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Given the inherent limitations of spinal endoscopic surgery, proper lighting and visualization are of tremendous importance. These limitations include a small field of view, significant potential for disorientation, and small working cannulas. While modern endoscopic surgery has evolved in spite of these shortcomings, further progress in improving and enhancing visualization must be made to improve the safety and efficacy of endoscopic surgery. However, in order to understand potential avenues for improvement, a strong basis in the physical principles behind modern endoscopic surgery is first required. Having established these principles, novel techniques for enhanced visualization can be considered. Most compelling are technologies that leverage the concepts of light transformation, tissue manipulation, and image processing. These broad categories of enhanced visualization are well established in other surgical subspecialties and include techniques such as optical chromoendoscopy, fluorescence imaging, and 3-dimensional endoscopy. These techniques have clear applications to spinal endoscopy and represent important avenues for future research.

AIM AND OBJECTIVES Evaluation of the root canal morphology of maxillary premolars was the primary objective of this study, on the criteria of the roots present, canals detected in the roots, and anatomical canal patterns according to Vertucci's classification observed in the Saudi population using cone-beam computed tomography (CBCT) radiographic analysis comparing them to previous reports in the same population. MATERIALS AND METHODS A total of 710 maxillary 1st and 2nd premolars were considered in this research; of which 351 were 1st premolars and 359 were 2nd premolars. These premolars were investigated for their external and internal anatomy using CBCT. Teeth with apical closure and complete root development were included in the study. Endodontically treated teeth, teeth with calcified canals or resorbed roots, as well as unclear teeth on CBCT images were excluded. RESULTS Among the 351 maxillary 1st premolars, 40.7% of teeth had 1 root, 57.5% had 2 roots, and 1.7% had 3 roots. Around 93.2% of teeth had 2 canals, 3.7% had 1 canal, 2.6% had 3 canals, and 0.4% had 4 canals. According to Vertucci's classification, 63.8% of teeth had class IV configuration, 14.8% had class V configuration, 7.7% had class III configuration, and 6.8% had class II configuration. Likewise, among the maxillary second premolars, 88% of teeth had 1 root and 12% of teeth had 2 roots. Around 38.2% of teeth had a single canal while 61.0% of teeth had 2 canals, and 3 teeth were found with the extra canal (had 3 canals). More than one-third (38.2%) of teeth had Vertucci type I, 19.2% had Vertucci type IV, 15.3% had Vertucci type III, and 12.3% had Vertucci type V. CONCLUSION Maxillary first premolars had a higher prevalence of 2 roots, whereas one root was predominant in second premolars. Most of the maxillary premolars had 2 canals with the majority having Vertucci type IV in the first premolars and type I in the second premolars. CLINICAL SIGNIFICANCE Maxillary premolars present with external and internal anatomical variations, so clinician should be aware about these varieties by taking small field of view CBCT when needed which will be of great value.

In situations in when a dermoscopic record of a large lesion is desirable, the resulting images are usually restricted to a small field of view due to the limited diameter of dermatoscope lenses. This limitation often produces several photographs separately, thus losing the possibility of a single-image global evaluation. In these case reports, we show examples of a recently published image montage technique called Wide Area Digital Dermoscopy, in this case, applied to basal cell carcinomas.

Objectives To evaluate the distribution of metal artifacts from the exomass in small field-of-view (FOV) cone beam computed tomography (CBCT) scans. Study Design An image phantom was scanned by using 3 CBCT units. Metal objects were positioned in the exomass, and additional CBCT scans were obtained. Mean gray values were obtained from 16 homogeneous areas and the standard deviation was calculated to quantify gray level inhomogeneity according to distinct zones of the FOV: total area and outer, inner, right, left, and mid-zones. The discrepancy between each zone and the total area was calculated to compare different CBCT units. Mean gray, gray level inhomogeneity, and discrepancy values were separately assessed by using analysis of variance (ANOVA) and Tukey's test (α = 0.05). Results Overall, the mean gray values were significantly lower in the inner zone, and the gray level inhomogeneity values were significantly higher in the inner and mid-zones irrespective of the presence of metal objects in the exomass. The 3 CBCT units presented significantly different discrepancy values in most conditions. Conclusions The distribution of metal artifacts from the exomass follows the inherent gray value dispersion of CBCT images, with greater inhomogeneity in the inner zone of the FOV. This is exacerbated when metal objects are in the exomass.

In this paper, a stereo calibration method for binocular ultra-wide angle long-wave infrared camera is proposed on the basis of an equivalent small field of view camera. Extrinsic parameters are ca...

