Dose–response relationship for radiation-induced pneumonitis after pulmonary stereotactic body radiotherapy

• Published in: Radiotherapy and oncology 2010-10, Vol.97 (1), p.65-70
• Main Authors: Guckenberger, Matthias, Baier, Kurt, Polat, Buelent, Richter, Anne, Krieger, Thomas, Wilbert, Juergen, Mueller, Gerd, Flentje, Michael
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - radiotherapy; Adult; Aged; Aged, 80 and over; Carcinoma, Squamous Cell - radiotherapy; Chi-Square Distribution; Cone-Beam Computed Tomography; Dose Fractionation; Dose-Response Relationship, Radiation; Female; Hematology, Oncology and Palliative Medicine; Humans; Image-guided radiotherapy (IGRT); Lung Neoplasms - radiotherapy; Lung Neoplasms - secondary; Male; Mean lung dose; Middle Aged; Monte Carlo Method; Non-small cell lung cancer; Radiation Pneumonitis - etiology; Radiation-induced pneumonitis; Radiography, Interventional; Radiosurgery - adverse effects; Radiotherapy Dosage; Retrospective Studies; Risk Factors; Statistics, Nonparametric; Stereotactic body radiotherapy (SBRT)
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2010.04.027

Abstract Purpose To evaluate dosimetric factors predictive for radiation-induced pneumonitis (RP) after pulmonary stereotactic body radiotherapy (SBRT). Materials and methods A retrospective analysis was performed based on 59 consecutive patients treated with cone-beam CT-based image-guided SBRT for primary NSCLC ( n = 21) or pulmonary metastases ( n = 54). The majority of patients were treated with radiosurgery of 26 Gy to 80% ( n = 29) or three fractions of 12.5 Gy to 65% ( n = 40). To correct for different single fraction doses, local doses were converted to 2 Gy equivalent normalized total doses (NTDs) using α/β ratio of 3 Gy for RP. Dose–volume parameters and incidences of RP ⩾ grade II SWOG were fitted using NTCP models. Results Eleven patients developed RP grade II. With an average MLD of 10.3 ± 5.6 Gy to the ipsilateral lung, a significant dose–response relationship was observed: the MLD was 12.5 ± 4.3 Gy and 9.9 ± 5.8 Gy for patients with and without development of RP, respectively. Additionally, volumes of the lung exposed to minimum doses between 2.5 and 50 Gy ( V2.5 – V50 ) were correlated with incidences of RP with a continuous decrease of the goodness of fit for higher doses. Conclusions The MLD and V2.5 – V50 of the ipsilateral lung were correlated with incidences of RP after pulmonary SBRT.