title: Effects of oral contrast on dose in abdominopelvic computed tomography with pure iterative reconstruction.
abstract: OBJECTIVE
  To assess the effect of neutral (NC) and positive (PC) oral contrast use on patient dose in low-dose abdominal computed tomography (CT).
  
  
  METHODS
  Low-dose clinically indicated CTs were performed on 79 Crohn's patients (35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index (BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded. Data was reconstructed with pure model-based iterative reconstruction. Image quality was objectively and subjectively analysed. Data analysis was performed with Statistical Package for Social Scientists.
  
  
  RESULTS
  Higher doses were seen in neutral contrast CTs (107.60 ± 78.7 mGy.cm, 2.47 ± 1.21 mGyvs85.65 ± 58.2 mGy.cm, 2.18 ± 0.96 mGy). The difference was significant in 2 of 4 BMI groups and in those that had both NC and PC investigations. Image-quality assessment yielded 6952 datapoints. NC image quality was significantly superior (P< 0.001) (objective noise, objective signal to noise ratio, subjective spatial resolution, subjective contrast resolution, diagnostic acceptability) at all levels. NC bowel distension was significantly (P< 0.001) superior.
  
  
  CONCLUSIONS
  The use of polyethylene glycol as a neutral OC agent leads to higher radiation doses than standard positive contrast studies, in low dose abdominal CT imaging. This is possibly related to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Murphy
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Liam J
authors.initials: LJ
authors.lastname: Healy
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Lee
authors.initials: L
authors.lastname: Crush
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Maria
authors.initials: M
authors.lastname: Twomey
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Fiachra
authors.initials: F
authors.lastname: Moloney
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Sexton
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Owen J
authors.initials: OJ
authors.lastname: O'Connor
authors.affiliation: Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O'Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Maher
keywords: Abdominal imaging; Computed tomography; Low dose computed tomography; Oral contrast; Radiation dose