Visibility Improvement Research Articles

Optimal Contrast Concentration for CT-Guided Epidural Steroid Injections

Contrast is used in CT-guided epidural steroid injections to ensure proper needle placement. Once injected, undiluted contrast often obscures the needle, hindering subsequent repositioning. The purpose of this investigation was to establish the optimal contrast dilution for CT-guided epidural steroid injections. This investigation consisted of an initial phantom study, followed by a prospective, randomized, single-center trial assessing a range of contrast dilutions. In the phantom study, a phantom housing a chamber containing a 22-gauge needle and various dilutions of contrast was scanned, and images were evaluated for needle visibility. On the basis of these results, concentrations of 66, 100, 133, and 150 mg/mL iodine were selected for evaluation in a clinical study. Patients presenting for CT-guided epidural steroid injections were randomly assigned to a contrast dilution, and images from the procedure were evaluated by 2 readers blinded to the contrast assignment. Needle visibility was scored by use of a 5-point scale. In the phantom study, the needle was not visible at contrast concentrations of ≥133 mg/mL. In the clinical study, needle visibility was strongly associated with contrast concentration (P < .0001). Significant improvements in visibility were found in 66 mg/mL and 100 mg/mL compared with higher iodine concentrations; no difference was found comparing 66 mg/mL with 100 mg/mL iodine. Neither injection location (cervical versus lumbar) nor technique (interlaminar versus transforaminal) influenced visibility scores. For CT-guided epidural steroid injections, the optimal contrast concentration is 66-100 mg/mL iodine. Because these concentrations are not commercially available, proceduralists must dilute their contrast for such procedures.

Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings

The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 μm using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method.

A new single-image fog removal algorithm based on physical model

Based on the physical model of atmospheric scattering and the optical reflectance imaging model, three major factors which affect the effect of fog removal are discussed in detail, dark channel phenomenon is explained via the optical model, and an approach for solving the parameter in the atmospheric scattering model is rigorously derived from a new perspective. Using gray-scale opening operation and fast joint bilateral filtering techniques, the proposed algorithm can effectively obtain the global atmospheric light and greatly improve the speed and accuracy of atmospheric scattering function solving. Finally, the scene albedo is recovered by inverting this model. Compared with existing algorithms, complexity of the proposed method is only a linear function of the number of input image pixels and this allows a very fast implementation. The simulation results show that the processing time of images with a resolution of 576*768 is only 1.7s; Results on a variety of outdoor foggy images demonstrate that the proposed method achieves good restoration for contrast and color fidelity, resulting in a great improvement in image visibility.

Understanding of the formation mechanisms of ozone and particulate matter at a fine scale over the southeastern U.S.: Process analyses and responses to future-year emissions

Ozone (O3) and fine particle (PM2.5) formation over the southeastern U.S. are of a major concern due to high emissions of precursors and special weather conditions that are conducive to their formation. In this study, the Community Multiscale Air Quality (CMAQ) modeling system is applied to simulate the formation of major air pollutants over an area in the southeastern U.S. at a 4-km horizontal grid resolution for January, April, July, and October in 2002 and 2018. Model performance evaluation shows an overall satisfactory performance for O3 in all months and for PM2.5 in January and October at rural sites and in January, April, and October at urban sites. Large underpredictions in PM2.5 concentrations occur in April and July at rural sites and in July at urban sites, because of biases in meteorological predictions and underestimation of emissions of precursors. The model performance at 4-km in terms of O3, PM2.5 and PM2.5 components show some improvements but overall are not always better than that at 12-km. O3 chemistry is VOC-limited in urban areas and NOx-limited over the west of the mountain regions and the southern Georgia throughout the year, and VOC-limited over the rest of areas in January but NOx-limited in other months. Among all photochemical indicators examined, PH2O2/PHNO3 and O3/NOy are the most robust indicators. The domain is NH3-rich or neutral in all months, indicating a high potential for NH4NO3 formation and the sensitivity of PM2.5 formation to the emissions of SO2, NOx, and NH3. Surface O3 is accumulated primarily through vertical transport in urban, rural and coastal areas and both horizontal and vertical transport in mountain regions and produced via gas-phase chemistry at non-urban sites during daytime. The loss of O3 is attributed to gas-phase chemistry via NO titration in urban areas, and dry deposition and transport processes in rural and mountain areas. PM2.5 is produced by primary emissions and PM processes and lost through vertical and horizontal transport in urban areas. The combined effects of transport, emissions, and PM processes influence PM concentrations in other areas. The 2018 simulations project a decrease in PM2.5 concentrations and an improvement in visibility over almost the entire domain, slight decreases in O3 mixing ratios in urban areas in July and most non-urban areas in April and October but large increases in the rest of areas in other months, and a decrease in total N deposition fluxes in most areas except for central and eastern North Carolina and northern Georgia. The development of integrated emission control strategies should consider region-specific seasonality and differences in the responses of O3, PM2.5, visibility, and nitrogen deposition.

