AdSense targetting the wrong keywords – can I specify?

I’ve got AdSense setup on my Photoshop/Gaming blog, but it keeps pulling items like Frog Statues and Steel brushes (see my name).
Is there a way I can tell AdSense to pull ads for Photoshop and Gaming stuff and nothing else?
[EDIT] Did I post this in the right forum by the way?

See original post by steelfrog