
<b>Lung</b>
 
Radiation therapy produces dramatic effects in the lung. Radiation pneumonitis [lung inflammation] can be a major complication for patients receiving chest irradiation. Pulmonary necrosis is an uncommon, severe, late complication of adjuvant postoperative irradiation. Bronchiolitis obliterans with organizing pneumonia is a distinct separate entity characterized by patchy, migratory, peripheral air-space infiltrates. Radiation therapy can also cause spontaneous pneumothorax, mesothelioma, and lung cancer.

Acute radiation-induced pulmonary effects on Xray and CT scan must be differentiated from malignancies and other abnormalities. The CT scan results from acute radiation to the chest were lung opacities in an irregular pattern within the radiation beam boundaries. There was increased lung density, loss of lung volume, and pleural thickening. Sharply defined nodular opacities are atypical of radiation damage. Confinement of the findings within the irradiated volume was the only specific characteristic of post-irradiation changes.
 
For the lung, the blood flow was the function most affected by radiation. In some cases in which the Xray changes were mild, the functional measurements indicated severe vascular damage. The radiation appears to reduce the number and efficiency of functioning lung units within the irradiated region. 