Complex surgical interventions can be performed faster with fewer postoperative complications when surgeons use state-of-the-art navigation technology. Uptake has been limited, however, because of mechanical limitations and cost. New RFID-based navigation systems address those issues.
By: M. Böhme, amedo Smart Tracking Solutions GmbH, Bochum, Germany
Current navigation technology
Modern navigation technology has revolutionised how we get from point A to point B quickly and safely in airplanes, ships and cars. It also plays a considerable role precisely positioning instruments during minimally invasive computer-assisted surgical procedures. For complicated surgical interventions that involve the spinal cord or brain or organs such as the lung or liver that are in constant motion, surgical navigation systems provide the surgeon with a high level of safety and precision. The patient benefits from a gentler, faster and safer procedure and fewer postsurgical complications than would be possible using conventional techniques.
Currently, optical and electromagnetic systems typically are used to locate and position surgical instruments in real time. The position of the instrument is projected onto two- or three-dimensional maps of the body generated by computed tomography (CT) or magnetic resonance imaging (MRI) systems.
Optical systems, which have been in use for more than 15 years, rely on stereo cameras that use infrared light and reflectors attached to the surgical instruments to determine positioning. These systems are precise to within 1 mm. Their clinical use is limited, however, by the high cost of the disposable parts and the fact that the reflectors can only be mounted on rigid surgical instruments. Moreover, if people are in the camera’s light path or the reflectors are contaminated, navigation will be compromised.
Navigable electromagnetic instruments may be used in biopsies, for example. Tiny coils are built into the tip of the instrument to achieve exact positioning and navigation capabilities. These types of medical devices are expensive to manufacture, however, which is a considerable handicap in a cost-conscious healthcare market.
RFID technology achieves sub-millimetre positioning
A new technology uses a radiofrequency identification (RFID) transponder for precise positioning applications (Figure 1). RFID is commonly used to tag inventory in the apparel industry, to identify animals or to verify the authenticity of drugs or banknotes, but this is the first time the technology has been used in an application of this type.
The measurement method is very simple. The RFID transponder, which has a rewritable memory, consists of a millimetre-sized microchip and wafer-thin antenna. A reader generates an alternating electromagnetic field, usually in the shortwave (13.56 MHz) or UH (865–869 MHz) frequency, activates the RFID transponder and receives the requested information via frequency modulation. As with identification scanning technology, the position of the RFID transponder is determined by an alternating electromagnetic field in the UHF range and is projected on a three-dimensional map for accurate navigation. In addition, information may also be read out from the existing RFID memory. This technology enables, for the first time, three-dimensional localisation of an RFID transponder at millimetre-scale precision.
This innovative technology is expected to expand the use of medical navigation. Initial clinical trails at the Grönemeyer Institute for Microtherapy in Bochum, Germany, using CT and MRI images have been successful. RFID transponders are inexpensive to manufacture and they can be easily embedded in rigid or flexible surgical instruments.
The future of RFID tracking technology
This new RFID technology overcomes the limitations of existing surgical navigation systems. It offers precision at a cost that is attractive to healthcare purchasers grappling with budget constraints. Surgical procedures using navigation technology achieve better outcomes with fewer complications resulting in lower overall treatment costs. The new RFID technology is feasible not only for surgical interventions but also for therapeutic or patient management applications. The first commercial applications of this technology are being finalised and will be in clinical use soon. Automated automobile production and analytical laboratories, where millimetre-precise positioning is critical, also show great promise.
Marc Böhme, PhD, is CEO
at amedo Smart Tracking Solutions GmbH, Universitätsstr. 142 D-44799 Bochum, Germany
tel. +49 2347 7728 627
This article first appeared in German in the October 2010 issue of >>inno<< magazine, which is published three times a year by IVAM.
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