Long-term trends and characteristics of visibility in two megacities in southwest China: Chengdu and Chongqing

Visibility is a good indicator of air quality because it reflects the combined influences of atmospheric pollutants and synoptic processes. Trends in visibility and relationships with various factors in Chengdu and Chongqing, two megacities in southwest China, were analyzed using daily data from National Climatic Data Center and the Air Pollution Index (API) of the Ministry of Environmental Protection of China. Average annual visibility during the period of 1973–2010 was 8.1 ± 3.9 in Chengdu and 6.2 ± 4.3 km in Chongqing. PM10 dominates the reported primary pollutants in both cities, although concentrations have decreased from a high of 127.9 and 150 µg m3 before 2005 to 100.4 and 93.5 µg m−3 in Chengdu and Chongqing, respectively. Low average visibility and extremely high levels of PM10 were observed in winter, whereas relative humidity had irregular and weak seasonal variations. Visibility in both cities has deteriorated in comparison to the 1960s and 1970s, mostly due to the elevation of optical depth caused by anthropogenic pollution. Correlations and principal component analysis (PCA) were undertaken to determine the key factors affecting visibility. Visibility was only moderately correlated with PM10. In Chengdu, visibility displayed weak correlations with various factors, whereas visibility in Chongqing was most strongly related to relative humidity due to the atmospheric particulates in the region containing more hygroscopic components. PCA results further confirmed that high relative humidity and low wind speed increased the occurrence of low visibility events under high PM10 concentrations. Temperature and pressure, as indicators of weather systems, also played important roles in affecting visibility. Mathematical models of visibility prediction indicated that wind speed had the largest coefficients among all meteorological factors, and reductions in PM10 concentration only led to minor improvements in visibility. Implications: Long-term data indicates that visibility in Chengdu and Chongqing has been lower than 10 km since the 1970s, and the poor visibility primarily results from anthropogenic pollution. Although PM10 concentrations have decreased consistently to around 100 μg m−3, trends of visibility have shown no improvement but much fluctuation. Correlation and principal component analysis demonstrate that low visibility in Chengdu is influenced by high relative humidity, while in Chongqing the degrading visibility is related with high relative humidity and pressure and low wind speed under a stable weather system. The results are important to understand the widespread haze event in the two megacities of southwest China. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association.

Estimating the Impact of Impaired Visibility on the Demand for Visits to National Parks

The authors fitted a number of time-series econometric models to monthly visitation data of a national park to examine the effect of impaired visibility on visitation demand. Using a polynomial distributed lag model, the long-run elasticity of demand with respect to visibility in the Great Smoky Mountain National Park (GSMNP) was estimated. The GSMNP, the most visited national park in the USA, has significant air quality issues. Although the park has observed some fluctuation in visitation, the results indicate that the demand for visitation in general and for specific recreational visits are mean reverting and highly stable. Further, park visitation in a given month is significantly affected by the cumulative effect of the visibility condition in both the current and preceding months. Estimated elasticity reveals that a programme aiming to improve the average visibility by 10% (5.5 km) from the current level could result in an increase of roughly one million recreational visits annually, and that the increase would be higher for overnight visitors than for day visitors because of overnight visitors' relatively elastic demand. This demand model could assist park managers in their planning as they weigh the anticipated benefits of a visibility improvement programme against increased visitation and its associated costs.

