title: Influence of radiation dose and iterative reconstruction algorithms for measurement accuracy and reproducibility of pulmonary nodule volumetry: A phantom study.
abstract: OBJECTIVE
  To evaluate the influence of radiation dose settings and reconstruction algorithms on the measurement accuracy and reproducibility of semi-automated pulmonary nodule volumetry.
  
  
  METHODS
  CT scans were performed on a chest phantom containing various nodules (10 and 12mm; +100, -630 and -800HU) at 120kVp with tube current-time settings of 10, 20, 50, and 100mAs. Each CT was reconstructed using filtered back projection (FBP), iDose(4) and iterative model reconstruction (IMR). Semi-automated volumetry was performed by two radiologists using commercial volumetry software for nodules at each CT dataset. Noise, contrast-to-noise ratio and signal-to-noise ratio of CT images were also obtained. The absolute percentage measurement errors and differences were then calculated for volume and mass. The influence of radiation dose and reconstruction algorithm on measurement accuracy, reproducibility and objective image quality metrics was analyzed using generalized estimating equations.
  
  
  RESULTS
  Measurement accuracy and reproducibility of nodule volume and mass were not significantly associated with CT radiation dose settings or reconstruction algorithms (p>0.05). Objective image quality metrics of CT images were superior in IMR than in FBP or iDose(4) at all radiation dose settings (p<0.05).
  
  
  CONCLUSIONS
  Semi-automated nodule volumetry can be applied to low- or ultralow-dose chest CT with usage of a novel iterative reconstruction algorithm without losing measurement accuracy and reproducibility.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: khj.snuh@gmail.com.
authors.forename: Hyungjin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea; Cancer Research Institute, Seoul National University, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: cmpark@radiol.snu.ac.kr.
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Park
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: terasong@gmail.com.
authors.forename: Yong Sub
authors.initials: YS
authors.lastname: Song
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: sangmin.lee.md@gmail.com.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea; Cancer Research Institute, Seoul National University, 101, Daehangno, Jongno-gu, Seoul 110-744, Republic of Korea. Electronic address: jmgoo@plaza.snu.ac.kr.
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Goo
mesh_terms: D000465:Algorithms; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D047368:Tumor Burden
keywords: Computer-assisted image processing; Lung neoplasms; Multidetector computed tomography; Pulmonary nodule; Radiation dosage; Reproducibility of results