5,274 research outputs found
Precise Proximal Femur Fracture Classification for Interactive Training and Surgical Planning
We demonstrate the feasibility of a fully automatic computer-aided diagnosis
(CAD) tool, based on deep learning, that localizes and classifies proximal
femur fractures on X-ray images according to the AO classification. The
proposed framework aims to improve patient treatment planning and provide
support for the training of trauma surgeon residents. A database of 1347
clinical radiographic studies was collected. Radiologists and trauma surgeons
annotated all fractures with bounding boxes, and provided a classification
according to the AO standard. The proposed CAD tool for the classification of
radiographs into types "A", "B" and "not-fractured", reaches a F1-score of 87%
and AUC of 0.95, when classifying fractures versus not-fractured cases it
improves up to 94% and 0.98. Prior localization of the fracture results in an
improvement with respect to full image classification. 100% of the predicted
centers of the region of interest are contained in the manually provided
bounding boxes. The system retrieves on average 9 relevant images (from the
same class) out of 10 cases. Our CAD scheme localizes, detects and further
classifies proximal femur fractures achieving results comparable to
expert-level and state-of-the-art performance. Our auxiliary localization model
was highly accurate predicting the region of interest in the radiograph. We
further investigated several strategies of verification for its adoption into
the daily clinical routine. A sensitivity analysis of the size of the ROI and
image retrieval as a clinical use case were presented.Comment: Accepted at IPCAI 2020 and IJCAR
Spatial representation of temporal information through spike timing dependent plasticity
We suggest a mechanism based on spike time dependent plasticity (STDP) of
synapses to store, retrieve and predict temporal sequences. The mechanism is
demonstrated in a model system of simplified integrate-and-fire type neurons
densely connected by STDP synapses. All synapses are modified according to the
so-called normal STDP rule observed in various real biological synapses. After
conditioning through repeated input of a limited number of of temporal
sequences the system is able to complete the temporal sequence upon receiving
the input of a fraction of them. This is an example of effective unsupervised
learning in an biologically realistic system. We investigate the dependence of
learning success on entrainment time, system size and presence of noise.
Possible applications include learning of motor sequences, recognition and
prediction of temporal sensory information in the visual as well as the
auditory system and late processing in the olfactory system of insects.Comment: 13 pages, 14 figures, completely revised and augmented versio
Quantile-based optimization under uncertainties using adaptive Kriging surrogate models
Uncertainties are inherent to real-world systems. Taking them into account is
crucial in industrial design problems and this might be achieved through
reliability-based design optimization (RBDO) techniques. In this paper, we
propose a quantile-based approach to solve RBDO problems. We first transform
the safety constraints usually formulated as admissible probabilities of
failure into constraints on quantiles of the performance criteria. In this
formulation, the quantile level controls the degree of conservatism of the
design. Starting with the premise that industrial applications often involve
high-fidelity and time-consuming computational models, the proposed approach
makes use of Kriging surrogate models (a.k.a. Gaussian process modeling).
Thanks to the Kriging variance (a measure of the local accuracy of the
surrogate), we derive a procedure with two stages of enrichment of the design
of computer experiments (DoE) used to construct the surrogate model. The first
stage globally reduces the Kriging epistemic uncertainty and adds points in the
vicinity of the limit-state surfaces describing the system performance to be
attained. The second stage locally checks, and if necessary, improves the
accuracy of the quantiles estimated along the optimization iterations.
Applications to three analytical examples and to the optimal design of a car
body subsystem (minimal mass under mechanical safety constraints) show the
accuracy and the remarkable efficiency brought by the proposed procedure
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