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The review presents methods that are used frequently for multi-analytical study of fossil resins. The preliminary characterization relies on physical methods such as microhardness, density and fluorescence in UV light measurements. The spectroscopic methods: infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy are also presented in the paper. Besides that, the review also contains examples of the application of chromatographic methods: gas chromatography, thin layer chromatography, high-performance liquid chromatography, two-dimensional gas chromatography coupled to time-of-flight mass spectrometry as well as sample preparation methods for chromatographic studies such as pyrolysis. Additionally, thermal methods such as thermogravimetric analysis and differential scanning calorimetry also are covered by the review. Beside the examples of application, a detailed description with development history and perspective for further improvement are presented for each method. Moreover, fit-for-purpose assessment of each method is illustrated based on many examples from literature. The paper also contains examples of the application of multivariate statistical analysis and chemometric methods for comparing multiple properties of different fossil resin specimens for differentiation and classification purposes. [ABSTRACT FROM AUTHOR]

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The aim of this study was to evaluate the relationship between soft tissue dimensions and radial root position (RRP) classification for immediate implant placement on maxillary anterior teeth. Maxillary anterior teeth (n = 420) were analyzed in the radial plane of cone beam computed tomography (CBCT) scans. Each tooth was classified according to its RRP: class I, (IA, IB); class II (IIA, IIB) class III; class IV, and class V. Soft tissue thickness at different landmarks, supracrestal soft tissue height, and crestal bone thickness were measured in CBCT. Keratinized tissue width was clinically measured. Gingival phenotype (thick or thin) was evaluated by transparency of the periodontal probe and at the landmark 2 mm from the gingival margin in CBCT. Class I tooth position accounted for 31.7%, class II for 45%, class III for 13.3%, class IV for 0.5%, and class V for 9.5%. The gingival phenotype was associated with RRP (χ2 test, p < 0.05). Soft tissue dimensions were significantly different over RRP classes (ANOVA and Tukey tests, p < 0.05). Types IA and IIA presented both thick soft and hard tissues. When planning immediate implants in the anterior maxilla, soft tissue dimensions evaluation should be incorporated into RRP classification to increase the accuracy and predictability of treatment outcomes. [ABSTRACT FROM AUTHOR]

Non-line-of-sight (NLOS) imaging is a novel radar sensing technology that enables the reconstruction of hidden targets. However, it may suffer from synthetic aperture length reduction caused by ambient occlusion. In this study, a complex total variation (CTV) regularization-based sparse reconstruction method for NLOS three-dimensional (3-D) imaging by millimeter-wave (mmW) radar, named RM-CSTV method, is proposed to improve imaging quality and speed. In this scheme, the NLOS imaging model is first introduced, and associated geometric constraints for NLOS objects are established. Second, an effective high-resolution NLOS imaging method based on the range migration (RM) kernel and complex sparse joint total variation constraint, dubbed as modified RM-CSTV, is proposed for 3-D high-resolution imaging with edge information. The experiments with multi-type NLOS targets show that the proposed RM-CSTV method can provide effective and high-resolution NLOS targets 3-D imaging.

Cone Beam Computed Tomography (CBCT) has emerged as a pivotal imaging modality across various disciplines, providing three-dimensional visualisation with significant applications in dentistry, medical diagnostics, and industrial fields. This article presents a comprehensive overview of key aspects in CBCT imaging, encompassing the critical topics of Field of View (FOV), Resolution, Dose Considerations, and Artefacts. The Field of View (FOV) is a fundamental parameter influencing the scope and application of CBCT. This article explores the impact of different FOV settings on image acquisition, highlighting considerations for selecting an optimal FOV based on the specific diagnostic requirements of diverse clinical scenarios. Resolution plays a pivotal role in defining the clarity and precision of CBCT images. The article delves into the nuances of spatial and contrast resolution in CBCT, addressing the technological advancements and challenges associated with achieving high-resolution imaging while minimizing radiation exposure. Dose considerations are paramount in any medical imaging technique, and CBCT is no exception. This article provides an analysis of radiation dose management strategies in CBCT, emphasizing the importance of balancing diagnostic efficacy with patient safety. It explores dose optimization techniques, dose monitoring, and advancements in technology aimed at minimizing radiation exposure. Artefacts are inherent challenges in CBCT imaging that can compromise diagnostic accuracy. Understanding artefacts is crucial for practitioners to enhance the reliability and interpretability of CBCT images. [ABSTRACT FROM AUTHOR]

This article uses the inverse synthetic aperture radar (ISAR) imaging method to present real-world tests on 3-D radar imaging of noncooperative air targets. Initially, the fundamentals of 3-D ISAR are introduced. This is followed by a discussing of the challenges of obtaining high-quality 3-D radar images. An essential feature of the applied method is its basis on the back-projection family of techniques, eliminating the need for iterative image reconstruction. These theoretical concepts are validated using both simulations and real-life signals. This article also provides insights into the measurement campaign and the signal processing techniques applied to achieve the presented results.

Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneurons. However, current research on the spatial location of the spinal motoneurons innervating different muscles is limited. In this study, we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs, which were innervated by the obturator nerve, femoral nerve, inferior gluteal nerve, deep peroneal nerve, and tibial nerve. Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared organs (3DISCO) and 3-D imaging technology based on lightsheet fluorescence microscopy (LSFM). Additionally, we propose the hypothesis that “messenger zones” exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups. We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons. Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse. Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles, but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.

Space situation awareness (SSA) has gained much more attention in the last decades due to the increasing number of spacecraft in space, which provides powerful space surveillance, and hence, ensures the safe flight of spacecraft. Inverse synthetic aperture radar (ISAR) is an effective tool for uncooperative target recognition and has been widely used in ground-based SSA systems. Due to the increasing usage of small spacecraft in missions and the similar appearance of most spacecraft, the high-resolution imaging is more highly needed for reliable spacecraft recognition than before, which is also desired by the component-level recognition. Furthermore, the 3-D image reconstruction of spacecraft is very helpful in evaluating the structures due to the addition of the 3-D information, and hence, has become a very promising tool for deep target analysis. This article proposes a high-resolution spaceborne 3-D ISAR imaging method with fewer requirements on the antenna configuration and high computational efficiency. First, dedicated processing is designed to get high azimuthal resolution using large target-to-radar rotational angle accumulation. We address associated issues including the migration through resolution cell phenomenon and the high-order azimuthal phase modulation leading to defocusing of the resultant spacecraft images. Second, with the generated high-resolution 2-D images, we use dual-antenna interferometric processing to acquire the 3-D coordinates. To get precise coordinates of scatterers in both vertical and horizontal directions, the cross-range scaling technique is used. Finally, interferometric processing is used for locating the targets' height coordinates. Simulation results indicate that the presented method can provide 3-D images of spacecraft of higher resolution with a simple system structure than the traditional interferometric ISAR image methods.

