Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system



To assess visualization tasks using cone-beam CT (CBCT) compared to multi-detector CT (MDCT) for musculoskeletal extremity imaging.


Ten cadaveric hands and ten knees were examined using a dedicated CBCT prototype and a clinical multi-detector CT using nominal protocols (80kVp-108mAs for CBCT; 120kVp- 300mAs for MDCT). Soft tissue and bone visualization tasks were assessed by four radiologists using five-point satisfaction (for CBCT and MDCT individually) and five-point preference (side-by-side CBCT versus MDCT image quality comparison) rating tests. Ratings were analyzed using Kruskal–Wallis and Wilcoxon signed-rank tests, and observer agreement was assessed using the Kappa-statistic.


Knee CBCT images were rated “excellent” or “good” (median scores 5 and 4) for “bone” and “soft tissue” visualization tasks. Hand CBCT images were rated “excellent” or “adequate” (median scores 5 and 3) for “bone” and “soft tissue” visualization tasks. Preference tests rated CBCT equivalent or superior to MDCT for bone visualization and favoured the MDCT for soft tissue visualization tasks. Intraobserver agreement for CBCT satisfaction tests was fair to almost perfect (κ ~ 0.26–0.92), and interobserver agreement was fair to moderate (κ ~ 0.27–0.54).


CBCT provided excellent image quality for bone visualization and adequate image quality for soft tissue visualization tasks.

Key Points

CBCT provided adequate image quality for diagnostic tasks in extremity imaging.

CBCT images were “excellent” for “bone” and “good/adequate” for “soft tissue” visualization tasks.

CBCT image quality was equivalent/superior to MDCT for bone visualization tasks.

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Cone-beam computed tomography


Multidetector computed tomography


Magnetic resonance imaging


Computed tomography dose index


Contrast-to-noise ratio


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The scientific guarantor of this publication is Dr. Shadpour Demehri. The authors of this manuscript declare relationships with the following companies: Carestream Health, Inc. The research was supported by National Institutes of Health Grants 2R01-CA-112163 and R21-AR-062993 and academic-industry partnership with Carestream Health (Rochester NY). One of the authors has significant statistical expertise. Institutional Review Board approval was not required because this study does not involve any human subjects. All data was collected using cadavers, and state and institutional requirements were followed. Methodology: retrospective, observational, performed at one institution

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Correspondence to S. Demehri.



Technical aspects of our CBCT scanner prototype illustrated in Fig. 1 were detailed previously [15]. The scanner includes motorized rotation of an X-ray tube and flat-panel detector (FPD). The X-ray tube (XRS-125-7 K-P, Source-Ray, Ronkonkoma, NY) has a stationary anode with 0.5 mm focal spot, 0.875 kW maximum power, 10 mA maximum tube current, and 60–120 kVp range. The X-ray tube is pulsed up to 30 pulses/sec (nominally 25 pulses/sec in studies herein), with a pulse width of 10–30 ms. Total added filtration was 2 mm Al +0.2 mm Cu. A bowtie filter was not used in the current configuration. A custom anti-scatter grid (10:1 grid ratio, 40–70 cm focal range, Jungwon Precision Industries, South Korea) was attached to the FPD. The detector was a PaxScan 3030+ (Varian Medical Systems, Palo Alto, CA) with a 0.5-mm-thick CsI:Tl X-ray converter and 1536 × 1536 pixels at 0.194 mm pitch. The FPD was operated nominally at 25 frames/sec with 2 × 2 pixel binning (768 × 768 pixels at 0.388 mm pitch) and dynamic gain readout [34]. The system can also be operated at full-resolution 1536 × 1536 pixel format, but at half the readout speed. The source-detector distance (SDD) was 550 mm, source-isocentre distance (SID) was 420 mm, magnification factor was 1.3, and the reconstruction field of view was 22 × 22 × 22 cm3. The source and detector traverse a circular orbit with angular extent 240° (exceeding the half-scan range of 180° + fan ≈ 212°). Nominal protocols acquired 490 projections with an imaging time of 20 s.

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Demehri, S., Muhit, A., Zbijewski, W. et al. Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system. Eur Radiol 25, 1742–1751 (2015).

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  • Cone-beam computed tomography
  • Musculoskeletal
  • Orthopedics
  • Rheumatology
  • Weight-bearing