CXR has been shown to have an overall sensitivity of only 67%!
Recent literature and a large, recently published, authoratative book by one of the world's leading authorities on aortic dissection support the notion that a negative highly sensitive d-dimer rules out aortic dissection.
CT scan is the test of choice, but be aware that many authorities are starting to recommend beta blockade before CT to reduce the most common artifact, motion at the aortic root that simulates a dissection flap
MRI and TTE are reasonable alternatives if a CT can not be ontained
The most common theme found in malpractice claims against emergency physicians is failure to address the combination of chest/back, back/abdominal pain.