Introduction: The radiographic examination of alveolar bone using 3D radiographic examination is essential in dental implant treatment planning. Our study aimed to systematically review and quantitatively analyze the correlation between alveolar bone parameters, specifically bone density and cortical bone thickness, assessed using cone beam computed tomography (CBCT) and/or multidetector computed tomography (MDCT); and primary implant stability (PIS) determined using implant stability quotient (ISQ), Periotest® value (PTV), and insertion torque value (ITV). Methods: This review was registered in the PROSPERO database (registration number CRD42022307245). An electronic literature search was conducted on the PubMed, SCOPUS, and Web of Science databases for papers published until February 2022. The Quality Assessment in Prognostic Studies (QUIPS) tool was used to assess risk of bias. Meta‐analyses were conducted to calculate the estimated average correlation coefficient based on a multilevel random‐effects model, followed by subgroup analysis. Results: Twenty‐six studies were included in this review, consisting of 17 prospective cohort studies, eight retrospective cohort studies, and one nonrandomized controlled trial. A total of 3109 implants placed in 1171 subjects were analyzed. Twenty‐three studies were evaluated using meta‐analysis. The alveolar bone condition was significantly correlated with ISQ (r = 0.60; p <.001), IT (r = 0.52; p <.001), and PTV (r = −0.42; p <.05). Conclusion: Alveolar bone condition is significantly associated with PIS. Low bone density and thin cortical bone can lead to low PIS; therefore, modification of treatment planning and surgical procedures might be needed to avoid poor osseointegration. [ABSTRACT FROM AUTHOR]

Background and Aims During the analysis of plant male meiocytes coming from destroyed meiocyte columns (united multicellular structures formed by male meiocytes in each anther locule), a considerable amount of information becomes unavailable. Therefore, in this study intact meiocyte columns were studied by volume microscopy in wild-type rye for the most relevant presentation of 3-D structure of rye meiocytes throughout meiosis. Methods We used two types of volume light microscopy: confocal laser scanning microscopy and non-confocal bright-field scanning microscopy combined with alcohol and aldehyde fixation, as well as serial block-face scanning electron microscopy. Key Results Unusual structures, called nuclear protuberances, were detected. At certain meiotic stages, nuclei formed protuberances that crossed the cell wall through intercellular channels and extended into the cytoplasm of neighbouring cells, while all other aspects of cell structure appeared to be normal. This phenomenon of intercellular nuclear migration (INM) was detected in most meiocytes at leptotene/zygotene. No cases of micronucleus formation or appearance of binucleated meiocytes were noticed. There were instances of direct contact between two nuclei during INM. No influence of fixation or of mechanical impact on the induction of INM was detected. Conclusions Intercellular nuclear migration in rye may be a programmed process (a normal part of rye male meiosis) or a tricky artefact that cannot be avoided in any way no matter which approach to meiocyte imaging is used. In both cases, INM seems to be an obligatory phenomenon that has previously been hidden by limitations of common microscopic techniques and by 2-D perception of plant male meiocytes. Intercellular nuclear migration cannot be ignored in any studies involving manipulations of rye anthers. [ABSTRACT FROM AUTHOR]

The liver lymphatic system is essential for maintaining tissue fluid balance and immune function. The detailed structure of lymphatic vessels (LVs) in the liver remains to be fully demonstrated. The aim of this study is to reveal LV structures in normal and diseased livers by developing a tissue-clearing and coimmunolabeling protocol optimized for the tissue size and the processing time for three-dimensional (3-D) visualization and quantification of LVs in the liver. We showed that our optimized protocol enables in-depth exploration of lymphatic networks in the liver, consisting of LVs along the portal tract (deep lymphatic system) and within the collagenous Glisson's capsule (superficial lymphatic system) in different species. With this protocol, we have shown 3-D LVs configurations in relation to blood vessels and bile ducts in cholestatic mouse livers, in which LVs were highly dilated and predominantly found around highly proliferating bile ducts and peribiliary vascular plexuses in the portal tract. We also established a quantification method using a 3-D volume-rendering approach. We observed a 1.6-fold (P < 0.05) increase in the average diameter of LVs and a 2.4-fold increase (P < 0.05) in the average branch number of LVs in cholestatic/fibrotic livers compared with control livers. Furthermore, cholestatic/fibrotic livers showed a 4.3-fold increase (P < 0.05) in total volume of LVs compared with control livers. Our optimized protocol and quantification method demonstrate an efficient and simple liver tissueclearing procedure that allows the comprehensive analysis of liver lymphatic system. [ABSTRACT FROM AUTHOR]

This PRISMA-compliant systematic review aimed to investigate the use of and the most common procedures performed with the novel 3D 4K exoscope in surgical pediatric head and neck settings. Methods: Search criteria were applied to PubMed, EMBASE and the Cochrane Review databases and included all studies published up to January 2023 reporting 3D 4K exoscope-assisted surgeries in pediatric patients. After the removal of duplicates, selection of abstracts and full-text articles, and quality assessment, we reviewed eligible articles for number of patients treated, age, surgical procedures, and outcomes. Results: Among 54 potentially relevant records, 5 studies were considered eligible and included in this systematic review, with reported treatment data for 182 patients. The surgical procedures belong to the otologic field (121 cases), head and neck surgery (25 cases) and transoral surgery (36 cases). Exoscopy allowed high quality visualization of anatomical structures during cochlear implantation and during reconstruction in head and neck surgery; moreover, it improved the surgical view of surgeons, spectators and ENT students. Conclusions: The use of 3D 4K exoscopy has shown promising potential as a valuable tool in pediatric ORL-head and neck surgery; nevertheless, further validation of these encouraging outcomes is necessary through larger-scale studies specifically focused on pediatric patients. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to determine the association between periodontal supracrestal soft tissue dimensions (PSSTDs) and other phenotypic features in non‐molar maxillary teeth. Materials and Methods: Adult subjects in need of comprehensive dental treatment were recruited. Periodontal phenotypic variables (i.e., facial and palatal gingival thickness [GT], alveolar bone thickness [BT], and PSSTDs, namely distance from the gingival margin to the bone crest defined as periodontal supracrestal tissue height [PSTH] and distance from the cementoenamel junction to the bone crest [CEJ‐BC]) were recorded using cone‐beam computed tomography scans. Standardized intraoral photographs were obtained to assess facial keratinized tissue width (KTW) and other anatomical parameters (i.e., tooth type, gingival architecture, and interproximal papilla height). Results: The study sample was constituted of 87 participants that contributed with a total of 522 maxillary anterior teeth. Differences in mean values of PSSTDs, KTW, GT, and BT were observed between tooth types and sex. Males exhibited a thicker GT and BT, and taller PSTH and KTW compared to females. Shorter CEJ‐BC was associated with shorter PSTH, wider KTW, and thicker GT and BT. Shorter PSTH was associated with thicker facial BT. Notably, BT and GT were positively correlated at both facial and palatal sites, meaning that the thicker the gingival phenotype, the thicker the bone morphotype. Facial BT and facial GT were positively correlated with KTW. A flat gingival architecture was associated with the thick periodontal phenotype. Square teeth had shorter CEJ‐BC, wider KTW, and thicker GT. Conclusions: Periodontal phenotypic features vary across and within subjects, between facial and palatal sites at different apico‐coronal levels, and as a function of sex and tooth type. The shorter the PSSTDs, the wider the KTW and the thicker the GT and BT. PSSTDs, particularly PSTH, should be considered an integral component of the periodontal phenotype. [ABSTRACT FROM AUTHOR]

