The chest X-ray is the most common radiologic procedure. The X-ray is projected toward the chest to show the heart and lungs, bones and soft tissues. The actual time of the average X-ray exposure is extremely short -- often less than one-half second. Some of the radiation penetrates the part of the body being examined and thus creates the X-ray image.

To understand what happens when an X-ray is taken, a comparison can be made with the use of a camera in taking a photograph.

The X-ray exposes the film to form an image just as the light exposes the film inside a camera. The film in a camera is developed and used to make a photographic print or it is used directly as a slide. The X-ray film is also developed and viewed with transmitted light on a light box or computer screen.

The chest X-ray technique in young children involves two views. The initial view is from the front, and the second is a side view.

In young children, the patient lies on the table and the hands are held above the head.

In an older patient, the child stands upright for one image and then turns sideways for the second image. The technologist tries to focus the radiation beam using a light on the patient's chest. This reduces the amount of radiation to other parts of the body.

After taking the X-ray, the radiologist reviews the film. They can compare it with prior films, which is important when evaluating heart size and blood flow to the lungs. They share the results with the cardiologist and the referring doctor.