Magnification Rates Research Articles

A Monocular Variable Magnifications 3D Laparoscope System Using Double Liquid Lenses.

During minimal invasive surgery (MIS), the laparoscope only provides a single viewpoint to the surgeon, leaving a lack of 3D perception. Many works have been proposed to obtain depth and 3D reconstruction by designing a new optical structure or by depending on the camera pose and image sequences. Most of these works modify the structure of the conventional laparoscopes and cannot provide 3D reconstruction of different magnification views. In this study, we propose a laparoscopic system based on double liquid lenses, which provide doctors with variable magnification rates, near observation, and real-time monocular 3D reconstruction. Our system composes of an optical structure that can obtain auto magnification change and autofocus without any physically moving element, and a deep learning network based on the Depth from Defocus (DFD) method, trained to suit inconsistent camera intrinsic situations and estimate depth from images of different focal lengths. The optical structure is portable and can be mounted on conventional laparoscopes. The depth estimation network estimates depth in real-time from monocular images of different focal lengths and magnification rates. Experiments show that our system provides a 0.68-1.44x zoom rate and can estimate depth from different magnification rates at 6fps. Monocular 3D reconstruction reaches at least 6mm accuracy. The system also provides a clear view even under 1mm close working distance. Ex-vivo experiments and implementation on clinical images prove that our system provides doctors with a magnified clear view of the lesion, as well as quick monocular depth perception during laparoscopy, which help surgeons get better detection and size diagnosis of the abdomen during laparoscope surgeries.

Machine Learning Model with Texture Analysis for Automatic Classification of Histopathological Images of Ocular Adnexal Mucosa-associated Lymphoid Tissue Lymphoma of Two Different Origins

Purpose The purpose of this study was to develop artificial intelligence algorithms that can distinguish between orbital and conjunctival mucosa-associated lymphoid tissue (MALT) lymphomas in pathological images. Methods Tissue blocks with residual MALT lymphoma and data from histological and flow cytometric studies and molecular genetic analyses such as gene rearrangement were procured for 129 patients treated between April 2008 and April 2020. We collected pathological hematoxylin and eosin-stained (HE) images of lymphoma from these patients and cropped 10 different image patches at a resolution of 2048 × 2048 from pathological images from each patient. A total of 990 images from 99 patients were used to create and evaluate machine-learning models. Each image patch of three different magnification rates at ×4, ×20, and ×40 underwent texture analysis to extract features, and then seven different machine-learning algorithms were applied to the results to create models. Cross-validation on a patient-by-patient basis was used to create and evaluate models, and then 300 images from the remaining 30 cases were used to evaluate the average accuracy rate. Results Ten-fold cross-validation using the support vector machine with linear kernel algorithm was identified as the best algorithm for discriminating between conjunctival mucosa-associated lymphoid tissue and orbital MALT lymphomas, with an average accuracy rate under cross-validation of 85%. There were ×20 magnification HE images that were more accurate in distinguishing orbital and conjunctival MALT lymphomas among ×4, ×20, and ×40. Conclusion Artificial intelligence algorithms can successfully distinguish HE images between orbital and conjunctival MALT lymphomas.

Mapping of a multilayer panoramic radiography device.

To map the shape, location, and thickness of the focal trough of a panoramic radiography device with a multilayer imaging program. An acrylic plate (148 × 148 × 3 mm) containing 1156 holes distributed in a matrix of 34 × 34 rows was placed in the OP300 Maxio at the levels of the maxilla and mandible. 20 metal spheres (3.5 mm in diameter) were placed on the holes of the plate under 15 different arrangements and panoramic images were acquired for each arrangement at 66 kV, 8 mA, and an exposure time of 16 s. The resulting panoramic radiographs from the five image layers were exported, the horizontal and vertical dimensions of the metal spheres were measured in all images using the Image J software, and the magnification and distortion rates of the spheres were calculated. All metal spheres presenting a magnification rate lower than 30% in both vertical and horizontal dimensions and a distortion rate lower than 10% were considered to map the focal troughs of each of the five image layers. All panoramic image layers had a curved shape ranging from 39° to 51° for both dental arches and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to the anterior region of the mandible for all layers. Image layers are thicker at the level of the mandible than those at the level of the maxilla; also, inner layers were thinner and outer layers were thicker. All image layers in the studied panoramic radiography device had a curved shape and varied in position and thickness. The anterior region of maxilla was anteriorly displaced when compared to that of the mandible for all layers.

