title: Initial Results of a Single-Source Dual-Energy Computed Tomography Technique Using a Split-Filter: Assessment of Image Quality, Radiation Dose, and Accuracy of Dual-Energy Applications in an In Vitro and In Vivo Study.
abstract: The aim of this study was to investigate the image quality, radiation dose, and accuracy of virtual noncontrast images and iodine quantification of split-filter dual-energy computed tomography (CT) using a single x-ray source in a phantom and patient study.
  
  
  
  In a phantom study, objective image quality and accuracy of iodine quantification were evaluated for the split-filter dual-energy mode using a tin and gold filter. In a patient study, objective image quality and radiation dose were compared in thoracoabdominal CT of 50 patients between the standard single-energy and split-filter dual-energy mode. The radiation dose was estimated by size-specific dose estimate. To evaluate the accuracy of virtual noncontrast imaging, attenuation measurements in the liver, spleen, and muscle were compared between a true noncontrast premonitoring scan and the virtual noncontrast images of the dual-energy scans. Descriptive statistics and the Mann-Whitney U test were used.
  
  
  
  In the phantom study, differences between the real and measured iodine concentration ranged from 2.2% to 21.4%. In the patient study, the single-energy and dual-energy protocols resulted in similar image noise (7.4 vs 7.1 HU, respectively; P = 0.43) and parenchymal contrast-to-noise ratio (CNR) values for the liver (29.2 vs 28.5, respectively; P = 0.88). However, the vascular CNR value for the single-energy protocol was significantly higher than for the dual-energy protocol (10.0 vs 7.1, respectively; P = 0.006). The difference in the measured attenuation between the true and the virtual noncontrast images ranged from 3.1 to 6.7 HU. The size-specific dose estimate of the dual-energy protocol was, on average, 17% lower than that of the single-energy protocol (11.7 vs 9.7 mGy, respectively; P = 0.008).
  
  
  
  Split-filter dual-energy compared with single-energy CT results in similar objective image noise in addition to dual-energy capabilities at 17% lower radiation dose. Because of beam hardening, split-filter dual-energy can lead to decreased CNR values of iodinated structures.
authors.affiliation: From the *Clinic of Radiology and Nuclear Medicine, University Hospital Basel, Basel, Switzerland; †Siemens Healthcare, Forchheim, Germany; and ‡Department of Diagnostic Radiology, Hospital Center of Biel, Biel, Switzerland.
authors.forename: André
authors.initials: A
authors.lastname: Euler
authors.forename: Anushri
authors.initials: A
authors.lastname: Parakh
authors.forename: Anna L
authors.initials: AL
authors.lastname: Falkowski
authors.forename: Sebastian
authors.initials: S
authors.lastname: Manneck
authors.forename: David
authors.initials: D
authors.lastname: Dashti
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szucs-Farkas
authors.forename: Sebastian T
authors.initials: ST
authors.lastname: Schindera
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007455:Iodine; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011860:Radiography, Abdominal / Q000379:methods; D015900:Radiography, Dual-Energy Scanned Projection / Q000295:instrumentation / Q000379:methods; D013902:Radiography, Thoracic / Q000379:methods; D015203:Reproducibility of Results; D013154:Spleen / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*
chemical_list: D007455:Iodine