They didn’t actually do that. That is my subjective interpretation as a random person of the language of the current ACGME Common Program Requirements (emphasis mine):
For many aspects of patient care, the supervising physician may be a more advanced resident or fellow. Other portions of care provided by the resident can be adequately supervised by the immediate availability of the supervising faculty member, fellow, or senior resident physician, either on site in the institution or by means of telephonic and/or electronic modalities. Some activities require the physical presence of the supervising faculty member. In some circumstances, supervision may include post-hoc review of resident-delivered care with feedback.
I think imaging has and should continue to fall under “some circumstances.” Until the machines take over, hold-out radiology programs should strive to maintain their status quos of “post-hoc review.” Efforts should absolutely be made to improve that review process and help residents learn and iterate toward improvement, but the last thing we need in the era of increasing mid-level autonomy is to have graduating residents unable to make a call.