Researchers at UCD are using computer models of the skull to understand serious injuries and devise ways of improving safety equipment, writes Dick Ahlstrom
Regardless of what is going on inside it, the head is a remarkably complex structure. It is a mix of hard and soft, liquid and solid, and it responds to injuries in a similarly complex way.
A team at UCD is developing a way to understand this difficult composite structure using advanced computer modelling. The object is to create computer simulations that can predict how the head will respond to injury without having to find volunteers willing to hurt themselves.
Dr Michael Gilchrist of the Department of Mechanical Engineering leads the research programme, which involves the work of six staff plus students. He is also director of UCD's Materials Ireland Research Centre, labs that conduct research into materials and their properties.
Gilchrist, who started the work in 1998, says it grew out of his interest in materials science and composite materials. "From a materials point of view, [the head] is a complex composite material," he says. It includes a thin shelled structure enclosing a "visco-elastic material floating within a fluid", tethered by nerves and blood vessels. This doesn't prevent modelling, however. "We can treat the human head from a solid mechanics point of view."
His department includes a lot of researchers interested in bio- engineering, including synthetic bone materials, prosthetic design and joint simulation. Gilchrist got funding from a UCD President's Research Award and additional backing came from Enterprise Ireland and the HEA via the PRTLI programme.
It has been a collaborative project involving, among others, Dr W. T. O'Connor at UCD and Prof Jack Phillips and Dr Phil Thomas at Beaumont Hospital.
The research group began with a two-dimensional model of the head. It was based on "computational mechanics", using a well-tried modelling method based on finite element analysis. This involves separating each component of a system, calculating its performance and then summing these parts to predict how the whole performs.
Gilchrist says there was little surprise when the 2-D model provided a good qualitative mirror of the response to injury. It readily predicted the "engineering strains that would be set up within the skull".
This encouraged the group to produce a much more complex 3-D model. "This is one of the best anywhere in the world," says Gilchrist. "It is quite a sophisticated model."
THIS version takes many tissue types into account, including skin, bone, grey and white brain tissue, cerebro-spinal fluid, and the dura. It even assesses how blood vessels will be affected. It calculates two types of acceleration: linear acceleration that is exerted along a line, and rotational acceleration, typical of the movement of a boxer's head,say, after an uppercut when the head pivots.
The model takes into account both how a blow to the head might be delivered and the material involved in inflicting the injury. The brain responds differently to a fall on concrete than it does to the complex motions that can occur during a car accident.
The research would have application both as a clinical tool and as a means to designing better safety equipment, Gilchrist believes. There are, unfortunately, plenty of serious head injuries, with 12,000 people being admitted to hospital each year, he says.
It would not be used to model an individual patient's injuries but to provide a range of injury scenarios for a treating clinician. "What you could actually use is a 'what if' scenario," Gilchrist says, to give early warning to emergency room staff. "We can build up a reasonable database of hypothetical accidents."
"It may help the clinicians in their initial diagnosis of a particular injury type. I think it might also lead to some input on the treatment," he adds.
It could also be used to train surgeons. "The other big area - and the area of more immediate concern - is in the design of safety equipment," says Gilchrist.