Evaluation of aniseikonia with an auto-stereoscopic smartphone.

An auto-stereoscopic smartphone can produce 3D images without the need for the viewer to wear glasses. The purpose of this study was to evaluate whether this technology could be utilized to measure aniseikonia. A 2K auto-stereoscopic smartphone was used to imitate the Awaya new aniseikonia test. In test 1, four pairs of lenses combined with a trial frame were used to create 4 different magnification rates in 10 subjects. In test 2, 40 subjects whose anisometropia was higher than 2.00D were recruited. No significant difference between the results of the Awaya new aniseikonia test and auto-stereoscopic smartphone test (Wilcoxon signed-rank test: test 1, P=0.85; test 2, P=0.53). Bland-Altman plots showed that the difference between the two tests was ≤1% in both tests 1 and 2. An auto-stereoscopic smartphone can be an effective tool for evaluating aniseikonia.

Comparison of digital panoramic radiography versus cone beam computerized tomography for measuring alveolar bone

BackgroundCone beam computerized tomography (CBCT) has been widely used in dental implanting. However, the local hospitals usually don’t have access to CBCT due to the cost and medical investment, especially in West of China. The doctors in local hospitals have to make reasonable dental planting using orthopantomography (OPG) to reduce risks. Therefore, it is clinically meaningful to determine the magnification rate of OPG to obtain correct diagnosis. This study investigated the magnification rate of OPG in measuring different maxillofacial loci compared with CBCT.MethodsEighty-six patients demanding dental implanting were scanned by CBCT and OPG. The vertical distance between the alveolar ridge crest of the maxillary first molar and the sinus bottom of the upper jaw, the distance between the alveolar ridge crest of the mandibular first molars and the top of nerviduct in the mandibular alveolar, and the distance between the alveolar ridge crest of the maxillary central incisors and the bottoms of the nasal cavities were measured. The horizontal distance in those loci were also measured. The distances derived from CBCT were used as reference. The distances between the two methods were compared using paired t-test. The magnification rates at these positions were calculated. The relationship between the data acquired from the two methods was analyzed Pearson correlation.ResultsThe correlation coefficients (R) between the paired samples obtained from OPG and CBCT were highly related (P < 0.05) with R values varying from 0.840 and 0.959 in vertical distances and R values varying from 0.703 and 0.904 in horizontal distances. Compared with data obtained from CBCT, the mean vertical magnification rates were 11.38% and 12.95% vertically and 8.55% and 9.43% horizontally for the first molars in the right and left maxilla respectively; 7.26% and 6.35% vertically and 5.33% and 4.96% horizontally for the first molars in the right and left mandible respectively; and 5.55% and 4.84% vertically and 6.53% and 7.47% horizontally for the central incisors in the upper right and left jaws respectively.ConclusionThe magnification rates of OPG at these teeth are different. The distances measured by OPG were highly correlated with that measured by CBCT.

Impact of imaging approach on radiation dose and associated cancer risk in children undergoing cardiac catheterization.

To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, antiscatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. We used anthropomorphic phantoms (ages: newborn and 5 years old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies' Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20 cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. For the newborn and 5-year-old phantoms, respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20 cm increase in source-to-image-distance; -42% and -48% with addition of 1-inch periphery collimation; -31% and -46% with removal of the antiscatter grid. Compared with an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and fourfold (5 years old). Estimated cancer LAR from 30-min of posteroanterior fluoroscopy using optimized versus suboptimal imaging, respectively was 0.42% versus 1.23% (newborn female), 0.20% versus 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% versus 0.69% (5-year-old male). Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. © 2016 Wiley Periodicals, Inc.