Evaluation of Peanut Agrochemical Efficacy in Situations where Spray Solution Application is Delayed

ABSTRACT The effect of delayed application of spray solutions is poorly understood with respect to efficacy of fungicides, insecticides, inoculants, and plant growth regulators commonly used in peanut (Arachis hypogaea L.). Research was conducted in North Carolina during 2009 and 2010 to determine if tobacco thrips (Frankliniella fusca Hinds) control by acephate; early leaf spot (caused by Cercospora arachidicola Hori) and late leaf spot (caused by Cercosporidium personatum Berk. and Curt.) control by chlorothalonil, prothioconazole plus tebuconazole, pyraclostrobin, and tebuconazole; Sclerotinia blight (caused by Sclerotinia minor Jagger) control by boscalid and fluazinam; and improvement in row visibility by prohexadione calcium were affected by the time interval between solution preparation and application. Performance of the inoculant Bradyrhizobium was also compared when prepared in 25 different sources of water when application was delayed after preparation of solutions. Agrochemicals and prohexadione calcium solutions were prepared the d of application or 3, 6, and 9 d prior to application with all solutions applied on the same d. Similarly, inoculant solutions were prepared the d of application or 4 and 8 d prior to application and applied on the same d. Performance of fungicides, insecticides, inoculant, and prohexadione calcium was not reduced in most instances when left in spray solution up to 8 or 9 d. The magnitude of difference in efficacy was minor when differences were observed.

車載複数カメラによる夜間雨天時における路面反射グレア領域の検出と画像改善

車載複数カメラによる夜間雨天時における路面反射グレア領域の検出と画像改善

An Evaluation Method of the Flickering Patterns of LED Warning Lights for Visibility Improvement Based on Mental Measurements

An Evaluation Method of the Flickering Patterns of LED Warning Lights for Visibility Improvement Based on Mental Measurements

LED警光灯の視認性向上のための感性指標に基づく点滅パターン解析

LED警光灯の視認性向上のための感性指標に基づく点滅パターン解析

Enhancing the Visibility of Injuries with Narrow‐Banded Beams of Light within the Visible Light Spectrum

The use of narrow-banded visible light sources in improving the visibility of injuries has been hardly investigated, and studies examining the extent of this improvement are lacking. In this study, narrow-banded beams of light within the visible light spectrum were used to explore their ability in improving the visibility of external injuries. The beams of light were induced by four crime-lites(®) providing narrow-banded beams of light between 400 and 550nm. The visibility of the injuries was assessed through specific long-pass filters supplied with the set of crime-lites(®) . Forty-three percent of the examined injuries improved in visibility by using the narrow-banded visible light. In addition, injuries were visualized that were not visible or just barely visible to the naked eye. The improvements in visibility were particularly marked with the use of crime-lites(®) "violet" and "blue" covering the spectrum between 400-430 and 430-470nm. The simple noninvasive method showed a great potential contribution in injury examination.

Combined posterior tympanotomy/endomeatal access in cochlear implantation

Alternative techniques for cochlear implant surgery have been described, such as endomeatal- and suprameatal-alone approaches, without traditional posterior tympanotomy. A combined posterior tympanotomy/endomeatal approach is proposed as a way to enhance surgical safety and effectiveness. 64 patients, 34 men and 30 women, mean age 28 (range 1-81 years), 26 pre-verbal and 38 post-verbal, were submitted to cochlear implantation, 32 by means of the described combined posterior tympanotomy/endomeatal approach and 32 with traditional posterior tympanotomy-alone approach. Good anatomic and functional results were observed, with intraoperative improvements in visibility and accessibility of cochleostomy site in difficult cases without any complication, such as tympanic membrane perforation, external canal skin lesions, or extrusion at 12 months. No significant differences were found with traditional technique complication rates excepting for partial insertion data, with statistically significant better results with combined access. The combined posterior tympanotomy/endomeatal approach facilitates the array insertion in conditions of bad exposition/accessibility of promontory and round window. Moreover, this double-way access hinders an incomplete or incorrect positioning. It should be always considered as an alternative to the traditional posterior tympanotomy of one-way access.

Does secretin add value in pediatric magnetic resonance cholangiopancreatography?

