Radiation-Induced Pulmonary Injury after Cyberknife Radiosurgery for Lung Malignancy: CT Appearance

Abstract

Copyrights © 2011 The Korean Society of Radiology Purpose: To evaluate the CT appearance of radiation-induced pulmonary injury in patients who have undergone cyberknife radiosurgery for lung malignancy. Materials and Methods: Thirty-four patients with 39 malignant lung tumors who underwent cyberknife radiosurgery were enrolled for evaluation. A total of 24-60 Gy was administered in 3 fractions. We evaluated the CT appearance of radiation pneumonitis and radiation fibrosis. We also evaluated the location of radiation pneumonitis and the minimal dose which causes radiation pneumonitis. Results: Radiation pneumonitis and radiation fibrosis occurred in 95% and 90% of cases, respectively. CT patterns of radiation pneumonitis demonstrated 20 cases (54%) as ground glass opacities (GGO). GGO included only 7 cases (19%), while 6 cases (16%) had patchy consolidations and 4 cases (11%) were diffuse consolidations, respectively. Radiation pneumonitis demonstrated 30 cases (81%) as concentric patterns surrounding the tumor, while 7 cases (19%) included the eccentric patterns. The radiation pneumonitis appeared within the 13-38 Gy (mean 21 Gy). CT findings of radiation fibrosis demonstrated as the modified conventional patterns, which decreased to 17 cases (65%), while 7 cases (27%) had mass-like patterns and 2 cases (8%) had scar-like patterns, respectively. Conclusion: Radiation pneumonitis after cyberknife radiosurgery commonly develops as concentric patterns surrounding a tumor. The mass-like pattern of radiation fibrosis was sometimes difficult to distinguish from tumor recurrence. Thus, knowledge of the CT finding of radiation-induced lung injury might be helpful in distinguishing pulmonary changes from tumor recurrence. Index terms Neoplasm, Lung Radiation Injuries CT Stereotactic Radiosurgery Radiation-Induced Pulmonary Injury after Cyberknife Radiosurgery for Lung Malignancy: CT Appearance 악성 폐종양의 사이버나이프 방사선수술 후 방사선 폐손상의 CT 소견