Effects of Tablet Size and Head Posture on Drug Swallowing: A Preliminary Examination Using Endoscopy in Healthy Subjects

Tablet size and head posture have been reported to affect swallowing of medications, but no previous studies have evaluated their effects in detail. Our aim was to investigate for the first time the effect of tablet size and head posture on drug swallowing by endoscopic evaluation in healthy subjects. Round tablets (7 , 10 , 12, and 14 mm in diameter) were swallowed by 15 healthy adults with an endoscope inserted in the neutral, head flex-ion, and head extension positions. Evaluation of swallowing difficulty using a numeric rating scale (NRS), presence or absence of pharyngeal residue and its location, and tablet oral transit time (TOTT) were recorded. In the neutral position, the NRS score was higher with the 14 mm tablets than with the 7 mm tablets. The TOTT with the 7 mm tablets was significantly shorter in the head extension than in the neutral position. Swallowing difficulty increased when the tablet diameter was more than 7 mm. Residues were found in the epi-glottis, pyriform sinus, and tongue base. These findings suggest that head extension shortens the TOTT and assists oral-pharyngeal transport

Abstract

Acquiring 3D models of intricate objects (like tree branches, bicycles and insects) is a hard problem due to severe self-occlusions, repeated thin structures and surface discontinuities. In theory, a shape-from-silhouettes (SFS) approach can overcome these difficulties and use many views to reconstruct visual hulls that are close to the actual shapes. In practice, however, SFS is highly sensitive to errors in silhouette contours and the calibration of the imaging system, and therefore not suitable for obtaining reliable shapes with a large number of views. We present a practical approach to SFS using a novel technique called coplanar shadowgram imaging, that allows us to use dozens to even hundreds of views for visual hull reconstruction. Here, a point light source is moved around an object and the shadows (silhouettes) cast onto a single background plane are observed. We characterize this imaging system in terms of image projection, reconstruction ambiguity, epipolar geometry, and shape and source recovery. The coplanarity of the shadowgrams yields novel geometric properties that are not possible in traditional multi-view camerabased imaging systems. These properties allow us to derive a robust and automatic algorithm to recover the visual hull of an object and the 3D positions of light source simultaneously, regardless of the complexity of the object. We demonstrate the acquisition of several intricate shapes with severe occlusions and thin structures, using 50 to 120 views. 1

Hardware-Accelerated Visualization of Volume-Sampled Distance Fields

We present a method of visualizing volume-sampled distance fields, taking advantage of hardware-acceleration of modern graphics hardware. Although conventional distance fields can represent only 2-manifold surfaces in a stable way, we have developed a technique of representing both manifold and non-manifold surfaces in a volume created by sampling a segmented distance field. The volumesampled distance fields can be visualized effectively with pre-integrated volume rendering by embedding the interpolating function as a lookup table called vertex generation diagram into graphics hardware. We developed a simple system for smoothly blending two surface models in the distance function domain, and confirmed that our proposed representation of surface models is applicable to existing methods of geometric processing using implicit representations. We also confirmed that proposed methods of deformation and visualization can be executed at su#cient quality and speed using commodity graphics hardware on a standard PC