental composition, and to compare the composition of Artefact corrosion layer and uncorroded core. The results showed that the objects were in an overall good preservation state. Decuprification and dezincification represented the probable main corrosion processes resulting in the formation of smooth corrosion layers or patinas. The major elemental composition of the Artefacts’ uncorroded cores showed a wide-range variability most likely associated with recycling practices of scrap metal during the 3^rd century CE.
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The use of Hand-Held XRF for investigating the composition and corrosion of Roman copper-alloyed Artefacts
Heritage Science, 2013Co-Authors: Ricardo Fernandes, Bertil Jh Van Os, Hans Dj HuismanAbstract:The study of archaeological Artefacts using deployed in situ analytical instruments presents some obvious advantages. Including, obtaining an immediate feedback that can be used to redefine in real-time fieldwork strategies. Ideally analytical field instruments should also have characteristics that limit damage to the studied Artefact. Here, we present a case study on the use of a Hand Held XRF (HH XRF) device employed to define the composition of copper-alloyed Artefacts retrieved from the Roman military site of Fectio in the vicinity of Vechten (The Netherlands). The goals of the study were to establish Artefact preservation status, to investigate Artefact elemental composition, and to compare the composition of Artefact corrosion layer and uncorroded core. The results showed that the objects were in an overall good preservation state. Decuprification and dezincification represented the probable main corrosion processes resulting in the formation of smooth corrosion layers or patinas. The major elemental composition of the Artefacts’ uncorroded cores showed a wide-range variability most likely associated with recycling practices of scrap metal during the 3^rd century CE.
Marc Kachelriess - One of the best experts on this subject based on the ideXlab platform.
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frequency split metal Artefact reduction in pelvic computed tomography
European Radiology, 2013Co-Authors: Michael Lell, Rainer Raupach, Esther Meyer, Matthias Schmid, Matthias May, Michael Uder, Marc KachelriessAbstract:Objectives Artefacts from total hip replacement affect image quality and the visualisation of pelvic lesions on computed tomography (CT). We propose a frequency split (FS) approach in addition to the normalised metal Artefact reduction (NMAR) algorithm that aims to suppress Artefacts and improves image quality in patients with orthopaedic hardware.
Ricardo Fernandes - One of the best experts on this subject based on the ideXlab platform.
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The use of Hand-Held XRF for investigating the composition and corrosion of Roman copper-alloyed Artefacts
Heritage Science, 2013Co-Authors: Ricardo Fernandes, Hans Dj HuismanAbstract:The study of archaeological Artefacts using deployed in situ analytical instruments presents some obvious advantages. Including, obtaining an immediate feedback that can be used to redefine in real-time fieldwork strategies. Ideally analytical field instruments should also have characteristics that limit damage to the studied Artefact. Here, we present a case study on the use of a Hand Held XRF (HH XRF) device employed to define the composition of copper-alloyed Artefacts retrieved from the Roman military site of Fectio in the vicinity of Vechten (The Netherlands). The goals of the study were to establish Artefact preservation status, to investigate Artefact elemental composition, and to compare the composition of Artefact corrosion layer and uncorroded core. The results showed that the objects were in an overall good preservation state. Decuprification and dezincification represented the probable main corrosion processes resulting in the formation of smooth corrosion layers or patinas. The major elemental composition of the Artefacts’ uncorroded cores showed a wide-range variability most likely associated with recycling practices of scrap metal during the 3^rd century CE.
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The use of Hand-Held XRF for investigating the composition and corrosion of Roman copper-alloyed Artefacts
Heritage Science, 2013Co-Authors: Ricardo Fernandes, Bertil Jh Van Os, Hans Dj HuismanAbstract:The study of archaeological Artefacts using deployed in situ analytical instruments presents some obvious advantages. Including, obtaining an immediate feedback that can be used to redefine in real-time fieldwork strategies. Ideally analytical field instruments should also have characteristics that limit damage to the studied Artefact. Here, we present a case study on the use of a Hand Held XRF (HH XRF) device employed to define the composition of copper-alloyed Artefacts retrieved from the Roman military site of Fectio in the vicinity of Vechten (The Netherlands). The goals of the study were to establish Artefact preservation status, to investigate Artefact elemental composition, and to compare the composition of Artefact corrosion layer and uncorroded core. The results showed that the objects were in an overall good preservation state. Decuprification and dezincification represented the probable main corrosion processes resulting in the formation of smooth corrosion layers or patinas. The major elemental composition of the Artefacts’ uncorroded cores showed a wide-range variability most likely associated with recycling practices of scrap metal during the 3^rd century CE.
