Search

Purpose: As a promising intravascular therapeutic approach for autonomous catheterization, especially for thrombosis treatment, a microrobot or robotic catheter driven by an external electromagnetic actuation system has been recently investigated. However, the three-dimensional (3D) real-time position and orientation tracking of the microrobot remains a challenge for precise feedback control in clinical applications owing to the micro-size of the microrobot geometry in vessels, along with bifurcation and vulnerability. Therefore, in this paper, we propose a 3D posture recognition method for the unmanned microrobotic surgery driven by an external electromagnetic actuator system.Methods: We propose a real-time position and spatial orientation tracking method for a millimeter-sized intravascular object or microrobot using a principal component analysis algorithm and an X-ray reconstruction. The suggested algorithm was implemented to an actual controllable wireless microrobot system composed of a bullet-shaped object, a biplane X-ray imaging device, and an electromagnetic actuation system. Numerical computations and experiments were conducted for the performance verification.Results: The experimental results showed a good performance of the implemented system with tracking errors less than 0.4 mm in position and 2° in orientation. The proposed tracking technique accomplished a fast processing time, ~ 0.125 ms/frame, and high-precision recognition of the micro-sized object.Conclusions: Since the suggested method does not require pre-information of the object geometry in the human body for its 3D shape and position recognition, it could be applied to various elliptical shapes of the microrobot system with computation time efficacy and recognition accuracy. Hence, the method can be used for therapeutic millimeter- or micron-sized manipulator recognition in vascular, as well as implanted objects in the human body. [ABSTRACT FROM AUTHOR]

Micro-computed tomography (MCT) provides a tool for creating three-dimensional images of a sample by combining a series of two-dimensional "slices" of the object. This capability has led to an increasing number of applications of MCT data in research, including non-destructive evaluation and three-dimensional reconstructions of objects. However, a lack of standardization in the imaging process may lead to inconsistent results if the researcher is not aware of the factors which impact the resolution, detail, and density accuracy of the scan. This work addresses the variability present in the Xradia MCT-400 data and suggests techniques for controlling that variability. Sample preparation, including size, placement, and composition, imaging parameters such as threshold values, x-ray sample counts, scan resolution, and conversion of the output format for subsequent use of the data are discussed in the context of non-destructive evaluation of weld quality for friction stir welding of aluminum, but are universal for all applications. This work was performed in part during the Research Experience for Undergraduates (REU) hosted at SDSM&T in the summer of 2013. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we deal with uniqueness and reconstruction problems in Discrete Tomography. For a finite set of directions in , we introduce the class of -inscribable lattice sets, and give a detailed description of their geometric structure. This shows that such sets can be considered as the natural discrete counterpart of the same notion known in the continuous case, as well as a kind of generalization of the class of the so-called -convex polyominoes (or moon polyominoes). In view of reconstruction from projections along the directions in , two related questions of tomographic interest are investigated, namely uniqueness and additivity. We show that both properties are fulfilled by -inscribable lattice sets. Moreover, concerning the case , we provide an explicit reconstruction algorithm from the knowledge of directed horizontal and vertical X-rays, jointly with a few preliminary results towards a possible sharp stability inequality. [Copyright &y& Elsevier]

In this paper, we describe the work done in order to run the CT 3-D reconstruction algorithm on the 120 GB raw data from the more than 25\thinspace000 radiographs acquired from the Kongo Rikishi (XIII century) Japanese wooden statue. The work was done using the Microsoft (Redmond) HPC cluster and then on a local cluster at the INFN of Bologna. A speed-up factor of 75 was reached. [ABSTRACT FROM PUBLISHER]