Objective: The aims of this study were to visualize and quantify relative bone positions in the feet of individuals with cerebral palsy (CP) with a foot deformity and compare bone positions with those of typically developed (TD) controls. Materials and methods: Weight-bearing CT images of 14 individuals with CP scheduled for tendon transfer and/or bony surgery and of 20 TD controls were acquired on a Planmed Verity WBCT scanner. Centroids of the navicular and calcaneus with respect to the talus were used to quantify foot deformities. All taluses were aligned and the size and dimensions of the individuals' talus were scaled to correct for differences in bone sizes. In order to visualize and quantify variations in relative bone positions, 95% CI ellipsoids and standard deviations in its principle X-, Y-, and Z-directions were determined. Results: In individuals with CP (age 11–17), a large variation in centroid positions was observed compared to data of TD controls. Radiuses of the ellipsoids, representing the standard deviations of the 95% CI in the principle X-, Y-, and Z-directions, were larger in individuals with CP compared to TD controls for both the calcaneus (3.16 vs 1.86 mm, 4.26 vs 2.60 mm, 9.19 vs 3.60 mm) and navicular (4.63 vs 1.55 mm, 5.18 vs 2.10 mm, 16.07 vs 4.16 mm). Conclusion: By determining centroids of the calcaneus and navicular with respect to the talus on WBCT images, normal and abnormal relative bone positions can be visualized and quantified in individuals with CP with various foot deformities. [ABSTRACT FROM AUTHOR]

Shear wave elasticity imaging (SWEI) usually assumes an isotropic material; however, skeletal muscle is typically modeled as a transversely isotropic material with independent shear wave speeds in the directions along and across the muscle fibers. To capture these direction-dependent properties, we implemented a rotational 3-D SWEI system that measures the shear wave speed both along and across the fibers in a single 3-D acquisition, with automatic detection of the muscle fiber orientation. We tested and examined the repeatability of this system's measurements in the vastus lateralis of 10 healthy volunteers. The average coefficient of variation of the measurements from this 3-D SWEI system was 5.3% along the fibers and 8.1% across the fibers. When compared with estimated respective 2-D SWEI values of 16.0% and 83.4%, these results suggest using 3-D SWEI has the potential to improve the precision of SWEI measurements in muscle. Additionally, we observed no significant difference in shear wave speed between the dominant and non-dominant legs along (p = 0.26) or across (p = 0.65) the muscle fibers. [ABSTRACT FROM AUTHOR]

Abstract Introduction Optical three‐dimensional scanning devices can produce geometrically accurate, high‐resolution models of patients suitable for clinical use. This article describes the use of a metrology‐grade structured light scanner for the design and production of radiotherapy medical devices and synthetic water‐equivalent computer tomography images. Methods Following commissioning of the device by scanning objects of known properties, 173 scans were performed on 26 volunteers, with observations of subjects and operators collected. Results The fit of devices produced using these scans was assessed, and a workflow for the design of complex devices using a treatment planning system was identified. Conclusions Recommendations are provided on the use of the device within a radiation oncology department.

We have designed and implemented a dual-mode adaptive optics (AO) imaging system that combines spectral domain optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) for in vivo imaging of the human retina. The system simultaneously acquires SLO frames and OCT B-scans at 60 Hz with an OCT volume acquisition time of 4.2 s. Transverse eye motion measured from the SLO is used to register the OCT B-scans to generate three-dimensional (3-D) volumes. Key optical design considerations include: minimizing system aberrations through the use of off-axis relay telescopes, conjugate pupil plane requirements, and the use of dichroic beam splitters to separate and recombine the OCT and SLO beams around the nonshared horizontal scanning mirrors. To demonstrate system performance, AO-OCT-SLO images and measurements are taken from three normal human subjects ranging in retinal eccentricity from the fovea out to 15-deg temporal and 20-deg superior. Also presented are en face OCT projections generated from the registered 3-D volumes. The ability to acquire high-resolution 3-D images of the human retina in the midperiphery and beyond has clinical importance in diseases, such as retinitis pigmentosa and cone-rod dystrophy.

Joint arthropathies often require continuous monitoring of the joint condition, typically performed using magnetic resonance (MR) or ultrasound (US) imaging. US imaging is often the preferred screening or diagnostic tool as it is fast and inexpensive. However, conventional 2-D US has limited capability to compare imaging results between examinations because of its operator dependence and challenges related to repeat imaging in the same location and orientation. Comparison between several imaging sessions is crucial to assess the interval progression of joint conditions. We propose a novel 3-D US scanner for ankle joint assessment that can partially overcome these issues by enabling 3-D imaging. Here, we (i) present the design of the 3-D US ankle scanner system, (ii) validate the geometric reconstruction accuracy of the system, (iii) provide preliminary images of healthy volunteer ankles and (iv) compare 3-D US imaging results with MR imaging. The 3-D ankle scanner consists of a tub filled with water, a linear US probe attached to the wall of the tub and a motorized unit that rotates the US probe 360° around the center of the tub. As the probe rotates, a 3-D US image is formed of the ankle of the patient positioned in the middle of the tub. US probe height, angle and distance from the tub center can be adjusted. The reconstruction accuracy of the system was validated in each of the coordinate directions at different probe angles using two test phantoms. A phantom consisting of numerous Ø200-µm nylon threads with known spacing and a metal rod with machined grooves was used for validation in the horizontal and vertical directions, respectively. The volumetric reconstruction accuracy validation was performed by imaging an agar phantom with two embedded spheres of known volumes and comparing the segmented sphere volume and surface area with the expected. Three-dimensional US and MR images of both ankles of five healthy volunteers were acquired. Distal tibia and proximal talus were segmented in both imaging modalities and the surfaces of these segmentations were compared using the 95% Hausdorff and mean surface distances. The observed mean linear measurement error in all the coordinate directions and over several probe angles was 2.98%. The mean measured volumetric measurement error was 3.45%. The volunteer study revealed useful features for joint assessment present in the 3-D ankle scanner images, such as joint spacing, distal tibia and proximal talus. The mean 95% Hausdorff and mean surface distances between segmentations in 3-D US and MR images were 5.68 ± 0.83 and 2.01 ± 0.30 mm, respectively. In this proof-of-concept study, the 3-D US ankle scanner enabled visualization of the ankle joint features that are useful for joint assessment. [ABSTRACT FROM AUTHOR]

