Imaging of local recurrence of lung cancer after radiation therapy

Local recurrences in 7 patients with lung cancer who have undergone prior chest irradiation of about 50 ∼ 70 Gy were observed. It is often difficult to distinguish radiation fibrosis from recurrent tumor or residual tumor. The most useful imaging modality was computed tomography, in which newly developed descrete mass or focal cavitation was recognized around the area of radiation fibrosis. On chest X-ray, the findings of increased opacity within the radiation fibrosis and soft tissue mass density crossing over the linear lateral margin of the radintion field were significant. On Ga scan image, more intense abnormal accumulation than that of radiation fibrosis would be significant findings to detect recurrent neoplasm. (author)