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The Compact thermal neutron imaging systems have become an important development trend. Compact thermal neutron imaging systems can use neutron tubes as neutron sources because of their low cost, small size, and portability. In order to achieve optimal imaging quality, the moderator and collimator in a neutron imaging system based on neutron tubes source are designed and simulated using SuperMC. The entrance position of the collimator is determined by analyzing the performance of different materials with their parameter's optimization. It is suggested that a cylinder-shaped structure made of carbon, hydrogenous materials, and heavy metals can significantly increase the thermal neutron flux at the sample location. Further dimension optimization is carried out to improve the neutron beam collimation performance. A vertically divergent collimator with a divergence angle of 5° and an air gap is selected, along with the addition of a B4C lining material. According to the modelling results, the sample position can be as far away from the neutron source as 77 cm with a neutron source yield of 1.14 × 109 n/s. The collimation ratio is 29, the thermal neutron flux is 1.08 × 103 n/cm2·s, and n/γ is 1.44 × 1012 n/cm2·Sv, which is suitable for thermal neutron radiography. [ABSTRACT FROM AUTHOR]

Minimally invasive endodontics has recently become popular in research. This study aimed to develop a new quantifiable straight-line minimally invasive endodontic cavity (SMIEC) for 3-rooted maxillary first molar based on the anatomical features of the coronal part of root canal. Cone-beam computed tomography (CBCT) images of 80 teeth were converted into models in Mimics Research software. Anatomical features of the coronal part of root canal were measured to develop SMIECs with straight-line accesses to root canals in 3-matic Research software. Twenty models were randomly sampled and each was duplicated for 8 simulation groups: non-treated (NT), traditional endodontic cavity (TEC), ninja endodontic cavity (NEC) and 5 SMIECs. Post-simulation models were subjected to finite element analysis to detect von-Mises stresses in ABAQUS software. Distributions of straight-line accesses to protogenetic root canals had certain manners, hence we developed 5 SMIECs. NEC and SMIECs had less hard tissue loss than TEC and presented different numerical rankings in different structures (P < 0.05). NEC had a less narrow surgery field than SMIECs except SMIEC 2/4 (P < 0.05). The peak pericervical stresses of SMIECs were similar, lower than TEC and higher than NEC and NT (P < 0.05). The stress distributions of the 8 groups had certain manners. Five SMIECs with straight-line accesses to root canals were developed, whose biomechanical properties were worse than NEC but better than TEC. Having appropriate structure preservation and surgery field, SMIEC 2/4 was a preferred SMIEC. [ABSTRACT FROM AUTHOR]

Post-ERCP pneumobilia is not uncommon; however, studies focusing on the long-term prognosis of patients with post-ERCP pneumobilia are limited. This study aimed to explore long-term prognosis and risk factors associated with post-ERCP pneumobilia in patients with common bile duct stones (CBDSs). We conducted a retrospective analysis of 1380 patients who underwent ERCP for CBDSs at our hospital from January 2010 to December 2017. Patients were selected based on inclusion and exclusion criteria and divided into pneumobilia and nonpneumobilia groups, followed by propensity score matching. The matched groups were then compared in terms of incidence rates of both single and multiple recurrences of CBDSs, acute cholangitis, and acute cholecystitis. Multivariate logistic regression analysis was used to explore risk factors associated with pneumobilia. After propensity matching, there was no significant difference in the rate of single recurrence of CBDSs (22.5% vs 30%; P =.446) between the pneumobilia and nonpneumobilia groups. However, the incidences of multiple recurrences of CBDSs (32.5% vs 12.5%; P =.032) and acute cholangitis without stone recurrence (32.5% vs 2.5%; P = <.001) were significantly higher in the pneumobilia group. Based on multivariate logistic regression analysis, in addition to a dilated CBD (diameter of >1 cm) (odds ratio [OR], 2.48; 95% confidence interval [CI], 1.03-3.76; P =.043), endoscopic sphincterotomy with moderate incision (OR, 5.38; 95% CI, 1.14-25.47; P =.034) and with large incision (OR, 8.7; 95% CI, 1.83-41.46; P =.007) were identified as independent risk factors for pneumobilia after initial ERCP. Patients with post-ERCP pneumobilia have increased risk of multiple recurrences of CBDSs and acute cholangitis without stone recurrence. Independent risk factors for pneumobilia include peripapillary diverticulum, a dilated CBD (>1 cm), and endoscopic sphincterotomy with moderate and large incisions. A normal-sized CBD appears to serve as a secondary barrier against enterobiliary reflux, necessitating further research for confirmation. [ABSTRACT FROM AUTHOR]

