As a graduate of an LCME medical school you can enter the Canadian residency match. Most schools require you to be a permanent resident of Canada (similar to a US green card) so you would need to apply for that in advance, unlike the US however it is not that hard to obtain.
The problem is that radiology is very competitive in Canada. Therefore you are generally much better off applying to a few more American programs if you are just trying to increase your chances of matching. Even the less popular programs will interview 5-10 candidates per spot, and will reject many more.
On the plus side, the Canadian programs (even the smaller ones) are generally solid IMHO. All programs are university affiliated and usually affiliated with every major hospital in the city (unlike the American model, you will not usually have multiple medical schools or programs in one city, and you match to a university, not to a single hospital) so you are assured of a fairly broad exposure.
As a Canadian grad you are eligible for both the Canadian and American board exams, so you could return to the US for fellowship or jobs as desired. I believe american grads from american programs are also eligible for the canadian board exams (which unlike ABR certification is required, not voluntary, to practice radiology) so you could always take them later if you wanted to practice in Canada.