SCALE-models of X-ray equipment promise to make life easier for radiologists and safer for their patients, says a Dutch researcher. In a demonstration this week in Vienna, Sven Ploem showed how a radiologist can guide real X-ray machines by manipulating one of his models instead of the normal knobs, buttons and joysticks.
Ploem says that his idea could allow a single X-ray machine to perform a range of tasks that are normally assigned to separate, purpose-calibrated fluoroscopy machines. He says that at the hospital in Nijmegen, where he works as a radiologist, there are five X-ray instruments which cost around 拢800 000 each. Individual machines are set up exclusively for particular fields of study, such as cardiology, or bowel examinations. 鈥淗alf of the time, they are idle,鈥� he says.
Ploem鈥檚 equipment is based on 鈥渕aster-slave鈥� robotics systems of the type developed by the nuclear industry for repairing and manipulating machinery in highly radioactive areas. The 鈥渟lave鈥� is the actual X-ray machine. It is controlled by engineers as they manipulate a miniaturised mock-up, which acts as the 鈥渕aster鈥�.
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In Ploem鈥檚 system, the master, which is approximately one-tenth of full size, has two components: a combination mock-up of the patient and the table on which they lie, and a model of the equipment used for manoeuvring the X-ray tube around the patient鈥檚 body. Radiologists can operate the machine entirely by feel, so they can keep their eyes on the X-ray image throughout an examination. This is not possible with conventional, joystick-operated instruments, says Ploem, because operators have to use separate controls to move different parts of the equipment, and constantly have to glance at the control panel and the table to check the X-ray tube鈥檚 position.
鈥淭he new system is so natural, you shine through the patient as if you had a flashlight in your hand,鈥� says Ploem. He reckons that the scans will be between 20 and 50 per cent quicker, reducing the doses of radiation to which patients have to be exposed.
One danger that the system must guard against is the possibility that the operator might injure patients by forcing parts of the X-ray equipment against them. Ploem has created a safety margin by building the model patient to a slightly larger scale than the model of the equipment. 鈥淚f the models collide, there is only air there in the real world, so it鈥檚 collision-proof,鈥� says Ploem.
Aart Hemmink of Fokker Control Systems, the Amsterdam-based subsidiary of Fokker Aircraft, is working with Ploem to optimise the system. He says that the masters send their instructions to the slaves electronically. 鈥淥n each hinge in the master is a motor carrying a torque transducer, a device which senses the turning force applied to the hinge,鈥� says Hemmink. The master is coupled electronically to the corresponding hinges in the slave, which carries out the same movements.
鈥淚 don鈥檛 know of anything like this that already exists,鈥� says Keith Tonge, a radiologist at St Thomas鈥� Hospital in London, who gives the device a cautious welcome. 鈥淚鈥檓 a bit sceptical, but it鈥檚 a good idea and I鈥檇 like to see it work,鈥� he says.
The system that Ploem demonstrated in Vienna this week is a 鈥減re-prototype鈥� version. But he is confident that its development will be rapid. In addition to the backing from Fokker, Ploem has enlisted the support of a major European manufacturer of X-ray instruments.
