General inquiry about DC games\ regions.

[Tosted0105]

I just picked up a dreamcast from a friend and I need some info. so here I go
By use of a boot disk or self boot game can I play imports(I'm in North america) such as euro or japanese just like any other game or do I need to patch them. If I need to patch could someone either explain the process of doing so and what I'd need to do it, I already have some games as cdi files so I need to know where to go from there(assuming I would need a patch.
any help would be great.