Correlation between spatial resolution and ball distortion rate of panoramic radiography

Abstract Background The purpose of this study was to analyze the correlation between spatial resolution and ball distortion rate of panoramic radiography and to elucidate the minimum criterion for ball distortion rate, which is very relevant to clinical readability. Methods Horizontal and vertical spatial resolution and ball distortion rates were calculated in the same position, such as the incisor, premolar, molar, and temporomandibular joint area with various object depths corresponding to 48 mm. Three devices were evaluated. A region showing spatial resolution above the reference standard was selected, and the ball distortion rate corresponding to the same region was divided into horizontal and vertical phantom groups. The mean and standard deviation of the obtained ball distortion rates were calculated. Students t-test was used to statistically analyze the mean difference in ball distortion rates between vertical and horizontal phantom groups. Results In all devices, the horizontal line pair phantom, but not the vertical line pair phantom, was readable in all areas measured at the line pair value of at least 1.88 lp/mm. The line pair value tended to be higher toward the center and lower toward the outside. The ball distortion rate tended to decrease closer to the center and increased further away. In addition, ball distortion rates could not be measured at some areas as they were not recognized as balls due to the high degree of distortion at the outermost and innermost sides. The number of balls satisfying the reference value using the horizontal line pair phantom was 102 (mean of ball distortion rates, 20.98; standard deviation, 15.25). The number of balls satisfying the reference value using the vertical line pair phantom was 49 (mean of ball distortion rates, 16.33; standard deviation, 14.25). However, mean ball distortion rate was not significantly different between the two groups. Conclusions Image layer of panoramic radiography could be evaluated by the spatial resolution using horizontal and vertical line pair phantoms and by assessing ball distortion rates through a ball-type panorama phantom. A ball distortion rate of 20% could be used as a threshold to evaluate the image layer of panoramic radiography

FRAST\mathsf{FRAST}: TFHE-friendly Cipher Based on Random S-boxes

A transciphering framework, also known as hybrid homomorphic encryption, is a practical method of combining a homomorphic encryption~(HE) scheme with a symmetric cipher in the client-server model to reduce computational and communication overload on the client side. As a server homomorphically evaluates a symmetric cipher in this framework, new design rationales are required for ``HE-friendly\u27\u27 ciphers that take into account the specific properties of the HE schemes. In this paper, we propose a new TFHE-friendly cipher, dubbed $\mathsf{FRAST}$, with a TFHE-friendly round function based on a random S-box to minimize the number of rounds. The round function of $\mathsf{FRAST}$ can be efficiently evaluated in TFHE by a new optimization technique, dubbed double blind rotation. Combined with our new WoP-PBS method, the double blind rotation allows computing multiple S-box calls in the round function of $\mathsf{FRAST}$ at the cost of a single S-box call. In this way, $\mathsf{FRAST}$ enjoys $2.768$ (resp. $10.57$) times higher throughput compared to $\mathsf{Kreyvium}$ (resp. $\mathsf{Elisabeth}$) for TFHE keystream evaluation in the offline phase of the transciphering framework at the cost of slightly larger communication overload

Controllable Thickness Inhomogeneity and Berry Curvature Engineering of Anomalous Hall Effect in SrRuO3 Ultrathin Films

In quantum matters hosting electron−electron correlation and spin−orbit coupling, spatial inhomogeneities, arising from competing ground states, can be essential for understanding exotic topological properties. A prominent example is Hall anomalies observed in SrRuO 3 films, which were interpreted in terms of either magnetic skyrmion-induced topological Hall effect or inhomogeneous anomalous Hall effect (AHE). To clarify this ambiguity, we systematically investigated the evolution of AHE with controllable inhomogeneities in SrRuO 3 film thickness (t SRO ). By exploiting the step-flow growth of SrRuO 3 films, we induced a microscopically ordered stripe pattern with one-unit-cell differences in t SRO . The associated spatial distribution of momentum-space Berry curvatures enables a two-channel AHE with hump-like Hall anomalies, which can be continuously engineered according to non-integer t SRO . We further microscopically characterized the stripe-like ferromagnetic domains and two-step magnetic switching behavior in the inhomogeneous SrRuO 3 film. These unique features can be utilized to identify the two-channel AHE model and understand its microscopic origin. © 2020 American Chemical Society11Nsciescopu