Street surface weakening, for example, potholes, has caused drivers substantial money-related harm each year. Notwithstanding, viable street condition observing has been a proceeding with a challenge to street proprietors. Profundity cameras have a small field of view and can be effectively influenced by vehicle bobbing. Customary picture handling strategies are dependent on calculations. For example, the division can't adjust to shifting ecological and camera situations. In this paper, the object detection API for pothole detection is used to test the set of images and videos and give the output results of the tested images and videos. By evaluating the R-CNN algorithm and SSD mobile net algorithm, the results of the test showed successful results in getting potholes from test images with a maximum confidence level of 93%.

We investigate the [CII] line intensity mapping (IM) signal from galaxies in the Epoch of Reionization (EoR) to assess its detectability, the possibility to constrain the $L_{\rm CII}-{\rm SFR}$ relation, and to recover the [CII] luminosity function (LF) from future experiments. By empirically assuming that ${\rm log}L_{\rm CII}={\rm log}A+\gamma {\rm SFR}\pm\sigma_L$, we derive the [CII] LF from the observed UV LF, and the [CII] IM power spectrum. We study the shot-noise and the full power spectrum separately. Although, in general, the shot-noise component has a much higher signal-to-noise ratio than the clustering one, it cannot be used to put independent constraints on log$A$ and $\gamma$. Full power spectrum measurements are crucial to break such degeneracy, and reconstruct the [CII] LF. In our fiducial survey S1 (inspired by CCAT-p/1000 hr) at $z \sim 6$, the shot-noise (clustering) signal is detectable for 2 (1) of the 5 considered $L_{\rm CII}-{\rm SFR}$ relations. The shot-noise is generally dominated by galaxies with $L_{\rm CII}\gtrsim 10^{8-9}~L_\odot$ ($M_{\rm UV}\sim-20$ to $-22$), already at reach of ALMA pointed observations. However, given the small field of view of such telescope, an IM experiment would provide unique information on the bright-end of the LF. The detection depth of an IM experiment crucially depends on the (poorly constrained) $L_{\rm CII}-{\rm SFR}$ relation in the EoR. If the $L_{\rm CII}-{\rm SFR}$ relation varies in a wide log$A - \gamma$ range, but still consistent with ALMA [CII] LF upper limits, even the signal from galaxies with $L_{\rm CII}$ as faint as $\sim 10^7~L_\odot$ could be detectable. Finally, we consider the contamination by continuum foregrounds (CIB, dust, CMB) and CO interloping lines, and derived the requirements on the residual contamination level to reliably extract the [CII] signal., Comment: 17 pages, 17 Figures. Accepted for publication in MNRAS. Comments welcome

We carried out an experiment to examine emotional effect associated with images displayed in small field of view (FOV) telescope like virtual screen environment with VR-HMDs. We manipulate FOV of a virtual camera in VR to change the view of contents. Decreasing FOV makes view of angle narrow, and therefore, the view in VR looks like telescope, in which environment the view greatly moves with even small HMD movement. With smaller value of FOV, the view in VR is more sensitive to HMD movement and requires subjects to keep concentrating not to move their heads to watch target contents properly. Stronger emotional responses were observed with smaller value of FOV in the experiment. The result indicates the possibility of controlling effectiveness of the same contents with the same VR-HMD. This result is expected to improve a wide range of medical usage of VR contents.

Optical coherence tomography (OCT) is a near-infrared light based imaging modality that enables depth scans with a high spatial resolution. By scanning along the lateral dimensions, high-resolution volumes can be acquired. This allows to characterize tissue and precisely detect abnormal structures in medical scenarios. However, its small field of view (FOV) limits the applicability of OCT for medical examinations. We therefore present an automated setup to move an OCT scan head over arbitrary surfaces. By mounting the scan head to a highly accurate robot arm, we obtain precise information about the position of the acquired volumes. We implement a geometric approach to stitch the volumes and generate the surface scans. Our results show that a precise stitching of the volumes is achieved with mean absolute errors of 0.078 mm and 0.098 mm in the lateral directions and 0.037 mm in the axial direction. We can show that our setup provides automated surface scanning with OCT of samples and phantoms larger than the usual FOV.

The visualization of the whole eye fundus with enough resolution to discriminate single photoreceptors would be of an enormous interest for understanding retinal diseases and distrophies. In this work, we present a versatile and flexible SLO device that is able to provide high quality images in real time either in large field of view (40ox30o) or small field of view but with high-resolution (4ox3o). The combination of an efficient electronics design and the optical system with adaptive optics provides a large set of customization parameters.

