Liljoe
I recommend surgery, transitional or medicine. It will help you survive GMO and prepare you for a rad residency.
You need to get face time with radiologists at the major hospital that governs over your duty station. It would help if you did a research project or publication during internship.
During internship, I did two presentations. During GMO, I have submitted two articles for publication. I also asked for NO COST TAD to do a rotation at a civilian hospital for training outside of the Nav.
If you decide on a Navy residency, Go to San Diego (it is strong, but you may want to check on their board passing rates - I don't know what they have been recently but there are usu >97%). Find out what billets are avail for rads in the nav. You may end up as the sole rad and work in a rad 'sweat shop' on call 24/7 for 3 years. Keep in mind that you will probably have to do a payback tour prior to doing a fellowship.
You can consider doing a res before going into the navy but if you don't end up on a major hosp (portsmouth,beth,san diego) you may lose some skills (some hosp have no MRI/CT or angio suites). If you end up in ports/beth/san diego/AFIP, you will become one of the strongest rads in the country, since you are rotated through every section throughout the year (except nuclear med).