Median nerve swelling is one of the features of carpal tunnel syndrome (CTS), and ultrasound measurement of maximum median nerve cross-sectional area is commonly used to diagnose CTS. We hypothesized that volume might be a more sensitive measure than cross-sectional area for CTS diagnosis. We therefore assessed the accuracy and reliability of 3-D volume measurements of the median nerve in human cadavers, comparing direct measurements with ultrasound images interpreted using deep learning algorithms. Ultrasound images of a 10-cm segment of the median nerve were used to train the U-Net model, which achieved an average volume similarity of 0.89 and area under the curve of 0.90 from the threefold cross-validation. Correlation coefficients were calculated using the areas measured by each method. The intraclass correlation coefficient was 0.86. Pearson's correlation coefficient R between the estimated volume from the manually measured cross-sectional area and the estimated volume of deep learning was 0.85. In this study using deep learning to segment the median nerve longitudinally, estimated volume had high reliability. We plan to assess its clinical usefulness in future clinical studies. The volume of the median nerve may provide useful additional information on disease severity, beyond maximum cross-sectional area. [ABSTRACT FROM AUTHOR]

The 3-D imaging light detection and ranging (LiDAR) with a wide scanning angle of 147.5° $\times 11.6$ ° is shown. The LiDAR has the micro-electromechanical system (MEMS) scanner, which is the electromagnetic driving type produced by the silicon-on-insulator (SOI) process. The scanner has a large aperture size of 7 mm $\times $ 5 mm with the mechanical tilt angle of ±12.5° $\times $ ±3.4°. The rib structure of the MEMS mirror realizes the small distortion on the mirror surface in addition to the lightweight. The three laser diodes (LDs) are used to realize the wide scanning angle. The optics has the unique design and covers the three transmitting directions of the LDs with only one small photodetector that has a diameter of 0.5 mm. This single photodetector configuration contributes to the compactness in addition to low cost. The maximum measurable range of 40 m is demonstrated with the frame rate of 28 frames per second (fps) and $282\times 31$ pixels. [ABSTRACT FROM AUTHOR]

For drone vision and navigation, low-power 3-D depth sensing with robust operations against strong/weak light and various weather conditions is crucial. CMOS image sensor (CIS) and light detection and ranging (LiDAR) can provide high-fidelity imaging. However, CIS lacks depth sensing and has difficulty in low light conditions. LiDAR is expensive with issues of dealing with strong direct interference sources. Ultrasound imaging system (UIS), on the other hand, is robust in various weather and light conditions and is cost-effective. However, in air channel, it often suffers from long image reconstruction latency and low framerate. To address these issues, we present a UIS application-specific integrated circuit (ASIC) that adopts the one-shot transmitter (TX) and on-chip per-voxel receiver (RX) beamfocusing (PV-RXBF) image reconstruction scheme. The ASIC adopts the designs of fully differential charge-reuse high-voltage TX (FDCR-HVTX), digital back-end (DBE), and an on-chip power management unit (PMU). FDCR-HVTX generates 28 $\text{V}_{\mathrm {pp}}$ pulses and reduces the average power consumption by 25% by charge reuse (CR). The DBE achieves 7.76- $\mu \text{s}$ processing latency and 9.83M-FocalPoint/s throughput to effectively translate real-time 3-D image streaming at 24 frames/s. A prototype UIS, with an $8\times 8$ bulk piezo transducer array, is assembled with the proposed ASIC and a wireless data transmission module [field-programmable gate array (FPGA) + ESP32] on an entry-level consumer drone, and the real-time wireless 3-D image streaming at 24 frames/s with a range of 7 m is verified while the drone is flying. The ASIC implemented in 180-nm 1P6M Standard CMOS occupies 32.5 mm2 and consumes 142.3 mW. [ABSTRACT FROM AUTHOR]

Background/objectives: This retrospective longitudinal outcome study comparing orthodontic extraction modalities, including extraction of maxillary first or second molars, aimed to compare the three-dimensional tooth movement of maxillary canines (C), premolars (P1, P2), and molars (M1, M2) in Class II division 1 malocclusion treatment with fixed appliances. Methods: A sample of 98 patients (mean age 13.20 ± 1.46 years) was selected for the M1 group, and 64 patients (mean age 13.20 ± 1.36 years) were chosen for the M2 group. Tooth movement was analyzed three-dimensionally on pre-treatment (T0) and post-treatment (T1) digital dental casts. Regression analyses compared the tooth movements (in mm) between the M1 and M2 groups. Results: The mean treatment duration for the M1 group was 2.51 ± 0.55 year, while, for the M2 group, it was 1.53 ± 0.37 year. The data showed limited distal movements of the C, P1, and P2 of approximately 2 mm in the M1 group and 1 mm in the M2 group during orthodontic treatment, but the M1 group exhibited significantly more distal movements than the M2 group (mean difference 1.11 to 1.24 mm). Vertical movements of the C, P1, and P2 in both groups were also minor (0.16 to 1.26 mm). The differences between groups did not exceed 0.2 mm and were not significant. Both treatment modalities resulted in a significant degree of anchorage loss with a distinct mesialization (8.40 ± 1.66 mm) of M2 in the M1 group and limited distalization (0.83 ± 0.98 mm) of M1 in the M2 group. Conclusions: The findings highlight the importance of thorough case evaluation when choosing between extraction modalities in Class II treatment. If a large distal movement of canines and premolars is required, additional anchorage mechanics should be considered.

