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Background: Although the bismuth breast shield can reduce radiation exposure to the breast during dual-energy computed tomography (DECT), it can potentially affect material quantification on DECT due to artifacts.Purpose: To evaluate the effects of bismuth breast shielding on iodine quantification and radiation exposure in DECT.Material and Methods: Small balloons were made with 0.2%, 0.6% and 1.0% blended iodinated contrast (370 mg/mL of iodine) with water. The balloons were located at both anterior and posterior lungs in an adult anthropomorphic chest phantom. DECT was performed with and without breast shielding. Afterwards, iodine concentration values were measured for each balloon on the iodine maps. Absorbed radiation doses in the breast were measured with the optically stimulated luminescence dosimeter.Results: After shielding, we obtained significantly decreased iodine quantification for all three concentrations with 0.78 ± 0.13 to 0.46 ± 0.13 mg/mL, 2.31 ± 0.17 to 1.68 ± 0.19 mg/mL, and 3.82 ± 0.10 to 2.84 ± 0.20 mg/mL at the anterior location, and 0.72 ± 0.11 to 0.48 ± 0.09 mg/mL, 2.24 ± 0.13 to 1.87 ± 0.21 mg/mL, and 3.75 ± 0.16 to 3.15 ± 0.14 mg/mL at the posterior location for the 0.2%, 0.6%, and 1.0% balloons, respectively ( P = 0.001 for all). After shielding, absorbed radiation doses to the breast significantly decreased by 14.8% (4.32 ± 0.33 to 3.68 ± 0.30 mGy; P = 0.005).Conclusion: Although using the bismuth breast shield may decrease radiation exposure to the breast on DECT, it may also significantly affect iodine quantification. [ABSTRACT FROM AUTHOR]

Background: Lung cancers are occasionally detected on coronary artery calcium (CAC)-scoring computed tomography (CT). However, the cause of delayed diagnosis and prognostic factors have not been studied. Purpose: To investigate the causes of delayed diagnosis of lung cancer in patients who undergo CAC-scoring CT and to identify predictors of mortality. Material and Methods: A total of 151 patients who were diagnosed with lung cancer and had undergone CAC-scoring CT from January 2010 to December 2014 were retrospectively enrolled. The reasons for delayed diagnosis were reviewed. Follow-up data on all-cause mortality were obtained. Cox proportional hazards regression analysis was used to identify predictors of mortality. Analyses of solid and subsolid subgroups were performed. Results: Among the 151 patients, 86 lesions (56.9%) were solid and 63 (41.7%) were subsolid. The main causes of delayed diagnosis were detection (48%) and interpretation (22%) errors. Age, size, unresectable stage at the time of diagnosis, and stage shift were independent prognostic factors throughout the entire and in the solid subgroup (all P < 0.2). There were no significant prognostic factors in the subsolid subgroup. Conclusion: In conclusion, avoidance of detection and interpretation errors may prevent delayed diagnosis of lung cancer on CAC-scoring CT. Older age, larger tumor size, unresectable stage at the time of diagnosis, and stage shift were associated with poor survival in patients with solid lung cancers but not in those with subsolid lung cancers. [ABSTRACT FROM AUTHOR]