Newsletters: 2002, Issue 2

Medical Technology at PSI

PSI focuses on technology development for emerging medical device applications

PSI's Medical Technology R&D Area

PSI Medical Technology's mission is to conduct government and corporate sponsored R&D focusing on technology development for emerging medical device applications. For over a decade, our activities have ranged from developing physical models of medical laser/tissue interactions to developing innovative electro-optic and electro-mechanical medical devices and instrumentation. These projects have been sponsored by the National Institutes of Health, the Department of Defense, corporate funding and venture capital. Recent R&D efforts have focused largely on the development of advanced ophthalmic and endoscopic optical imaging technologies, spectroscopic-based approaches for blood analysis, and new technologies for breath analysis diagnostics. A major portion of these R&D efforts are carried out in close collaboration with recognized medical research institutions as well as established corporate partners in the medical industry. Some of these activities are described in the following pages.

Dr. David Rosen, Group Leader, Medical Technology

Advanced Ophthalmic Imaging Technologies

PSI is actively engaged in several R&D efforts to develop advanced ophthalmic imaging technologies. These efforts include: application of our patented high-speed, high- precision eye tracking technology to retinal image stabilization, development of a compact, high performance digital ophthalmoscope, and development of a multichannel low- coherence imaging system. As an example, highlighted below are ongoing efforts to incorporate a high speed, stabilized imaging capability into a scanning laser ophthalmoscope (SLO).

Tracking Scanning Laser Ophthalmoscope (TSLO)

The confocal scanning laser ophthalmoscope is an approach to ophthalmic imaging that offers high image contrast with reduced susceptibility to media opacities, while using low light levels in the visible and near IR. As with other scanning imagers, the SLO is susceptible to motion artifacts. To overcome this, PSI researchers and engineers have added a high performance image stabilization capability. Stabilized imaging promises a number of clinical advantages, including a solution to the problem of poor visual fixation, reduced noise and blurriness of retinal images, enhanced visual field testing, and higher magnification imaging of the retina.

Tracking Scanning Laser ophthalmoscope

PSI's approach to high speed image stabilization entails the implementation of real-time, non-imaging, feature-based tracking. Specifically, the approach employs a closed loop servo system with optical feedback and fast aperture-steering mirrors. Two-dimensional tracking is achieved with a single eye-safe beam and a photodetector. Demonstrated in human subjects, the TSLO maintains precision tracking for large random eye motion at hundreds of degrees per second and with rms precision to 10 mm.

Development and testing of the TSLO has been carried out in close cooperation with collaborators at the Schepens Eye Research Institute (SERI). PSI is also working with other clinical and commercial partners to pursue additional clinical applications of its high speed tracking/image stabilization technology.

Laryngeal Endoscopes

PSI recently completed a project for the National Institutes of Health in collaboration with researchers at the Massachusetts Eye and Ear Infirmary. The feasibility of developing an optically-based metrology system for the calibrated sizing of objects viewed through laryngeal endoscopes (including flexible transnasal fiberscopes) was demonstrated. The system allows for the easy and accurate determination of the dimensions of vocal structures and/or pathologic conditions, such as glottal closure characteristics and lesions.

Image of excised human vocal fold acquired with PSI's measuring endoscope system.

The metrology approach employed is essentially a hybrid of two well-known techniques: optical triangulation and structured lighting. The sizing system itself has three basic parts: an auxiliary fiberoptic-based laser illumination channel, an endoscopic imaging device equipped with a video camera, and dedicated video image analysis software. The auxiliary fiberoptic illumination channel serves to project a known, recognizable pattern of distinctly colored fiducial reference rays into the imaging system's field of view. The video analysis software then uses the viewed location of those rays intersecting the object to calculate the object range. Range information, in addition to the angular information normally available with conventional videoendoscopy, allows the absolute determination of lateral dimensions and absolute object coordinates.

Rapid Screening of Donated Blood

Lab prototype reflectometer for raid, routine bacterial screening of blood products

Transfusion-transmitted sepsis (TTS) is an established cause of morbidity and mortality in recipients of blood components. Despite this, no routine test exists for screening packed red blood cells (RBCs) for bacteria. While contaminated units are known to darken in color due to bacterially-induced hemolysis and deoxygenation, this visual color change is not detectable until late in storage, is difficult to recognize, and has a high false-positive rate. In response to this problem, PSI researchers, under NIH support, have developed a spectral scanning method that can identify the bacterially- induced color change. Studies to date have demon-strated the ability of PSI's technique to consistently detect the presence of dangerous levels of Yersinia enterocolitica, Serratia liquefaciens, and Pseudomonas fluorescens contamination in RBC's. This method provides quantifiable, non-invasive testing criteria that overcomes the shortcoming of subjective visual inspections, while greatly reducing false positive rates.

This research has been carried out in collaboration with the Dartmouth Hitchcock Medical Center and the University of Minnesota Department of Laboratory Medicine and Pathology.

Turning Goals Into Reality Award

TGIR Award Reipients L-R: Dave Green, Mike Hinds, Prakash Joshi, and George Caledonia.

Recently, several staff scientists received Turning Goals into Reality (TGIR) awards from the Jet Propulsion Laboratory for their contributions to the successful development and demonstration of the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) Ion Propulsion System on the New Millennium Deep Space 1 mission. The success of NSTAR/DS1 has made the capabilities of ion propulsion available for solar system exploration missions and has forever changed the way NASA performs these missions.

A publication of
Physical Sciences Inc.
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