Karla De Faria Vasconcelos - One of the best experts on this subject based on the ideXlab platform.
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Artefact expression associated with several cone beam computed tomographic machines when imaging root filled teeth
International Endodontic Journal, 2015Co-Authors: Karla De Faria Vasconcelos, Laura Ferreira Pinheiro Nicolielo, M C Nascimento, Francisco Haiterneto, Frab Norberto Boscolo, J Van Dessel, Mostafa Ezeldeen, Ivo LambrichtsAbstract:Aim To evaluate the characteristic Artefact patterns associated with teeth root filled with Gutta-percha when scanned with four cone-beam CT devices. Methodology Whilst using soft tissue simulation, ten root filled human premolars were placed in empty sockets in a dry human skull. Subsequently, the skull was scanned using 3D Accuitomo 170®, WhiteFox®, Cranex 3D® and Scanora 3D® following clinical protocols with the highest resolution and Artefact reduction. After proper image registration in OnDemand3D® software (Cybermed, Seoul, Korea), each image slice was evaluated by three trained and calibrated dentomaxillofacial radiologists, which scored absence (0) and presence (1) of cupping Artefact, hypodense halos and streak Artefacts. Kappa test was performed for intra- and interobserver agreement. Results A moderate to perfect agreement for each observer (intra-observer κ = 0.5–1.0) was found. Agreement between the different observers was moderate to almost perfect for the different Artefact patterns (interobserver κ = 0.55–0.9). Cupping Artefact was the most prevalent (70%), followed by a hypodense halo (35%) and streak Artefacts (16%). The Chi-squared test revealed significantly more streaks in axial slices (P < 0.0001), with some CBCT systems yielding significantly inferior results to others (P < 0.05). The dedicated EndoMode and Artefact reduction did not improve the result significantly. Conclusions The variation of Artefact expression was significantly different amongst CBCT machines for root filled teeth. Continuous efforts are needed to improve CBCT reconstruction algorithms, with a specific focus on reducing Artefacts induced by dense dental materials, whilst striving for enhanced image quality at low-radiation doses.
Habib Zaidi - One of the best experts on this subject based on the ideXlab platform.
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Deep learning–based metal Artefact reduction in PET/CT imaging
European Radiology, 2021Co-Authors: Hossein Arabi, Habib ZaidiAbstract:Objectives The susceptibility of CT imaging to metallic objects gives rise to strong streak Artefacts and skewed information about the attenuation medium around the metallic implants. This metal-induced Artefact in CT images leads to inaccurate attenuation correction in PET/CT imaging. This study investigates the potential of deep learning–based metal Artefact reduction (MAR) in quantitative PET/CT imaging. Methods Deep learning–based metal Artefact reduction approaches were implemented in the image (DLI-MAR) and projection (DLP-MAR) domains. The proposed algorithms were quantitatively compared to the normalized MAR (NMAR) method using simulated and clinical studies. Eighty metal-free CT images were employed for simulation of metal Artefact as well as training and evaluation of the aforementioned MAR approaches. Thirty ^18F-FDG PET/CT images affected by the presence of metallic implants were retrospectively employed for clinical assessment of the MAR techniques. Results The evaluation of MAR techniques on the simulation dataset demonstrated the superior performance of the DLI-MAR approach (structural similarity (SSIM) = 0.95 ± 0.2 compared to 0.94 ± 0.2 and 0.93 ± 0.3 obtained using DLP-MAR and NMAR, respectively) in minimizing metal Artefacts in CT images. The presence of metallic Artefacts in CT images or PET attenuation correction maps led to quantitative bias, image Artefacts and under- and overestimation of scatter correction of PET images. The DLI-MAR technique led to a quantitative PET bias of 1.3 ± 3% compared to 10.5 ± 6% without MAR and 3.2 ± 0.5% achieved by NMAR. Conclusion The DLI-MAR technique was able to reduce the adverse effects of metal Artefacts on PET images through the generation of accurate attenuation maps from corrupted CT images. Key Points • The presence of metallic objects, such as dental implants, gives rise to severe photon starvation, beam hardening and scattering, thus leading to adverse Artefacts in reconstructed CT images. • The aim of this work is to develop and evaluate a deep learning–based MAR to improve CT-based attenuation and scatter correction in PET/CT imaging. • Deep learning–based MAR in the image (DLI-MAR) domain outperformed its counterpart implemented in the projection (DLP-MAR) domain. The DLI-MAR approach minimized the adverse impact of metal Artefacts on whole-body PET images through generating accurate attenuation maps from corrupted CT images.
