Radiology (X-rays) is used in the diagnosis of tuberculosis. Abnormalities on chest radiographs may be suggestive of, but are never diagnostic of TB, but can be used to rule out pulmonary TB. Chest X-ray A posterior-anterior (PA) chest X-ray is the standard view used; other views (lateral or lordotic) or CT scans may be necessary. In active pulmonary TB, infiltrates or consolidations and/or cavities are often seen in the upper lungs with or without mediastinal or hilar lymphadenopathy. However, lesions may appear anywhere in the lungs. In HIV and other immunosuppressed persons, any abnormality may indicate TB or the chest X-ray may even appear entirely normal. Old healed tuberculosis usually presents as pulmonary nodules in the hilar area or upper lobes, with or without fibrotic scars and volume loss. Bronchiectasis and pleural scarring may be present. Nodules and fibrotic scars may contain slowly multiplying tubercle bacilli with the potential for future progression to active tuberculosis. Persons with these findings, if they have a positive tuberculin skin test reaction, should be considered high-priority candidates for treatment of latent infection regardless of age. Conversely, calcified nodular lesions (calcified granuloma) pose a very low risk for future progression to active tuberculosis. Abnormalities on chest radiographs may be suggestive of, but are never diagnostic of, TB. However, if a person has a positive response to the tuberculin skin test and no symptoms of the disease, chest radiographs can be used to rule out the possibility of pulmonary TB. CDC guidelines for evaluating CXR The chest X-ray and classification worksheet by the Centers for Disease Control and Prevention (CDC) of the United States is designed to group findings into categories based on their likelihood of being related to TB or non-TB conditions needing medical follow-up. Normal findings These are films that are completely normal, with no identifiable cardiothoracic or musculoskeletal abnormality. Abnormal findings Chest X-ray findings that can suggest active TB This category comprises all findings typically associated with active pulmonary TB. In the US, refugees or immigration applicants with any of the following findings must submit sputum specimens for examination. 1. Infiltrate or consolidation - Opacification of airspaces within the lung parenchyma. Consolidation or infiltrate can be dense or patchy and might have irregular, ill-defined, or hazy borders. 2. Any cavitary lesion - Lucency (darkened area) within the lung parenchyma, with or without irregular margins that might be surrounded by an area of airspace