Diagnostic Radiology - Chest X-Ray
What is a Chest X-Ray or Radiography?
A chest x-ray is the most commonly performed of all the x-ray examinations. A chest x-ray is usually performed to check lungs, heart and chest wall for abnormalities. Medical conditions such as pneumonia, heart failure, emphysema, and lung cancer can often be diagnosed with a chest x-ray.
What are some common uses of the procedure?
A chest x-ray is usually the first diagnostic test for symptoms like shortness of breath, a persistent cough, chest pain or injury or a high fever. Patients who may have medical conditions such as congestive heart failure or cancer may undergo chest x-rays to map changes that would require any change in their treatment.
How should I prepare for the procedure?
There is no special preparation for this exam. Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.
What does the x-ray equipment look like?
The most common radiography equipment used for chest x-rays consists of a box-like apparatus containing either film or a digital recording plate against which the individual places his/her chest—and the apparatus containing the x-ray tube, usually positioned about six feet away. Some studies will use another piece of equipment, which consists of a large, flat table with a drawer that holds an x-ray film cassette or a digital recording plate. With this arrangement, the x-ray tube is suspended above the table.
How does the procedure work?
Radiography exposes a part of the body to a small dose of radiation to produce an image of the internal organs. When x-rays penetrate the body, they are absorbed in varying amounts by different parts of the body. The ribs and spine, for example, absorb much of the radiation and appear white or light gray on the image. Lung tissue absorbs very little of the radiation and will appear dark on the image. Depending upon the type of image-recording medium, chest x-rays can be maintained as hard-copy film for filing or, more commonly, as filmless digital images that are archived electronically. Digital images can also be transferred for storage onto CD-ROM. Stored images may be used to compare with later images if the patient’s illness develops. Historical comparison films are often used when deciding whether a finding clinically important or not.
How is the procedure performed?
Patients should remove all their clothing, including undergarments if underwear has metal such as underwire bras. Patients will also be asked to remove all metallic jewelry that may interfere with the x-rays. The hospital will give the patient a loose-fitting gown to wear. Normally, a frontal or posteroanterior view is taken, and the patient stands with the chest pressed to the photographic plate, with hands on hips and elbows pushed in front in a somewhat exaggerated position. The technologist will ask the patient to be still, take a deep breath and to hold it. Holding the breath reduces the possibility of a blurred image and also enhances the quality of the x-ray image, since abnormalities in air-filled lungs are easier to see than in deflated lungs. Next, the technologist walks into a separate area to shoot the film and a beam of x-rays is emitted from the x-ray source behind the patient, through the patient's chest and to the film or digital cassette.
The technologist may need to take additional views to properly see all parts of the chest or may take a side view, or lateral view, of the chest. For a lateral view, the patient stands sideways to the photographic plate with arms elevated, and the film is shot. Views from other angles may be obtained if the radiologist needs to evaluate additional areas of the chest. Finally, a chest x-ray may be repeated within hours, days or months to evaluate for any changes. These repeated examinations are called serial chest x-rays.
When the chest x-rays are completed you will be asked to wait until the technologist checks the images for motion and makes sure that the entire chest is included. Ultimately, a radiologist will interpret the chest x-ray images using a lighted view box to review films or a computer and monitor to review digital images.
What will I experience during the x-ray procedure?
This is a painless procedure. The primary discomfort may come from the coldness of the recording plate. Individuals with arthritis or injuries to the chest wall, shoulders or arms may have discomfort trying to maintain position for the chest x-ray. In these circumstances, the technologist will assist you in finding a position that still ensures diagnostic image quality.
Who interprets the results and how do I get them?
A radiologist, who is a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report with his interpretation to your referring physician, who will inform you of your test results.
Benefits vs. Risks
- A physician may recommend a chest x-ray for a patient with shortness of breath, a bad or persistent cough, chest pain or injury. In the instances of pneumonia, it will appear white on the image.
- A chest x-ray may also show advanced emphysema, as well as other lung conditions, such as pulmonary fibrosis.
- Lung cancers and tumors that spread to the lung may be visible on a chest x-ray. However, lesions that are small or superimposed on normal structures may not always be visible.
- Heart irregularities, an enlarged heart, abnormal heart anatomy or congestive heart failure caused by fluid around the heart (pericardial effusion) may also be visible on a chest x-ray.
- Pleural effusions (fluid around the lungs) on one or both sides can be detected. Usually the cause of such fluid may be deduced from clinical data or other findings on the chest x-ray, but it may be necessary to sample the fluid to determine its cause.
- X-rays are a type of electromagnetic radiation, are invisible and create no sensation when they pass through the body. The chest x-ray is one of the lowest forms of radiation exposure examinations performed today.
- Special care is taken during chest x-ray examinations to ensure maximum safety for the patient by paying attention to correct x-ray beam energies. Shielding the abdomen and pelvis with a lead apron helps reduce unnecessary radiation to the abdomen and pelvis. Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.
- The effective radiation dose from this procedure is about 0.1 mSv, which is about the same as the average person receives from background radiation in 10 days.
Radiation risks are further minimized by:
- Technique standards are continually reviewed by national and international radiology protection councils.
- Modern, state-of-the-art x-ray systems that have tightly controlled x-ray beams with significant x-ray beam filtration and dose control methods. Thus, stray or scatter radiation is minimized, and those parts of a patient's body not being imaged receive minimal exposure.
What are the limitations of Chest Radiography?
The chest x-ray is a very useful examination, but it has limitations. Some conditions of the chest will not show up on the image. A normal chest x-ray may not rule out all chest problems. A patient with asthma exacerbations could have a normal chest x-ray and there are some cancers that are too small or are difficult to see and may not be identified. Blood clots to the lungs (pulmonary embolism) cannot be seen on chest x-rays and may require further testing.