In vivo confocal microscopy (IVCM) is a non-invasive imaging technique facilitating real-time acquisition of images from the live cornea and its layers with high resolution (1–2 µm) and high magnification (600 to 800-fold). IVCM is extensively used to examine the cornea at a cellular level, including the subbasal nerve plexus (SBNP). IVCM of the cornea has thus gained intense interest for probing ophthalmic and systemic diseases affecting peripheral nerves. One of the main drawbacks, however, is the small field of view of IVCM, preventing an overview of SBNP architecture and necessitating subjective image sampling of small areas of the SBNP for analysis. Here, we provide a high-quality dataset of the corneal SBNP reconstructed by automated mosaicking, with an average mosaic image size corresponding to 48 individual IVCM fields of view. The mosaic dataset represents a group of 42 individuals with Parkinson’s disease (PD) with and without concurrent restless leg syndrome. Additionally, mosaics from a control group (n = 13) without PD are also provided, along with clinical data for all included participants., Measurement(s)Prominent corneal nerve fibers • Dendritic CellTechnology Type(s)confocal microscopyFactor Type(s)disease status • comorbiditySample Characteristic - OrganismHomo sapiens Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.16691452

Technical parameters of today’s Optical See-Through Head Mounted Displays (OST-HMDs) do not fully match the industrial requirements yet: Especially the small field of view (FoV) of current OST-HMDs is a hindrance for industrial use. The FoV is a technical parameter the user is always confronted with while the immersive experience of Augmented Reality takes place: It defines the extent of the observable augmented world where virtual objects can be perceived. This experience is limited by the augmented objects being cut off at the screen boundaries. This paper describes a scientific approach to simulate the FoV of OST-HMDs with the help of AR and VR devices. It aims at enabling tests and validation of necessary FoV-specifications of HMDs. Therefore, a study to simulate different FoVs and evaluate the necessary FoV size for manual two-handed automotive assembly tasks is presented. Results show significant differences in ratings between AR and VR but nearly no differences between the participant groups “AR/VR experts” and “assembly line workers”.

The field of teleophthalmology has been expanding in recent years due to the development and advancement of mobile fundus cameras. Many of these devices involve taking a video of the retina using a smartphone coupled with an attachable lens system. Despite recent advances, the videos that are obtained with these devices can sometimes be difficult to use for clinical purposes. This is because the videos often have a small field of view and can include blurry frames and blinks. In order to improve the ease at which these videos can be obtained and interpreted, a stabilization system and Android application for processing these videos was created. This Android application is intended to exclude unusable video frames, and stitch together the remaining frames into a single image. The effectiveness of this application is tested using videos obtained with the D-EYE device. These images are then compared to clinical images, and images obtained from the DEYE without the image stitching application. In this study, the image quality of the stitched images was found to be worse than that obtained from a clinical device.

In order to overcome the shortcomings of traditional vision methods in the field of vehicle driving assistance, include visible light imaging system is vulnerable to the influence of illumination conditions and small field of view (FOV) imaging system has a large blind area, this paper proposed an environmental perception method based on ultra-wide FOV infrared imaging system. However, due to the compression of the Ultra-wide FOV infrared lens, the target occupies fewer pixels, and the detection distance is greatly limited. Therefore, this paper studies the feasibility of the application of Ultra-wide FOV infrared imaging system in the vehicle auxiliary driving system from the road objectives imaging size. Firstly, the general model of fisheye camera is used to build the imaging model of the Ultra-wide FOV infrared camera. Then, the vehicle driving safety distance and pedestrian imaging size characteristics are analyzed. Then the pedestrian detection distance of the Ultra-wide FOV infrared imaging system is simulated theoretically. Finally, a set of Ultra-wide FOV imaging system, which the FOV is 143° × 106° FOV and the detector resolution is 800 × 600, is used to carry out the experiment. The experiment shows that the pedestrian detection distance of the system proposed in this paper is more than 100 m, which can meet the needs of assistant driving at medium and low speeds.

The three-dimensional automated breast ultrasound system (3D ABUS) is a new device which represents a huge innovation in the breast ultrasound field, with several application scenarios of great interest. ABUS's aim is to solve some of the main defects of traditional ultrasound, such as lack of standardization, high level of skill non-reproducibility, small field of view and high commitment of physician time. ABUS has proven to be an excellent non-ionising alternative to other supplemental screening options for women with dense breast tissue; also, it has appeared to be very promising in daily clinical practice. The purpose of this paper is to present a summary of current applications of ABUS, focusing on clinical applications and future perspectives as ABUS is particularly promising for studies involving artificial intelligence, radiomics and evaluation of breast molecular subtypes.

