ObjectiveTo determine whether dual-energy computed tomography (DECT) of the chest can
be performed at a reduced radiation dose, with an emphasis on images
generated with post-processing techniques.Materials and MethodsIn 21 patients undergoing DECT of the chest in a dual-source scanner, an
additional image series was acquired at a reduced radiation dose. Four
thoracic radiologists assessed both image series for image quality, normal
thoracic structures, as well as pulmonary and mediastinal abnormalities, on
virtual monochromatic images at 40 keV and 60 keV. Data were analyzed with
Student's t-test, kappa statistics, analysis of variance, and the Wilcoxon
signed-rank test.ResultsThe overall image quality of 60 keV virtual monochromatic images at a reduced
radiation dose was considered optimal in all patients, and no abnormalities
were missed. Contrast enhancement and lesion detection performance were
comparable between reduced-dose images at 40 keV and standard-of-care images
at 60 keV. The intraobserver and interobserver agreement were both good. The
mean volumetric CT dose index (CTDIvol), size-specific dose estimate (SSDE),
dose-length product (DLP), and effective dose (ED) for reduced-dose DECT
were 3.0 ± 0.6 mGy, 4.0 ± 0.6 mGy, 107 ± 30 mGy.cm, and
1.5 ± 0.4 mSv, respectively.ConclusionDECT of the chest can be performed at a reduced radiation dose (CTDIvol <
3 mGy) without loss of diagnostic information.