Unfortunately, x-rays taken of patients with coccyx pain often do not actually include the coccyx at all - instead they cover the lumbo-sacral region, which is most of the source of low-back pain. You can see a video about coccyx x-rays for tailbone pain from Dr Patrick Foye, www. tailbonedoctor.com.
An x-ray shows bones clearly and other tissues faintly. It may show up a tumor (cancer), though it is very rare that this is the cause of coccyx pain.
Most often, the x-ray shows nothing abnormal, and other tests like the dynamic sit/stand x-ray, or injection with local anesthetic, will be needed to find the cause of the pain.
An x-ray may show that the coccyx has a bend in the middle, that it points more to one side than the other, or that it is made up of more than one piece. Many doctors do not realise that most people's coccyxes are made up of more than one bone. When they see a coccyx in two pieces, they may tell you that it is broken, because many medical text books tell them that it should be in one piece. They are almost always wrong (see the normal coccyx).