Evaluation of Image Magnification in Digital Panoramic Radiography

Journal of Dentomaxillofacial Radiology, Pathology and Surgery Vol 5, No 1, Spring 2016 Received: Oct 19, 2015 Accepted: May 23, 2016 Introdouction: The aim of the present study was to investigate image magnification in digital panoramic radiography and assess the effect of anatomical sites on the magnification in both males and females. Materials and methods: In this retrospective study, digital panoramic radiographs of 48 patients with 202 implants were investigated. Implant diameter and length were measured on panoramic radiographs and the horizontal and vertical magnification rates of each placed area were calculated based on the length and width of the placed implant. A twoway ANOVA test was used to evaluate the magnification rate in regard to implant location and gender. Results: The range of the magnification factor of the width was 111.09–126.02, which was lowest in the maxillary molar region and greatest in the mandibular anterior region. While the lowest magnification value of the length (111.58) was observed in the mandibular molar region, the highest value (116.09) appeared in the maxillary premolar area. Hence, there were no significant differences in image magnification with regard to anatomical site and gender. Conclusion: Digital panoramic radiography can be reliably used for pre-implant evaluation in various anatomical sites of the jaws in both genders.

Rheological Properties of Polypropylene Reinforced Asphalt Binder

Polypropylene fibers (PP fibers) were used as additives to prepare fiber-reinforced asphalt binders in this work, with concentrations varying from 0 to 2.5 % in increments of 0.5 % by weight of asphalt. The microstructure of fibers and dispersion of fibers in the asphalt were analyzed via scanning electron microscopy (SEM) using a ZEISS microscope at different magnification rates. Penetration, softening point, dynamic shear rheometer (DSR), and Multiple Stress Creep Recovery (MSCR) tests were conducted to study the rheological properties and the results are compared. With the increase in the dosage of PP fibers, the penetration values were decreased while the softening points increased. Complex shear modulus was increased and phase angles were decreased. The Strategic Highway Research Program (SHRP) rutting parameter G*/Sinδ and the Shenoy’s rutting parameter, G*/(1 − (1/sinδ.tanδ)), were improved with fibers. MSCR results indicate that the non-recoverable creep compliance (Jnr) and percent of recovery (R%) are decreased and increased, respectively, with the addition of fibers. The results indicate that the asphalt with PP fiber reduces thermal sensitivity and increased resistance to permanent deformation at high temperatures. The Shenoy’s rutting parameter has better correlation with non-recoverable creep compliance (Jnr) and it can be considered as a better rutting predictor than G*/Sinδ for fiber modified asphalt binders.

Dynamic Radiographic Criteria for Detecting Pseudarthrosis Following Anterior Cervical Arthrodesis

While interspinous motion analysis is commonly used to determine the status of an anterior cervical fusion, the accuracy of this technique is unclear. We believed that three questions needed to be answered. What degree of image magnification is ideal? How much motion should be considered "adequate" for making dynamic radiographs? What is the optimal amount of interspinous motion for detecting pseudarthrosis? We performed a retrospective study of 125 patients (109 fused segments and 153 pseudarthrotic segments) who had undergone reexploration with confirmation of fusion status. Interspinous motion at each operatively treated level and one superjacent level was measured by two independent investigators twice. Reliabilities of interspinous motion analysis at different magnification rates (25%, 100%, 150%, and 200%) were evaluated for fifty randomly selected segments to determine the optimal magnification, which we used for the remainder of the measurements. Fusion status was also determined on computed tomography (CT) by two other raters. We compared the intraoperative findings with those based on dynamic radiographs (with use of cutoff values of 1 and 2 mm of interspinous motion as the indication of pseudarthrosis) and CT. On radiographs, both 150% and 200% magnification yielded higher interobserver and intraobserver reliabilities compared with 25% and 100% magnification, and the reliabilities at 150% and 200% were similar to each other, so subsequent measurements were made at 150%. The cutoff value of interspinous motion for detecting pseudarthrosis was 0.9 mm as determined with receiver operating characteristic curve analysis. Compared with CT, interspinous motion of ≥ 1 mm showed relatively low sensitivity (79.5%) and negative predictive value (77.1%) and similar specificity (97.0%) and positive predictive value (97.4%). Using interspinous motion of ≥ 2 mm as the cutoff decreased the sensitivity and negative predictive value to 46.6% and 56.8%, respectively. Our evaluation of what constituted adequate dynamic motion for making the radiographs showed that, with use of interspinous motion of ≥ 1 mm as the cutoff for detecting pseudarthrosis, superjacent interspinous motion of ≥ 4 mm increased the sensitivity and negative predictive value (86.3% and 83.4%) compared with those associated with alternative cutoffs of superjacent interspinous motion (≥ 3.5, ≥ 5, and ≥ 6 mm), and the specificity (96.1%) and positive predictive value (96.9%) were reasonable. Use of interspinous motion of ≥ 1 mm as the cutoff for detection of anterior cervical pseudarthrosis on radiographs magnified 150% and made with superjacent interspinous motion of ≥ 4 mm yielded accuracies comparable with those of CT.