Adaptive optics (AO) systems for retinal imaging have a small field of view (FoV) of 1°-2°. To increase the FoV we developed a multi-conjugated AO-system. By choosing different scanning patterns, aberrations introduced by the eye at different locations within the FoV can be measured by a Shack Hartmann wavefront sensor. A second deformable mirror that is conjugated to a plane anterior to the retina corrects for varying aberrations across the field. Retinal imaging using spectral-domain optical coherence tomography is performed with 4o x 4o FoV and imaging data including the visualization of the cone mosaic is presented.

Gastrointestinal ultrasound (GIUS) has been increasingly used for the management of gastrointestinal disorders due to its potentialities as a cheap, widely available and safe examination with comparable accuracy to other techniques such as Computed Tomography or Magnetic Resonance Imaging. However, some limitations have been stated to justify its underuse such as its dependency on the operator, small field of view and penetration and need of expertise. However, most of these limitations are inherent to any technique. The main problems with GIUS are lack of standardized definitions, adequate training programs and measures to assess the quality. The definition of universally applicable standardized measurements, the implementation of an internationally recognized curriculum as well as an agreed set of core competencies and the assessment of performance will hopefully overcome its potential limitations and implement its utilization universally in clinical practice.

T1 and T2 relaxation times are MR-specific intrinsic properties of tissue. These characteristic times affect all MR images, and MR images are made intentionally more sensitive to differences in T1 or T2 relaxation times, or in other words, are T1 or T2 “weighted.” Prostate anatomy is best depicted on high resolution, small field of view, T2 weighted images. Using three-plane T2 weighted images in sagittal, coronal and axial planes, it is possible to visualize the different zones of prostate as described by McNeal.

Direct Ophthalmoscopy [1]; (a) is better than indirect ophthalmoscopy; (b) is a monocular test; (c) high-magnification up to ×15; (d) small field of view; (e) it is great for the periphery.

Star sensors make use of astronomical information in stars to determine attitude for spacecrafts by star image recognition. For low-cost star sensors with small field of view, fusion of observed images from multiple fields of view is performed and a novel recognition algorithm based on path optimization by randomly distributed ant colony is proposed. According to pheromone intensity, the ant colony can autonomously figure out a close optimal path without starting or ending point, rather than certifying a starting point first. Feature patterns extracted from the optimal path in guiding template and observed image after fusion are compared to perform star recognition. By the proposed algorithm, starting point for path optimization has no influence on the extracted feature pattern. Thus the star recognition rate is improved due to the higher stability of the extracted pattern. Simulations indicate that the algorithm improves recognition accuracy and robustness against noise for sensors with multiple fields of view., SCOPUS: ar.j, info:eu-repo/semantics/published

AIM To determine if small and medium field of view (FOV) cone beam computed tomography (CBCT) adjusted grey density values can be used to distinguish between periapical cystic and solid lesions. METHODOLOGY Fifty-seven patients with periapical lesions having retrievable small or medium FOV CBCT images and biopsy samples were included. Two oral and maxillofacial pathologists examined the biopsy samples to provide the gold standard diagnosis of cystic or solid lesion. From the CBCT images, two independent examiners recorded the minimum adjusted grey density value of each lesion twice. Intra-examiner and inter-examiner reliability of the measurements were analysed, and sensitivity, specificity and accuracy of the minimum grey values in distinguishing a solid from cystic lesion were calculated. A receiver operating curve for diagnostic ability of adjusted grey density values to differentiate between periapical cystic and solid lesions was obtained, and the area under the curve (AUC) was calculated. RESULTS The intra- and inter-examiner reliability of the grey density values of the lesions and dentine were excellent. The AUC was 0.44 (P-value = 0.45). The adjusted grey density value with the greatest accuracy for differentiating between cystic and solid lesions had an accuracy, sensitivity and specificity of 0.54, 1.00 and 0.075, respectively. CONCLUSIONS Small FOV CBCT adjusted grey density values obtained by the device used in the study could not distinguish between periapical cystic and solid lesions. Further developments in CBCT devices are needed to improve the accuracy of grey density measurements.

Mineralogical analysis performed by automatic techniques, it includes qualitative and quantitative data about composition, grain size and mineral liberation, is a very important process while being the first step in the mineral processing and is one of the most useful parameters for metallurgists. Currently, there are many mineralogical analysis methods, but the problem is that analysis equipment is expensive and in-situ analysis is not possible. Therefore, in this paper, we have proposed an in-situ mineralogical analysis method using a relatively inexpensive handheld microscope. At this time, image stitching was applied to solve the inconvenience of observation due to the small field of view of the microscope. Experiments using a ferruginous quartzite ore confirmed that this method is very useful for immediate mineralogical analysis and detection of interesting areas for more detailed analysis. The algorithm suggested in this paper can be applied to the development of a dedicated mineralogical analysis system in future.

