Radiation pneumonitis is an important cause of morbidity after concurrent thoracic chemoradiotherapy (CCRT). However, asymptomatic changes in lung density on computed tomography (CT)-scans occur more commonly, and correspond to regions of inflammatory changes. Characterization of dose- and time-related changes in radiological lung density (RLD) may facilitate improved radiation planning, and allow for a more objective measure for assessing damage. We studied changes in RLD following CCRT with cisplatin-etoposide, using deformable registration to co-register follow-up scans. All CT-scans performed for up to 24 months post-treatment were evaluated in 25 patients treated with CCRT for stage III non-small-cell lung cancer. A total of 104 scans (median of 3 per patient) were co-registered with planning scans using a deformable registration tool (VelocityAI, Atlanta, USA). Last follow-up scan was at median 9.4 months (range 3.4-22.6 months). Seven patients developed clinical radiation pneumonitis. RLD changes (in Hounsfield units) were measured in regions receiving 3-66. Gy. Linear mixed models were used to study dose-density changes over time. No significant changes in RLD were observed in the first 3 months post-treatment. Increases in RLD were observed at 3-6 months (p<0.0001) and 6-12 months (p=0.006), but stabilized at 1 year. Increases were most evident in regions receiving >30. Gy, with only minor density changes at lower dose levels. Planning target volume size was significantly associated with RLD changes (p=0.03). Limiting lung doses to ≤30. Gy during CCRT may limit sub-clinical damage, and the time-course of RLD changes may allow for early quantification of pulmonary damage when evaluating novel treatment strategies.
- Concurrent chemoradiotherapy
- Lung cancer
- Radiation-induced lung disease
- Toxicity scoring
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cancer Research