WHAT can dock the space shuttle and spot a brain tumour? No, it鈥檚 not an
astronaut鈥檚 personal physician鈥攊t鈥檚 a neural networking computer algorithm
designed by engineers at NASA. The system has become so adept at analysing the
large amount of data needed to dock a spacecraft that it is also being harnessed
by doctors to analyse tumours.
Recognising patterns is neural networks鈥� forte
(see 鈥淕as on the brain鈥�, p 36).
They do pretty well with a small number of parameters, but go beyond 10 or
so inputs and the neural nets get confused and become hard to train.
For humans, by contrast, this sort of task comes quite naturally. For
example, a surgeon taking a look at a chunk of tissue might subconsciously
analyse its colour, consistency and shape, and conclude that it鈥檚 a malignant
growth. All this can happen in a split second, without the surgeon being aware
of the process.
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Now a neural computer that handles many pieces of data at once has been
designed by a team led by Robert Mah, an engineer at NASA鈥檚 Ames Research Center
at Moffett Field, California. 鈥淚t鈥檚 a neural net where lots of parameters are
analysed in real time,鈥� explains Mah. 鈥淚t鈥檚 looking at 25 or more; it鈥檚 pretty
hard to do that.鈥�
Mah鈥檚 neural net can take the data from a surgical probe鈥攕uch as speed
of blood flow, fluid pressure or optical reflectance鈥攁nd discriminate
between cancerous and healthy cells. 鈥淵ou鈥檒l get real-time feedback about what
tissue is at the tip of the probe during a biopsy,鈥� says Mah. 鈥淭he goal,
initially, for brain applications, is to avoid hitting blood vessels.鈥� Clinical
trials are scheduled to start soon at Stanford University.
The neural net can also do things that are more obviously useful to
NASA鈥攍ike docking the space shuttle with the International Space Station.
Instead of taking data from a biopsy probe, the neural network is connected to
the space shuttle鈥檚 navigational system. In simulations, and after a few test
manoeuvres to learn the weight characteristics of the spacecraft, the neural net
outperformed NASA鈥檚 highly trained shuttle astronauts. Coming after the
near-disaster aboard Mir due to a docking mishap with a cargo ship, more
reliable docking systems would do wonders for NASA鈥檚 confidence. The only risk
is bruising the crew members鈥� egos. 鈥淎stronauts want to be in control,鈥� says
Mah. Another application for the network might be in helping to learn the way a
spacecraft rotates in space while firing its impulse jets. The system would then
precisely slow the craft鈥檚 rotation by burning the jets for the correct
period.
But NASA鈥檚 work remains promising for doctors and their patients. 鈥淭here鈥檚 no
question that what he鈥檚 doing is potentially very important,鈥� says Faina Shtern,
the assistant director for research and technological affairs with the US
Department of Health and Human Services. She hopes the neural net will be able
to find out whether tumours and lesions are malignant without causing the
patient unnecessary discomfort.