Three dimensional-digital image correlation (3D-DIC) is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digital image correlation (DIC) has been thoroughly studied theoretically and numerically, verification experiments have seldom been performed, especially for complex surfaces with a small field of view (FOV). In this work, the shape of a 1-yuan coin was measured using 3D-DIC; the shape was complex due to the presence of many fine details, and the FOV was relatively small because the coin diameter was only 25 mm. During the experiment, a novel strategy for speckle production was developed: white paint was simply sprayed onto the surface. Black paint was not used; instead, taking advantage of the reflective nature of the coin surface, polarized light and a Polaroid filter were introduced, and the polarization direction was carefully adjusted, ensuring that the spray pattern was extremely thin and that high-quality speckle images with significant contrast were captured. The three-dimensional coin shape was also successfully determined for comparison using a stylus profiler. The results demonstrate that 3D-DIC provides high precision in shape measurement even for complex surfaces with small FOV. The precision of 3D-DIC can reach 1/7000 of the field of view, corresponding to about 6 μm in this experiment.

The past 2 decades have seen a substantial increase in hip joint preserving procedures, primarily secondary to not only hip dysplasia, but the recognition and description of femoroacetabular impingement (FAI), and its association with chondral lesions, as a potentially pre-arthritic condition. Morphological magnetic resonance imaging (MRI) plays an essential role in the preoperative assessment of osseous deformities and in particular of the resulting joint degeneration. An accurate descriptive report of chondrolabral lesions is warranted describing the tear pattern, size, localization, and extension of the lesions. This is important because different damage patterns and localization of the lesions may determine the surgical approach. The current imaging standard is direct magnetic resonance arthrography (MRA) with a small field of view, with acquisition of radial images in addition to the classic coronal, sagittal, and axial-oblique images. Early cartilage damage detected on direct MRA obtained with or without traction can predict long-term failure after FAI surgery.

INTRODUCTION Hybrid imaging has proven to be a major innovation in nuclear medicine, allowing the fusion of functional information with anatomical detail. In the past, the use of hybrid imaging such as PET-CT, PET-MRI and SPECT-CT has been of great clinical benefit; however, these scanners are relatively large and bulky. We have developed and investigated the clinical application of a compact small field of view hybrid gamma camera (HGC) that is suitable for small-organ imaging at the patient bedside. PATIENTS AND METHODS The HGC - consisting of a CsI(Tl) scintillation crystal coupled to an electron-multiplying charge-coupled device and an optical camera - was used in this study. Eligible patients attending the nuclear medicine clinic at Queen's Medical Centre, Nottingham University Hospitals NHS Trust, Nottingham, UK, were invited to take part in this study. Following the standard injection of either a Tc-labelled or I-labelled radiopharmaceutical, images of the patient were acquired using the HGC and presented in a fused optical-gamma display. RESULTS There were 24 patients enrolled in the study (age range between 30 and 83 years, mean: 58.6 years), images of 18 of whom were successfully acquired. These included patients who were undergoing bone, thyroid, lacrimal drainage, DaTscan and lymphatic imaging. In general, the small field of view system was well suited to small-organ imaging. The uptake could be clearly seen in relation to the patient surface anatomy and showed particular promise for lymphatic, thyroid and lacrimal drainage studies. CONCLUSION This pilot study has demonstrated the first clinical results of hybrid optical-gamma imaging in patients. The use of this system has raised new possibilities for small-organ imaging, in which the localization of radiopharmaceutical uptake can be presented in an anatomical context using optical imaging. The compact nature of the hybrid system offers the potential for bedside investigations and intraoperative use.

The use of cone-beam computed tomography (CBCT) in endodontics has increased in recent years. In clinical application of small field of view (FOV) CBCTs, these scans are not reviewed routinely by a radiologist. Studies of large FOV CBCT scans show the prevalence of incidental findings to be greater than 90%. The purpose of this study was to evaluate the prevalence of missed findings by endodontic residents as compared with a radiologist on small FOV CBCT scans.Two hundred three small FOV CBCTs obtained for endodontic purposes were analyzed by an endodontic resident and a medical radiologist. The reported findings of each practitioner were compared to evaluate for missed incidental findings by the endodontic resident.The radiologist reported abnormalities in 176 of the 203 subjects (87%), with a total of 310 abnormalities reported. The endodontic resident reported abnormalities in 102 of the 203 subjects (50%), with a total of 126 abnormalities reported. The percentage of scans with any abnormality reported by the radiologist was significantly greater than the endodontic resident (P .001). There was no significant difference between jaw locations in percentage of missed findings for the 3 most common types of finding-rarefying osteitis, sinusitis/mucosal lining thickening, and excess restorative material in the periapical area. Rarefying osteitis was missed significantly less than the other 2 types of findings (P .001).A radiologist is significantly more likely to identify incidental findings in small FOV CBCT scans than an endodontic resident. Scan location had no significant association with the rate of missed findings.

