Video Endoscopy SystemEVIS LUCERA ELITEImproved patient comfort, greater operational efficiency for doctors

Founded in 1919 as a manufacturer of microscopes, Olympus has taken the precision machining and assembly technologies it has honed in the field of microscopy and applied them to the manufacture of medical endoscopes. The company now has an approximate 70% share of the global market for gastrointestinal endoscopes (based on its own market research), and has recently developed a new system called the EVIS LUCERA ELITE*. Designed to deliver even greater imaging performance and to be easier to use for doctors performing colonoscopies, the EVIS LUCERA ELITE features many new and innovative technologies.

* Disclaimer:
Available in Japan, U.K. and parts of the near and Middle East, Africa and Asia Pacific upon product registration or market clearance in each country's jurisdiction.

Information of this article is based on the facts as of February 28, 2013.

Hidenobu Kimura

General Manager
Endoscope Department, R&D Division 1 Olympus Medical Systems Corp.

After graduating with a degree in mechanical engineering, Mr. Kimura joined the company with a desire to develop industrial endoscopes. His work included the development of fiber-optic scopes for industrial endoscopes, and beginning in his second year he worked on medical endoscopes. Since then, he has been involved primarily in the development of endoscopic videoscope systems for overseas markets.

The three key concepts behind our development of endoscopic videoscope systems are: (1) easier operation, (2) high resolution video imaging, and (3) enhanced reliability. Achieving these goals has required completely new ideas and thorough, steady testing.


Components and functions of video endoscope system
1: connector, 2: bending section, 3: distal end, 4: insertion section(shaft), 5: control section


Components and functions of video endoscope system
1: LCD monitor
2: Image management hub and other accessories
3: Video system center: The viedo processor converts electrical signals from the scope into video signals and displays them on the monitor.
4: Light source: The light source uses a xenon lamp to produce light similar to natural light, which is transmitted to the scope's distal end, and also incorporates a pump for supplying water and air to the scope.

Bends naturally upon contact with colon wall

Our initial focus was on improving ease of use. While most people would think of endoscopic examinations as being painful and stressful, the narrower and more flexible insertion sections of modern endoscopes combined with a variety of structural innovations mean that an increasing number of patients find the procedure to be relatively comfortable.

Nevertheless, endoscopy is not always completely pain-free. When a colonoscope is used for an endoscopic examination or treatment of the colon, for example, the doctor inserts the distal end of the scope into the patient's anus and uses the controls on the endoscope unit to manipulate it into the colon. However, the twisted path taken by the colon includes bends of more than 90 degrees. When the scope's bending section hits the colon wall in such locations, the patient may feel a dull ache similar to that experienced with an upset stomach.


Functional imagery of passive bending

While skilled doctors can successfully maneuver the scope through such bends, we have searched to find ways to make the instrument easier to use for a wider range of doctors. The solution we have adopted is to incorporate a passive bending section into the colonoscope behind the main bending section. This forms a special mechanism that works in tandem with the main bending section, whereby the passive bending section bends automatically in response to the force of the main bending section coming into contact with the colon wall. The result is to redirect the force exerted against the colon wall so that it instead causes the endoscope's distal end to advance further along the colon.

Flexible shaft transmits force easily

Another innovation in our colonoscope is the "high force transmission function," in the scope's shaft (insertion section). While we want the shaft to be flexible so that it can make progress along the complex, winding path taken by the colon, the problem with this is that the force exerted by the doctor for pushing and twisting can get transmitted to the colon instead, thereby obstructing the forward progress of the colonoscope.

Functional imagery of high force transmission

A cross-section of the shaft shows how it is divided into three layers. As each layer is made of a different material, bending and twisting of the shaft causes these to rub against each other so that some of the force applied to the shaft is lost. Loss also occurs in the transmission of force to the scope. The engineers working on the development of the colonoscope came up with the surprising suggestion that eliminating the interference between the layers to achieve smoother movement might also facilitate the transmission of force to the distal end of the colonoscope. Despite the realization that putting this into practice would demand a complete rethink of production processes that had been built up over many years, they decided that was no reason not to try and, accordingly, they went to work with the manufacturing department to find ways of implementing the idea.

Of course, we couldn't conduct testing on patients during the research stage. So, to obtain objective data for comparison, we built a model using tubing similar to the drainage hose from a washing machine instead, and conducted countless tests with force measurement sensors attached. Through trial and error we ultimately came up with both; a shaft that was flexible and capable of transmitting force in the desired way, and also a manufacturing process for its production.

NBI for enhancing the visualization of the capillary network and mucosal morphology.

There was another opportunity for improving the ease-of-use of endoscopic video systems, particularly in relation to the imaging technology called narrow band imaging (NBI) that was first developed by Olympus and commercialized in 2006. Conventionally, examining for lesions with an endoscope is performed using white light made up of the three primary colors: red, green, and blue (RGB). In contrast, NBI excludes red and uses blue and green only.


