Abstract
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.
Highlights
The concept of dual-energy computed tomography (DECT) is almost as old as the CT technology itself, DECT initially required substantially higher radiation doses and presented problems associated with spatial misregistration of the two different kV image datasets between the two separate acquisitions[1]
We found no significant difference in image noise between the standard-of-care and reduced-dose
In patients with a body mass index (BMI) < 32 kg/m2, DECT of the chest can be performed at reduced doses without a loss of diagnostic information
Summary
The concept of dual-energy computed tomography (DECT) is almost as old as the CT technology itself, DECT initially required substantially higher radiation doses (nearly two times higher than that employed in single-energy CT) and presented problems associated with spatial misregistration of the two different kV image datasets between the two separate acquisitions[1]. In the 1990s, there was renewed interest in DECT for the characterization of solitary pulmonary nodules, several studies highlighting the value of DECT over single-energy CT techniques[2]. Technological advances in multidetector CT have enabled near simultaneous acquisition of DECT datasets, and some authors have reported that DECT can be performed at radiation doses similar to those employed in single-energy CT[5]. Recent studies have reported that the post-processing of DECT images (the synthesis of virtual monochromatic images and the use of material separation techniques) is useful in the assessment of the lung parenchyma and of pulmonary embolisms[8,9]
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