Secretin--a hormone that stimulates pancreatic exocrine secretion--is described to improve visualization of the pancreatic duct by magnetic resonance cholangiopancreatography (MRCP). In our pediatric practice, however, we have not observed substantial benefit with the use of secretin. To determine whether secretin dilates and improves visualization of the pancreatic duct in pediatric MRCP. Retrospective evaluation of secretin-enhanced MRCPs performed over a 15-month period. One reviewer measured the pancreatic duct pre- and post-secretin and two reviewers, blinded to the administration of secretin, assessed image quality and subjective duct visibility. Similar assessments of the biliary tree served as internal controls. We reviewed 20 MRCPs in 17 children. Following secretin administration, there was a small (0.3 mm) but statistically significant increase in pancreatic duct diameter (P = 0.002) and small (<0.2 mm) but significant increase in intrahepatic bile duct diameter (P = 0.0104). On subjective review, there was no significant difference in image quality or duct visibility based on the administration of secretin. Secretin induces dilatation of the pancreatic duct but the value of that effect in pediatric MRCP is suspect given the small change in duct diameter and the lack of improvement in image quality and duct visibility.

최대 색차신호 표를 이용한 Retinex 영상의 컬러 향상

Retinex algorithm enhances the contrast of image through visibility improvement. However, the conventional Retinex methods may produces color distortions due to error of hue representation and over-saturation since the methods work in RGB color space. In this paper, we propose a new Retinex algorithm with color correction, which improves contrast by using MSR(Multi-Scale Retinex) working in YCbCr color space and adaptively compensates the color saturation based on the maximum color difference table. Our algorithm maps the color difference signals to the correct gamut to prevent over-saturation phenomenon by considering the correlation between luminance and hue dependent saturation. Simulations results show that the proposed method gives better color improvement compared to the conventional methods.

Posterior Tympanotomy/Endomeatal Combined Approach in Cochlear Implantation

Objective: An alternative posterior tympanotomy/endomeatal combined approach for cochlear implantation is presented. Surgical steps and our results in 64 patients, 32 submitted to combined posterior tympanotomy/endomeatal approach and 32 underwent to traditional surgery, are reported. Method: Sixty-four patients, 34 men and 30 women, mean age 28 years (range, 1-81 years), 26 preverbal and 38 postverbal, were submitted to cochlear implantation, 32 by means of a combined posterior tympanotomy/endomeatal approach and 32 with traditional posterior tympanotomy alone approach. Results: We reported good anatomic and functional results with intraoperative improvements in visibility and accessibility of cochleostomy site in difficult cases. At 12 months we did not observe any complication such as tympanic membrane perforation, external canal skin lesions, or extrusion. No significant differences were found with traditional technique complication rates excepting for partial insertion data, with statistically significant better results with combined access. Conclusion: The combined posterior tympanotomy/endomeatal approach facilitates the array insertion in conditions of bad exposition/accessibility of promontory and round window. Moreover, this double way access hinders an incomplete or incorrect positioning. It should be always considered as an alternative to the traditional posterior tympanotomy 1-way access.

Visibility Improvement for Dichromats by Lightness Modification Based on Craik-O'Brien Effect

Visibility Improvement for Dichromats by Lightness Modification Based on Craik-O'Brien Effect

Spectral CT with Metal Artifacts Reduction Software for Improvement of Tumor Visibility in the Vicinity of Gold Fiducial Markers

To evaluate spectral computed tomography (CT) with metal artifacts reduction software (MARS) for reduction of metal artifacts associated with gold fiducial seeds. Thirteen consecutive patients with 37 fiducial seeds implanted for radiation therapy of abdominal lesions were included in this HIPAA-compliant, institutional review board-approved prospective study. Six patients were women (46%) and seven were men (54%). The mean age was 61.1 years (median, 58 years; range, 29-78 years). Spectral imaging was used for arterial phase CT. Images were reconstructed with and without MARS in axial, coronal, and sagittal planes. Two radiologists independently reviewed reconstructions and selected the best image, graded the visibility of the tumor, and assessed the amount of artifacts in all planes. A linear-weighted κ statistic and Wilcoxon signed-rank test were used to assess interobserver variability. Histogram analysis with the Kolmogorov-Smirnov test was used for objective evaluation of artifacts reduction. Fiducial seeds were placed in pancreas (n = 5), liver (n = 7), periportal lymph nodes (n = 1), and gallbladder bed (n = 1). MARS-reconstructed images received a better grade than those with standard reconstruction in 60% and 65% of patients by the first and second radiologist, respectively. Tumor visibility was graded higher with standard versus MARS reconstruction (grade, 3.7 ± 1.0 vs 2.8 ± 1.1; P = .001). Reduction of blooming was noted on MARS-reconstructed images (P = .01). Amount of artifacts, for both any and near field, was significantly smaller on sagittal and coronal MARS-reconstructed images than on standard reconstructions (P < .001 for all comparisons). Far-field artifacts were more prominent on axial MARS-reconstructed images than on standard reconstructions (P < .01). Linear-weighted κ statistic showed moderate to perfect agreement between radiologists. CT number distribution was narrower with MARS than with standard reconstruction in 35 of 37 patients (P < .001). Spectral CT with use of MARS improved tumor visibility in the vicinity of gold fiducial seeds.

