Figure 3b. Nodular radiation pneumonitis in a 65-year-old woman with adenocarcinoma of the left lower lobe and left hilar and mediastinal adenopathy. (a) CT scan obtained before treatment shows a mass in the left lower lobe. (b) CT scan obtained 5 months after completion of radiation therapy shows a decrease in the size of the tumor and a new nodular area of increased attenuation in the left lower lobe (arrow). The nodular area of increased attenuation is due to radiation injury. (c) CT scan obtained 9 months after completion of radiation therapy shows evolution to fibrosis, with coalescence of the nodular area of increased attenuation and the residual tumor.