Radiographic chest assessment of lung injury following hemithorax irradiation for pleural mesothelioma.

To characterize the nature, extent and time-course of radiation-induced lung injury, and to evaluate the usefulness of serial chest radiographs in this assessment, we studied 253 chest radiographs of 46 patients with pleural mesothelioma given hemithorax irradiation according to one of four different regimens: I 20 Gy; II 55 Gy; III hyperfractionation 70 Gy; IV hyperfractionation 35 Gy followed by local hypofractionation 36 Gy. Lung injury on the chest radiograph was graded from 0 (none) to V (maximal) based on the degree of loss of aerated lung tissue. Grade I changes were present 1-2 mths after radiotherapy in regimens II-IV. Grade V injury had developed in all but 3 out of 4 patients of the 20 Gy group by 6-12 months after irradiation. The extent and time-course of radiation-induced lung injury could be defined by serial chest radiographs alone. However, the documentation of tumour status and/or infections needed additional imaging or laboratory investigation, especially when grade IV-V lung injury was present. For research protocols evaluating radiation-induced lung injury serial chest X-rays are recommended at the following time-points: before treatment and 2, 6 and 12 mths after treatment, with additional computerized tomographic (CT) scans as required for differential diagnosis.