Put it all down. If it is possible to tailor your resume per program, change the ordering to highlight the specialty you are applying to. However, I do not recommend deleting things from your resume. Electives are on your transcript and research / papers simply should not be deleted. If it is not possible to submit multiple resumes, try to subtly emphasize your preferred specialty but not too much.
Also, try to brainstorm way to relate your other specialty to radiology (easy for surgery, internal, hard for gas, optho, derm, plastics). This will ready you for the inevitable questions.
Another strategy is to preempt them by including your experience in the other specialty while discussing your reasons for choosing rads (often one of the first questions asked).
Good luck.