title: Influence of dose reduction and iterative reconstruction on CT calcium scores: a multi-manufacturer dynamic phantom study.
abstract: To evaluate the influence of dose reduction in combination with iterative reconstruction (IR) on coronary calcium scores (CCS) in a dynamic phantom on state-of-the-art CT systems from different manufacturers. Calcified inserts in an anthropomorphic chest phantom were translated at 20 mm/s corresponding to heart rates between 60 and 75 bpm. The inserts were scanned five times with routinely used CCS protocols at reference dose and 40 and 80% dose reduction on four high-end CT systems. Filtered back projection (FBP) and increasing levels of IR were applied. Noise levels were determined. CCS, quantified as Agatston and mass scores, were compared to physical mass and scores at FBP reference dose. For the reference dose in combination with FBP, noise level variation between CT systems was less than 18%. Decreasing dose almost always resulted in increased CCS, while at increased levels of IR, CCS decreased again. The influence of IR on CCS was smaller than the influence of dose reduction. At reference dose, physical mass was underestimated 3-30%. All CT systems showed similar CCS at 40% dose reduction in combinations with specific reconstructions. For some CT systems CCS was not affected at 80% dose reduction, in combination with IR. This multivendor study showed that radiation dose reductions of 40% did not influence CCS in a dynamic phantom using state-of-the-art CT systems in combination with specific reconstruction settings. Dose reduction resulted in increased noise and consequently increased CCS, whereas increased IR resulted in decreased CCS.
authors.affiliation: Department of Radiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands. n.r.vanderwerf@umcutrecht.nl.|Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. n.r.vanderwerf@umcutrecht.nl.
authors.forename: N R
authors.initials: NR
authors.lastname: van der Werf
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Willemink
authors.affiliation: Department of Radiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
authors.forename: T P
authors.initials: TP
authors.lastname: Willems
authors.affiliation: Department of Radiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
authors.forename: M J W
authors.initials: MJW
authors.lastname: Greuter
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Leiner
mesh_terms: D000072226:Computed Tomography Angiography / Q000295:instrumentation* / Q000379:methods; D017023:Coronary Angiography / Q000295:instrumentation* / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D004867:Equipment Design; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000009:adverse effects / Q000517:prevention & control*; D011857:Radiographic Image Interpretation, Computer-Assisted; D015898:Tomography Scanners, X-Ray Computed; D061205:Vascular Calcification / Q000000981:diagnostic imaging*
keywords: Calcium score; Computed tomography; Coronary calcium; Iterative reconstruction CT; Low dose CT