The evolution towards minimally invasive surgery has a significant impact on the way surgeons operate. In open surgery, a surgeon’s eyes and hands are his or her main assets. In minimally invasive surgery, the camera – and obviously the medical displays – become the eyes of the surgeon and surgical staff. It means that the quality of the images needs to be impeccable and 100% reliable at all times.
In this article, I’ll discuss which video quality specs you need to consider to ensure precise procedures. These specs not only apply to surgical displays. They also apply to the video integration system that connects all operating room equipment. The one can’t function without the other…
1. Display resolution
10 years ago HD was the dominant resolution, now we have 4K, and 8K is on the verge. The general trend is that newer applications use higher resolutions. The benefits of 4K in surgical imaging are enormous. They result in increased depth perception and better hand-eye coordination for surgeons.New 4K technology is impressive.
However, it’s important to understand that there are often legacy imaging systems in the operating room. Applications for the OR have a long lifetime so you need to make sure that the video quality of every device, both new and existing, is used at its best. This requires a good video integration system that supports a wide range of video interfaces and resolutions.
2. Scaling and aspect ratio
A system that requires a lot of scalers and conversion boxes is an absolute no-go in the operating room. They scale video content multiple times before it is shown on the display. By doing so, the quality of the image is reduced. Ideally, the resolution of the image source is identical to the resolution of the display and the video is not scaled. If you can’t avoid scaling, make sure the aspect ratio is preserved, by adding black borders around the image.
There are two scanning methods to create a picture on the screen: interlaced and progressive. The interlaced scanning method first transmits the odd pixel lines and then the even pixel lines. Interlaced scanning is common on analog video interfaces such as VGA, Composite and S-Video. It is rarely used in digital video interfaces, except for the SDI standard.
When presented on a digital display, all interlaced video will be converted to progressive video before it is shown. This means that the image will be created by scanning pixel rows in a sequential order. The process of converting interlaced video to progressive video is called deinterlacing. There are different ways to do this: via weaving, blending, etc. You can read more about this in our white paper .
If you’re looking for the best video quality in the operating room, then first of all, interlaced sources must be allowed on all video inputs. Secondly, deinterlacing of video should be done via the weaving method. It is the only method that guarantees low latency and that maintains the image quality of the source.
Framerate refers to how many images are shown per second. Surgical images, and especially images at UHD and 4K resolution, should always be shown at a framerate of 50 or 60 frames per second. So make sure your video integration system and surgical monitors can support this. In addition, using a higher framerate results in shorter latency and can reduce eye-fatigue for the surgeon.
5. Chroma subsampling
Chroma subsampling is a technique of encoding images with less color but with the same luminance. It is a widely used technique to reduce bandwidth. Chroma subsampling works fine for consumer applications. However, due to the loss of color in the image, this technique is not recommended for the OR. Color accuracy is indispensable in the operating room.
That’s why you need to look for the best color reproduction methods. The 4:4:4 indication means that no chroma subsampling or compression has been done. All color information has been preserved. This is of vital importance to surgeons.