Fig. 2.
59-year-old male with squamous cell carcinoma. a Axial CT image of the lung window showing an oval mass in the right lower lobe. b–d Axial CT images of the mediastinal window in non-contrast-enhanced scanning (b) and arterial phase (c), and artificial color map of iodine concentration in venous phase (d) showing internal necrosis with ring enhancement. e An effective atomic number image showing that the effective atomic number for necrosis in non-contrast-enhanced scanning is 7.63. f The gradually declining spectral curve for necrosis in non-contrast-enhanced scanning showing a K40–65 keV of 0.24