Object shape dependency of in-plane resolution for iterative reconstruction of computed tomography. (January 2017)

• Record Type: Journal Article
• Authors: Takata, Tadanori; Ichikawa, Katsuhiro; Mitsui, Wataru; Hayashi, Hiroyuki; Minehiro, Kaori; Sakuta, Keita; Nunome, Haruka; Matsubara, Kousuke; Kawashima, Hiroki; Matsuura, Yukihiro; Gabata, Toshifumi
• Is Part Of: Physica medica. Volume 33(2017)
• Page Start: 146
• Page End: 151
• Publication Date: 2017-01
• Subjects: Computed tomography -- Iterative reconstruction -- Modulation transfer function -- Spatial resolution; Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2017.01.001
• Languages: English
• ISSNs: 1120-1797

Abstract

Highlights: The present study investigated the shape dependency of IR resolution properties. Modulation transfer functions (MTFs) of IR and FBP were measured at two scan doses. Similar MTF results of FBP images for different shapes were obtained. For IR, MTF results of different shapes were similar at each contrast and dose. Both circular and linear edge methods are useful for evaluating IR resolution. Abstract: The present study aimed to investigate whether the in-plane resolution property of iterative reconstruction (IR) of computed tomography (CT) data is object shape-dependent by testing columnar shapes with diameters of 3, 7, and 10 cm (circular edge method) and a cubic shape with 5-cm side lengths (linear edge method). For each shape, objects were constructed of acrylic (contrast in Hounsfield units [ΔHU] = 120) as well as a soft tissue equivalent material (ΔHU = 50). For each shape, we measured the modulation transfer functions (MTFs) of IR and filtered back projection (FBP) using two multi-slice CT scanners at scan doses of 5 and 10 mGy. In addition, we evaluated a thin metal wire using the conventional method at 10 mGy. For FBP images, the MTF results of the tested objects and the wire method showed substantial agreement, thus demonstrating the validity of our analysis technique. For IR images, the MTF results of different shapes were nearly identical for each object contrast and dose combination, and we did not observe shape-dependent effects of the resolution properties of either tested IR. We conclude that both the circular edge method and linear edge method are equally useful for evaluating the resolution properties of IRs.