The aim of this study is to design and evaluate a multi-pinhole (MP) collimator for a gamma imaging system that requires a high sensitivity, organ-specific, and small footprint. To ensure these requirements, we designed an eight-hole collimator that can be integrated into a small field-of-view gamma camera for imaging the thyroid or relatively sized organs. Each pinhole was designed to have a cylindrical shape with a 2-mm diameter. Experiments were performed with both a two-sphere phantom and a four-rod phantom. An image reconstruction based on the maximum likelihood expectation maximization with the distance-driven method was used for obtaining a 3-dimensional image. For improving the uniformity of the reconstruction image, we modeled the sensitivity of the cylindrical pinhole by calculating the area of the overlapped circle. The results show that the full width at half maximum values of the two-sphere phantom and the four-rod phantom were 7.56 mm (5-mm-diameter source) and 6.84 mm (5-mm-diameter rod), respectively. The scanning time can be reduced by up to 20 minutes in small-organ applications by using developed MP collimator. Thus, the results indicate that the proposed MP collimator is suitable for a fast scan time, as well as for organ-specific and small-footprint applications.

Optical coherence tomography angiography (OCTA) is a novel imaging modality that incorporates blood motion contrast to create angiograms of the retinal vasculature in a noninvasive manner, without the use of dye. It is a safe procedure and can be repeated as frequently as desired. The use of OCTA for delineation of choroidal neovascular membranes, for the study of microvascular abnormalities in diabetic patients, to assess nonperfused areas in retinal occlusions and vascular changes in macular telangiectasia are some of the potential OCTA applications. However, it is not free of drawbacks. Major limitations include the small field of view and its great sensitivity to movement. As a result, it is prone to motion artifacts, leading to poor-quality images. The scope of the body literature regarding this new modality rapidly increases as we learn how to better use this technology. Our objective is to point overall aspects of OCTA, including its limitations and review some of its initial reports on chorioretinal diseases.

The aim of this study was to develop a high-throughput imaging method for single-photon emission computed tomography. We developed a target-oriented multi-pinhole collimator and limitedangle method for scanning small organs such as the thyroid. To maximize the resolution and the sensitivity of the collimator, we designed a two-level multi-pinhole collimator whose levels were optimized for concave body contours. One level had a center hole whereas the other had surrounding holes. The limited-angle scanning method was employed to obtain tomographic images by using the collimator located near the body contour of the target, and a corresponding image reconstruction algorithm was implemented. A small-field-of-view gamma camera was used to achieve a smaller footprint. The design of the collimator also considered the dimensions of used gamma camera. Evaluation studies were conducted using the Geant4 application for tomographic emission. The results showed the resolution of the proposed collimator to be more than twice that of the previously designed multi-pinhole collimator while maintaining the same efficiency. Given that the designed collimator can be changed by simply replacing the center hole, the suggested imaging method is suitable for studying not only the thyroid but also any organ whose diameter is less than 90 mm.

Locating virtual objects (e.g., holograms) in head-mounted Augmented Reality (AR) can be an exhausting and frustrating task. This is mostly due to the limited field of view of current AR devices, which amplify the problem of objects receding from view. In previous work, EyeSee360 was developed to address this problem by visualizing the locations of multiple out-of-view objects. However, on small field of view devices such as the Hololens, EyeSee360 adds a lot of visual clutter that may negatively affect user performance. In this work, we compare three variants of EyeSee360 with different levels of information (assistance) to evaluate in how far they add visual clutter and thereby negatively affect search time performance. Our results show that variants of EyeSee360 with less assistance result into faster search times.