A dynamic product quality evaluation based pricing model for perishable food supply chains

Waste stemmed from inappropriate quality control and excessive inventories is a major challenge for perishable food management in grocery retail chains. Improvement of visibility and traceability in food supply chains facilitated by tracking and tracing technologies has great potential to improve operations efficiency. This research aims to reduce food spoilage waste and maximise food retailer's profit through a pricing approach based on dynamically identified food shelf life. The proposed model is evaluated through different pricing policies to exploit the benefits from utilising accurate product shelf life information captured through innovated tracking and monitoring technologies. Numerical analysis is conducted in an illustrative case study.

Spectral-Domain Optical Coherence Tomography Enhanced Depth Imaging of the Normal and Glaucomatous Nonhuman Primate Optic Nerve Head

To test whether the enhanced depth imaging (EDI) modality improves anterior and posterior lamina cribrosa surface (ALCS and PLCS) visibility compared with conventional spectral-domain optical coherence tomography (SD-OCT). Conventional and EDI SD-OCT scans were obtained 30 minutes after IOP was manometrically lowered to 10 mm Hg in both eyes of 14 nonhuman primates (NHPs) with unilateral experimental glaucoma (EG). Thirteen horizontal and seven vertical radial B-scans of each SD-OCT data set were delineated by one operator masked to image type. Delineated ALCS and PLCS points were projected to 1 of 100 equal-sized subregions of the neural canal opening (NCO) reference plane, and the number of delineated subregions (≥2 points) was counted. Poisson regression was used to analyze the effects of image type, treatment, and quadrant. Two additional delineations were performed for three NHPs to compare reproducibility. EDI increased the number of subregions delineated for both the ALCS (by 28%; P < 0.0001) and PLCS (by 225%; P < 0.0001). EDI improvement in ALCS visibility was significant in the superior quadrant only and was not different in EG versus control eyes, whereas EDI improvement in PLCS visibility was significant in all four quadrants (P < 0.005) and greater in EG eyes (P < 0.001), nasally and temporally. Intradelineator reproducibility was not different between image types. EDI and standard ONH parameter values were similar except for PLCS depth which was deeper in the EDI data sets (P = 0.0002). ALCS and PLCS visibility within control and EG NHP ONHs increased in EDI compared to conventional SD-OCT data sets. Further study of EDI effects on PLCS parameterization is required.

Regression Analyses between Recent Air Quality and Visibility Changes in Megacities at Four Haze Regions in China

The Chinese government has put forward a series of aggressive control measures to tackle environmental problems, such as poor visibility, since the first year of its 11th five-year plan (2006-2010). Recently recorded visibility, air quality and meteorological data in four major megacities (Beijing, Shanghai, Guangzhou and Chengdu) in different haze regions (and climatic zones) of China were analyzed with the aim of evaluating the extent to which the control actions have affected these measures. The ambient concentrations of three major air pollutants (SO2, NO2 and PM10) in these cities all decreased in the years 2005-2009. However, improved visibility was observed only in Beijing and Guangzhou; it remained steady in Shanghai, and showed a decreasing trend in Chengdu. The results highlight the fact that the correlation between air quality and visibility is complex. Optimal empirical regression models were developed, based on measured air quality and meteorological parameter data, to better isolate possible causal correlations between visibility and air quality, as well as meteorological conditions. Our results show that the improvement in visibility in both Beijing and Guangzhou was mainly due to the reduced PM10 concentration. In Guangzhou, improved atmospheric visibility was also helped by a reduction in SO2 concentration in winter. In contrast, lower wind speed, together with possible changes in fine particle concentration and composition, could explain why no improvement in visibility trend was found in Shanghai or Chengdu.