title: OBJECTIVE TASK-BASED ASSESSMENT OF LOW-CONTRAST DETECTABILITY IN ITERATIVE RECONSTRUCTION.
abstract: Evaluating image quality by using receiver operating characteristic studies is time consuming and difficult to implement. This work assesses a new iterative algorithm using a channelised Hotelling observer (CHO). For this purpose, an anthropomorphic abdomen phantom with spheres of various sizes and contrasts was scanned at 3 volume computed tomography dose index (CTDIvol) levels on a GE Revolution CT. Images were reconstructed using the iterative reconstruction method adaptive statistical iterative reconstruction-V (ASIR-V) at ASIR-V 0, 50 and 70 % and assessed by applying a CHO with dense difference of Gaussian and internal noise. Both CHO and human observers (HO) were compared based on a four-alternative forced-choice experiment, using the percentage correct as a figure of merit. The results showed accordance between CHO and HO. Moreover, an improvement in the low-contrast detection was observed when switching from ASIR-V 0 to 50 %. The results underpin the finding that ASIR-V allows dose reduction.
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland damien.racine@chuv.ch.
authors.forename: Damien
authors.initials: D
authors.lastname: Racine
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland.
authors.forename: Julien G
authors.initials: JG
authors.lastname: Ott
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Ba
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland.
authors.forename: Nick
authors.initials: N
authors.lastname: Ryckx
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland.
authors.forename: François O
authors.initials: FO
authors.lastname: Bochud
authors.affiliation: Institute of Radiation Physics, CHUV, Lausanne, Switzerland.
authors.forename: Francis R
authors.initials: FR
authors.lastname: Verdun
mesh_terms: D000465:Algorithms; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015588:Observer Variation; D000069079:Radiation Exposure / Q000032:analysis / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*