I was told from a chief resident/attending at a few places that it was a factor that they looked at as a plus for the application. It would NOT take the place of a good USMLE/COMLEX score or anything of the sort. They do in fact like to see it in Rads... if it could be helped. One of the harder ways to get a paper as a med student in Rads, is the IRB associated with patients and radiation. US is a good modality as a MS.
I hope this maybe helps some....