A motion artifact reduction method for dental CT based on subpixel-resolution image registration of projection data

Eldib, Mohamed Elsayed,Hegazy, Mohamed A.A.,Cho, Myung Hye,Cho, Min Hyoung,Lee, Soo Yeol Elsevier 2018 Computers in biology and medicine Vol.103 No.-

<P><B>Abstract</B></P> <P>High-resolution imaging is essential in three-dimensional (3D) CT image-based digital dentistry. A small amount of head motion during a CT scan can degrade the spatial resolution of the images to the extent where the efficacy of 3D image-based digital dentistry is greatly compromised. We introduce a retrospective motion artifact reduction (MAR) method for dental CTs that eliminates the necessity for any external motion tracking devices. Assuming that rigid-body motions are dominant in a dental scan of a human head, we extracted motion information from the projection data. By taking the cross-correlation between two successive projection data for every projection view, we determined the displacement of the projection data at each view. We experimentally found that any motion of the imaging object during the scan resulted in displacement of the projection data proportional to the motion amplitude. We decomposed the displacement into two components, one caused by translational motion and the other caused by rotational motion. The displacement components were used to correct the projection data before CT image reconstruction. We experimentally verified the MAR method using the projection data of a few phantoms acquired through a clinical dental CT machine. When the MAR performance was evaluated by the structural similarity index (SSIM) and the normalized absolute error (NAE) in reference to the motion-less images, the SSIM improved to 99% while the NAE was reduced by 80–90%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We introduce a retrospective motion artifact reduction (MAR) method for a dental CT. </LI> <LI> A subpixel image registration technique is used to estimate the motion-induced displacements. </LI> <LI> The proposed method can estimate all the motion components including translation and rotation. </LI> <LI> Actuator-controlled and manual motions have been applied on phantoms using a clinical dental CT. </LI> <LI> The experimental results demonstrate the high performance of the proposed method. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Planning and decommissioning of a disused Theratron- 780 teletherapy machine and the dose assessment methodology for normal and radiological emergency conditions

Mohamed M.Elsayed Breky,Muhammad S. Mansy,A.A. El-Sadek,Yousif M. Mousa,Yasser T. Mohamed 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1

The present work represents a technical guideline for decommissioning a disused teletherapy machine model Theratron-780 and contains category one 60Co radioactive source. The first section predicts the dose rate from the source in case of normal and radiological emergency situations via FLUKA-MC simulation code. Moreover, the dose assessment for the occupational during the whole process is calculated and compared to the measured values. A suggested cordoned area for safety and security in a radiological emergency is simulated. The second section lists the whole process's technical procedures, including (preview, dismantle, securing, transport and storage) of the disused teletherapy machine. Results show that the maximum obtained accumulated dose for occupational were found to be 24.5 ± 4.9 mSv in the dismantle and securing process in addition to 3.5 ± 1.8 mSv during loading on the transport vehicle and unloading at the storage facility. It was found that the measured accumulated dose for workers is in good agreement with the estimated one by uncertainty not exceeding 5% in normal operating conditions

A head motion estimation algorithm for motion artifact correction in dental CT imaging

Hernandez, Daniel,Eldib, Mohamed Elsayed,Hegazy, Mohamed A A,Cho, Myung Hye,Cho, Min Hyoung,Lee, Soo Yeol Institute of Physics in association with the Ameri 2018 Physics in medicine & biology Vol.63 No.6

<P>A small head motion of the patient can compromise the image quality in a dental CT, in which a slow cone-beam scan is adopted. We introduce a retrospective head motion estimation method by which we can estimate the motion waveform from the projection images without employing any external motion monitoring devices. We compute the cross-correlation between every two successive projection images, which results in a sinusoid-like displacement curve over the projection view when there is no patient motion. However, the displacement curve deviates from the sinusoid-like form when patient motion occurs. We develop a method to estimate the motion waveform with a single parameter derived from the displacement curve with aid of image entropy minimization. To verify the motion estimation method, we use a lab-built micro-CT that can emulate major head motions during dental CT scans, such as tilting and nodding, in a controlled way. We find that the estimated motion waveform conforms well to the actual motion waveform. To further verify the motion estimation method, we correct the motion artifacts with the estimated motion waveform. After motion artifact correction, the corrected images look almost identical to the reference images, with structural similarity index values greater than 0.81 in the phantom and rat imaging studies.</P>

