PubMed - search for articles. ** Note that this is not a comprehensive search as references may appear in other databases.
RSNA Journals - Special focus: COVID-19 collection - not all of these articles are indexed in PubMed and so will not be found from the search above.
CovED - "free virtual clinical environment that helps clinicians to become better at recognising the early CT signs of COVID-19"
** Most major publishers have made all COVID-19 papers available open access. In general it is advisable to follow the Get it @ E/SMHS button to reach full text to avoid paywalls. Quick ways to connect to paywalled full text - bookmarklets and the LibKey Nomad browser plug-in (note the caveats - these are effective but not 100% effective).