Search results for "contour"
showing 10 items of 99 documents
Global treatment of chromatographic data with MICHROM
1997
Abstract The program MICHROM for the general treatment of chromatographic data is presented. MICHROM takes part in all the stages of the analytical process. It allows determination of dead time, smoothing of chromatograms, measurement of peak parameters, fitting of skewed peaks, and deconvolution of overlapped peaks. Tools for the experimental design, optimization of the mobile phase composition to resolve a mixture of analytes, and simulation of chromatograms in several experimental conditions, are implemented. Routines for the graphical representation of chromatograms, resolution surfaces, contour maps, management of data series, optimization and regression analysis, are also included. Th…
A musical reading of a contemporary installation and back: mathematical investigations of patterns in Qwalala
2021
Mathematical music theory helps us investigate musical compositions in mathematical terms. Some hints can be extended towards the visual arts. Mathematical approaches can also help formalize a "translation" from the visual domain to the auditory one and vice versa. Thus, a visual artwork can be mathematically investigated, then translated into music. The final, refined musical rendition can be compared to the initial visual idea. Can an artistic idea be preserved through these changes of media? Can a non-trivial pattern be envisaged in an artwork, and then still be identified after the change of medium? Here, we consider a contemporary installation and an ensemble musical piece derived from…
An Automatic HEp-2 Specimen Analysis System Based on an Active Contours Model and an SVM Classification
2019
The antinuclear antibody (ANA) test is widely used for screening, diagnosing, and monitoring of autoimmune diseases. The most common methods to determine ANA are indirect immunofluorescence (IIF), performed by human epithelial type 2 (HEp-2) cells, as substrate antigen. The evaluation of ANA consist an analysis of fluorescence intensity and staining patterns. This paper presents a complete and fully automatic system able to characterize IIF images. The fluorescence intensity classification was obtained by performing an image preprocessing phase and implementing a Support Vector Machines (SVM) classifier. The cells identification problem has been addressed by developing a flexible segmentati…
Subpixel determination of imperfect circles characteristics
2008
This article deals with the problem of the determination of characteristics of imperfect circular objects in discrete images, namely the radius and center coordinates. To limit distortion, a multi-level method based on active contours was developed. Its originality is to furnish a set of geometric envelopes in one pass, with a correspondence between grayscale and a regularity scale. The adequacy of this approach was tested with several methods, among them is the Radon-based method. More particularly, this study indicates the relevance of the use of active contours combined with a Radon transform-based method which was improved using a fitting considering the discrete implementation of the R…
Cone-beam computed tomography in lung stereotactic ablative radiation therapy: predictive parameters of early response
2016
To analyze lung lesion volume variations by contouring on cone-beam CT (CBCT) images to evaluate the early predictive parameters of stereotactic ablative radiation therapy (SABR) treatment response.The prescribed dose of SABR was varied according to the tumour site (central or peripheral) and maximum diameter of the lesions by using a strategy of risk-adapted dose prescription with a dose range between 48 and 70 Gy in 3-10 consecutive fractions. For the purpose of the analysis, the gross tumour volume (GTV) was recontoured for each patient at first and last CBCT using two lung levels/windows: (a) -600/1000 HU and (b) -1000/250 HU. Univariate analysis was performed to evaluate a correlation …
Model of a CNC Feed Drive for On-Site Tuning of the Controllers for Single Axis Motion
2016
The accuracy of CNC machine-tools is heavily influenced by the correct tuning of the feed drives controllers. While an initial tuning is performed by the machine-tool manufactures, in time the values have to be changed by the user in order to preserve positioning and contouring accuracy of the machine. This paper presents a model of a CNC feed drive, for a particular CNC machine-tool, but with a high degree of generality. The objective is to provide the user the necessary knowledge, together with a simple, yet accurate simulation tool, in order to assist him in the process of tuning the controllers.
9 Development of an experimental tool to evaluate normal tissue 3D doses in external-beam radiotherapy
2018
Introduction Recently, cancer treatment improvement enabled an increase in patients’ survival rate. In more than half of the cases, radiotherapy participates in the cure for cancer. The efficacy of this technique is well known but it inevitably delivers doses to normal tissues exposing them to radio-induced complications risks [1] . Moreover, the longer patients’ life expectancy increases the risk of developing long-term complications such as second cancers. Thus, evaluating the risks following cancer treatment involving radiotherapy constitutes a major challenge. In this context, an experimental tool has been developed to evaluate normal tissue doses delivered by the different radiotherapy…
SU-FF-T-365: Practical Reconstruction Method for 3D CT-Based Brachytherapy with Shielded Colpostats
2006
Introduction and purpose.‐ The most extended worldwide HDR and PDR afterloading machines are from Nucletron, using the Plato Treatment Planning System (TPS) to perform the clinical dosimetry. The Fletcher‐Williamson (FW) vaginal colpostat applicators are widely used with these machines, they are made of a very dense material (densimet‐17) which allows shielding up to 50% of the dose. Almost all the TPS have incorporated the CT‐Based Brachytherapy (BT), in which the CT catheters and applicators reconstruction is based on contiguous CT transverse slices where the user points the catheter position. The problem with these applicators is the production of artefacts that makes the reconstruction …
2020
One crucial parameter to evaluate the state of the heart after myocardial infarction (MI) is the viability of the myocardial segment, i.e., if the segment recovers its functionality upon revascularization. MRI performed several minutes after the injection of a contrast agent (delayed enhancement-MRI or DE-MRI) is a method of choice to evaluate the extent of MI, and by extension, to assess viable tissues after an injury. The Emidec dataset is composed of a series of exams with DE-MR images in short axis orientation covering the left ventricle from normal cases or patients with myocardial infarction, with the contouring of the myocardium and diseased areas (if present) from experts in the dom…