Projected lung area using dynamic X-ray (DXR) with a flat-panel detector system and automated tracking in patients with chronic obstructive pulmonary disease (COPD)

Assessment of pulmonary function in COPD patients using dynamic digital radiography: A novel approach utilizing lung signal intensity changes during forced breathing

“…Healthy volunteers took several tidal breaths followed by one forced breath, while COPD patients took tidal breaths and a forced breath separately. Imaging parameters for DDR were almost the same as the previous reports [16] , [18] : tube voltage, 100 kV; tube current, 50 mA; pulse duration of pulsed X-ray, 1.6 ms; source-to-image distance, 2 m; additional filter, 0.5 mm Al plus 0.1 mm Cu. The additional filter was used to remove soft X-rays.…”

“…The multivariate linear regression analysis revealed significant differences in the SImax/SImin between the severe COPD and the normal groups, as well as between the severe COPD and the mild groups. While multiple studies to date have demonstrated the utility of quantitative DDR markers in assessing pulmonary function in COPD patients [10] , [12] , [14] , [16] , [17] , [18] , [20] , [23] , this is the first report to focus on the signal intensity changes of the entire lung fields on DDR images in COPD patients and investigate the correlation with PFT parameters and the differences by disease severity.…”

“…The contour extraction was performed using prototype software with standard settings (Konica Minolta Inc., Tokyo, Japan) installed in a standalone workstation (Operating system: Windows 7 Professional 64-bit Service Pack 1; Microsoft, Redmond WA; CPU: Intel® CoreTM i5–6500, 3.20 GHz; random access memory, 16 GB). Lung contour detection was fully automated, and the accuracy and reproducibility of contour extraction in a previous study [18] . The average signal intensity values within the corresponding lung contour on gray-scale images were calculated on all image frames.…”

“…Dynamic digital radiography (DDR) is a novel functional imaging technique that utilizes sequential images obtained by a pulsed X-ray generator and a flat panel detector (FPD) with a large field of view and can be used in routine clinical practice [8] , [9] , [10] . DDR can not only quantitatively assess pulmonary ventilation and perfusion but also offer a non-invasive and comprehensive evaluation of pulmonary function, potentially impacting clinical practice significantly [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] . Previous studies have focused on the dynamic changes in X-ray translucency of the lung fields during respiration, which mainly reflect the changes of air volume inside the alveoli.…”

“…However, limited research has examined the utility in assessing pulmonary function in COPD patients [23] . Recently, we developed a fully automated software that continuously contours and tracks lung fields during the examination [18] , facilitating the measurement of average signal intensity changes of entire lung fields on DDR images during respiration.…”