Radiology residency quality is a complicated topic. There is a discussion ongoing related to "top" radiology residency programs at Auntminnie.com, that can be accessed here:
http://www.auntminnie.com/forum/tm.aspx?m=342082
For non-members, here's the breakdown (remember, these are not hard and fast rankings, just a delineation of commonly competitive academic programs -- for more info, read the discussion on the above linked forum):
1) UCSF
1) MGH
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2) PENN
2) MIR
2) Hopkins
2) Duke
2) U Michigan
2) U Washington
2) Stanford
2) BWH
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3) Mayo Clinic - Rochester
3) UCLA
3) UCSD
3) NYU
3) BID
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4) Wake Forest
4) U Virginia
4) U Pittsburgh
4) U Wisconsin
4) UTSW
4) Cleveland Clinic
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5) Cornell
5) UNC
5) Indiana
5) Thomas Jefferson
5) Northwestern
5) U Chicago
5) UAB
5) Vanderbilt
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Honorable Mention: USC, OHSU, Utah, Colorado, Brown, Iowa, Minnesota, Davis, Irvine, Florida-Gainesville, Emory, South Carolina, Maryland, Baylor-Houston, Arkansas, Baylor-Dallas, UT-Houston, UIC, Rush, Loyola, MCW, Albert Einstein, New Mexico, Virginia Mason, Scott and White, Santa Clara Valley, Mount Auburn, Maine Medical Center, USA, William Beaumont, Henry Ford, Yale