Pediatric Radiology

, Volume 46, Issue 3, pp 303–315 | Cite as

Knowledge-based iterative model reconstruction: comparative image quality and radiation dose with a pediatric computed tomography phantom

  • Young Jin Ryu
  • Young Hun ChoiEmail author
  • Jung-Eun Cheon
  • Seongmin Ha
  • Woo Sun Kim
  • In-One Kim
Original Article



CT of pediatric phantoms can provide useful guidance to the optimization of knowledge-based iterative reconstruction CT.


To compare radiation dose and image quality of CT images obtained at different radiation doses reconstructed with knowledge-based iterative reconstruction, hybrid iterative reconstruction and filtered back-projection.

Materials and methods

We scanned a 5-year anthropomorphic phantom at seven levels of radiation. We then reconstructed CT data with knowledge-based iterative reconstruction (iterative model reconstruction [IMR] levels 1, 2 and 3; Philips Healthcare, Andover, MA), hybrid iterative reconstruction (iDose4, levels 3 and 7; Philips Healthcare, Andover, MA) and filtered back-projection. The noise, signal-to-noise ratio and contrast-to-noise ratio were calculated. We evaluated low-contrast resolutions and detectability by low-contrast targets and subjective and objective spatial resolutions by the line pairs and wire.


With radiation at 100 peak kVp and 100 mAs (3.64 mSv), the relative doses ranged from 5% (0.19 mSv) to 150% (5.46 mSv). Lower noise and higher signal-to-noise, contrast-to-noise and objective spatial resolution were generally achieved in ascending order of filtered back-projection, iDose4 levels 3 and 7, and IMR levels 1, 2 and 3, at all radiation dose levels. Compared with filtered back-projection at 100% dose, similar noise levels were obtained on IMR level 2 images at 24% dose and iDose4 level 3 images at 50% dose, respectively. Regarding low-contrast resolution, low-contrast detectability and objective spatial resolution, IMR level 2 images at 24% dose showed comparable image quality with filtered back-projection at 100% dose. Subjective spatial resolution was not greatly affected by reconstruction algorithm.


Reduced-dose IMR obtained at 0.92 mSv (24%) showed similar image quality to routine-dose filtered back-projection obtained at 3.64 mSv (100%), and half-dose iDose4 obtained at 1.81 mSv.


Children Computed tomography Infants Iterative model reconstruction Iterative reconstruction Knowledge-based iterative reconstruction Pediatric Radiation 



We thank Young Mi Chun, CT clinical scientist manager, Philips Healthcare Korea, for technical support. We thank Allison Alley for language consultation and editing.

Compliance with Ethical Standards

Conflicts of interest



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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Young Jin Ryu
    • 1
    • 2
  • Young Hun Choi
    • 1
    • 2
    Email author
  • Jung-Eun Cheon
    • 1
    • 2
    • 3
  • Seongmin Ha
    • 4
  • Woo Sun Kim
    • 1
    • 2
    • 3
  • In-One Kim
    • 1
    • 2
    • 3
  1. 1.Department of RadiologySeoul National University HospitalSeoulKorea
  2. 2.Department of RadiologySeoul National University College of MedicineSeoulKorea
  3. 3.Institute of Radiation MedicineSeoul National University Medical Research CenterSeoulKorea
  4. 4.Dalio Institute of Cardiovascular ImagingNew York-Presbyterian Hospital and the Weill Cornell Medical CollegeNew YorkUSA

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