What Is the Purpose of a Chest X-Ray?

A chest x-ray (CXR), also known as a chest radiograph, is an imaging study that provides a significant amount of information to doctors and other health care providers. Often it is one of the first studies obtained when evaluating a variety of symptoms, as it is a safe, quick, and low-cost study. The chest x-ray can be used to evaluate the heart, the lungs, and the bones. It is often done in the setting of acute trauma to rule out a number of life-threatening conditions.

In order to understand the purpose of a chest x-ray, it helps to know what this imaging study evaluates. An x-ray machine provides a two-dimensional image of the body’s internal structures. When aimed at the chest, the x-ray image displays the lungs, the heart, the rib cage, the sternum, the diaphragm, and the spine. Many times two images are taken, one from an anterior perspective and one from a lateral perspective. Having images from two vantage points allows people interpreting the study to reconstruct a three-dimensional image in their minds.

An important purpose of the chest x-ray is to examine the lungs. One of the first steps in evaluating a patient with symptoms such as shortness of breath, cough, or wheezing is to take a radiograph of the chest. This provides information about how well the lungs inflate, whether there is any abnormal material present within the lungs, and if fluid has collected around the lungs. Information from the study can support making diagnoses such as pneumonia, asthma, and chronic obstructive pulmonary disease (COPD).

The chest x-ray can also evaluate the heart. Often patients with symptoms such as sudden chest pain, palpitations, shortness of breath with activity, and an inability to lie flat due to shortness of breath undergo this imaging test. Radiologists can examine the borders of the heart to see if any of the heart chambers are enlarged. They can also evaluate whether the overall size of the heart is increased, which can signify the presence of a number of heart diseases.

Bone is another anatomic structure that can be evaluated with the chest x-ray. Characteristics of the ribs, spinal column, and sternum can be identified on this imaging study. Types of abnormal findings can include linear fractures, compression fractures, and osteoporosis, which is a condition characterized by having thin, weak bones.

Another important application of the chest x-ray is to evaluate patients who have experienced trauma, as they can have a number of dangerous complications. For example, the force of the trauma could have caused the aorta, the blood vessel leading the heart, to tear. This can be a life-threatening situation because a massive loss of blood could send the patient into shock. Occasionally, trauma can result in the collapse of a lung, which can be dangerous because the blood might not be able to pick up enough oxygen to supply the rest of the body. Both of these conditions can typically be identified on CXR.