title: Determination of optimal imaging settings for urolithiasis CT using filtered back projection (FBP), statistical iterative reconstruction (IR) and knowledge-based iterative model reconstruction (IMR): a physical human phantom study.
abstract: OBJECTIVE
  The purpose of this study was to compare CT image quality for evaluating urolithiasis using filtered back projection (FBP), statistical iterative reconstruction (IR) and knowledge-based iterative model reconstruction (IMR) according to various scan parameters and radiation doses.
  
  
  METHODS
  A 5 × 5 × 5 mm(3) uric acid stone was placed in a physical human phantom at the level of the pelvis. 3 tube voltages (120, 100 and 80 kV) and 4 current-time products (100, 70, 30 and 15 mAs) were implemented in 12 scans. Each scan was reconstructed with FBP, statistical IR (Levels 5-7) and knowledge-based IMR (soft-tissue Levels 1-3). The radiation dose, objective image quality and signal-to-noise ratio (SNR) were evaluated, and subjective assessments were performed.
  
  
  RESULTS
  The effective doses ranged from 0.095 to 2.621 mSv. Knowledge-based IMR showed better objective image noise and SNR than did FBP and statistical IR. The subjective image noise of FBP was worse than that of statistical IR and knowledge-based IMR. The subjective assessment scores deteriorated after a break point of 100 kV and 30 mAs.
  
  
  CONCLUSIONS
  At the setting of 100 kV and 30 mAs, the radiation dose can be decreased by approximately 84% while keeping the subjective image assessment.
  
  
  CONCLUSIONS
  Patients with urolithiasis can be evaluated with ultralow-dose non-enhanced CT using a knowledge-based IMR algorithm at a substantially reduced radiation dose with the imaging quality preserved, thereby minimizing the risks of radiation exposure while providing clinically relevant diagnostic benefits for patients.
authors.affiliation: 1 Department of Urology, The Armed Forces Il-Dong Hospital, Pocheon, Republic of Korea.|2 Department of Urology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
authors.forename: Se Y
authors.initials: SY
authors.lastname: Choi
authors.affiliation: 3 Department of Urology, KEPCO Medical Center, Seoul, Republic of Korea.
authors.forename: Seung H
authors.initials: SH
authors.lastname: Ahn
authors.affiliation: 3 Department of Urology, KEPCO Medical Center, Seoul, Republic of Korea.
authors.forename: Jae D
authors.initials: JD
authors.lastname: Choi
authors.affiliation: 3 Department of Urology, KEPCO Medical Center, Seoul, Republic of Korea.
authors.forename: Jung H
authors.initials: JH
authors.lastname: Kim
authors.affiliation: 4 Radiation Health Research Institute, Korea Hydro and Nuclear Power, Seoul, Republic of Korea.
authors.forename: Byoung-Il
authors.initials: BI
authors.lastname: Lee
authors.affiliation: 4 Radiation Health Research Institute, Korea Hydro and Nuclear Power, Seoul, Republic of Korea.
authors.forename: Jeong-In
authors.initials: JI
authors.lastname: Kim
authors.affiliation: 5 Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung B
authors.initials: SB
authors.lastname: Park
mesh_terms: D000465:Algorithms; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014567:Urography / Q000295:instrumentation / Q000379:methods*; D052878:Urolithiasis / Q000000981:diagnostic imaging*