X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body structures onto specially-treated plates (similar to camera film) and a "negative" type picture is made (the more solid a structure is, the whiter it appears on the film).

When x-rays are performed, different tissues allow varying penetration of the x-ray beams. The soft tissues in the body (such as blood, skin, fat, and muscle) allow most of the x-ray to pass through and appear dark gray on the film. A bone or a tumor, which is more dense than the soft tissues, allows few of the x-rays to pass through and appears white on the x-ray. At a break in a bone, the x-ray beam passes through the broken area and appears as a dark line in the white bone.

How are X-rays Performed?
Although each treatment facility may have specific protocols in place, generally, an x-ray procedure follows this process:

The patient will be asked to remove any clothing or jewelry which might interfere with the exposure of the body area to
   be examined. The patient will be given a gown to wear if clothing must be removed.

The patient is carefully positioned on a table so that the body part being studied is between the X-ray machine and a
   cassette containing the X-ray film. X-ray examinations may be performed with the patient lying, sitting or standing.

Body parts not being imaged may be covered with a lead apron (shield) to avoid exposure to the x-rays.

The x-ray beam is then focused on the area to be photographed.

The patient must be very still or the image will be blurred.

The technician steps behind a protective window and the image is taken.

Sometimes, various x-rays may have to be taken at different angles, such as the front and side view during a chest X-ray