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. 2017 Apr;46(4):20160452.
doi: 10.1259/dmfr.20160452. Epub 2017 Feb 17.

Spatial and contrast resolution of ultralow dose dentomaxillofacial CT imaging using iterative reconstruction technology

Gerlig Widmann  1 , Alexander Bischel  2 , Andreas Stratis  3 , Hilde Bosmans  3 , Reinhilde Jacobs  3 , Eva-Maria Gassner  1 , Wolfgang Puelacher  2 , Ruben Pauwels  3   4
Affiliations

Spatial and contrast resolution of ultralow dose dentomaxillofacial CT imaging using iterative reconstruction technology

Gerlig Widmann et al. Dentomaxillofac Radiol. 2017 Apr.

Abstract

Objectives: The objective of this study was to determine how iterative reconstruction technology (IRT) influences contrast and spatial resolution in ultralow-dose dentomaxillofacial CT imaging.

Methods: A polymethyl methacrylate phantom with various inserts was scanned using a reference protocol (RP) at CT dose index volume 36.56 mGy, a sinus protocol at 18.28 mGy and ultralow-dose protocols (LD) at 4.17 mGy, 2.36 mGy, 0.99 mGy and 0.53 mGy. All data sets were reconstructed using filtered back projection (FBP) and the following IRTs: adaptive statistical iterative reconstructions (ASIRs) (ASIR-50, ASIR-100) and model-based iterative reconstruction (MBIR). Inserts containing line-pair patterns and contrast detail patterns for three different materials were scored by three observers. Observer agreement was analyzed using Cohen's kappa and difference in performance between the protocols and reconstruction was analyzed with Dunn's test at α = 0.05.

Results: Interobserver agreement was acceptable with a mean kappa value of 0.59. Compared with the RP using FBP, similar scores were achieved at 2.36 mGy using MBIR. MIBR reconstructions showed the highest noise suppression as well as good contrast even at the lowest doses. Overall, ASIR reconstructions did not outperform FBP.

Conclusions: LD and MBIR at a dose reduction of >90% may show no significant differences in spatial and contrast resolution compared with an RP and FBP. Ultralow-dose CT and IRT should be further explored in clinical studies.

Keywords: CT; contrast resolution; iterative reconstruction technology; spatial resolution; ultralow dose.

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Figures

Figure 1
Figure 1
Line-pair visibility. ASIR, adaptive statistical iterative reconstruction; FBP, filtered back projection; LD, ultralow-dose protocols; MBIR, model-based iterative reconstruction; RP, reference protocol; SP, sinus protocol; std, standard.
Figure 2
Figure 2
Contrast resolution showing insert hydroxyapatite 200 mg cm−3. ASIR, adaptive statistical iterative reconstruction; FBP, filtered back projection; LD, ultralow-dose protocols; MBIR, model-based iterative reconstruction; RP, reference protocol; SP, sinus protocol; std, standard.
See this image and copyright information in PMC

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