Well, its not good. A few rads lectures over a month or 3 doesn't really constitute exposure. Will you have LORs? Something to actually talk about on interviews?
Rads tends to be a little more lax about these things, but you need to get your priorities straight here. IMO, I'd move heaven and earth to get an elective in my chosen field done before/early applying. IR is not a replacement for a dx rads elective - very different world and a small potato compared to the rest of the field. Don't let a Sub-I or some other random 4th year requirement come between it, talk to higher ups if you have to.
Anything else and you risk looking insincere on the trail, and hell, if you don't have real reading room exposure - you still aren't 100% sure. Do you at least have shadowing time down there or something?
I don't mean to sound defeatist, but demonstrating committment to the field, and interest level and reason for it is paramount in these things. Good luck!