The changes of distance between nipples following correction of women pectus excavatum

Abstract The breasts in women pectus excavatum patients frequently appear to be slanting medially along the inclination of the distorted ribs. This study aims to evaluate changes in the distance between the nipples and to find out whether medially slanting breasts are corrected in women pectus excavatum patients following modified Nuss procedure. This case series analysis enrolled 22 young women patients with pectus excavatum between October 2011 and September 2020. We measured all the patients’ distances from the sternal midline to the right and left nipples, based on chest computerized tomography. We calculated the distances between nipples as being the sum of the right and left distances. The mean age of patients was 16.50 ± 4.73 years, and the follow-up periods were 35.59 ± 20.23 months. The postoperative Haller indices (2.89 ± 0.43) were significantly lower than the preoperative Haller indices (5.14 ± 1.96) (p = 0.000). The distances between the nipples before and after Nuss procedure were 145.17 ± 17.73 mm and 172.29 ± 19.11 mm, which is a significant increase following surgery. (p = 0.000). Our results demonstrated that skeletal correction with modified Nuss procedure in pectus excavatum increased the distance between nipples, indicating that medially slanting breasts had been corrected

Development of panorama resolution phantom for comprehensive evaluation of the horizontal and vertical resolution of panoramic radiography

Panoramic radiography is the most commonly used equipment in the dental field, but there is no comprehensive standard about how to evaluate the spatial resolution of panoramic radiography. In this study, panorama resolution phantoms were developed for evaluation of horizontal and vertical resolution reflecting unique characteristics of panoramic radiography. Four horizontal resolution phantoms of staircase shape were designed to obtain images of horizontal lead line pairs in a 52 mm width. Four vertical resolution phantoms with vertical lead line pairs placed at an oblique angle were also designed. A phantom stand was made. Three machines were evaluated twice by two oromaxillofacial radiologists. The horizontal lead line pairs were readable over the entire measured area at the values of 1.88, 2.32, and 2.58 lp/mm for all machines. A readable area of horizontal 3.19 lp/mm was observed in the lingual side. In the vertical resolution phantoms, it was possible to read a narrower range. By using the panorama resolution phantoms and phantom stand, it was possible to evaluate the resolution of a wide buccolingual width in four significant areas. By evaluating the resolution of the vertical and horizontal compartments separately, it was possible to gain a better understanding of the obtained images.Y

Correlation analysis between radiation exposure and the image quality of cone-beam computed tomography in the dental clinical environment

© 2022 by Korean Academy of Oral and Maxillofacial RadiologyPurpose: This study was conducted to measure the radiation exposure and image quality of various cone-beam computed tomography (CBCT) machines under common clinical conditions and to analyze the correlation between them. Materials and Methods: Seven CBCT machines used frequently in clinical practice were selected. Because each machine has various sizes of fields of view (FOVs), 1 large FOV and 1 small FOV were selected for each machine. Radiation exposure was measured using a dose-area product (DAP) meter. The quality of the CBCT images was analyzed using 8 image quality parameters obtained using a dental volume tomography phantom. For statistical analysis, regression analysis using a generalized linear model was used. Results: Polymethyl-methacrylate (PMMA) noise and modulation transfer function (MTF) 10% showed statistically significant correlations with DAP values, presenting positive and negative correlations, respectively (P<0.05). Image quality parameters other than PMMA noise and MTF 10% did not demonstrate statistically significant correlations with DAP values. Conclusion: As radiation exposure and image quality are not proportionally related in clinically used equipment, it is necessary to evaluate and monitor radiation exposure and image quality separatelyY

Nasal cavity perforation by implant fixtures: case series with emphasis on panoramic imaging of nasal cavity extending posteriorly

