Video images in the OR may come from several sources: the endoscope camera, a surgical field camera mounted in the handle of the surgical lamp, and other digital images stored on digital media (CD, DVD) or an outside source. In the past, the signal could have been analog along its path from camera to monitor, requiring analog-to-digital conversion along the way, possibly degrading image resolution.

Over the past decade, the camera systems have become more digital, using direct digital-information transfer and signal processing all the way from the camera's chip (or chips) to the video display and recording devices. They've become smaller and more reliable. Color and spatial resolution have significantly improved, and manufacturers are now beginning to introduce surgical video in high-definition television (HDTV) format.

All these improvements make choosing an image processing system more complicated; thankfully, video processors for rigid and flexible endoscopes have similar features. Here's what you need to know about the variety of features available across the general category of video processors.

Mapping image systems
Image processors have controls similar to your television - there are adjustments for color, tint, brightness and contrast. Setting these various levels lets the surgeon select the best combination for the anatomy being viewed. The better your image-processing equipment, the better your control over enhancement done by the processor.

The video camera is the first link in the image-processing chain; think of it as an eyeball. The chip (or chips) in the camera is the retina, and the camera head and lens are the rest of this electronic eyeball. It is the camera-control unit and secondary image processing that are the brains of this vision system. These brains that see and interpret the video image are what we will consider.

First, we need to address brains that do not think. These are the basic camera-control units that don't offer image enhancement beyond the usual color-television adjustments. They get the image from the camera to the screen and offer outputs to send the signal elsewhere, say to a printer or video-switching system.

Brains that do think, as it were, to one degree or another, are the advanced video processors. Features with these thinkers:

• keyboard entry of patient information,
• voice-activated controls,
• freeze frame or shutter mode to allow capture of close-up images without camera movement,
• digital zoom,
• reorientation of the image on the screen,
• automatic control of the scope's light source,
• color-optimization controls,
• procedure-specific presets,
• image-enhancement levels and
• the ability to be upgraded by software additions.

Proprietary features vary by manufacturer. Typical features offered on scopes and processors working as a system include ability for the surgeon to control image brightness and print images via switches on the camera head. Linvatec's IM3300 and Richard Wolf's Endocam 5516, for example, both have settings for color correction, illumination and contrast enhancement. One other technology that enhances images is fully digital transfer - systems on which there is no analog component, such as with Karl Storz's Image 1 and Stryker's 1088 HD.

How you benefit
Enhanced images are not the only benefits of these new systems; better risk management and documentation can also be realized.

The Olympus CV-160 flexible endoscopic processor receives and displays data from a chip in the compatible Olympus EVIS Extra 160 scopes, telling the scope's model name, serial number and the number of times it has been connected to the CV-160. This should help you in tracking the endoscope's usage history for purposes in infection control and routine maintenance.

Digital-signal processing is a method of image enhancement through which the camera chip picks up and transmits the raw data. From there, it is sorted, sifted and arranged to provide a more accurate signal to be displayed on the surgeon's monitor. This digital-signal enhancement mostly occurs in the camera-control unit, although Fujinon now has a line of high-resolution flexible endoscopes, the S400 Series, that features digital-signal processing in both the endoscope and the processing platform. These Fuji scopes come in either 410,000-pixel or 850,000-pixel resolution. The S400 Series platform will soon be able to support megapixel (more than 1 million pixels) formats, says Fujinon.

The continued improvements in lens optics, video chips and image processing are pushing manufacturers to develop new tools for virtual biopsy or video biopsy of tissues, which allows for cellular-level direct visualization of suspect tissues. Pentax is one of the companies working toward that goal and says its EPK1000 flexible endoscope processor will support these high-resolution images. Software tools are also being developed around this emerging microscopic video application.

Another feature found in some image processors include picture-in-picture capabilities. This feature can display a previously captured image from the scope or from an outside source such as an ultrasound, CT or MRI. This feature requires the use of an outboard source, usually a PC, to pre-process the image for display through the endoscopic image processor. For example, Smith & Nephew's 640 Image Management System is compatible with Windows 2000 and Arthrex's C3 program with Olympus's Visera allows capture and storage of images on SmartMedia cards.

How to choose
When evaluating image processors for your facility, you should consider the following:

• What range of specialties will use the video system? Video systems are used by virtually all surgical specialties in an ASC, but especially orthopedists (arthroscopy), general surgeons and gynecologists (laparoscopy), and otorhionlaryngologists (ENT endoscopic sinus surgery). These surgeons use rigid endoscopes. Flexible endoscopic video systems are used by gastroenterologists and general surgeons (colonoscopy, gastroscopy) and pulmonologists or chest surgeons (bronchoscopy.)
• What is the acceptable camera resolution? What is acceptable is totally dependent on the surgeon, so you'll have to arrange for him to trial the equipment before you buy it. In my experience, if he is paying out of his own pocket for the video system, his tolerance for lower image quality will amazingly increase.
• Are specialty-specific presets desired? This is a feature found on rigid endoscope video processors; you can set the color, tint, brightness and contrast to levels that will enhance visualization of the anatomy. Presets are typically available for laparoscopy, arthroscopy, cystoscopy and sinuscopy.
• How are digital images currently stored? Images can be stored in any number of media formats available today: There's PC, CD-ROM, DVD-ROM, MiniDV, MiniDisc, Digital 8, SmartMedia card, Flash Media, magneto optical disk, or your computer's hard drive. Each company has its own approach, and most video processors will export the images to second-party storage devices.
• What are the future plans? If you want to use images in endoscopic or surgical reporting software and electronic medical records, you need to buy your image-processing equipment based on this. Usually, you'll want something that will let you incorporate the images into the actual digital patient chart or paste them into a post-procedure report in a system like EndoWorks.
• What outboard or accessory equipment will be needed? This depends on the desired outcome for documentation and display. For documentation, the outboard equipment could include color still-image printers, video cassette recorders, DVD recorders, or any number of still- or moving-image storage methods. For display, the equipment could be as simple as a single video monitor or as complex as a Stryker Switchpoint system that is networked to multiple input sources, multiple video displays and tied into the Internet.
• Is existing equipment compatible with the system being evaluated? Although they do not usually mention it, some flexible endoscope companies offer adapters to use their competitors' video scopes with their video processors. You do not necessarily have to scrap a scope collection to upgrade the video-processing capabilities. Rigid optical scopes, the kind you couple a camera head onto, do not know or care what video system is attached. Flexible optical scopes don't care, either. Remember for coupling cameras - video is video, although camera heads will vary by specialty.

Rigid video scopes, or chip-on-a-stick scopes, usually only work with their proprietary video processors. Some manufacturers' products are backward-compatible within their brand.

Remember what's important
There's little point in getting into the salesmen's rhetoric of "my three-chip camera is better than your single-chip camera," or "progressive-scan technology is the best" or "digital is the only way to go," because there's a broad range of great surgical and endoscopic camera systems that can capture your image. The surgical camera systems available in the U.S. market are generally high quality and are offered at many price points, depending on configuration and level of image quality. You'll be happiest with your equipment if you focus instead on the image processing system's compatibility with your current equipment, specialties and future plans.