Highlights • A novel medical images enhancement method based on luminance modulation and gradient modulation (LM&GM) is proposed. • The LM is adopted for adjusting luminance and increasing contrast by shrinking the global dynamic range of input image. • The GM is used for enhancing details and textures of the images on the basis of the luminance modulation. • The performance of the proposed method is compared with the popular enhancement methods. • Quantitative analyses are applied to demonstrate the significance of LM&GM superior to other methods. Abstract Medical images play a significant role in modern diagnosis but often suffer from non-uniformity and low-luminance, which always affects the results of diagnosis and even leads to misdiagnosis in real applications. To obtain a clear and accurate view of the medical images, a new method based on luminance-level modulation and gradient modulation (LM&GM) is proposed in this paper. LM&GM is a two-stage approach that, first, increases the visual perception using the luminance-level modulation (LM) operation by compressing the range of luminance levels of the input image, and second, uses the gradient modulation (GM) operation to enhance the details of the previous step result. Experimental results on CT images, X-ray images and MRI images from medical image datasets and quantitative analyses by structural similarity index measurement (SSIM), average gradient (AG), relative enhancement in contrast (REC) and information entropy (IE) demonstrate that the results of the proposed method are competitive and overwhelm those of the existing methods. [ABSTRACT FROM AUTHOR]

• A robust edge extraction method is proposed for medical images based on improved local binary pattern combined with edge-aware filtering. • Edge-aware filtering (EF) is adopted to suppress noise and enhance contrast, while avoid artifacts on the border of strong edges. • An improved local binary pattern embedded with an accumulation function (ALBP) is used to extract the crucial edges of medical images. • Visual assessment and quantitative analysis prove that the proposed method is superior to other popular methods in terms of robustness. Edge-based processing and analysis of medical images are indispensable in modern diagnosis and the application value of edge extraction technology is rising with this tide. For medical images containing redundant noise, blurred details, and low contrast, a robust edge extraction method based on edge-aware filtering and improved local binary pattern (EF-ALBP) is proposed in this paper. EF-ALBP contains two parts: the edge-aware filtering (EF) is proposed to suppress noise and enhance contrast while preserve edges, and ALBP is used to extract the crucial edge features of the previous step results accurately by introducing an accumulation function into local binary pattern. Quantitative analyses and visual evaluation for experimental results on X-ray, CT, and MRI images from medical image datasets demonstrate that the proposed method is competitive in robustness and outperforms those of the popular methods. [ABSTRACT FROM AUTHOR]

In this paper, a soft-equalization-based single iterative receiver is proposed for the recently proposed PAM-DMT-based hybrid optical orthogonal frequency division multiplexing (PHO-OFDM) system to enhance its bit error rate (BER) performance. The interlayer interference and clipping noise of the pulse amplitude modulated discrete multitone (PAM-DMT) branch and DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) branch are first reduced by a soft-equalization method in the frequency domain. Then, the pairwise clipping (PC) and pairwise averaging (PA) are further introduced to correct the regenerated time-domain branch signals according to the corresponding branch symmetry properties. Numerical simulations demonstrate that the proposed receiver can realize improved BER performance over the conventional counterpart under both the linear and nonlinear transmission model. [ABSTRACT FROM AUTHOR]