Hello, I'm Justin Rowlat. Welcome to Business Daily's latest look at the role that the chemical elements play in the global economy.

And this week, we have an element you've probably never heard of because it's made up, literally in a nuclear reactor.

When it was discovered, it was imagined, then in fact it would only ever be made

artificially and that it would not be found in nature. This synthesized element has come to play

a critical role in medicine, as we'll discover, and yet supplies of it are far from guaranteed.

What happens now if one of these nuclear reactors goes down

is it creates a global shortage,

and then doctors cannot get the images

that they need to diagnose disease,

and that's a huge problem.

So what is it? Technetium.

So we are outside, one of the leading hospitals in Britain, University College London Hospital,

which is associated, of course, with University College London, the home of Professor Andrea Seller,

well his academic home anyway. And why have you brought me here?

Well, I've brought you here because of a really interesting element, an element that's beloved of chemists, because almost none of us

have actually seen it. And this is the element technetium. Now, technetium is exciting because it's one of

only four elements that was predicted by Mendeleif when he constructed his periodic table.

And he was the guy who first proposed that you could organize the chemical elements in a table.

He was the man who first came up with this systematic scheme for the elements,

and he spotted four gaps in this table.

And one of them was right in the middle of the table amongst

the transition metals with manganese above it and renium below and there was this hole.

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