Introduction The aims of this in vivo cone-beam computed tomographic (CBCT) study were to evaluate the prevalence, characteristics, and correlations between the fused rooted maxillary first and second molars as well as their consequent merged and C-shaped canals in a Saudi Arabian population. Methods CBCT imaging of 726 maxillary first and second molars from 208 subjects of Saudi origin were evaluated in the present study. The prevalence of fused rooted maxillary molars, merged canals, C-shaped configurations, and correlations between the presence of fused rooted teeth between first and second molars were examined as the primary outcome. Differences by sex, location in the jaw, and bilateral symmetry (similarity between right- and left-side teeth in the same patient) were evaluated as the secondary outcome. The Z test was used for differences in the independent proportions, the chi-square test was used for differences between sex and locations, and the Cohen kappa test was used for bilateral symmetry. The kappa test was also used for intrarater reliability. A value of P Results The prevalence of fused rooted maxillary first and second molars was 7% and 21%, respectively. Within fused rooted teeth, the presence of merged canals was 8.3% and 32.1%, whereas the prevalence of C-shaped canals was 8.3% and 5.1% in first and second maxillary molars, respectively. Among 57 subjects who had fused rooted maxillary molars, 19.3% showed a correlation between first and second molars. In fused rooted maxillary molars, 3.8% first molars and 13% second molars were bilaterally symmetrical. There were no statistically significant differences between sexes and right- and left-sided fused rooted maxillary molars, merged canals, or C-shaped canals. Conclusions Maxillary second molars presented more complex external and internal morphology compared with maxillary first molars, with an overall prevalence of 14% of fused rooted maxillary molars and 3.7% merged and 0.8% C-shaped canal configurations for all maxillary molars. The clinician should be aware of such challenges, and for a better treatment outcome, the use of CBCT imaging (small field of view) and an operative dental microscope can be considered when a preoperative periapical radiograph shows signs of fused rooted maxillary molars.

Apparently similar but multifaceted photometric systems are currently being used to investigate the multiple stellar populations in globular clusters, without the concrete general agreement on the definition of the multiple populations. In recent years, an attractive idea of utilization of the widely used UBI photometry, C_{UBI}, for the populational tagging of the giant stars in globular clusters has been emerged. We perform a critical analysis of the cn_{JWL} and the C_{UBI} indices, finding that the populational tagging from the C_{UBI} index may not be reliable, due to the inherited trait of the broad-band photometry. As a consequence, the populational number ratios and the cumulative radial distributions from the C_{UBI} index can be easily in error. The results for M3, which shows a very strong radial gradient in the populational number ratio, highlights the strengths of our cn_{JWL} index: both the HST imaging and the ground-based spectroscopy failed to grasp the correct picture, that can be easily achieved with our cn_{JWL} index with small aperture ground-based telescopes, due to the small field of view or crowdedness in the central part of the cluster., Accepted for publication in ApJ

Object recognition conventionally requires a sufficiently large field of view that could fully encompass an object. However, we have discovered that, under coherent illumination, one can use a much smaller field of view for object recognition without loss of accuracy. This is because part of the speckle pattern related to an object contains some of its global information. Our approach can be applied to covert imaging and non-line-of-sight object recognition and image reconstruction.

Variable emission is one of the defining characteristic of active galactic nuclei (AGN). While providing precious information on the nature and physics of the sources, variability is often challenging to observe with time- and field-of-view-limited astronomical observatories such as Imaging Atmospheric Cherenkov Telescopes (IACTs). In this work, we address two questions relevant for the observation of sources characterized by AGN-like variability: what is the most time-efficient way to detect such sources, and what is the observational bias that can be introduced by the choice of the observing strategy when conducting blind surveys of the sky. Different observing strategies are evaluated using simulated light curves and realistic instrument response functions of the Cherenkov Telescope Array (CTA), a future gamma-ray observatory. We show that strategies that makes use of very small observing windows, spread over large periods of time, allows for a faster detection of the source, and are less influenced by the variability properties of the sources, as compared to strategies that concentrate the observing time in a small number of large observing windows. Although derived using CTA as an example, our conclusions are conceptually valid for any IACTs facility, and in general, to all observatories with small field of view and limited duty cycle., Comment: 14 pages, 11 figures

Present head-mounted displays (HMDs) for Augmented Reality (AR) devices have narrow fields-of-view (FOV). The narrow FOV further decreases the already limited human visual range and worsens the problem of objects going out of view. Therefore, we explore the utility of augmenting head-mounted AR devices with MonoculAR, a peripheral light display comprised of twelve radially positioned light cues, to point towards out-of-view objects. In this work, we present two implementations of MonoculAR: (1) On-screen virtual light cues and (2) Off-screen LEDs. In a controlled user study we compare both approaches and evaluate search time performance for locating out-of-view objects in AR on the Microsoft Hololens. Key results show that participants find out-of-view objects faster when the light cues are presented on the screen. Furthermore, we provide implications for building peripheral HMDs.

