Room: AAPM ePoster Library
Purpose: such as chronic obstructive pulmonary disease(COPD) primarily affect small airways. The purpose of this study was to assess small airway dimensions using high-resolution computed tomography (CT) as compared with standard resolution CT.
Methods: 10-cm diameter cylindrical polyurethane phantom, with 14 silicone tubes of different dimensions, was placed inside an anthropomorphic thorax phantom. The inner diameters (ID) of the tubes were in the range of 0.3 – 3.4 mm and wall thicknesses (WT) ranged from 0.15 – 1.6 mm. A high resolution CT scanner (Aquilion Precision, Canon Medical) was used to acquire images of the phantom in both super high resolution “SHR” (0.25 x 0.25 mm detector configuration) and normal resolution “NR” (0.5 x 0.5 mm) acquisition modes at 80, 100, 120, 140 kV. Filtered back projection and a hybrid iterative algorithm were used with several different kernels for reconstruction. The ID and WT were measured using an automated full-width half-maximum (FWHM) method.
Results: the tubing with ID>2mm, the mean error for NR and SHR modes was measured to be 0.12 ± 0.05 mm (4.54%) and 0.26 ± 0.08 mm (9.83%), respectively. For the tubing with ID<2mm, the mean error for NR and SHR modes was measured to be 0.30 ± 0.08 mm (33.8%) and 0.15 ± 0.05 mm (17.1%), respectively. For the WT measurement, the overall accuracy of SHR was significantly improved as compared with NR mode, with a root-mean-square error (RMSE) of 0.29 and 0.44 mm, respectively, and a mean error of 0.25 ± 0.06 mm (70.5%) and 0.39 ± 0.07 mm (108.1%), respectively. The CTDI_vol values were in the range of 0.2-6.2mGy.
Conclusion: CT can provide more accurate measurement of airway dimensions as compared with normal resolution CT, which can potentially improve quantitative assessment of pathologies such as COPD.