A new geometrical method for 3D evaluation of non-rigid registration methods for radiotherapy in prostate cancer

Three-dimensional conformal radiotherapy aims at delivering a high dose of radiation to the tumour, while sparing the surrounding normal tissue to a maximum extent. Image registration is an essential tool for monitoring radiation therapies, since allows morphological comparisons in presence of anatomic variations. The evaluation of non-rigid registration methods is very complicated owe to the absence of a known pointwise correspondence. The use of analysis of variations in target volume delineations has been proposed in the past for the evaluation of non-rigid registration methods. Delineation of the target volume is usually accomplished by outlining the contour of the volume in each separate tomographic slice. In the studies of reference, the 3D surface is rendered from the contours by means of a Delauney triangulation. This geometrical method only works correctly for convex structures. However the volumes involved on pelvic anatomy, such as bladder or prostate including the seminal vesicles, have relevant concavities that introduce a huge error in the evaluation. A new geometrical method for the evaluation of convex-concave target volumes delineation is proposed

Empirical evaluation of educational interactive systems

[EN ]Educational software systems are usually highly interactive systems that needs to be evaluated from two different perspectives, first as interactive software, mainly using usability and accessibility approaches, and second as an educational product that needs to be evaluated from its learning impact. The empirical evaluation methods may be quantitative, with a more deductive reasoning, or qualitative, with a more inductive reasoning, oriented, however mixed approaches have been used extensively because they combine the both main methods with a more pragmatic knowledge focusing on knowing the consequences or solving problems. The empirical evaluation of interactive educational software due to its own characteristics requires a mixed approach typically. This special issue is devoted to identify, share and valorise best practices and experiences, with a very solid modelling background, that are focused on the empirical evaluation of educational interactive systems with a special emphasis on mixed quantitative and qualitative approaches

Electric and magnetic dipolar response of Germanium spheres: Interference effects, scattering anisotropy and optical forces

We address the scattering cross sections, and their consequences, for submicrometer Germanium spheres. It is shown that there is a wide window in the near infrared where light scattering by these particles is fully described by their induced electric and magnetic dipoles. In this way, we observe remarkable anisotropic scattering angular distributions, as well as zero forward or backward scattered intensities, which until recently was theoretically demonstrated only for hypothetically postulated magnetodielectric spheres. Also, interesting new effects of the optical forces exerted on these objects are now obtained.Comment: 13 pages, 4 figure

Conceptualización, léxico y gramática: los principios de traducibilidad y sinonimia

Ministerio de Ciencia e Innovación del Gobierno de España

Extracción Automática de la Línea Central de Estructuras Tubulares: Implementación Matricial

Se propone una nueva implementación matricial de un algoritmo para la extracción automática de la línea central de estructuras tubulares. El algoritmo seleccionado calcula la línea central de estructuras complejas sin la necesidad de interacción con el usuario. En el trabajo se explica detalladamente cómo llevar a cabo la implementación matricial utilizando el lenguaje de computación de Matlab. La implementación matricial permite el cálculo de la línea central en pocos segundos, mejorando en varios grados de magnitud la implementación disponible en ITK

Segmentation and 3D reconstruction approaches for the design of laparoscopic augmented reality environments

A trend in abdominal surgery is the transition from minimally invasive surgery to surgeries where augmented reality is used. Endoscopic video images are proposed to be employed for extracting useful information to help surgeons performing the operating techniques. This work introduces an illumination model into the design of automatic segmentation algorithms and 3D reconstruction methods. Results obtained from the implementation of our methods to real images are supposed to be an initial step useful for designing new methodologies that will help surgeons operating MIS techniques

A new method for quantitative evaluation of target volume variations in radiotherapy planning

A new method for three-dimensional quantitative evaluation of target volume delineation is presented. It is composed by a new 3D reconstruction method called Origami, based on the combination of two bidimensional analysis of the volume of each organ instead of one 3D analysis, and a 3D description of the error distribution in the space. The Origami method avoid external errors introduced by a 3D rendering and has shown to work correctly in both convex and convex-concave volumes, accurately fitting the contours of the planning study. Its performance has been evaluated comparing it with the Convex Hull algorithm using Delaunay triangulation, resulting in a much more adjusted evaluation. Moreover, Origami computes thousands of control points in less than one second in a common PC

Comparativa del uso de HLLs en FPGA, GPU y Multicore para la aceleración de una aplicación de red IP

Afrontar la creación de aplicaciones a partir de lenguajes de alto nivel (High Level Lenguajes - HLLs) tiene la incuestionable ventaja de reducir el tiempo de desarrollo. Con ello, es viable una evaluación anticipada del prototipo para conocer cuanto antes si se alcanza el rendimiento especificado como objetivo. En este trabajo se han utilizando tres tecnologías de aceleración: multicore, coprocesador gráfico y coprocesador reconfigurable, que aprovechan el procesamiento paralelo, y se ha realizado una discusión crítica de su experiencia de uso a través de abstracciones de alto nivel. Las soluciones basadas en el uso de coprocesadores no sólo han aportado un nivel de rendimiento superior a la aplicación que se deseaba acelerar, sino que con vista al sistema final en producción, estas alternativas son especialmente interesantes por dejar libres los cores de procesamiento para la realización de las operaciones de envío/recepción en la red de comunicaciones

Laparoscopic tool tracking method for augmented reality surgical applications

Vision-based tracking of laparoscopic tools offers new possibilities for improving surgical training and for developing new augmented reality surgical applications. We present an original method to determine not only the tip position, but also the orientation of a laparoscopic tool respect to the camera coordinate frame. A simple mathematical formulation shows how segmented tool edges and camera field of view define the tool 3D orientation. Then, 3D position of the tool tip is determined by image 2D coordinates of any known point of the tool and by tool’s diameter. Accuracy is evaluated in real image sequences with known ground truth. Results show a positioning error of 9,28 mmRMS, what is explained by inaccuracies in the estimation of tool edges. The main advantage of proposed method is its robustness to occlusions of the tool tip

Study of the Dependence of Solar Radiation Regarding Design Variables in Photovoltaic Solar Installations with Optimal Dual-Axis Tracking

Solar tracking is an efficient strategy to increase the radiative capture of photovoltaic collectors. Within the multiple efforts made in recent decades to improve the production of these facilities, various works have studied solutions to optimize the number of rotation axes (single or dual rotation axes), the degree of collector coverage, the distances between trackers, the geometric arrangement of trackers or the minimization of shading between collectors. However, although in this type of installation it is common to find collectors with geometric shapes other than rectangles, no studies on the influence of the shape of the collectors on the radiative incidence are found in the literature. In this connection, the present work systematically addresses the study of incident solar radiation in photovoltaic installations with dual-axis trackers with collectors of different geometric shapes. By means of the exhaustive study, the conclusion is drawn that, for dual-axis photovoltaic installations with an optimal tracking strategy, the main variables that influence the annual radiative incidence are the spacing between collectors, the coverage ratio (GCR), and the collector surface, while the type of arrangement of collectors and the shape of these do not show predictive values