[Computed tomographic determination of the target volume and the evaluation of remission after radiation of bronchial carcinoma]

434 CT examinations of 133 patients with histologically proven bronchogenic carcinoma (22 out of 133 with small cell lung cancer) were analysed before and after radiotherapy. The study evaluates the use of CT for determining target volume, tumour volume and remission rate: 1. Concerning determination of target volume conventional roentgen diagnostic simulator methods are much inferior to CT aided planning: as for our patients changes of the target volume were necessary in 50%, in 22% the changes were crucial. This happened more often in non-small cell lung cancer than in small cell carcinomas. 2. The response rate (CR + PR) after radiotherapy (based on the calculated tumour volumes by CT) was 70 to 80%. The rate of CR of the primary was 45% (non-small cell carcinoma) and 67% (small cell carcinoma). 3. The crucial point for the evaluation of tumour remission after radiotherapy is the point of time. One to three months and four to nine months after irradiation we found complete remissions in 19% and 62%, respectively. Hence, the evaluation of treatment results earlier than three months after radiotherapy may be incorrect. We deem it indispensable to use CT for determination of target, calculation of dose distribution and accurate evaluation of tumour remission and side effects during and after irradiation of patients with bronchogenic carcinoma.