What is it? 
A chest X-ray is a picture of the heart, lungs and bones of the chest.  A chest X-ray doesn’t show the inside structures of the heart though.

Why is it done? 
A chest X-ray shows the location, size and shape of the heart, lungs and the blood vessels.

How is it done? 
A technologist positions you (a hospital gown may be worn over the chest) next to the X-ray film. Older children will be asked to hold their breath and be very still for two or three seconds; infants may require some restraint. An X-ray machine will be turned on for a fraction of a second. During this time, a small beam of X-rays passes through the chest and makes an image on special photographic film. Sometimes two pictures are taken — a front and side view. The X-ray film takes about 10 minutes to develop. Sometimes your cardiologist needs more than just the front and side chest X-rays. 

Does it hurt? 
No, it doesn’t. You won’t feel the X-rays as the pictures are taken.

Is it harmful? 
The amount of radiation used in a chest X-ray is very small — one-fifth the dose a person gets each year from natural sources such as the sun and ground. This small amount of radiation isn’t considered dangerous. However, pregnant women should avoid even this low level of radiation, when possible.