OR technology: developing more flexibility and usability

Interview with Prof. Erwin Keeve, Berliner Zentrum für Mechatronische Medizintechnik BZMM (Berlin Center for Mechatronic Medical Technology) at Charité Berlin

Gentle, safe, precise, fast – surgical interventions need to meet many demands: laws and regulations concerning safety, the desire for the best possible health outcome, economic requirements of hospitals and ever-changing technology make up today’s framework for surgery.


Photo: Prof. Erwin Keeve

Prof. Erwin Keeve; ©private

As a consequence, operating theaters and the way they are equipped change, too.

At MEDICA.de, Prof. Erwin Keeve from the Berliner Zentrum für Mechatronische Medizintechnik BZMM (Berlin Center for Mechatronic Medical Technology) at Charité Berlin talks about the new intraoperative 3D scanner ORBIT, navigation of surgical devices and the ORs of the future from an engineer’s point of view.

Prof. Keeve, what role does intraoperative imaging play at the moment?

Erwin Keeve: Large investments are being made and high technological goals tackled to realize intraoperative imaging. Certain interventions can actually not be performed at all without this technology, for instance inserting a stent or implants in the spinal area. You need it for all interventions where the surgeon needs to know exactly where the instruments and implants are located.

You developed ORBIT, an intraoperative 3D scanner at the BZMM. How does it work?

Keeve: Conventional imaging systems either take 2D images or only move on one level in a circular path around the patient when they take 3D images. In doing so, they encircle the patient as a closed system. This also means that the device is obstructing access to the patient. We have resolved this constraint with ORBIT. Its X-ray source and image detector are each mounted on a robotic arm and rotate around the patient in any angled trajectory.

This way, we are able to ensure access to the patient at any time on the one hand, while also improving image quality on the other.
Photo: X-ray scanner ORBIT ist tested with a phantom body

ORBIT's X-ray source and image detector are each mounted on a robotic arm and rotate around the patient in any angled trajectory; ©BZMM

How did existing technologies need to be further developed to realize this system?

Keeve: 3D reconstruction played a central part in this. At first, individual images are being taken in 2D for 3D imaging. ORBIT handles this the same way as those systems that orbit in circular motion around the patient. However, image reconstruction for an arbitrary trajectory around the patient is more complex than in a circular path. Until a few short years ago, the required calculations could not be performed in a short amount of time. In this instance, an in-house development was able to assist us in this area. What is more, computer capacity today is so large that picture and reconstruction process nearly run down at the same speed.

Navigating the surgical device in the body is very crucial for endoscopic interventions. How does it work?

Keeve: There are two options: either optical or electromagnetic navigation. With optical navigation the endoscope shaft, which is always on the outside of the body, has attached locators that are captured via camera systems. Usually two cameras allow a stereoscopic view. Using this and through the geometry of the instrument, the position of the tip of the instrument inside the body can be calculated.

With electromagnetic navigation, a relatively homogeneous electromagnetic field is generated on the patient. A small reel at the tip of the device causes changes in field intensity, which provides clues on the tip’s position.

And how is the instrument located in relation to the patient with these technologies?

Keeve: Graphic recording is in charge of this. Of course, it is not enough to only record the instrument position. The position of the patient also needs to be captured and both positions need to be congruent.

Just like with navigational systems in the car, you need a signal on the one hand and a map on the other. The signal comes from the instrument, while we utilize CT data as a map. Both datasets are brought together by measuring distinctive points of patient anatomy and aligning them with the CT data, for instance the tip of the nose, point of the chin or ear canal.
Photo: Modern OR at Charité

The equipment in future ORs does not stand in the way of the surgery's success: technologies are more flexible, have more usability and do not hinder surgeons; ©BZMM

Your Institute develops endoscopic and navigation technologies. What innovations are there in this field?

Keeve: On the one hand, there is a technology marketed by the Scopis Company, which is a spin-off of our Institute. It combines both types of navigation, optical and electromagnetic. In addition, it uses a technology that measures the distance from the endoscope to the tissue. Corresponding centimeter data is being displayed in the endoscopic image. In doing so, instruments can be more safely navigated to the destination.

Secondly, for the Trumpf Medizinsysteme GmbH we are evaluating a voice-controlled endoscope holder that can be mounted to the operating table. Voice control enables the surgeon to move the endoscope by himself, so he does not depend on the help of an assistant, who might possibly translate instructions differently from what the surgeon intended. What is more, compared to human beings, the holding device operates without shaking.

What direction will computer-assisted surgery take in the future?

Keeve: As engineers in medical technology, the usability of the equipment demands a lot of our attention. It is not easy for a physician to master all high tech equipment in today’s operating rooms. The endoscopy holder is a good example of a solution: the surgeon can achieve something with simple speech input for which he or she otherwise needs the help of another person. This person in turn requires space in the operating room, which could be used for other things. Voice-controlled mechanics therefore saves room next to the patient and reduces processes in the operating room.

Overall, we need to develop technologies in the operating room to operate better and not stand in the way of a surgery’s success.

Photo: Timo Roth; Copyright: B. Frommann

© B. Frommann

The interview was conducted by Timo Roth and translated from German by Elena O'Meara.