Using nano-magnesium oxide/bentonite composite for cadmium removal from industrial wastewater

Elsayed A. Elkhatib,Mohamed L. Moharem,Ahmed F. Saad,Farida A. Attia 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.2

Nowadays, the removal of toxic heavy metals from industrial wastewater is a long standing problem due to the industrial progress worldwide. This study mainly focused on the production of a novel nMgO-bentonite nanocomposite using sol–gel method to enhance Cd ions removal from industrial wastewater. The nMgO-bentonite nano-composite was characterized for structural morphology and presence of functional groups using SEM/EDS, XRD and FTIR analysis. Cadmium sorption equilibrium and kinetic data were well fitted to Langmuir and power function models respectively as confirmed by the highest R² (0.965), and the lowest SE (38<SUP>*</SUP>10<SUP>-6</SUP>) values among other studied models. The Langmuir removal capacity of the nanocomposite is 200 ㎎/g which is 60 times greater than that of bentonite. Increased Cd sorption on nano-composite with increased temperature from 287 to 307K and the thermodynamic results revealed that Cd adsorption process was endothermic and spontaneous. The data also showed highly repetitive application of nano-composite during six cycles of adsorption/ desorption experiment. The final results pointed out that nMgO-bentonite nano-composite has great adsorption affinity for Cd and could potentially employ as a cost-effective, ecofriendly and efficient sorbent for Cd removal from contaminated wastewater.

Dual-phase-lag model on microstretch thermoelastic medium with diffusion under the influence of gravity and laser pulse

Mohamed I. A. Othman,Elsayed M. Abd-Elaziz,Ibrahim E.A. Mohamed 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.2

This investigation is to study the effect of gravitational field and diffusion on a microstretch thermoelastic medium heating by a non-Gaussian laser beam. The problem was studied in the context of the dual-phase-lag model. The normal mode analysis is used to solve the problem to obtain the exact expressions for the non-dimensional displacement components, the micro-rotation, the stresses, and the temperature distribution. The effect of time parameter, heat flux parameter and gravity response of three theories of thermoelasticity i.e. dual-phase-lag model (DPL), Lord and Shulman theory (L-S) and coupled theory (CT) on these quantities have been depicted graphically for a particular model.

Seismic response evaluation of fixed jacket-type offshore structures by random vibration analysis

Shehata E. Abdel Raheem,Elsayed M. Abdel Aal,Aly G.A. AbdelShafy,Mohamed F.M. Fahmy 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.2

Offshore platforms in seismically active areas must be designed to survive in the face of intense earthquakes without a global structural collapse. This paper scrutinizes the seismic performance of a newly designed and established jacket type offshore platform situated in the entrance of the Gulf of Suez region based on the API-RP2A normalized response spectra during seismic events. A nonlinear finite element model of a typical jacket type offshore platform is constructed taking into consideration the effect of structure-soil-interaction. Soil properties at the site were manipulated to generate the pile lateral soil properties in the form of load deflection curves, based on API-RP2A recommendations. Dynamic characteristics of the offshore platform, the response function, output power spectral density and transfer functions for different elements of the platform are discussed. The joints deflection and acceleration responses demands are presented. It is generally concluded that consideration of the interaction between structure, piles and soil leads to higher deflections and less stresses in platform elements due to soil elasticity, nonlinearity, and damping and leads to a more realistic platform design. The earthquake-based analysis for offshore platform structure is essential for the safe design and operation of offshore platforms.

