Inventions in one sector not infrequently find their application in an entirely different sector. For instance, years ago at the NASA - A Human Adventure exhibition in the Dutch gallery, we saw a presentation by Demcon. A company that has a so-called 'mechatronic conscience', with multidisciplinary ambitions and as focus areas high-tech, industrial systems & vision, embedded, optomechatronic and medical systems. What we saw at the time, an aerospace development that found hugely valuable application in healthcare, made our ears prick up when we heard of their new project. A special needle positioning system. Oh, CT-compatible please.
A needle positioning system for treating liver cancer. What else is special about it? 'Staying as close as possible to the current workflow and within it automating the step most critical to the result.' In doing so, the system architecture, based on the current medical workflow, had to literally and figuratively create as few barriers as possible to physician use. A second challenge was the form factor. The system is intended for use ín the CT scanner. So it has to fit into the tight space between the patient and the ring of the CT scanner. But the biggest challenge was CT compatibility. The system largely enters the scanner's X-ray field, but must not interfere with imaging. This immediately ruled out common materials such as steel, copper and titanium.
No more than necessary
In the most common treatment of liver cancer, the tumour is surgically removed. Because of the complicated procedure, it is necessary to remove healthy liver tissue as well. An undesirable side effect. An alternative treatment method is to use radio or microwave radiation to 'burn away' the tumour. The doctor manually inserts a needle from the outside into the tumour, with imaging from a CT scanner helping to determine its exact location.
No major surgery is required and as little healthy liver tissue as possible is removed or damaged. The other side of the coin: it is very difficult for the doctor to position the needle correctly directly in the tumour. In practice, this means that the doctor inserts the needle, takes a CT scan and can then assess whether the position is correct or not. This process often repeats itself several times, until the correct position is achieved. A time-consuming procedure and burdensome for the patient.
Research project
Various solutions that had been thought up by other parties before had not yet led to the solution. They proved awkward to use, or not functional enough. Demcon took part in a European research project with partners such as Philips and Elekta and saw opportunities within this project to develop a system that places the needle in the right position and in the right way in one go, while also fitting in with the doctor's existing working procedures. A patient- and doctor-friendly solution. To develop it, Demcon worked closely with specialists from the University Medical Centre Groningen and the Erasmus MC in Rotterdam.
'First time right'
'Staying as close as possible to the current workflow and, within it, automating the step most critical to the result.' So that was the main premise. 'First time right' was decisive. That most critical step is determining the angle at which the needle enters the body. The result is a system consisting of a head with needle guidance mechanism that can be manually positioned around the patient, and an arm that fixes the head in relation to the patient table at the push of a button. After the system is fixed, system and patient are brought into the CT scanner together. The position of the tumour relative to the head is determined and the system automatically directs the needle guidance mechanism in the required direction. The needle is then clamped into the guidance mechanism and inserted into the body by the doctor himself.
Materials
CT compatibility meant that for several parts of the system, conventional materials immediately dropped out. For rigid structural parts and suspension elements, composites were used. Ceramics were used for high-loaded precision parts and ball bearings. Carbon nanotubes were used for power wires and switches and plastic optical fibres ensured that encoder positions could be read remotely. For this, Demcon worked with suppliers such as Ceratec and Futura Composites.
The result? A system that ensures correct and precise needle guidance, with a margin of less than 2 mm at a depth of 25 cm. That ensures minimal tissue damage to the patient, and a much shorter procedure time for the medical team. That in turn means a cheaper procedure that is also less stressful for the patient. Win-win-win.
By: Janet Kooren
Photos: Demcon
Source: Demcon
