Yes. The best way to attach such document would be to open the Health menu option, click the note (pencil)  icon, enter a note and attach the file. 

There is a ‘task’ section. You can customize this list in team settings to include ‘X-Ray’ and once you’ve done that, you can ‘tag’ the new note and attached document. This will make it easier to retrieve all x-ray results for this athlete.