Performance of Ultra-High-Resolution Computed Tomography in Super High–Resolution Mode at the Routine Radiation Dose: Phantom Study. Issue 6 (18th November 2022)

• Record Type: Journal Article
• Authors: Kitera, Nobuo; Fujioka, Chikako; Higaki, Toru; Nishimaru, Eiji; Yokomachi, Kazushi; Kiguchi, Masao; Awai, Kazuo
• Is Part Of: Journal of computer assisted tomography. Volume 46:Issue 6(2022)
• Page Start: 900
• Page End: 905
• Publication Date: 2022-11-18
• Subjects: ultra-high-resolution computed tomography -- image quality -- super high–resolution mode -- spatial resolution -- radiation dose -- CT-AEC - CT-automatic exposure control -- D-FOV - display field-of-view -- NPS - noise power spectrum -- MTF - modulation transfer function -- ROI - region of interest -- SHR mode - super high–resolution mode -- U-HRCT - ultra-high-resolution computed tomography; Tomography -- Periodicals; Tomography -- Periodicals; Tomography; Periodicals; 616.0757
• DOI: 10.1097/RCT.0000000000001351
• Languages: English
• ISSNs: 0363-8715

Abstract

Abstract : Objective: Using a chest phantom, we compared the image quality of ultra-high-resolution computed tomography (U-HRCT) images acquired in super high–resolution (SHR) and normal resolution (NR) mode and at the routine radiation dose. The detector size was 0.25 and 0.5 mm, respectively. Methods: A chest phantom was scanned on a U-HRCT scanner. The scan parameters were tube voltage 120 kV and volume CT dose index 13.0 mGy, the routine radiation dose for conventional scans. The rotation time was 0.5 s/rot, the number of matrices was 512 in NR and 1024 in SHR mode. For physical evaluation, the modulation transfer function was measured on the spherical simulated nodule, and the noise power spectrum on the cylindrical water phantom. A CT value profile curve was created using an in-house simulated bronchial phantom. For visual evaluation, 3 radiologists and 3 radiology technologists evaluated overall image quality using a 4-grade scale (grade 1, poor; and grade 4, excellent). Results: The 10% of modulation transfer function was 13.5 lp/cm in NR and 14.9 lp/cm in SHR mode ( P <0.01). ƒpeak was 5.6 lp/cm in NR and 8.8 lp/cm in SHR mode ( P <0.01), and the peak of noise power spectrum shifted. On the profile curves, the CT value at the edge changed in NR but not in SHR mode. The overall image quality was grade 3.0 ± 0.7 in SHR and grade 2.0 ± 0.7 in NR mode ( P <0.01). Conclusions: The image quality of SHR mode with U-HRCT was superior to that of NR mode at the routine radiation dose.