title: Ultra-low-dose chest CT with iterative reconstruction does not alter anatomical image quality.
abstract: OBJECTIVE
  To evaluate the effect of dose reduction with iterative reconstruction (IR) on image quality of chest CT scan.
  
  
  METHODS
  Eighteen human cadavers had chest CT with one reference CT protocol (RP-CT; 120kVp/200mAs) and two protocols with dose reduction: low-dose-CT (LD-CT; 120kVp/40mAs) and ultra-low-dose CT (ULD-CT; 120kVp/10mAs). Data were reconstructed with filter-back-projection (FBP) for RP-CT and with FBP and IR (sinogram affirmed iterative reconstruction [SAFIRE®]) algorithm for LD-CT and ULD-CT. Volume CT dose index (CTDIvol) were recorded. The signal-to-noise (SNR), contrast-to-noise (CNR) ratios of LD-CT and ULD-CT and quantitative parameters were compared to RP-CT. Two radiologists reviewed the CT examinations assessed independently the quality of anatomical structures and expressed a confidence level using a 2-point scale (50% and 95%).
  
  
  RESULTS
  CTDIvol was 2.69 mGy for LD-CT (-80%; P<0.01) and 0.67 mGy for ULD-CT (-95%; P<0.01) as compared to 13.42 mGy for RP-CT. SNR and CNR were significantly decreased (P<0.01) for LD-CT and ULD-CT, but IR improved these values satisfactorily. No significant differences were observed for quantitative measurements. Radiologists rated excellent/good the RP-CT and LD-CT images, whereas good/fair the ULD-CT images. Confidence level for subjective anatomical analysis was 95% for all protocols.
  
  
  CONCLUSIONS
  Dose reduction with a dose lower than 1 mGy, used in conjunction with IR allows performing chest CT examinations that provide a high quality of anatomical structures.
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Department of emergency radiology, "Sapienza" university-hospital Um-berto I, 155, viale del Policlinico, 00161 Rome, Italy. Electronic address: francesco.macri@chu-nimes.fr.
authors.forename: F
authors.initials: F
authors.lastname: Macri
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France.
authors.forename: J
authors.initials: J
authors.lastname: Greffier
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France.
authors.forename: F R
authors.initials: FR
authors.lastname: Pereira
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France.
authors.forename: C
authors.initials: C
authors.lastname: Mandoul
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France.
authors.forename: E
authors.initials: E
authors.lastname: Khasanova
authors.affiliation: Department of emergency radiology, "Sapienza" university-hospital Um-berto I, 155, viale del Policlinico, 00161 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gualdi
authors.affiliation: Department of radiology, university hospital of Nîmes, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France; Research team EA 2415, 4, rue du Professeur Robert-Debré, 30029 Nîmes, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Beregi
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*
keywords: Dose reduction; Image quality; Safire(®); Sinogram affirmed iterative reconstruction; Ultra-low-dose chest CT