title: Intra-individual diagnostic image quality and organ-specific-radiation dose comparison between spiral cCT with iterative image reconstruction and z-axis automated tube current modulation and sequential cCT.
abstract: OBJECTIVE
  To prospectively evaluate image quality and organ-specific-radiation dose of spiral cranial CT (cCT) combined with automated tube current modulation (ATCM) and iterative image reconstruction (IR) in comparison to sequential tilted cCT reconstructed with filtered back projection (FBP) without ATCM.
  
  
  METHODS
  31 patients with a previous performed tilted non-contrast enhanced sequential cCT aquisition on a 4-slice CT system with only FBP reconstruction and no ATCM were prospectively enrolled in this study for a clinical indicated cCT scan. All spiral cCT examinations were performed on a 3rd generation dual-source CT system using ATCM in z-axis direction. Images were reconstructed using both, FBP and IR (level 1-5). A Monte-Carlo-simulation-based analysis was used to compare organ-specific-radiation dose. Subjective image quality for various anatomic structures was evaluated using a 4-point Likert-scale and objective image quality was evaluated by comparing signal-to-noise ratios (SNR).
  
  
  RESULTS
  Spiral cCT led to a significantly lower (p < 0.05) organ-specific-radiation dose in all targets including eye lense. Subjective image quality of spiral cCT datasets with an IR reconstruction level 5 was rated significantly higher compared to the sequential cCT acquisitions (p < 0.0001). Consecutive mean SNR was significantly higher in all spiral datasets (FBP, IR 1-5) when compared to sequential cCT with a mean SNR improvement of 44.77% (p < 0.0001).
  
  
  CONCLUSIONS
  Spiral cCT combined with ATCM and IR allows for significant-radiation dose reduction including a reduce eye lens organ-dose when compared to a tilted sequential cCT while improving subjective and objective image quality.
authors: Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Holger
authors: H
authors: Wenz
authors: Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Máté E
authors: ME
authors: Maros
authors: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Mathias
authors: M
authors: Meyer
authors: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Joshua
authors: J
authors: Gawlitza
authors: Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Alex
authors: A
authors: Förster
authors: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Holger
authors: H
authors: Haubenreisser
authors: Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Stefan
authors: S
authors: Kurth
authors: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Stefan O
authors: SO
authors: Schoenberg
authors: Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Christoph
authors: C
authors: Groden
authors: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany.
authors: Thomas
authors: T
authors: Henzler
keywords: ASPECTS, Alberta Stroke Program Early CT score; ATCM, automated tube current modulation; Automatic tube current modulation; DSCT, dual-source computed tomography; FBP, filtered back projection; HU, hounsfield units; ICRP, International Commission on Radiological Protection; IR, iterative image reconstruction; Iterative reconstruction; MDCT, multi-detector computed tomography; NC, caudate nucleus; ND, normally distributed data; NI, non-inferiority analysis; Organ-specific-radiation dose; SNR, signal-to-noise ratios; Sequential cranial CT; Spiral cranial CT; WM, white matter; cCT, cranial CT; cCT, cranial computed tomography