A medical robot can guide a flexible needle through the lungs of living pigs without direct human control. Over several additional tests on lungs removed from the pigs, the robot placed the needle more precisely than human doctors using a standard straight-needle procedure.
鈥淭here are many procedures, including biopsy or directed drug delivery or localised radiation cancer treatment, that involve using a needle to get to a specific target to perform the procedure where you鈥檙e manoeuvring that needle inside tissue,鈥� says at the University of North Carolina at Chapel Hill. 鈥淢any of these procedures could benefit from an autonomous steerable needle that is highly accurate.鈥�
A typical lung biopsy requires physicians to either guide straight needles down a person鈥檚 throat and a little way into a lung through a bronchoscope, or else use the needle to penetrate the chest between the ribs to reach a lung. But Alterovitz and his team designed an experimental flexible needle controlled by a robot that could enable safer and more accurate medical procedures.
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Before the robot was put to work, a human identified a target in the lungs of living pigs 鈥� in a person, it might be a potentially cancerous lump 鈥� based on 3D X-rays. Then, computer software mapped the best possible path for a needle to travel through lung tissue and enter a tumour.
Alterovitz and his colleagues developed algorithms that direct the robotic steering of the flexible needle around the maze of airways and avoid any obstacles in the lung鈥檚 dense network of blood vessels. The robot automatically started and stopped moving the needle during windows of opportunity created by a ventilator that filled a pig鈥檚 lungs and held them in an inflated position for 10 seconds at a time. It can also re-plan its route to the target and correct for deviations from its planned path if any uncertainties arise during the operation.
This robotic operation was performed three times on two living pigs with the needle tip ending up between 1.8 millimetres and 3.4 millimetres from the final target. Separate tests involving pig lungs already removed from the body showed that the autonomous, flexible needle provided accurate placement with targeting errors of just 3.4 millimetres on average 鈥� far more precise than the traditional bronchoscopy method involving straight, inflexible needles performed by two human physicians, which had targeting errors of about 14.7 millimetres on average.
鈥淭his is a proof of concept that an autonomous steerable needle has the potential to outperform instruments that are controlled by a human,鈥� says Alterovitz.
Such a surgical robot must still prove that it can deliver results consistently and reliably over many more trials, says at the University of Texas at Austin. But he described the study as 鈥渢he very beginning of very good results toward hopefully having a company doing this autonomously鈥�.
鈥淲ith a robot, you can go to the places that surgeons cannot go, because these devices are repeatable, reliable and they can access the points that normally surgeons cannot,鈥� says Alambeigi.
In the future, the researchers hope to test this robotic operation in a human cadaver, followed by human clinical trials.
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