so you have a 219 step 1 and a...gpa (??? that's college, right?). okay, i'm going to answer your question like you have a 219, poor preclinical grades, and medicocre clinical grades to date. it's definitely doable, but you have to get a little more proactive now. in this scenario in order to match you need to do the following:
1. do very well in your remaining third year courses
2. get a very strong rec from someone who believes in you. you can get this by doing well in a third year rotation, doing well in a preceptor-ship in fourth year, doing well in an away rotation (in july, august, early enough for rec to get out) or doing research with someone so they get to know you and give you a good rec.
3. kick butt on step 2 (preferably >230, and over 240 is looking really good)
4. a publication could look good, if you don't mind taking a year off and if you honestly think you might be interested in research.
5. talk to fourth years at your school and look at sites like this to get inside angles on the rads admissions game.
so the deal is your step 1 is low by radiology standards (actually it's above the national average for med students, but you'd never realize it in radiology b/c it's so competitive) and usmle doesn't allow you to retake it. you can, however, do better on step 2, which will address concerns about your ability to test well. think about it, if someone got a 1550 on the sat the second time you don't care so much that they got a 1000 the first time (oh, you'll think, they didn't take it seriously). same thing with the steps.
mediocre preclinical grades is not too big a deal. mediocre clinical grades is a double-whammy b/c clinical grades are important, and then it's also harder to get a good rec. trends are important. if you start doing very well at the end of third year then you'll fit into the 'late bloomer' narrative. in this story you've bloomed into the superstar student you really are and will be, whereas early medschool represents just several false starts on what will now a smooth road.
lastly, do not let yourself feel too insecure, b/c that feeling will hurt you more than numbers will. if you feel like you suck and you should've done better, you're hesitant, you question yourself, you get labeled in others' minds and not very good. people often label others based on weak psychological cues, and then they take any subsequent data (numbers, grades) and try to fit it into how they already feel about you. so you want to fit into a good psychological category, and not the opposite. this is a good life skill. so in this scenario, people will be like 'he/she's really great....hmm, low step 1, well it's not so important, and probably wasn't gunning and obsessive about it, and look here, they did well on step 2', vs. the opposite like 'he/she sucks...and other people think so too, see poor grades, forget it..)
hope that's helpful.