A chest X-ray is a good test to diagnose pneumonia. However, it cannot identify most breathing problems by itself. For some people with breathing problems, a CT scan of the chest is needed. This scan looks for any problems in the lungs. A CT scan uses X-rays and a computer to create detailed images. If you suffer with chronic sinusitis, your doctor may order a special sinus CT scan. This scan will be used to evaluate your sinuses.