The first medical robot designed to operate on the brain has begun clinical trials at Queen鈥檚 Medical Centre in Nottingham, UK. The robot could be used to take biopsies of brain tumours or implant electrodes to control Parkinson鈥檚 disease, say its developers.
The robot, called PathFinder, will not be able to do operations that are not already possible, but it could do them much faster and more accurately, says Patrick Finlay of Armstrong Healthcare in High Wycombe, Buckinghamshire.
鈥淎ll the surgeon has to do is look at a scan of the patient鈥檚 head, then tell the computer the target and the entry point,鈥� says Finlay.
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Right now, to take a sample of tissue from inside the brain for testing, a circular metal frame called a halo is first bolted to the patient鈥檚 head before they have a CT scan. The path for the biopsy needle is then calculated manually by measuring the position of the rods that make up the frame as they appear in the scan images. The calculation can take half an hour.
鈥淎nother benefit is that the patient doesn鈥檛 have to wear this cage. It鈥檚 a separate operation and sometimes they have to wear it for a day before having the operation,鈥� says Finlay.
Solo operation
Before the robot goes to work, four or more small titanium beads are stuck at intervals around the patient鈥檚 head. The patient is then given a CT scan which takes a series of parallel, cross-sectional images of their head and recombines them to form a three-dimensional model. The titanium beads show up strongly in the image.
The surgeon marks on the image the region of tissue that needs to be tested 鈥� for example, a suspected tumour 鈥� and also the entry point for the needle that will take the biopsy. This is chosen so that the needle avoids vital parts of the brain on the way to the target site.
The robot then scans the patient鈥檚 head using a video camera and picks up the titanium markers. It uses the CT scan images to work out where the biopsy site lies in relation to these.
The robot鈥檚 arm 鈥� which contains a metal guide for a needle to be pushed through 鈥� then positions itself precisely at the point where the biopsy needs to be taken from.
The robot can currently show the surgeon where to cut a small hole in the skull and holds the needle steady while the surgeon takes a biopsy. But Finlay says that after 30 months of testing at Queen鈥檚 Medical Centre, the robot will be fitted with tools to do simple operations, like biopsies, itself.