A New Statistical Reconstruction Method for the Computed Tomography Using an X-Ray Tube with Flying Focal Spot

Abstract This paper presents a new image reconstruction method for spiral cone- beam tomography scanners in which an X-ray tube with a flying focal spot is used. The method is based on principles related to the statistical model-based iterative reconstruction (MBIR) methodology. The proposed approach is a continuous-to-continuous data model approach, and the forward model is formulated as a shift-invariant system. This allows for avoiding a nutating reconstruction-based approach, e.g. the advanced single slice rebinning methodology (ASSR) that is usually applied in computed tomography (CT) scanners with X-ray tubes with a flying focal spot. In turn, the proposed approach allows for significantly accelerating the reconstruction processing and, generally, for greatly simplifying the entire reconstruction procedure. Additionally, it improves the quality of the reconstructed images in comparison to the traditional algorithms, as confirmed by extensive simulations. It is worth noting that the main purpose of introducing statistical reconstruction methods to medical CT scanners is the reduction of the impact of measurement noise on the quality of tomography images and, consequently, the dose reduction of X-ray radiation absorbed by a patient. A series of computer simulations followed by doctor's assessments have been performed, which indicate how great a reduction of the absorbed dose can be achieved using the reconstruction approach presented here

A Practical Statistical Approach to the Reconstruction Problem Using a Single Slice Rebinning Method

The paper presented here describes a new practical approach to the reconstruction problem applied to 3D spiral x-ray tomography. The concept we propose is based on a continuous-to-continuous data model, and the reconstruction problem is formulated as a shift invariant system. This original reconstruction method is formulated taking into consideration the statistical properties of signals obtained by the 3D geometry of a CT scanner. It belongs to the class of nutating reconstruction methods and is based on the advanced single slice rebinning (ASSR) methodology. The concept shown here significantly improves the quality of the images obtained after reconstruction and decreases the complexity of the reconstruction problem in comparison with other approaches. Computer simulations have been performed, which prove that the reconstruction algorithm described here does indeed significantly outperforms conventional analytical methods in the quality of the images obtained

A practical statistical approach to the reconstruction problem using a single slice rebinning method

The paper presented here describes a new practical approach to the reconstruction problem applied to 3D spiral x-ray tomography. The concept we propose is based on a continuous-to-continuous data model, and the reconstruction problem is formulated as a shift invariant system. This original reconstruction method is formulated taking into consideration the statistical properties of signals obtained by the 3D geometry of a CT scanner. It belongs to the class of nutating reconstruction methods and is based on the advanced single slice rebinning (ASSR) methodology. The concept shown here significantly improves the quality of the images obtained after reconstruction and decreases the complexity of the reconstruction problem in comparison with other approaches. Computer simulations have been performed, which prove that the reconstruction algorithm described here does indeed significantly outperforms conventional analytical methods in the quality of the images obtained

Working Conditions and Their Importance for Eliminating Errors in the Order Picking Process, Using an E-Commerce Commercial Enterprise as an Example

The research presented herein aims to pinpoint the factors that cause errors in the order picking process in an e-commerce enterprise and to confirm or deny the assumption that these factors largely concern employees and their working conditions. Research method: A case study strategy, observation (non-compliance cards and identification of working conditions), and Lorenz–Pareto and Ishikawa were the methods used. Results: The research results indicate that working conditions are a key factor influencing the number of errors in the picking process. The usefulness of the research: The results show that paying particular attention to working conditions is not only good in the context of caring for the well-being of employees, but also as a means to reduce the number of errors and improve the pace of work. Limitations: Due to the methods used, which in turn result from the large variety of e-commerce entities, the research results are not universal and are limited to a specific situational context

Clinical, Dermoscopic, and Histological Characteristics of Melanoma Patients According to the Age Groups: A Retrospective Observational Study

Background: Although the role of melanoma risk factors is well documented, their correlation with patients’ age is less frequently analyzed. Method: The analysis was performed among 189 melanoma patients in different age groups, including 60 years, to investigate the risk factors, topography, and coexistence of morphological features of 209 melanomas (dermoscopic and histopathological). Results: Among the youngest age group, no correlation with the presence of estimated risk factors was found. The most common dermoscopic pattern was spitzoid and multicomponent asymmetric. The group of middle-aged patients was the most diverse in terms of the occurrence of risk factors, solar lentiginosis, dermoscopic patterns, topography, histological subtypes, and invasiveness of melanomas. The oldest group characterized a strong correlation between solar lentiginosis, NMSC comorbidity, the prevalence of facial melanomas, the dermoscopic pattern of melanoma arising on chronic sun-damaged skin, and regression. Conclusion: The findings regarding the presence of age-specific features in melanoma patients, especially in the youngest and middle-aged groups, might be helpful for clinicians and to target secondary prevention efforts

VM-Based Shared Memory on Low-Latency, Remote-Memory-Access Networks

Recent technological advances have produced network interfaces that provide users with very low-latency access to the memory of remote machines. We examine the impact of such networks on the implementation and performance of software DSM. Specifically, we compare two DSM systems—Cashmere and TreadMarks—on a 32-processor DEC Alpha cluster connected by a Memory Channel network. Both Cashmere and TreadMarks use virtual memory to maintain coherence on pages, and both use lazy, multi-writer release consistency. The systems differ dramatically, however, in the mechanisms used to track sharing information and to collect and merge concurrent updates to a page, with the result that Cashmere communicates much more frequently, and at a much finer grain. Our principal conclusion is that low-latency networks make DSM based on fine-grain communication competitive with more coarse-grain approaches,but that further hardware improvements will be needed before such systems can provide consistently superior performance. In our experiments, Cashmere scales slightly better than TreadMarks for applications with false sharing. At the same time, it is severely constrained by limitations of the current Memory Channel hardware. In general, performance is better for TreadMarks

VM-Based Shared Memory on Low-Latency, Remote-Memory-Access Networks

Link to published version: http://ieeexplore.ieee.org/iel3/4807/13287/00604674.pdf?tp=&arnumber=604674&isnumber=13287Recent technological advances have produced network interfaces that provide users with very low-latency access to the memory of remote machines. We examine the impact of such networks on the implementation and performance of software DSM. Specifically, we compare two DSM systems---Cashmere and TreadMarks---on a 32-processor DEC Alpha cluster connected by a Memory Channel network. Both Cashmere and TreadMarks use virtual memory to maintain coherence on pages, and both use lazy, multi-writer release consistency. The systems differ dramatically, however, in the mechanisms used to track sharing information and to collect and merge concurrent updates to a page, with the result that Cashmere communicates much more frequently, and at a much finer grain. Our principal conclusion is that low-latency networks make DSM based on fine-grain communication competitive with more coarse-grain approaches, but that further hardware improvements will be needed before such systems can provide consistently superior performance. In our experiments, Cashmere scales slightly better than TreadMarks for applications with false sharing. At the same time, it is severely constrained by limitations of the current Memory Channel hardware. In general, performance is better for TreadMarks