Which medical term refers to the collapse of a lung?

Atelectasis specifically refers to the collapse of a lung or a portion of a lung where the alveoli become deflated or filled with fluid. This condition can occur due to various reasons, such as obstruction of the airways, pressure from pleural effusion, or surfactant deficiency. Understanding atelectasis is crucial in radiologic technology, as it can be identified on imaging studies, where the affected area of the lung may appear denser or more opaque compared to healthy lung tissue.

In contrast, pneumothorax is the presence of air in the pleural cavity, which can also lead to lung collapse but is not synonymous with atelectasis. Hemothorax involves blood in the pleural space, while empyema refers to the accumulation of pus in the pleural cavity. Each of these terms describes different pathological conditions that can affect lung function and appearance on radiologic images.