Early and late CT findings following SBRT for lung tumors: Analysis of a monoinstitutional series.

Aims: Radiological lung density changes are commonly observed in patients undergoing SBRT. Early changes include consolidation and ground glass opacities, while late changes include fibrosis, bronchiectasis, loss of lung volume and further consolidation. This study retrospectively analyzed a monoinstitutional series of patients treated with lung SBRT and correlated the CT findings with a number of clinical and dosimetric parameters. Methods: Between December 2016 and March 2021 sixty patients with seventy primary or secondary lung lesions, were treated on a Linac platform with a VMAT technique to a BED10 ≥100 Gy. Patients, disease and treatment characteristics are summarized in Table 1. In order to describe the radiological findings over time, the follow-up was divided into two periods: early (within 6 months) (n=70) and late (> 6 months) (n=43) time after treatment. All the CTs were double-checked by 2 experienced radiation oncologists. Radiation-induced lung injuries were evaluated according to Ikezoe and Koening classification, respectively. The correlation between the CT pattern and clinical and dosimetric parameters was evaluated. Results: Median follow up was 9.6 months (1.5-26.8). Among the 70 CT examined at early time after SBRT, 31 had no evidence of increased density, 13 had diffuse consolidation, 11 had patchy consolidation, 8 had diffuse ground glass opacities, 6 had patchy ground glass and 1 had signs of progression. Late lung injuries were mass like pattern (20), modified conventional pattern (5), scar-like pattern (10). Eight lesions showed signs of progression. Neither clinical nor dosimetric characteristics were found to be significantly associated with a specific CT pattern, either in the early or late timeframe. Likewise, no significant correlation was found between early and late changes. Conclusion: Lung injuries represented common radiological findings after SBRT, irrespective of clinical symptoms. We found n [ABSTRACT FROM AUTHOR]