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New Scanner Technology Reveals Body’s Secrets (with Illustration), (Cybergenesis)

New Scanner Technology Reveals Body’s Secrets (with Illustration)
Scanner pictures body's hidden fat

19:00 03 September 03
A new kind of machine could soon be coming to your local gym - one that requires you to stand perfectly still. In 30 motionless seconds, the machine locates and measures your body fat.
It could then tell you exactly where you could do with losing a few pounds and even advise you on exercises for your problem areas. If the body fat scanner turns out to be accurate enough, its makers hope it could one day help doctors spot disease.
The scanner works by simultaneously building up an accurate 3D image of the body, while measuring the body's effect on an electromagnetic field. Combining the two measurements allows the researchers to work out the distribution of fat and water within. Neither method is new on its own, says Henri Tapp, at the Institute of Food Research in Norwich in the UK. "The smart thing is that we've put them in one machine."
And it is not just for gym users. The body fat scanner could be used to study fat deposition as children develop, while patients recover from injury, or during pregnancy. And since it uses radio waves rather than X-rays, Tapp's device is safe to use repeatedly.

Radioactive tracer
Body shape is known to be a risk indicator for heart disease and diabetes. So accurately quantifying fat distribution could help doctors suggest preventive measures to patients before problems arise.
At the moment, doctors estimate fat content from knowing body volume and water content. To a good approximation, says Tapp, anything that is not fat is water. The amount of water in the body is often measured by giving the subject a drink of water that contains a radioactive tracer. The level of tracer in the patient's urine after three hours reveals the total water volume.
To find out a body's volume, subjects are weighed while totally submerged in water, and this is subtracted from their normal weight to give the weight of water displaced, and hence the subject's volume. But it is scarcely practical for seriously ill people.
There are other ways to directly measure body fat, such as passing a minuscule current between the wrists and feet. The overall fat content can then be estimated from the body's resistance.
But this method does not take body shape into account - so a subject with particularly skinny legs might register a higher fat content than the true value. That is because skinny legs - with a lower cross-sectional area - will present higher resistance to current. So the machine thinks the water content of the body is lower - rating the subject as fatter. Also, the system can only give an overall measurement of fat.

Detector ring
Tapp's method uses similar calculations, but is more sophisticated because it tells you where the fat is. The subject stands in the scanner while a detector ring passes down the body (see graphic). At the same time, eight electrical coils also mounted on the ring generate a radio-frequency electromagnetic field.
through the body, the field's phase is shifted, depending on the conductivity of the tissue, and hence its water content. Eight detector coils record any shifts in the field's phase for each body slice.

At the same time, four lasers sweep across the body. The reflected light is picked up by four digital cameras which build up an extremely high-resolution image of the subject's shape. Combining body volume with water content for successive slices allows the system to calculate fat content in each slice and so tell the subject very accurately where they are piling on the pounds.

A long-term goal for the team, who this week presented their system at a conference on Industrial Process Tomography in Banff, Canada, will be detecting illnesses, such as liver disease, which result in excess water retention by the body. This is difficult, because calculating fat content is based on assumptions about what proportion of non-fat mass is made up of water.

"Sick patients with a lot of fluid could really throw the system out of gear," says Winston Koo, an expert on child body composition at Wayne State University in Detroit, Michigan. Koo believes that the system's convenience is a significant plus though. At least you do not have to dunk the patient in water, he adds.

Illustration of Operation of Bodyscanner

Fri Sep 26