Objectives: Evaluating the effect of shape and size of implant scan body on the accuracy of optical 3D scanning., Materials and Methods: Fifteen PEEK scan bodies were milled, including 1 spherical, 9 cylindrical, and 5 cuboidal. The 3D position and angulation of each scan body were measured using a CMM 3 times and a laboratory scanner 10 times. The linear and angular trueness and precision of the scans were calculated by comparing with the CMM measurements., Results: The linear accuracy of the cylindrical scan bodies (9.5 ± 6.2 µm) was significantly higher than those of the cuboidal (17.7 ± 8.1 µm) and spherical scan bodies (12.5 ± 6.5 µm). The cuboidal (0.050±0.009°) showed significantly better angular accuracy than the cylindrical (0.065±0.040°). In the cylindrical group, the narrow (∅4.8 mm) demonstrated significantly inferior accuracy than the wider (∅5.5 mm and ∅6.5 mm)(p = 0.003). The tall (12 mm) showed significantly higher angular trueness than the shorter (8 and 4 mm)(p < 0.001). In the cuboidal group, the 24 mm 2 exhibited significantly poorer angular trueness compared to the 18 mm 2 and 30 mm 2 (p < 0.001) CONCLUSIONS: The shape and size of the implant scan body significantly affect the scanning accuracy. Spherical scan bodies cannot transfer implant angulation. Scan bodies with a size of >∅4.8 mm and >8 mm seem accurate for transferring the 3D implant position., Clinical Significance: The shape and size of scan bodies directly influence the accuracy of 3D scanning. Well-designed scan bodies offer better transfer results, which is crucial for ensuring passive fit of implant prostheses and improving long-term clinical outcomes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A 240 $\times$ 160 single-photon avalanche diode (SPAD) sensor integrated with a 3D-stacked 65nm/65nm CMOS technology is reported for direct time-of-flight (dToF) 3D imaging in mobile devices. The top tier is occupied by backside illuminated SPADs with 16 $\mu {\mathrm{ m}}$ pitch and 49.7% fill-factor. The SPADS consists of multiple 16 $\times$ 16 SPADs top groups, in which each of 8 $\times$ 8 SPADs sub-group shares a 10-bit, 97.65ps and 100ns range time-to-digital converter (TDC) in a quad-partition rolling shutter mode. During the exposure of each rolling stage, partial histogramming readout (PHR) approach is implemented to compress photon events to in-pixel histograms. Since the fine histograms is incomplete, for the first time we propose histogram distortion correction (HDC) algorithm to solve the linearity discontinuity at the coarse bin edges. With this algorithm, depth measurement up to 9.5m achieves an accuracy of 1cm and precision of 9mm in office lighting condition. Outdoor measurement with 10 klux sunlight achieves a maximum distance detection of 4m at 20 fps, using a VCSEL laser with the average power of 90 mW and peak power of 15 W.

Ionoluminescence (IL) is introduced as an imaging technique which can reveal unique aspects of sample structure from depths of several tens of micrometers. Both 2-D and 3-D IL images of a natural sphalerite sample were provided and compared with the microscopic image and micro-PIXE 2-D and 3-D elemental based images of the sample. It was shown that IL images could present different structural aspects of the sample with a spatial resolution on the order of one micrometer. Regarding the capabilities of the IL imaging technique, it is suggested as a fast and non-destructive technique for structural investigation of different inhomogeneous samples. [ABSTRACT FROM AUTHOR]

This study compared the diagnostic accuracy of percutaneous fistula contrast-enhanced ultrasound (CEUS) combined with 360° 3-D transrectal ultrasound (TRUS) imaging (CEUS + 360°-TRUS) with that of conventional transrectal ultrasound in the diagnosis of complex anal fistulas. A total of 156 patients clinically diagnosed with complex anal fistula from January 2020 to December 2021 were studied and randomly divided into an experimental group (n = 82) and a control group (n = 74). Patients in the experimental group were examined by percutaneous fistula CEUS combined with CEUS + 360°-TRUS, while patients in the control group were examined using TRUS. The detection of fistulas (main tract, branch and internal orifice) and the accuracy of Parks classification were compared between the two groups. Recurrences were followed up at 1, 3 and 6 mo after the surgery. A total of 156 patients were included, aged 23-68 y (average: 37.7 ± 18.2 y). In both groups, the course of disease was <1 mo in 128 cases, 1-2 mo in 22 cases and >3 mo in 6 cases. A total of 474 fistulas were confirmed by surgery in the aforementioned patients, including 224 main fistulas, 250 branch pipes and 254 internal orifices. The CEUS + 360°-TRUS group had 96.87%, 90.41% and 90.14% diagnostic accuracy for the main tract, branch and internal orifice, which was statistically significant (p < 0.001) compared with the 85.00%, 70.00% and 72.46% for the TRUS group, respectively. The overall accuracy of Parks classification of anal fistula in the CEUS + 360°-TRUS group was significantly higher than that in the TRUS group (90.24% vs. 78.38%, p < 0.001). After 6 mo of follow-up, the recurrence rate in the CEUS + 360°-TRUS group was 4.87%, and the recurrence rate in the TRUS group was 18.91%. Percutaneous fistula CEUS combined with transrectal 360° 3-D imaging has significantly higher accuracy than conventional TRUS in the diagnosis of complex anal fistula, especially for anal fistula branches, internal openings and Parks classification and is beneficial in reducing post-operative occurrence of complex anal fistulas. [ABSTRACT FROM AUTHOR]

Spiral array transducers with a sparse 2-D aperture have demonstrated their potential in realizing 3-D ultrasound imaging with reduced data rates. Nevertheless, their feasibility in high-volume-rate imaging based on unfocused transmissions has yet to be established. From a metrology standpoint, it is essential to characterize the acoustic field of unfocused transmissions from spiral arrays not only to assess their safety but also to identify the root cause of imaging irregularities due to the array’s sparse aperture. Here, we present a field profile analysis of unfocused transmissions from a density-tapered spiral array transducer (256 hexagonal elements, 220- $\mu \text{m}$ element diameter, and 1-cm aperture diameter) through both simulations and hydrophone measurements. We investigated plane- and diverging-wave transmissions (five-cycle, 7.5-MHz pulses) from 0° to 10° steering for their beam intensity characteristics and wavefront arrival time profiles. Unfocused firings were also tested for B-mode imaging performance (ten compounded angles, −5° to 5° span). The array was found to produce unfocused transmissions with a peak negative pressure of 93.9 kPa at 2 cm depth. All transmissions steered up to 5° were free of secondary lobes within 12 dB of the main beam peak intensity. All wavefront arrival time profiles were found to closely match the expected profiles with maximum root-mean-squared errors of $0.054~\mu \text{s}$ for plane wave (PW) and $0.124~\mu \text{s}$ for diverging wave. The B-mode images showed good spatial resolution with a penetration depth of 22 mm in PW imaging. Overall, these results demonstrate that the density-tapered spiral array can facilitate unfocused transmissions below regulatory limits (mechanical index: 0.034; spatial-peak, pulse-average intensity: 0.298 W/cm2) and with suppressed secondary lobes while maintaining smooth wavefronts. [ABSTRACT FROM AUTHOR]

