Chest x-ray is the most commonly performed diagnostic x-ray examination. Approximately half of all x-rays obtained in medical institutions are chest x-rays. A chest x-ray is usually done for the evaluation of lungs, heart and chest wall. Pneumonia, heart failure, emphysema, lung cancer and other medical conditions can be diagnosed or suspected on a chest x-ray. Traditionally, chest x-rays have been taken prior to employment, prior to surgery or during immigration.