Computed tomography of bronchogenic carcinoma: findings and reevaluation after radiotherapy.

493 computed tomograms were performed in 150 patients with bronchogenic carcinomas after radiotherapy. In early controls after termination of the irradiation, tumors with atelectasis could be delineated slightly better. In tumors without atelectasis, however, delineation deteriorated. In 50 late controls the radiation-induced pulmonary injury resulted in further masking of the tumor area, independent of the initial degrees of airway obstruction. Post-radiation changes were always earlier and more extensively visible by CT than by conventional radiography. No radiation effect on delineation of the mediastinal lymph nodes was provable. In 87% of all cases the remission rate of the tumors could be adequately evaluated by CT. In 43% of the late controls a delayed complete remission was seen. Fifteen out of 20 tumor recurrences or progressions were recognizable only by CT. The most important diagnostic criteria after radiotherapy of bronchogenic carcinomas are: 1. Consideration of the irradiation modalities and timing of the CT examination. 2. knowledge about the course of the pulmonary reaction to irradiation and 3. subtle comparisons of serial CT examinations in tumor follow-up.