Abstract The nasal cavity is an important landmark when considering implant insertion into the anterior region of the maxillary arch. The perforation of implants into the nasal cavity may cause complications, such as implant migration, inflammation, or changes in nasal airflow; thus, precise assessment of the nasal cavity is mandatory. Three cases of nasal cavity perforation by dental implants are presented, including one case of implant fixture migration into the nasal cavity. On panoramic radiographs of the patients, the following common features were observed: the horizontal radiopaque line of the hard palate was observed to be inferior to or similar to that of the antral floor and the bone between the lateral wall of the nasal cavity and the medial wall of the maxillary sinus was emphasized in a triangular shape. When the maxillary sinus is small and alveolar bone resorption is severe, panoramic evaluation may cause overestimation of the available residual bone, particularly in the maxillary canine/premolar region. Therefore, the residual bone should be reevaluated three-dimensionally to measure the exact bony shape and volume

Tunable Two-Channel Magnetotransport in SrRuO3 Ultrathin Films Achieved by Controlling the Kinetics of Heterostructure Deposition

© 2021 Wiley-VCH GmbHIn the field of oxide heterostructure engineering, there are extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to the electronic structures near the Fermi surface driven by extensive physical parameters such as spin–orbit coupling and inversion symmetry breaking. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies.” Here, a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers is developed. The kinetic process of pulsed laser deposition by varying the growth pressure during LaAlO3 layer deposition is systematically controlled. Furthermore, the effects of nanoscale inhomogeneity on the Berry curvature near the Fermi surface in SrRuO3 films are investigated. It is found that the high kinetic energy of the capping layer adatoms induces stoichiometric modification and nanoscale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.11Nsciescopu

Oxygen Vacancy Engineering for Highly Tunable Ferromagnetic Properties: A Case of SrRuO 3

© 2020 Wiley-VCH GmbH. Oxide heterostructures have great potential for spintronics applications due to their well-defined heterointerfaces and vast functionalities. To integrate such compelling features into practical spintronics devices, effective control of the magnetic switching behavior is key. Here, continuous control of the magnetic coercive field in SrTiO3/SrRuO(3)ultrathin heterostructures is achieved by oxygen vacancy (V-O) engineering. Pulsed laser deposition of an oxygen-deficient SrTiO(3)capping layer can trigger V(O)migration into the SrRuO(3)layer while avoiding the formation of Ru vacancies. Moreover, by varying the thickness and growth conditions of the SrTiO(3)capping layer, the value of the coercive field (H-C) in the ferromagnetic SrRuO(3)layer can be continuously tuned. The maximum enhancement ofH(C)at 5 K is 3.2 T. Such a wide-range tunability ofH(C)may originate from a V-O-induced enhancement of perpendicular magnetic anisotropy and domain wall pinning. This study offers effective approaches for controlling physical properties of oxide heterostructures via V(O)engineering, which may facilitate the development of oxide-based functional devices11sciescopu

Colossal flexoresistance in dielectrics

© 2020, The Author(s). Dielectrics have long been considered as unsuitable for pure electrical switches; under weak electric fields, they show extremely low conductivity, whereas under strong fields, they suffer from irreversible damage. Here, we show that flexoelectricity enables damage-free exposure of dielectrics to strong electric fields, leading to reversible switching between electrical states—insulating and conducting. Applying strain gradients with an atomic force microscope tip polarizes an ultrathin film of an archetypal dielectric SrTiO3 via flexoelectricity, which in turn generates non-destructive, strong electrostatic fields. When the applied strain gradient exceeds a certain value, SrTiO3 suddenly becomes highly conductive, yielding at least around a 108-fold decrease in room-temperature resistivity. We explain this phenomenon, which we call the colossal flexoresistance, based on the abrupt increase in the tunneling conductance of ultrathin SrTiO3 under strain gradients. Our work extends the scope of electrical control in solids, and inspires further exploration of dielectric responses to strong electromechanical fields11sci