## How to spot the foreign body lurking deep within

> New Scientist vol 154 issue 2084 - 31 May 97, page 20

> FOREIGN objects in the body can be hard to find if they are made of materials that do not show up on X-rays. These include medical implants such as artificial joints and stents. But a polymer invented by Marc-Anton Kruft, of the Eindhoven University of Technology, could make them far easier to find.

> Kruft has created polymers containing iodine which show up far better on X-rays than existing medical materials.

> Doctors need to locate medical implants to ensure they are in the right place or are working properly. Currently, barium sulphate or zirconium dioxide are added to implants to make them stand out. Kruft says neither metal is completely incorporated into the polymer and each is toxic so any leaching can be hazardous. Both compounds also weaken the polymers, causing them to crack and making leaching more likely. He says his polymers are seven times more crack-resistant than these compounds.

> He made his first polymer by attaching a benzene ring containing a tightly bound iodine atom to a monomer called methyl-methacrylate. The result is suitable for medical appliances. Now he has developed a range of different polymers.

> The materials can also be used for plastic toys that could be swallowed by children.

> Jonathan Beard

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