3-D Respiratory Motion Compensation during EP Procedures by Image-Based 3-D Lasso Catheter Model Generation and Tracking

Abstract. Radio-frequency catheter ablation of the pulmonary veins attached to the left atrium is usually carried out under fluoroscopy guidance. Two-dimensional X-ray navigation may involve overlay im-ages derived from a static pre-operative 3-D volumetric data set to add anatomical details. However, respiratory motion may impair the utility of static overlay images for catheter navigation. We developed a system for image-based 3-D motion estimation and compensation as a solution to this problem for which no previous solution is yet known. It is based on 3-D catheter tracking involving 2-D/3-D registration. A biplane X-ray C-arm system is used to image a special circumferential (lasso) catheter from two directions. In the first step of the method, a 3-D model of the device is reconstructed. 3-D respiratory motion at the site of ablation is then estimated by tracking the reconstructed model in 3-D from bi-plane fluoroscopy. In our experiments, the circumferential catheter was tracked in 231 biplane fluoro frames (462 monoplane fluoro frames) with an average 2-D tracking error of 1.0 mm ± 0.5 mm.

Asymmetric secondary reflectors for multi-stage solar tower plants

We present asymmetric secondary reflectors made of plane facets for increasing the concentration of radiation from a field of heliostats. The reflectors are suited for partitioning the receiver in several parallel units. In the case of an asymmetric directional distribution of the radiation intercepted by the secondary reflector, asymmetric reflectors may significantly increase the concentration compared to their symmetric counterparts. Best results are obtained with reflectors based on rectangular entrance and exit apertures, without constraint on the shape of the exit aperture. For the example presented, the concentration may be increased by 90% under the constraint of an optical efficiency of 90%. Even if the shape of the exit aperture has to be close to circular, asymmetric reflectors based on hexagonal apertures may obtain 30% improvement in concentration

Optical in-situ analysis of secondary reflectors in solar tower plants

An optical measurement for radiation concentrators is proposed. A Lambertian light source is placed in the exit aperture of the concentrator. By taking pictures of the concentrator as seen from a remote location one gets the transmission patterns which carry the information of transmission with the four-dimensional resolution of the phase space of geometric optics. By matching ray tracing simulations to the measurement, one can achieve detailed and accurate information about the geometry of the concentrator. The reflectivity can be inferred by very simple means with 2% accuracy. This method has the potential to provide a handy tool to get automatically all optical information about a real size concentrator in situ

Business-Analytics im Marketing-Controlling

Die Digitalisierung verändert Geschäftsmodelle und betriebliche Prozesse. Zugleich beeinflussen auch eine verbesserte Datenverfügbarkeit und leistungsfähige analytische Methoden das Controlling und erfordern vermehrt das Einbringen statistischer und informationstechnologischer Fertigkeiten und Kenntnisse. An einem Fallbeispiel aus dem Marketing-Controlling zeigt der Beitrag den Einsatz von Methoden der Business Analytics und thematisiert die Aufgaben des Controllings im digitalen Zeitalter