| Abstract | The respiratory functions of the lung consist of ventilation, diffusion and perfusion, processes which result in the exchange of carbon dioxide for oxygen in the environment. Other functions are of a supporting nature and are non-respiratory. These include cough, ciliary activity, mucus secretion, and alveolar phagocytosis. The respiratory functions in particular have been studied by a variety of techniques. For example pulmonary blood flow has been measured by direct Fick, dye-dilution and body-plethysmographic methods. A reasonable question is what radioisotope methods provide that is new in the study of pulmonary diseases? What new role do these techniques play in the evaluation of lung function? The important contribution that these techniques have made is that they permit evaluation of lung function in particular regions of the lung. They make possible measurement of regional pulmonary blood flow, regional ventilation and clearance of particulate matter from various regions of the tracheobronchial tree and alveoli, using techniques made possible by the ability of gamma radiation to penetrate the body and be detected by externally-placed scintillation detectors. |
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