BackgroundThe purpose of the study was to design and pilot a synoptic scale for characterization of late radiographic changes after lung stereotactic body radiotherapy (SBRT). Patients and MethodsA participatory design process involving 6 radiation oncologists and 2 thoracic radiologists was used in the scale's design. Seventy-seven early-stage non–small-cell lung cancer patients who were treated with SBRT were included, and after treatment their serial computed tomography (CT) images were scored by 6 radiation oncologists. Gwet's First-order Agreement Coefficient (AC1) and a leave-one-out (LOO) analysis was used to assess interrater reliability and variability among raters, respectively. ResultsThe scale reports on 5 independent categories including “tumor in primary site,” “tumor in involved lobe,” “consolidation,” “volume loss,” and “ground-glass or interstitial changes.” At each time point, each category is reported as “increased,” “stable,” “decreased,” “obscured,” or “not present,” compared with the previous. The total number of rated images for the pilot ranged from 450 at 6 months to 84 at 48 months. The primary tumor site was scored as obscured in 38% to 40% of ratings from 12 months onward; 3% to 5% of primary tumors were scored as “increased.” Consolidation, volume loss, and ground-glass or interstitial changes were increasingly marked as “stable” with time. At 24 months, AC1 was 0.28 (LOO, 0.22-0.42), 0.47 (LOO, 0.39-0.72), 0.45 (LOO, 0.42-0.50), 0.21 (LOO, 0.15-0.26), and 0.25 (LOO, 0.20-0.38) for the 5 categories listed, respectively. ConclusionIn a population of clinicians, this scale could be implemented to characterize evolving lung changes after SBRT, and had fair to moderate interrater agreement. Obscured tumor site is a common challenge of follow-up CT imaging, and new imaging techniques should be explored. This scale provides a tool for communicating changes after SBRT.
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