Top-orthogonal-to-bottom electrode (TOBE) arrays, also known as row–column arrays, have shown great promise as an alternative to fully wired 2-D arrays, owing to a considerable reduction in channels. Novel imaging schemes with bias-switchable TOBE arrays were previously shown to offer promise compared with previous nonbias-switchable row–column imaging schemes and compared with previously developed explososcan methods, however, they required significant coherent compounding. Here, we introduce ultrafast orthogonal row–column electronic scanning (uFORCES), an ultrafast coded synthetic aperture imaging method. Unlike its FORCES predecessor, uFORCES can achieve coherent compounding with only a few transmit events and may, thus, be more robust to tissue motion. We demonstrate through simulations that uFORCES can potentially offer improved resolution compared with the matrix probes having beamformers constrained by the paraxial approximation. Also, unlike current matrix probe technology incorporating microbeamforming, uFORCES with bias-switchable TOBE arrays can achieve ultrafast imaging at thousands of frames per second using only row and column addressing. We also demonstrate the experimental implementation of uFORCES using a fabricated $128 \times 128$ electrostrictive TOBE array on a crossed 25- $\mu \text{m}$ gold wire phantom and a tissue-mimicking phantom. The potential for improved resolution and ultrafast imaging with uFORCES could enable new essential imaging capabilities for clinical and preclinical ultrasound. [ABSTRACT FROM AUTHOR]

Linear array maneuvering synthetic aperture radar (SAR) can push the limitations of classical SAR on foresight 3-D imaging, which has captured the attention of worldwide radar researchers for a long time. To reconstruct the position of foresight target, this article puts forward a nonlinear chirp scaling (NLCS) method for 3-D foresight linear array maneuvering SAR (FLAM-SAR). According to the novel geometry configuration, an NLCS operation is adopted to equalize the space-variant Doppler frequency modulation rate. The simulation results of the array point scatterers and real airplane target model are used to prove the validity of theoretical derivation and validate the 3-D imaging capacity of FLAM-SAR. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3‐D) analysis of human epidermal melanocytes is required for deeper understanding of melanocytic disorders. The purpose of this study was to standardize 3‐D imaging and quantification for the evaluation of epidermal melanocytes. The epidermal specimen was obtained using the suction blister method from a patient with melanocytic nevus on the forearm skin. Cutaneous ACT‐PRESTO, the tissue‐clearing and labeling technique, was subsequently performed. With the 3‐D image analysis program, morphological reconstruction and quantification of selected perilesional and melanocytic nevus areas were possible. The region of melanocytic nevus showed higher numbers of total melanocytic dendrites and similar numbers of cell bodies compared with perilesional area. In addition, the mean area and volume of cell bodies increased in the melanocytic nevus area compared with the results in the perilesional area. The 3‐D evaluation method of human epidermal melanocytes can be applied to investigate novel pathologies related to hyper‐ or hypo‐pigmentary disorders. [ABSTRACT FROM AUTHOR]

We present the design and characterization of a fully-integrated array of $16 \times 16$ Single-Photon Avalanche Diodes (SPADs) with fast-gating capabilities and 16 on-chip 6 ps time-to-digital converters, which has been embedded in a compact imaging module. Such sensor has been developed for Non-Line-Of-Sight imaging applications, which require: i) a narrow instrument response function, for a centimeteraccurate single-shot precision; ii) fast-gated SPADs, for time-filtering of directly reflected photons; iii) high photon detection probability, for acquiring faint signals undergoing multiple scattering events. Thanks to a novel multiple differential SPAD-SPAD sensing approach, SPAD detectors can be swiftly activated in less than 500 ps and the full-width at half maximum of the instrument response function is always less than 75 ps (60 ps on average). Temporal responses are consistently uniform throughout the gate window, showing just few picoseconds of time dispersion when 30 ns gate pulses are applied, while the differential non-linearity is as low as 250 fs. With a photon detection probability peak of 70% at 490 nm, a fill-factor of 9.6% and up to $1.6 \cdot 10^{8}$ photon time-tagging measurements per second, such sensor fulfills the demand for fully-integrated imaging solutions optimized for non-line-of-sight imaging applications, enabling to cut exposure times while also optimizing size, weight, power and cost, thus paving the way for further scaled architectures. [ABSTRACT FROM AUTHOR]

Abstract Objective The aim of this study was to propose and validate a three‐dimensional (3D) methodology for the assessment of canine eruption in patients born with unilateral cleft lip and palate (UCLP) following secondary alveolar bone graft (SABG). Methods and Materials A total of 10 patients (four females, six males; mean age: 8.8 years) with UCLP who underwent SABG were recruited. Pre‐ and 6‐month post‐operative cone‐beam computed tomography (CBCT) was acquired for all patients. Post‐operative data was registered onto pre‐operative data utilizing voxel‐based registration. Following superimposition, a segmentation process was applied to segment maxillary canine on both cleft and non‐cleft side. Thereafter, translational and rotational changes in canine position were assessed for both cleft and non‐cleft side by two observers. Results The intra‐class correlation coefficient (ICC) indicated excellent reliability (≥0.90) with inter and intra‐observer error of less than 0.05 mm. The overall ICC was found to be high for assessing both translational and rotational changes. The mean absolute inter‐ and intra‐observer difference for translational and rotational changes was found to be less than 1 mm and 3°. Conclusion The present method was found to be reliable proving to be clinically applicable for assessing maxillary canine eruption changes in both cleft and non‐cleft bone.

Abstract Background Dental implants are a common restorative method used to replace missing teeth. Implant placement techniques guided by three-dimensional imaging and navigation are becoming more widely available. Objective The present review focused on the following questions: 1. What are the advantages and disadvantages of 2-D versus 3-D imaging in dental implantology? 2. What are the advantages and disadvantages of freehand implant placement in comparison with navigation-guided implant placement? Methods A systematic review was performed, based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. The following libraries were searched for relevant literature: PubMed, Embase, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF) Online, and the Cochrane Library. The risk of bias was assessed using the Scottish Intercollegiate Guidelines Network (SiGN) checklist. A total of 70 studies were included after screening, and the evidence from these was gathered for review. Results Three-dimensional imaging is advantageous in terms of image quality, and it provides a distortion-free evaluation of the implant site. However, it is also associated with higher costs and increased radiation exposure. Dynamic and static navigation are equal in accuracy and are both more accurate compared with the freehand method. No benefit in terms of implant survival could be demonstrated within the first 5 years for any specific method. Discussion A panoramic X-ray with a reference body often provides sufficient imaging and is the primary method for two-dimensional imaging. Cone beam computed tomography with low-dose protocol settings should be used if three-dimensional imaging is needed. Navigational support should be considered in the event of especially complex cases. Conclusion The guidance technique used for implant placement should be decided on an individual basis. With the increasing availability of three-dimensional imaging, there should also be an increase in awareness of radiation exposure.