BACKGROUND Diagnosis of tooth root fractures is based on radiographic examination, which is not reliable in the case of oblique root fractures. OBJECTIVES The aim of the study was to evaluate the efficacy of cone beam computed tomography (CBCT) imaging of oblique root fractures. MATERIAL AND METHODS Twenty-four bovine incisors were used in the study. They were randomly divided into 2 groups: an experimental group with artificially created oblique root fractures and a control group without fractures. The teeth underwent a CBCT evaluation with a CS 9300 cone-beam scanner (Carestream, Rochester, USA) using a 5 × 5 cm field of view with the resolution up to 90 μm, and a dental radiography. The specimens were examined by 2 observers with different job experience. RESULTS In the CBCT scans, fracture lines were detected in 95.8% of cases (the 1st observer made a proper diagnosis in 100% of cases and the 2nd in 91.7%). Fracture lines were identified on radiographs in 33.3% of roots (the 1st observer was able to see the lines in 41.7% of cases and the 2nd in 25%). The inter-observer agreement was very high (the kappa coefficient for CBCT scans was 1.00 and 0.88 for radiographs). The best diagnostic value was recorded for contiguous slices. CONCLUSIONS Cone beam computed tomography with a small field of view and high resolution significantly surpasses radiographs in effective imaging of oblique tooth root fractures and should be the method of choice in the diagnosis of these fractures.

Diabetic retinopathy (DR) is one of the leading causes of blindness worldwide. Accurate investigative tools are essential for the early diagnosis and monitoring of the disease. Optical coherence tomography angiography (OCTA) is a recently developed technology that enables visualisation of the retinal microvasculature. A systematic review of the literature was performed to examine the diagnostic use of OCTA in DR to date. Medline, EMBASE, and Cochrane databases were searched to find relevant studies. Sixty-one original studies were selected for the review. OCTA has demonstrated the ability to identify microvascular features of DR such as microaneurysms, neovascularisation, and capillary non-perfusion. Furthermore, OCTA is enabling quantitative evaluation of the microvasculature of diabetic eyes. It has demonstrated the ability to detect early microvascular changes, in eyes with or without clinically evident DR. It has also been shown to detect progressive changes in the foveal avascular zone, and vascular perfusion density, with worsening severity of disease. It provides three-dimensional visualisation of the individual retinal vascular networks and is thereby enhancing our understanding of the role of the deeper vasculature in the pathogenesis of diabetic retinopathy and maculopathy. However, limitations exist with current OCTA technology, in respect to the small field of view, image quality, projection artefact, and inaccuracies in analysis of the deeper vascular layers. While questions remain regarding its practical applicability in its present form, with continuing development and improvement of the technology, the diagnostic value of OCTA in diabetic retinopathy is likely to become evident.

We present the performance evaluation of a small field of view planar scintigraphic system for 99mTc and 67Ga molecular imaging applications. Three different in geometry parallel hole collimators have been evaluated in terms of detector non-uniformity, energy resolution, system spatial resolution and sensitivity. Results show that all three collimators are suitable for 99mTc and 67Ga molecular imaging applications, given that only the first photopeak in the case of 67Ga shall be used, in order to avoid image degradation due to photon scattering and collimator wall penetration.

A novel small field of view Hybrid Gamma Camera (HGC) has been developed to facilitate the process of localizing radiopharmaceutical uptake during surgical procedures. The HGC is a scintillator-based detector consisting of an electron multiplying charge-coupled device coupled to a columnar scintillator (CsI[Tl]). This enables fusion scintigraphic and optical images offering new possibilities for assisting clinicians and surgeons in localising the site of uptake in a number of surgical procedures. This technology also offers bedside imaging for small organs in procedures such as thyroid scintigraphy. In this study, prototype anthropomorphic phantoms have been used to study the capability of the HGC. Images were acquired using a range of bespoke anthropomorphic phantoms. The gamma and hybrid optical images were acquired for the simulated sentinel lymph nodes and thyroid gland. The gamma images produced varied in terms of spatial resolution and detectability, however utilizing pinhole collimators of difference diameters (0.5 and 1.0mm) imaging was enhanced meeting the needs of small field gamma imaging. The hybrid images obtained demonstrated that the HGC is ideally suited for small organ imaging demonstrating good potential in clinical procedures, such as thyroid scintigraphy, when using acquisition times similar to those for conventional gamma imaging. Moreover, clinical scintigraphic images, from patients attending the nuclear medicine clinic, were acquired using the HGC and compared to images from a standard gamma camera. The results of our first clinical feasibility study using the HGC will be presented.

Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments. Moreover, due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed. © 2018 Elsevier Ltd