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Anatomically based procedures to ablate atrial fibrillation (AF) are often successful in terminating paroxysmal AF. However, the ability to terminate persistent AF remains disappointing. New mechanistic approaches use multiple-electrode basket catheter mapping to localize and target AF drivers in the form of rotors but significant concerns remain about their accuracy. We aimed to evaluate how e...

BACKGROUND AND PURPOSE Intensity-modulated radiotherapy (IMRT) credentialing for a EORTC study was performed using an anthropomorphic head phantom from the Radiological Physics Center (RPC; RPC(PH)). Institutions were retrospectively requested to irradiate their institutional phantom (INST(PH)) using the same treatment plan in the framework of a Virtual Phantom Project (VPP) for IMRT credential...

PURPOSE The aim of this study was to improve the image quality of cone-beam computed tomography (CBCT) mounted on the gantry of a linear accelerator used in radiation therapy based on the image information provided by planning multi-detector CT (MDCT). METHODS MDCT-based shading correction for CBCT and virtual monochromatic CT (VMCT) synthesized using the dual-energy method were performed. In...

Image-guided surgery can be broken down into two broad categories: frame-based guidance and frameless guidance. In order to reduce both the invasive nature of stereotactic guidance and the cost in equipment and time, we have developed a new guidance technique based on rapid prototyping (RP) technology. This new system first builds a computer model of the patient anatomy and then fabricates a ph...

We can supplement the clinical value of an optical colonoscopy procedure if we can continuously co-align corresponding virtual colonoscopy (from preoperative X-ray CT exam) and optical colonoscopy images. In this work, we demonstrate a computer vision algorithm based on optical flow to compute egomotion from live colonoscopy video, which is then used to navigate and visualize the corresponding ...

Haptics refers to the modality of touch and associated sensory feedback. Researchers working in the area are concerned with the development , testing, and refinement of tactile and force feedback devices and supporting software that permit users to sense (" feel ") and manipulate three-dimensional virtual objects with respect to such features as shape, weight, surface textures, and temperature....

This paper proposes a nonlinear controller to extend the Zwidth of a haptic device. A time-domain passivity analysis of the Z-width diagram leads to the new haptic controller, which employs acceleration feedback. The passivity condition for one degree of freedom (1DOF) haptic interaction with a virtual wall via the proposed controller is derived using passivity theory in the frequency domain. T...

The main aim was to investigate if short-term practice in exploration with a PHANToM can improve performance. A second aim was to find out if some exploration modes are more successful than other modes. Ten participants practiced exploration of nine blocks of 24 virtual objects distributed over three days. The result was that the performance for a majority improved during this practice, but tha...

Cataract is a clouding of the eye’s natural lens, normally due to natural aging changes, and involving at least half of the population over 65 years. Cataract extraction is the only solution for restoring a clear vision, and nowadays is probably the most frequently practiced surgical procedure. This paper describes a novel virtual reality simulation system for cataract surgery training, involvi...