Biomedical subjects

Jannick Rolland

Publications and source records attributed to Jannick Rolland.

6 recordsLinked to original sources

PubMed2005

Task-based optimization and performance assessment in optical coherence imaging.

Optimization of an optical coherence imaging (OCI) system on the basis of task performance is a challenging undertaking. We present a mathematical framework based on task performance that uses statistical decision theory for the optimization and assessment of such a system. Specifically, we apply the framework to a relatively simple OCI system combined with a specimen model for a detection task and a resolution task. We consider three theoretical Gaussian sources of coherence lengths of 2, 20, and 40 microm. For each of these coherence lengths we establish a benchmark performance that specifies the smallest change in index of refraction that can be detected by the system. We also quantify the dependence of the resolution performance on the specimen model being imaged.

Algorithms↗

PubMed2004

Albertian errors in head-mounted displays: I. Choice of eye-point location for a near- or far-field task visualization.

A theoretical investigation of rendered depth and angular errors, or Albertian errors, linked to natural eye movements in binocular head-mounted displays (HMDs) is presented for three possible eye-point locations: the center of the entrance pupil, the nodal point, and the center of rotation of the eye. A numerical quantification was conducted for both the pupil and the center of rotation of the eye under the assumption that the user will operate solely in either the near field under an associated instrumentation setting or the far field under a different setting. Under these conditions, the eyes are taken to gaze in the plane of the stereoscopic images. Across conditions, results show that the center of the entrance pupil minimizes rendered angular errors, while the center of rotation minimizes rendered position errors. Significantly, this investigation quantifies that under proper setting of the HMD and correct choice of the eye points, rendered depth and angular errors can be brought to be either negligible or within specification of even the most stringent applications in performance of tasks in either the near field or the far field.

Computer Simulation↗

PubMed2004

An adaptive driver and real-time deformation algorithm for visualization of high-density lung models.

Technological advances in Augmented Reality (AR) and extraction of 3D patient specific medical data led to the creation of medical visualization using AR environments, in which the 3D data is registered and synchronized with the position of the patient. One of the challenges in such visualization environments is maintaining an accurate shape of the 3D data for self-deformable models such as lungs. An accurate deformation of lung model with 3D visualization may significantly increase the teaching and diagnosing ability of physicians. Modeling the deformation of lungs primarily involves the accurate representation of Pressure-volume relationship and the hysteresis in the relationship during inhalation and exhalation. This paper explains a real-time physiologically accurate deformation algorithm and its hardware rendering. We then introduce a novel approach for the representation of accurate pressure volume relationship based on an analogy with classical mechanics. Our simulation results show that the hysteresis obtained is more accurate as compared to current lung models. Thus in our approach a physically realistic deformation of lung model is obtained by the integration of the accurate PV relationship with real-time deformation method.

Algorithms↗

PubMed2003

Augmented Reality for teaching endotracheal intubation: MR imaging to create anatomically correct models.

Clinical procedures have traditionally been taught at the bedside, in the morgue and in the animal lab. Augmented Reality (AR) technology (the merging of virtual reality and real objects or patients) provides a new method for teaching clinical and surgical procedures. Improved patient safety is a major advantage. We describe a system which employs AR technology to teach endotracheal intubation, using the Visible Human datasets, as well as MR images from live patient volunteers.

Computer Simulation↗

PubMed2003

Development of a training tool for endotracheal intubation: distributed augmented reality.

The authors introduce a tool referred to as the Ultimate Intubation Head (UIH) to train medical practitioners' hand-eye coordination in performing endotracheal intubation with the help of augmented reality methods. In this paper we describe the integration of a deployable UIH and present methods for augmented reality registration of real and virtual anatomical models. The assessment of the 52 degrees field of view optics of the custom-designed and built head-mounted display is less than 1.5 arc minutes in the amount of blur and astigmatism, the two limiting optical aberrations. Distortion is less than 2.5%. Preliminary results of the registration of a physical phantom mandible on its virtual counterpart yields less than 3mm rms. in registration. Finally we describe an approach to distributed visualization where a given training procedure may be visualized and shared at various remote locations. Basic assessments of delays within two scenarios of data distribution were conducted and reported.

Computer Simulation↗

PubMed2002

Optical assessment of head-mounted displays in visual space.

The optics of head-mounted displays (HMDs) is designed from the pupil of the eye to the miniature display, and the optics is thus commonly solely assessed in the plane of the miniature display. Such assessment does not provide information that usefully interfaces with task-based performance metrics. We present a comprehensive framework for the assessment of the optics of HMDs in visual space, which applies to nonrotationally symmetric systems as well. Four key measures of visual performance are presented, and macro files were implemented to validate the framework. We illustrate the methods using an Erfle eyepiece.

Data Display↗