Mercury biomagnification in a contaminated estuary food web: Effects of age and trophic position using stable isotope analyses

The main aim of this study was to ascertain the biomagnification processes in a mercury-contaminated estuary, by clarifying the trophic web structure through stable isotope ratios. For this purpose, primary producers (seagrasses and macroalgae), invertebrates (detritivores and benthic predators) and fish were analysed for total and organic mercury and for stable carbon and nitrogen isotopic signatures. Trophic structure was accurately described by δ15N, while δ13C reflected the carbon source for each species. An increase of mercury levels was observed with trophic level, particularly for organic mercury. Results confirm mercury biomagnification to occur in this estuarine food web, especially in the organic form, both in absolute concentrations and fraction of total mercury load. Age can be considered an important variable in mercury biomagnification studies, and data adjustments to account for the different exposure periods may be necessary for a correct assessment of trophic magnification rates and ecological risk.

Determining magnification for reading with low vision

Background: In the past, practitioners have used distance and/or near visual acuity (VA) to calculate required magnification for low vision aids. Magnification was usually under‐estimated when compared with the final magnification prescribed. Recent studies have emphasised the importance of acuity reserve in determining the required magnification for optimum reading rate. Two different approaches have been proposed for the appropriate acuity reserve to use in calculating magnification. These are a fixed acuity reserve of 0.3 log unit or an individual determination of optimum acuity reserve. The aim of this study was to investigate the magnification and reading rates with low vision aids selected by the two methods. Methods: Nineteen low vision subjects with age‐related macular degeneration (AMD) who were experienced magnifier‐users were recruited. Reading rates and near VA with low vision aids determined by the fixed and individual acuity reserve methods were compared with the same measures made with the subjects' own magnifiers. Results: There were no significant differences in reading rate and near VA measured with low vision aids selected by either the fixed or individual acuity reserve methods or the subjects' own magnifiers. Reading rate with low vision aids was not significantly different from reading rate for large print with conventional near additions. Thus, for experienced users, magnifiers do not cause reduced reading rate. Conclusions: The fixed acuity reserve method is simple to apply as only near VA and print size of the target reading task are required. For the individual acuity reserve method, reading rates at different print sizes need to be measured. We recommend the use of a fixed acuity reserve (0.3 log unit) for the calculation of required magnification for low vision patients. If near VA or reading rate are not satisfactory with the magnification calculated by this method, individual assessment of required acuity reserve is necessary.

Determination of age‐related changes in the morphological structure (sagging) of the human cheek using a photonumeric scale and three‐dimensional surface parameters

The usefulness of the photo standard for evaluating skin sagging in the face, especially in the cheeks, was evaluated. A six-stage photo standard was prepared using photos of women aged 17-83-years-old at three magnification rates (136-188 women in each group). Based on this photo standard, scoring was performed using a six-grade scoring system by two specialists to obtain the consensus score. Scoring was also performed in parallel by five general observers. The degree of agreement between the two scores was evaluated by calculating the Kappa value. In each group, the Kappa value was 0.452-0.563, indicating moderate agreement. Thus, the photo standard may be useful for evaluating sagging. Based on the photo standard, a score of 2, at which sagging becomes detectable appeared at the age of 40 years. In parallel, 3D analysis of replicas around the cheek was performed to morphologically analyse age-related changes in sagging. When the depth parameter was compared between the nasolabial groove and the mouth corners, a higher value was observed in the nasolabial groove until the age of 40 years, but higher values were seen in the mouth corners thereafter. This may have been because sagging in the cheeks descends to the area around the mouth, resulting in reversion in the sWv value. These findings indicated that sagging in the cheeks becomes morphologically distinct in women in their forties.

