I have not read the article but I believe that usually routine exams are done with X Ray, because it is quicker and cheaper. However if something is a bit worry

I have not read the article but I believe that usually routine exams are done with X Ray, because it is quicker and cheaper. However if something is a bit worrying, doctor may ask for a different type of exam, MRI or Ultrasound, to have some confirmation. But since this is rarer people who have MRI are already people at risk, so it makes sense to have a higher rate of biopsy in the end.