Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

This paper presents a new method—the Technique of Iterative Local Thresholding (TILT)—for processing 3D X-ray computed tomography (xCT) images for visualization and quantification of rock fractures. The TILT method includes the following advancements. First, custom masks are generated by a fracture-dilation procedure, which significantly amplifies the fracture signal on the intensity histogram used for local thresholding. Second, TILT is particularly well suited for fracture characterization in granular rocks because the multi-scale Hessian fracture (MHF) filter has been incorporated to distinguish fractures from pores in the rock matrix. Third, TILT wraps the thresholding and fracture isolation steps in an optimized iterative routine for binary segmentation, minimizing human intervention and enabling automated processing of large 3D datasets. As an illustrative example, we applied TILT to 3D xCT images of reacted and unreacted fractured limestone cores. Other segmentation methods were also applied to provide insights regarding variability in image processing. The results show that TILT significantly enhanced separability of grayscale intensities, outperformed the other methods in automation, and was successful in isolating fractures from the porous rock matrix. Because the other methods are more likely to misclassify fracture edges as void and/or have limited capacity in distinguishing fractures from pores, those methods estimated larger fracture volumes (up to 80 %), surface areas (up to 60 %), and roughness (up to a factor of 2). These differences in fracture geometry would lead to significant disparities in hydraulic permeability predictions, as determined by 2D flow simulations

Systematic review of international guidelines for perioperative antibiotic prophylaxis in Head & Neck Surgery. A YO‐IFOS Head & Neck Study Group Position Paper

BACKGROUND: Surgical site infection (SSI) is defined as an infection that occurs after a surgical incision or organ manipulation during surgery. The frequency reported for clean head and neck surgical procedures without antimicrobial prophylaxis is <1%. In contrast, infection rates in patients undergoing complicated cancer surgery are high, ranging from 24% to 87% of patients without antimicrobial prophylaxis. METHODS: Guidelines and recommendations about the use of antibiotics in head and neck surgery from 2004 to 2019 were reviewed. RESULTS: Four guidelines from Oceania, 5 from South America, 5 from North America, 2 from the United Kingdom, 11 from Europe, 1 from Africa, 1 from the Middle East, and 3 from Asia were included. A total of 118 papers were included for analysis and recommendation. CONCLUSION: Antibiotic prophylaxis can decrease the incidence of SSI. However, the risks associated with antibiotic exposure and the risk of antibiotic resistance need to be taken into consideration