title: How far can the radiation dose be lowered in head CT with iterative reconstruction? Analysis of imaging quality and diagnostic accuracy.
abstract: OBJECTIVE
  To evaluate the imaging quality of head CT at lowered radiation dose by combining filtered back projection (FBP) and iterative reconstruction (IR) algorithms.
  
  
  METHODS
  Experimental group A (n = 66) underwent CT with 43 % tube current reduction, and group B (n = 58) received an equivalent reduced dose by lowering the tube voltage. An age- and sex-matched control group (n = 72) receiving the conventional radiation dose was retrospectively collected. Imaging for the control group was reconstructed by FBP only, while images for groups A and B were reconstructed by FBP and IR. The signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), sharpness, number of infarcts and severity of subcortical arteriosclerotic encephalopathy (SAE) were compared to assess imaging quality and diagnostic accuracy.
  
  
  RESULTS
  There were no significant differences in SNRs and CNRs between group A and the control group. There were significantly decreased SNRs and increased CNRs in group B. Image sharpness decreased in both groups. Correlations between detected infarcts and severity of SAE across FBP and IR were high (r = 0.73-0.93). Head diameter was the only significant factor inversely correlated with infratentorial imaging quality.
  
  
  CONCLUSIONS
  Head CT with 43 % reduced tube current reconstructed by IR provides diagnostic imaging quality for outpatient management.
  
  
  CONCLUSIONS
  • Cranial CT using iterative reconstruction provides diagnostic images with 43 % mAs reduction. • Blurring of infratentorial images becomes evident using low-radiation head CT. • Head diameter was inversely correlated with imaging quality in the infratentorium. • Lowering tube kilovoltage requires a higher radiation dose to maintain image quality.
authors: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
authors: Tung-Hsin
authors: TH
authors: Wu
authors: Sheng-Che
authors: SC
authors: Hung
authors: Jing-Yi
authors: JY
authors: Sun
authors: Chung-Jung
authors: CJ
authors: Lin
authors: Chung-Hsien
authors: CH
authors: Lin
authors: Chen Fen
authors: CF
authors: Chiu
authors: Min-Jsuan
authors: MJ
authors: Liu
authors: Michael Mu Huo
authors: MM
authors: Teng
authors: Wan-Yuo
authors: WY
authors: Guo
authors: Cheng-Yen
authors: CY
authors: Chang
mesh_terms: D000368:Aged; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D015588:Observer Variation; D010045:Outpatients; D015995:Prevalence; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012542:Scattering, Radiation; D059629:Signal-To-Noise Ratio; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
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