[Eric A. Taylor (OP)]

I was just hearing about a problem they are having with medical radio isotopes. The problem isn't related to my question but they were talking with a scientist or doctor who wrote the paper. He stated that one of the most useful isotopes used in medicine is Technetium-99 (I think). He stated that it has a half-life of just 6 hours. This means that the stuff would need to be produced at the hospital just before it was needed. Storing something with a half-life that short even over night would seem impractical. Every 6th hour half the stuff would be gone! Am I missing something about how half-life works in radioactive stuff.

Here's what I think I know. You have one kilo of some radioactive something. In one "half-life" half of the radioactive atoms would have gone through decay to become something else (Uranium into lead say)...

With a 6 hour half life (something I'd like if the doctor wants to put it inside me) how could it possible be stored without it all decaying onto something else?

I said "Technetium-99 (I think)" because I might have looked up the wrong stuff. What the scientist was talking about is used in 60% of medical scans and has a half-life of 6 hours and produces gama-rays. According to Wikipedia Technetium-99 has a half life of 211000 years and produces beta-rays but NOT Gama-rays. If I'm wrong here please correct me. I hope I've given enough info about what I'm talking about so someone can identify it if I'm wrong.

[RD]

I said "Technetium-99 (I think)" because I might have looked up the wrong stuff.

Technetium-99m is a metastable nuclear isomer of technetium-99, symbolized as 99mTc.
 The "m" indicates that this is a metastable nuclear isomer, i.e., that its half life of 6 hours

http://en.wikipedia.org/wiki/Technetium-99m

[Eric A. Taylor (OP)]

I said "Technetium-99 (I think)" because I might have looked up the wrong stuff.

Technetium-99m is a metastable nuclear isomer of technetium-99, symbolized as 99mTc.
 The "m" indicates that this is a metastable nuclear isomer, i.e., that its half life of 6 hours

http://en.wikipedia.org/wiki/Technetium-99m

Thanks. I've had this stuff used on me for brain scans. It's a very strange sensation when it goes in, giving a warm and wet sensation especially between the legs where the huge femoral artery splits off. Is the sensation a result of the radiation?

[RD]

It's a very strange sensation when it goes in, giving a warm and wet sensation especially between the legs where the huge femoral artery splits off. Is the sensation a result of the radiation?

I doubt it: non-radioactive contrast media can also cause warm sensations when delivered intravenously ...

... Most patients feel some degree of warmth and get a salty taste in their mouth as the [non-radioactive] contrast is flowing through their blood vessels. These sensations last for just a few minutes

http://www.southvalleyimaging.com/faq.html

[Bored chemist]

The answer to the original question is given here
http://en.wikipedia.org/wiki/Technetium-99m_generator
they extract it on-site from a longer lived radioactive material.