Silence as strength: Magnetic bearings for computed tomography

_{^{22.09.2020 I Güllü Beydilli}}

Computed tomography today generate background noise that many patients find very unpleasant. A new magnetic bearing from thyssenkrupp is providing relief: an X-Ray camera can move on it almost in silence.

The examination starts. ”Please lie as still as possible.” The radiographer closes the door and the patient is alone. Accompanied by whirring and humming sounds, the examination table moves millimeter by milli meter through a tunnel, around which the X-ray camera rotates. Although computed tomography (CT) involves absolutely no contact with the patient, many find the examination stressful. While they are alone and surrounded by technology, seconds seem an eternity. It is hard to hold still, and the whirring and humming eat at their nerves – which are already on edge if they are afraid of the impending diagnosis.

Silence as a competitive advantage

“CT manufacturers are very interested in bringing scanners that are as quiet as possible onto the market. Lower noise is a measurable quality criterion that can be experienced by the patient,” explains Bernd Lüneburg, group leader for research and development at thyssenkrupp rothe erde. The same applies for speed: The faster a camera rotates, the more it reduces the length of the examination. Additionally, speed reduces the amount of exposure to radiation and as well as the costs.

“The magnetic bearing technology as a “digital bearing solution” opens up extensive possibilities, both for CT development and for the operation and service of CT scanners,” says Lüneburg. Thanks to the controllability of the bearing forces, for example, the camera can be precisely positioned. Further advantages lie in a possible integration of the drive unit and use of the sensor information for servicing the systems.

This is why Lüneburg’s team at thyssenkrupp is developing the “digital bearing solution” for the CT scanners of the future. The prototype is rotating on the wall of the test building in Lippstadt. There is no whirring or humming. The rotor weighing almost 300 kilo – grams moves silently round an inner ring the size of a CT tunnel. The “silent bearing” is stabilized by the invisible force of dozens of electromagnets.

Computed tomography: magnetic bearings beats rolling-contact bearings

The magnetic bearing in Lippstadt is currently one of the biggest and most powerful in the world. It is set to open up new possibilities for the makers of computed tomography equipment. Up to now, equipment manufacturers have been dependent on large-diameter rolling-contact bearings. In these huge bearings, balls or rollers reduce the friction when the stationary and rotating rings move against each other. In CT scanners, for example, the bearings en – sure that a heavy X-ray camera attached to the rotating ring circles at high speed round the patient and can perform the X-ray examination on them. On the opposite side of the ring, detectors capture the X-rays that have not been absorbed by the patient’s tissue or bones. On the basis of these signals, the computer generates three-dimensional cross-sectional images, with the help of which the radiologist can diagnose bone fractures, joint disease, or tumor-like changes to the organs.