title: Computed tomography (CT) of the chest at less than 1 mSv: an ongoing prospective clinical trial of chest CT at submillisievert radiation doses with iterative model image reconstruction and iDose4 technique.
abstract: OBJECTIVE
  To assess lesion detection and diagnostic confidence of computed tomography (CT) of the chest performed at less than 1 mSv with 2 iterative reconstruction (IR) techniques.
  
  
  METHODS
  Ten patients gave written informed consent for the acquisitions of images at submillisievert dose (0.9 mSv), in addition to clinical standard-dose (SD) chest CT (2.9 mSv). Submillisievert images were reconstructed with iDose and iterative model reconstruction (IMR). Two radiologists assessed lesion detection, margins, diagnostic confidence, and visibility of small structures. Objective noise and noise spectral density were measured.
  
  
  RESULTS
  Lesion detection was identical for standard-dose filtered back projection (FBP), submSv iDose, and submSv IMR. Lesion margins were better seen for 30% of detected lung lesions with submSv IMR compared to standard-dose FBP and submSv iDose (P < 0.05). Visibility of abdominal structures, and diagnostic confidence with submSv iDose and submSv IMR were similar to standard-dose FBP. There was 21% to 64% noise reduction with submSv IMR and 1% to 15% higher noise with iDose compared to standard-dose FBP (P < 0.0001).
  
  
  CONCLUSIONS
  Submillisievert IMR improves delineation of lesion margins compared to standard-dose FBP and submSv iDose.
authors.affiliation: From the *MGH Imaging, Division of Thoracic Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA; and †Philips Healthcare Research Team, Cleveland, OH.
authors.forename: Ranish Deedar Ali
authors.initials: RD
authors.lastname: Khawaja
authors.forename: Sarabjeet
authors.initials: S
authors.lastname: Singh
authors.forename: Matthew
authors.initials: M
authors.lastname: Gilman
authors.forename: Amita
authors.initials: A
authors.lastname: Sharma
authors.forename: Synho
authors.initials: S
authors.lastname: Do
authors.forename: Sarvenaz
authors.initials: S
authors.lastname: Pourjabbar
authors.forename: Atul
authors.initials: A
authors.lastname: Padole
authors.forename: Diego
authors.initials: D
authors.lastname: Lira
authors.forename: Kevin
authors.initials: K
authors.lastname: Brown
authors.forename: Jo-Anne O
authors.initials: JA
authors.lastname: Shepard
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
mesh_terms: D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*