Mechanisms of combustion wave propagation in heterogeneous reaction systems

For many condensed heterogeneous systems, the propagation of the combustion front occurs in a planar, steady manner, when observed using typical imaging rates (30 frames/s) and magnifications (4×). However, using much higher magnification (> 400×) and imaging rates (1000 frames/s), two different mechanisms ( quasihomogeneous and relay-race) of combustion propagation have been observed recently. For the former, the microstructure of the combustion wave resembles what is viewed macroscopically (i.e., at typical magnification and imaging rates). Under these conditions, steady, planar propagation occurs. In the relay-race mechanism, while planar at the macroscopic level, the combustion front profiles are irregularly shaped, with arc-shaped convexities and concavities at the microscopic level. Moreover, the reaction front propagation consists of a series of rapid jumps and hesitations. In this paper, based on the local conditions during combustion (i.e., the microstructure of the combustion wave), we develop and evaluate several new criteria for determining the mechanisms of combustion wave propagation. Using these criteria, the boundaries between quasihomogeneous and relay-race mechanisms are determined experimentally as a function of the initial organization of the reaction medium (i.e., particle size and porosity). Further, the characteristics of the two mechanisms in terms of temperature gradients and ignition delays are also studied.

Networking process and fractal dimensionality in percolation

The growth mechanism is studied for percolation networks on a square lattice by means of a Monte Carlo technique. The mechanism near the threshold ${p=p}_{c}$ is accompanied with the extensive linking of clusters during the random-increment process of occupied sites on the lattice. Local dimensionality is defined from the magnification rates of linking clusters. The linking mechanism characterizes the process for fractal growth in percolation.

Bio‐accumulation of metals in sewage‐fed aquatic systems—a case study from Calcutta (India)

Bio‐concentration of copper, lead, zinc and chromium in the sewage fed aquatic systems has been investigated in four trophic levels starting from producer, and primary, secondary and tertiary consumers. All the heavy metals have been found to increase considerably in all four trophic states. The relative magnification rates of heavy metals have been found to be as follows: lead, 67.86%‐80.45%; zinc, 36.11%‐77.67%; copper, 57.14%‐80.33%; and chromium, 25%‐72.73%, respectively. The sequence of bio‐concentration factors (BCF) in the different trophic levels were as follows: Pb, 3.111–5.111; Zn, 1.656–4.378; Cu, 2.333–5.083; and Cr, 1.333–3.667, respectively. This increase of metals in biosystem, may cause short‐as well as long‐term biohazards that will be harmful to regional sustainable development.

Effect of Profiles of Center and Center Hole on Rotation Accuracy of Workpiece.

In this paper we show the relationship between the rotation accuracy of the workpiece supported on two dead centers and the cross-sectional shapes of the center and the center hole theoretically, using a contact model of the center and the center hole. Some experiments were conducted in order to check this geometrical model. The main results obtained are as follows. Each harmonic component of the workpiece center hole is transmitted to the rotation error with magnification rates dependent on the locations of the contact points. If the profile of the center is ellipsoidal, or if the centers are misaligned, the center comes in contact with the center hole at two points. Then the even harmonic components of the center hole have little effect on the rotation accuracy. However, the odd harmonic components have a strong effect. When the center is in contact with the center hole at three points, the ellipsoidal component is transmitted strongly to the rotation error. The magnification factors of every component are changed during grinding because the center displacement by the grinding force moves the contact points. Therefore, no definite correlation between out-of-roundness of the center hole and the ground surface in cylindrical grinding can be obtained.

Determination of target point magnification rate on stereotactic angiography for radiosurgery--technical note.

We describe here a new method of calculating the target point magnification rate for radiosurgery by stereotactic angiography using a Leksell frame. As the distance (D) between the x-ray focus and the film plane is constant in each facility, the magnification rate (M) is determined by the equation: M = D/[D/Mp + t], where Mp is the magnification rate of the proximal (to the x-ray focus) frame projected on the film plane and t is the distance between the proximal frame plane and the target point. The t value is given by the three-dimensionally determined stereotactic coordinates of the target point. Only the Mp value on the stereotactic angiogram must be measured. This method is theoretically more correct and has less risk of human error than the conventional, graphically determined method which necessitates measuring both the distal and proximal frame magnification rates. Furthermore, the inherent theoretical error of the conventional method is largest around the frame center, which is frequently selected as the target point for radiosurgical treatment, possibly causing serious error in accurate dose planning.