You need to have a low blood glucose level, so that when they give you the radioactive glucose it goes to the metabolically most active cells. These happen to be cancer cells, but there are also other possibilities. If you were to be active once you get the glucose it would end up in the muscles that were exercised.

....try not to think to hard.... too funny!!! But you certainly should not agitate yourself.
If you look at a PET/CT scan have take a peek at your brain. The energy source for your brain is glucose and therefore it lights up like a christmas tree (which is normal).


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