The spread of high frame rate and 3-D imaging techniques has raised pressing requirements for ultrasound systems. In particular, the processing power and data transfer rate requirements may be so demanding to hinder the real-time (RT) implementation of such techniques. This paper first analyzes the general requirements involved in RT ultrasound systems. Then, it identifies the main bottlenecks in the receiving section of a specific RT scanner, the ULA-OP 256, which is one of the most powerful available open scanners and may therefore be assumed as a reference. This case study has evidenced that the "star" topology, used to digitally interconnect the system's boards, may easily saturate the data transfer bandwidth, thus impacting the achievable frame/volume rates in RT. The architecture of the digital scanner was exploited to tackle the bottlenecks by enabling a new "ring" communication topology. Experimental 2-D and 3-D high-frame-rate imaging tests were conducted to evaluate the frame rates achievable with both interconnection modalities. It is shown that the ring topology enables up to 4400 frames/s and 510 volumes/s, with mean increments of +230% (up to +620%) compared to the star topology. [ABSTRACT FROM AUTHOR]

The aim: to evaluate combined microscopy techniques for determining the morphological and optical properties of methadone hydrochloride (MDN) crystals. Materials and methods: MDN crystal formation was optimized using a closed container method and crystals were characterized using polarized light microscope (PLM), scanning electron microscopy (SEM) and confocal microscopy (CM). SEM and CM were used to determine MDN crystal thickness and study its relationship with crystal retardation colours using the Michel-Levy Birefringence approach. Results: Dimensions (mean±SD) of diamond shaped MDN crystals were confirmed using SEM and CM. Crystals were 46.4±15.2 Vs 32.0±8.3 μm long, 28.03±8.2 Vs 20.85±5.5 μm wide, and 6.62±2.9 Vs 9.6±4.6 μm thick, respectively. There were significant differences between SEM and CM thickness measurements (U=1283, p<0.05), as the SEM exhibited thinner diamond crystals. The combined use of PLM and Michel-Levy chart enabled the observation of a predominantly yellow coloured MDN crystal, mean thickness at (428 nm) mean retardation value. Conclusion: The SEM was superior and successfully determined MDN crystal dimensions for the first time, whilst the CM results were affected by the Rhodamine dye staining process used for visualisation. The qualitative analysis of the crystallinity status of methadone hydrochloride optimally achieved using a combination of PLM and SEM techniques. [ABSTRACT FROM AUTHOR]

Indirect time-of-flight (iToF) cameras operate by illuminating a scene with modulated light and inferring depth at each pixel by combining the back-reflected light with different gating signals. This article focuses on amplitude-modulated continuous-wave (AMCW) time-of-flight (ToF), which, because of its robustness and stability properties, is the most common form of iToF. The figures of merit that drive iToF performance are explained and plotted, and system parameters that drive a camera’s final performance are summarized. Different iToF pixel and chip architectures are compared and the basic phasor methods for extracting depth from the pixel output values are explained. The evolution of pixel size is discussed, showing performance improvement over time. Depth pipelines, which play a key role in filtering and enhancing data, have also greatly improved over time with sophisticated denoising methods now available. Key remaining challenges, such as ambient light resilience and multipath invariance, are explained, and state-of-the-art mitigation techniques are referenced. Finally, applications, use cases, and benefits of iToF are listed. [ABSTRACT FROM AUTHOR]

Three-dimensional (3-D) imaging plays a vital role in the recognition of spinning space debris. However, the image may be blurred due to the range migration caused by fast rotation of space debris. Moreover, the image quality, which depends on the estimation accuracy of Doppler frequency and chirp rate of scattering centers, is influenced by cross-terms and sidelobes. In this article, we propose a novel 3-D imaging method based on smoothed Lv distribution (SLVD). Firstly, the selection criterion for best imaging time based on the time–frequency moment is proposed to guarantee that the echo is approximated as a linear frequency modulation (LFM) signal. Then, we operate the Khatri–Rao product on the centroid frequency and chirp rate (CFCR) representation and the range-Doppler (RD) image to obtain the 3-D image. To decrease the influence of range migration, we process a short time window during the RD imaging procedure. For cross-term and sidelobe suppression, the SLVD is proposed to obtain the CFCR representation by expressing the Lv distribution (LVD) in a convolution form and introducing a centroid frequency window. Experimental results verify the effectiveness of the proposed imaging method and the good performance of the proposed SLVD for cross-term and sidelobe suppression. [ABSTRACT FROM AUTHOR]

Introduction: Optical three‐dimensional scanning devices can produce geometrically accurate, high‐resolution models of patients suitable for clinical use. This article describes the use of a metrology‐grade structured light scanner for the design and production of radiotherapy medical devices and synthetic water‐equivalent computer tomography images. Methods: Following commissioning of the device by scanning objects of known properties, 173 scans were performed on 26 volunteers, with observations of subjects and operators collected. Results: The fit of devices produced using these scans was assessed, and a workflow for the design of complex devices using a treatment planning system was identified. Conclusions: Recommendations are provided on the use of the device within a radiation oncology department. [ABSTRACT FROM AUTHOR]

This brief presents an overview of the recent progress on silicon-based millimeter-wave SoCs for short-range radar in imaging and sensing applications. The process, operating frequency, and basic architectures for short-range millimeter-wave radar are firstly summarized. Then, topology and performance of excellent radar SoCs are reviewed from different applications: automotive radar, gesture recognition, vital signs monitoring, security and biomedical sensing, industrial detection and imaging. Future trends in millimeter-wave SoCs for short-range radar are also discussed. [ABSTRACT FROM AUTHOR]

In this article, we present a CMOS image sensor (CIS) for coded-exposure-based compressive focal-stack imaging. The proposed CIS has a pixel design, which includes two capacitive trans-impedance amplifiers (CTIAs) and a static random access memory (SRAM), and is capable of per-frame exposure encoding with adjustable spatiotemporal resolutions. A proof-of-concept CIS prototype with a 192 $\times $ 192 pixel array is designed and fabricated in a 0.13- $\mu \text{m}$ CMOS process with a pixel size of 12.6 $\times $ 12.6 $\mu \text{m}^{2}$. Operating at 30 frames per second (fps), the CIS demonstrates spatial–temporal coded exposure at a maximum rate of 768 masks/frame. The column-wise 10-bit single-slope (SS) analog-to-digital converter (ADC) includes a ramp-slope adaptation feature used for power optimization. During a frame of coded exposure, a linear focal sweep is implemented by a voice-coil motor (VCM) lens mounted in front of the proposed CIS. Through the sparse reconstruction of the coded image, a focal stack consisting of a volume of defocused images is used to synthesize the scene depth map. By introducing coded exposure, the proposed on-chip compressive focal-stack imaging approach facilitates a frame-saving method for passive depth sensing in machine vision and other imaging applications. [ABSTRACT FROM AUTHOR]

