title: Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise.
abstract: OBJECTIVE
  The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT) by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP) and an iterative reconstruction (IR) algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany) was investigated.
  
  
  METHODS
  136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP), SOMATOM Definition Flash (IR), and SOMATOM Definition Edge (ICD and IR). Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product.
  
  
  RESULTS
  Dose-length product (DLP) with FBP for the average chest CT was 308 mGy*cm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGy*cm ± 68.8 (P = 0.0001). Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGy*cm ± 54.5 (P = 0.033). The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR) was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048). Overall contrast-to-noise ratio (CNR) improved with declining DLP.
  
  
  CONCLUSIONS
  The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations.
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Ebner
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Knobloch
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Huber
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Julia
authors.initials: J
authors.lastname: Landau
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ott
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Johannes T
authors.initials: JT
authors.lastname: Heverhagen
authors.affiliation: Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Christe
keywords: Dose reduction; low-dose CT; stellar detector