The chest x-ray is the most commonly performed radiographic exam. In fact, approximately 45% of all radiographic exams are chest x-rays. Over 150,000,000 chest x-rays are done yearly in the U.S.

The dose of radiation from a chest x-ray is very small (0.25 mRad). Although this unit of measurement is probably unfamiliar, we all receive approximately 100 mRad (400 times that of a chest x-ray) yearly from cosmic rays and the trace radioactive minerals in rocks and building foundations.

Many research studies have shown that radiologists are far more accurate than untrained physicians in the science of interpreting x-ray films.  In one study by Pennsylvania Blue Shield, a large percent (up to 40%) of significant abnormalities on chest x-rays were misinterpreted by non-radiologists.
 

Rheumatoid Arthritis
This X-ray shows erosion of both knee joints due to the severe  arthritis. Rheumatoid arthritis is one type of arthritis, a general term used to describe inflammation of the joints. The disease typically affects joints symmetrically: joints of the fingers, wrists, feet, ankles, hips and shoulders are also affected. The degree of severity varies considerably. Rheumatoid arthritis is diagnosed by a blood test that reveals the presence of the rheumatoid factor and by X-rays that show erosion of the joints. Anti-inflammatory drugs are used in treatment; severe cases may require replacement with an artificial joint.

Healthy lungs and heart. Colored X-ray of the chest of an 11-year-old boy showing normal lungs and heart. The lungs (dark bluish areas to the left and right of the spine) are enclosed by the ribs (pink bands). Both lung fields are clear with opacities (greenish yellow) due to the bronchi and pulmonary blood vessels (at the mid-center of each lung field). The heart (yellow) is protruding to the right of the spinal column and the diaphragm (green) is clearly visible at lower centre. Skeletal features include the thoracic spine (upper centre), the clavicles (collar bones; bones on top left and right slanting between shoulders and rib cage).

Osteoporosis fracture. Colored X-ray of the hip of an elderly woman with a fractured femur (lower right, red) caused by osteoporosis (brittle bone disease). The round femur head articulates with the pelvis at the hip socket (centre). The femur (thigh bone) is fractured at the neck between the head and shaft of the bone. Osteoporosis causes a loss in bone density, making the bones thinner, more brittle and more likely to break. In this case the femur fractured by a fall. Osteoporosis is most common in women after the menopause as their ovaries no longer produce the estrogen hormones which help to maintain bone mass.