Objective: To compare computer-based 3D-analysis for quantification of the femorotibial joint space width (JSW) using weight-bearing cone beam CT (WB-CT), non-weight-bearing multi-detector CT (NWB-CT), and weight-bearing conventional radiographs (WB-XR).Design: Twenty-six participants prospectively underwent NWB-CT, WB-CT, and WB-XR of the knee. For WB-CT and NWB-CT, the average and minimal JSW was quantified by 3D-analysis of the minimal distance of any point of the subchondral tibial bone surface and the femur. Associations with mechanical leg axes and osteoarthritis were evaluated. Minimal JSW of WB-CT was further compared to WB-XR. Two-tailed p-values of <0.05 were considered significant.Results: Significant differences existed of the average medial and lateral JSW between WB-CT and NWB-CT (medial: 4.7 vs 5.1 mm [P = 0.028], lateral: 6.3 vs 6.8 mm [P = 0.008]). The minimal JSW on WB-XR (medial:3.1 mm, lateral:5.8 mm) were significantly wider compared to WB-CT and NWB-CT (both medial:1.8 mm, lateral:2.9 mm, all p < 0.001), but not significantly different between WB-CT and NWB-CT (all p ≥ 0.869). Significant differences between WB-CT and NWB-CT existed in participants with varus knee alignment for the average and the minimal medial JSW (p = 0.004 and p = 0.011) and for participants with valgus alignment for the average lateral JSW (p = 0.013). On WB-CT, 25% of the femorotibial compartments showed bone-on-bone apposition, which was significantly higher when compared to NWB-CT (10%,P = 0.008) and WB-XR (8%,P = 0.012).Conclusion: Combining WB-CT with 3D-based assessment allows detailed quantification of the femorotibial joint space and the effect of knee alignment on JSW. WB-CT demonstrates significantly more bone-on-bone appositions, which are underestimated or even undetectable on NWB-CT and WB-XR. [ABSTRACT FROM AUTHOR]

For the target with 3-D rotation, the 3-D synthetic aperture radar (SAR) imaging is very important for the feature extraction and classification. To solve this issue, a novel 3-D imaging algorithm through the airborne SAR system with a single antenna is proposed in this article, which has great advantages for the simplification of system structure compared with the traditional interferometric system. The proposed 3-D airborne SAR imaging algorithm can be implemented with three steps: 1) the azimuth signal is modeled as multicomponent linear frequency modulation (LFM) signal due to the relative movement between the target and radar. 2) The scatterer height position can be obtained by estimating the frequency modulation rate (FMR) for the LFM signal. 3) The 3-D airborne SAR image is obtained via the range-Doppler (RD) algorithm. Furthermore, the reconstruction performance under different rotation patterns, including roll, pitch, and yaw, is analyzed. The availability of the presented novel technique is demonstrated by the results of simulated and real experimental data. [ABSTRACT FROM AUTHOR]

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Objectives: To compare 2 implant scan bodies with different geometry on the accuracy of the virtual alignment process in the digital workflow. Materials and Methods: A master model of the edentulous maxilla with 6 implants and multiunit abutments (MUA) inserted was fabricated. Six dome‐shaped and cuboidal scan bodies were mounted on the MUAs, respectively, and consecutively scanned by a laboratory scanner 10 times. The original scans were imported to a dental‐specific CAD software and virtually aligned with the default CAD model in the implant library. Thus, 10 aligned models were created. Both the original scans and the aligned models were evaluated by an inspection software for deviation of the scan body surfaces, the centroids of scan body and MUA, the scan body center‐axis, and the inter‐MUA distances/angles. The two‐sample T‐test/Mann–Whitney U test were used to analyze the data with the level of significance set at 0.05. Results: The cuboidal group showed significant greater deviations of the model surface (13.9 µm vs. 10.7 µm) and the MUA centroids (31.7 µm vs. 22.8 µm) but smaller deviation of the inter‐MUA angle (0.047° vs. 0.070°) than those of the dome‐shaped group (p <.05). No significant differences in the deviation of scan body centroids, center‐axis, and the inter‐MUA distances between the 2 groups were found. Conclusions: Virtual alignment of implant scan body affected the accuracy of the digital workflow for complete‐arch implant‐supported prostheses (up to ~30 µm/0.09°). Different geometries of the implant scan body could also influence the transfer accuracy in the CAD process. [ABSTRACT FROM AUTHOR]

A high-resolution vector-sum phase shifter fabricated using a 28 nm CMOS was developed for a 79 GHz imaging radar. The phase shifter incorporates a process and temperature (P/T) stable in-phase (I)/quadrature-phase (Q) signal generator with a robust matching network and highly linear variable gain amplifiers (VGAs) with a crossing metal-line layout. These techniques contribute to 0.5° phase-setting resolution and a 0.9° root-mean-square (rms) phase error with no calibration process. The developed phase shifters were applied to a 79 GHz imaging radar prototype that consists of eight-channel transmitters and eight-channel receivers. The measurement results show that our prototype can recognize human posture, recognize multiple people, and monitor vital signs. [ABSTRACT FROM AUTHOR]

High-performance millimeter-wave (mm-wave) multiple-in-multiple-out (MIMO) radars have been using efficient multiplexing with increasingly complicated radar waveforms, where conventional hardware architectures suffer from inevitably high design complexity and cost. This article presents a new software-defined mm-wave multistatic imaging system which provides great efficiency and flexibility to generate and process complicated radar waveforms. A general system block diagram and its signal model are proposed to use space-time-coded orthogonal frequency-division multiplexing (OFDM) for simultaneous MIMO transmission at the same time and frequency. The space-time coding (STC) is designed based on the Hadamard matrix which allows simple decoupling and decoding for imaging processing. A radar prototype is designed to validate the proposed system architecture, which operates at 83.5 GHz with a frequency bandwidth of 4.8 GHz. The mm-wave front-end consists of a metal-printed 8-by-8 waveguide array with a small element-separation of 9 mm to form 64 virtual channels for three-dimensional imaging. Experimental results show good imaging performance, giving great potential to design future cost-effective high-performance mm-wave imaging with efficient multiplexing. [ABSTRACT FROM AUTHOR]

We investigated the role of three-dimensional (3-D) CT in the diagnosis and management of four bipartite scaphoids in three patients. We computed the volume ratio, moment of inertia ratio and direction vector from the centroid of the scaphoid to the os centrale carpi. We found that the os centrale carpi was always smaller than the scaphoid and showed an elongated shape in the scaphoid longitudinal axis. Its position was always posterior compared with the scaphoid anteroposterior axis. The main morphological feature of bipartite scaphoids was the continuity of the scaphoid from its proximal to distal aspect along the longitudinal axis. These criteria from 3-D imaging should be considered useful in the diagnosis of bipartite scaphoid as it allows differentiation from nonunion. 3-D single-photon emission computed tomography (SPECT)/CT was helpful in the surgical decision-making when the patient was symptomatic. 3-D imaging was also used for the preoperative simulation and planning of bone fusion as it simplifies surgery and makes it more accurate. Here we provide clear criteria for diagnosing bipartite scaphoids and for the planning when surgery is deemed necessary. [ABSTRACT FROM AUTHOR]