NBI
1: Green light: Strongly absorbed by hemoglobin in blood vessels deeper in the tissue, and not reflected.
2: Green light: Strongly reflected by the tissue beneath the mucous membrane.
3: Blue light: Strongly absorbed by hemoglobin in capillaries near the tissue surface, and not reflected.
4: Blue light: Strongly reflected by the mucosal surface layer.
5: Monitor screen in NBI mode: A well-resolved image is produced by utilizing both reflected and non-reflected light.
6: Capillary in mucosal surface layer
7: Larger blood vessel in tissue below mucous membrane

The feedback we have received since we began introducing endoscopes that incorporate this technology has been positive. As NBI restricts itself to a narrow band of light (comprising two wavelengths only), it is no surprise that this lower light level produces images that are darker than those acquired using white light. Nevertheless, if doctors find NBI difficult to use in practice, it is our responsibility as the manufacturer to correct this concern.

Brighter NBI

We solved this problem in two different ways. One was to improve the light source itself. To provide illumination for endoscopic examinations, the videoscope system uses glass fiber to transmit light from a built-in light source (xenon lamp) to the distal end of the endoscope. To improve the operation, we modified the system to detect when a doctor switches from white light to NBI while examining a lesion and to increase the brightness of the lamp in the light source accordingly. Through improvements to the mechanical accuracy of the system's lenses and mirrors, we also made the light more concentrated, without lamp light leaking from the glass fiber inside the endoscope.


G: Green, B: Blue
left: Rotating filter used in EVIS LUCERA SPECTRUM
right: Filtering in EVIS LUCERA ELITE

The second improvement was a comprehensive revision of the filter design. Under normal lighting conditions, rotating red, green, and blue filters inside the light source provide alternating flashes of red, green, and blue light. For NBI imaging, in contrast, the light passes first through an NBI filter to produce green and blue light before passing through the rotating filters. Because the red component of the light has already been largely removed, no illumination results during the period when the red filter is in place.

NBI image from EVIS LUCERA SPECTRUM

NBI image from EVIS LUCERA ELITE

Recognizing how wasteful this was, one of our engineers kept wondering whether there might be a way to increase the number of light flashes by inserting a blue filter into the timing normally occupied by the red filter. The result was a new rotating filter specifically designed for the EVIS LUCERA ELITE. The new filter incorporates a mechanism for replacing the red filter with a blue one when the system switches to NBI. This innovation increases the level of illumination by having the rotating filter deliver three flashes of light per rotation rather than just two as in the past.

One-touch operation switches focus to near-field imaging

Moving on to the question of how we achieved high-resolution imaging, the biggest challenge we faced was the incorporation of a dual-focus mechanism. With a conventional endoscope, when a doctor whom has identified a lesion during an endoscopic examination attempts to move closer to get a better view, there is a point beyond which focus is lost and the image becomes blurred. This is because there is a limit to how close the endoscope can get while maintaining focus. In the case of special magnifying endoscopes, meanwhile, the range of distances at which focus can be maintained becomes very narrow when magnification is used. Accordingly, to use an endoscope in this situation, the doctor needs to nudge the distal end of the scope forward or backward to adjust the focus while operating the magnification control at the same time. Great skill is required to make the rapid adjustments needed to operate the remotely located end of the scope in this way.


Functional imagery of dual-focus mechanism

To deal with this problem, we developed a dual-focus mechanism that can switch between two different focus settings: normal and near-field (magnified) modes. This ability to achieve focus at the single press of a switch allows high-resolution images to be obtained with ease, even during close-up viewing of subjects such as mucous membranes or capillaries.

This mechanism posed the most technically difficult challenge during product development. In simple terms, the dual-focus mechanism itself required nothing more than moving one of a number of lenses into position, each lens being roughly 2 mm in diameter. However, because the distance to be moved was a mere 0.5 mm, the width of a single hair, this required a precise mechanism capable of operating an actuator over such a short range. Also, in order to avoid stressing the doctor, the mechanism needed to be able to make focus adjustments instantaneously. It required precise and rapid operation regardless of the shape into which the shaft was bent during an examination to follow the position of the patient. To ensure consistent quality, we devoted considerable effort to pinpointing the exact design requirements, undertaking numerous investigations based on a wide range of different scenarios.

Improving work efficiency and enhancing reliability


One-touch connector

Finally, we took on the challenge of improving reliability. By simplifying operation for the physicians, surgeons and reprocessing staff that work in situations where endoscopy is used, our aim has been to enhance reliability by preventing breakdowns caused by handling errors.

For the new system, we re-designed the shape of the connector used to connect the scope to the system's other devices. This eliminated the step of connecting the scope to the cable, providing a reliable one-touch connection between the scope and the light source and video system center.

We also made the connector completely waterproof so that the entire scope can be immersed in disinfectant when washing and disinfecting after use. Previous models required a water resistant cap to be placed over part of the scope each time it was washed. Waterproofing the connector not only completely eliminates damage to the endoscope caused by forgetting to attach the water resistant cap, it also made the scope easier to use.

Expanding the scope of qualitative diagnosis

While use of magnifying endoscopes for early diagnosis is becoming more widespread, feedback indicates that only those doctors with a high degree of skill in the use of endoscopes are able to utilize this equipment to its full extent.

With its enhanced ease-of-use and reliability, we believe that the new EVIS LUCERA ELITE will be able to be used with confidence even by less experienced doctors who have lacked the expertise to use previous models. It is our hope that this will lead to further improvements in the in the way physicians diagnose their patients.