Effect of endocrine disruptors on the ratio of X and Y chromosome-bearing live spermatozoa

Song, Won-Hee,Mohamed, Elsayed A.,Pang, Won-Ki,Kang, Kyu-Ho,Ryu, Do-Yeal,Rahman, Md Saidur,Pang, Myung-Geol Elsevier 2018 Reproductive toxicology Vol.82 No.-

<P><B>Abstract</B></P> <P>Although equal numbers of X and Y spermatozoa are produced during spermatogenesis, the sex chromosome ratio in ejaculated spermatozoa can be altered by exposure to endocrine-disrupting chemicals (EDCs), which can be reflected by altered sex ratios at birth. Here, we hypothesized EDCs affect sperm functions and viability of X and Y chromosome-bearing human spermatozoa. After exposure to genistein (Gen), bisphenol A (BPA), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dibromochloropropane (DBCP), and diazinon (Diaz), we evaluated motility, viability, capacitation, and differential viability of X and Y spermatozoa. All EDCs tested altered sperm viability, motility, and capacitation. Interestingly, the Y/X ratio of live spermatozoa was significantly lower in sperm treated with TCDD, DBCP, and Diaz than control spermatozoa. Our results suggest that some of EDCs have larger effects on the viability of Y spermatozoa than X spermatozoa, implicating that a reduction in Y sperm viability may result in a female-biased sex ratio of offspring at birth.</P> <P><B>Highlights</B></P> <P> <UL> <LI> EDCs tested have a negative impact on human sperm functions. </LI> <LI> There are no significant differences in the viability of euploidy and aneuploidy spermatozoa following exposure to EDCs. </LI> <LI> TCDD, DBCP, and Diaz adversely affect the viability of Y spermatozoa more than X spermatozoa. </LI> <LI> A reduction in Y sperm viability may result in a female-biased sex ratio of offspring at birth. </LI> </UL> </P>

Effect of magnetic field and gravity on thermoelastic fiber-reinforced with memory-dependent derivative

Mohamed I.A. Othman,Samia M. Said,Elsayed M. Abd-Elaziz Techno-Press 2023 Advances in materials research Vol.12 No.2

The purpose of this paper is to study the effects of magnetic field and gravitational field on fiber-reinforced thermoelastic medium with memory-dependent derivative. Three-phase-lag model of thermoelasticity (3PHL) is used to study the plane waves in a fiber-reinforced magneto-thermoelastic material with memory-dependent derivative. A gravitating magneto-thermoelastic two-dimensional substrate is influenced by both thermal shock and mechanical loads at the free surface. Analytical expressions of the considered variables are obtained by using Laplace-Fourier transforms technique with the eigenvalue approach technique. A numerical example is considered to illustrate graphically the effects of the magnetic field, gravitational field and two types of mechanical loads(continuous load and impact load).

A modified couple-stress magneto-thermoelastic solid with microtemperatures and gravity field

Samia M. Said,Elsayed M. Abd-Elaziz,Mohamed I.A. Othman 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.5

The present study deals with wave propagation in a modified couple-stress generalized thermoelastic solid under the effect of gravity and magnetic field. The problem is solved by a refined microtemperatures multi-phase-lags thermoelastic theory. The Fourier series and Laplace transforms will be used to obtain the general solution for any set of boundary conditions. Some comparisons have been shown in figures to estimate the effects of the gravity field, the magnetic field, and different theories of thermoelasticity in the presence of the hall current effect on all the physical quantities. Some particular cases of special interest have been deduced from the present investigation.

Dual‐energy‐based metal segmentation for metal artifact reduction in dental computed tomography

Hegazy, Mohamed A. A.,Eldib, Mohamed Elsayed,Hernandez, Daniel,Cho, Myung Hye,Cho, Min Hyoung,Lee, Soo Yeol Published for the American Association of Physicis 2018 Medical physics Vol.45 No.2

<P>Conclusions: The proposed dual-energy-based method has shown better performance in metal segmentation leading to better MAR performance in dental imaging. We expect the proposed metal segmentation method can be used to improve the MAR performance of existing MAR techniques that have metal segmentation steps in their correction procedures. (C) 2017 American Association of Physicists in Medicine</P>