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Light Source Enables Endoscope Miniaturization

This work will explore an illumination system's potential to miniaturize traditional endoscopes by shrinking the size of the channel used to deliver light.

Physical space constraints continue to impact advanced procedures such as single-incision laparoscopic surgery, robotic-assisted surgery, and other minimally invasive surgical procedures. Additional functionality and instruments are being squeezed through the smallest incisions possible. Available space continues to tighten with the migration of larger diameter, three-dimensional, high-definition endoscopic imaging systems into minimally invasive procedures. Fortunately, a significant portion of the endoscope, the light delivery channel, can be reduced in size, thereby allowing the space to be used for other purposes, or for shrinking the endoscope itself.1

altEndoscopic illumination most often consists of a single 3–5 millimeter diameter bundle containing thousands of very small individual fibers. The fiber optic bundle is integrated with the endoscope to channel light to the point of use.

Alternatively, when fiber bundles are too large for the space — for example within a human heart, lung, or eye — an individual fiber of sub-millimeter diameter may be used. The smaller-size light channel enables surgery that could never occur using a light channel that was 50 times larger. Further more, minimal patient disruptions from a sub-millimeter light channel could contribute to shorter healing periods and/or a decreased risk of infection.

altA new approach has been developed to couple radiation from a variety of sources into individual sub-millimeter diameter optical fibers or fiber bundles for medical and industrial applications.

This patent-pending technology allows the integration and mixing of multiple sources into an optical fiber to provide light for general illumination, fluorescence imaging, spectroscopy, laser ablation, and/or photodynamic therapy for medical applications (see Fig. 1).

The Hyperion™ 300 is designed to decrease the size of the latest generation of endoscopes by shrinking the size of the channel used to deliver light. Figure 2 is an image of an artificial knee taken using a three-sensor, high-resolution color camera in conjunction with an arthroscopic endoscope and a Hyperion 300 small fiber light source delivering light through a single sub-millimeter fiber. The image is a frame grab from the video produced during the experiment. The setup demonstrates the deep cavity illumination capability of the light source.

altFigure 3 is a photograph of a cross-section of a traditional endoscope tip showing the imaging area, light-emitting area, and protective exterior wall. The area dedicated to light delivery is 64 percent of the imaging area. Thirty-three percent of the total space is consumed by the lighting function. Shown at scale is the amount of space required for the Hyperion to deliver suitable illumination. The Hyperion light source consumes only 0.43–3% of the endoscope area, depending on implementation (see Table 1). Switching to an endoscope optimized for use with the Hyperion source saves up to 6.5 mm2, enough space for an instrument channel.

There is a continuous drive to reduce the size of imaging systems for medical applications. Micro-endoscopes permit the exploration of smaller cavities and reduce the impact on living organisms. Radiometric measurements of the Hyperion light source showed performance up to 60 times better than other systems. Performance exceeded expectations, especially when using smaller-diameter fibers, making it a particularly interesting candidate for minimally invasive surgical applications, fluorescence imaging, and spectroscopy.

altThis technology was done by Nathaniel Group, Vergennes, VT. For more information, visit http://info.hotims.com/40433-182.

Reference
1. Hermanowski, J., “High Intensity
Illumination from Small Fibers for In-Vivo
Medical Lighting”, www.nathaniel.com,
August 2011.