Try:

     m/\Wradio\W|^radio\W|\Wradio$/
[download]

I wanted to really say something like:

     m/[^\W]radio[\W$]/
[download]

Excpet that means something radically different than what I would be trying say which "Match anthing that either starts at the begining of a line or starts on a word boundery that has the text "radio" and ends on a word boundery or the end of a line." That is not what the thing above means though, so you have to settle for the first (unless someone else has a more simplified way of doing it).

Cheers...james