Jie Zhang PhD, Presenter: Nothing to Disclose

Jessica L. Cornett, Abstract Co-Author: Nothing to Disclose

Karsten D. Colwell, Abstract Co-Author: Nothing to Disclose

Gerald Ball Broussard MD, Abstract Co-Author: Nothing to Disclose

Edward Joel Escott MD, Abstract Co-Author: Royalties, Thieme Medical Publishers, Inc Researcher, Athersys, Inc Grant, Athersys, Inc

Currently we treat Computed Tomography (CT) chest & neck examinations as separate scans, using two separate topograms and dividing the contrast 60/40. Depending upon the patient’s body habitus this amount of contrast for each scan may not be sufficient to opacity the vessels properly. Acquiring one topogram with the arms up then having the patient move their arms up/down during the chest/neck scan allows one bolus of contrast to be administered, but has the potential to increase radiation. The purpose of this study is to investigate the difference in patient radiation dose for combined chest & neck CT examinations when one topogram with the arms up is used, compared with two separate topograms with the arms up and down respectively.

Between 2/1/2014 and 4/5/2014, patients who received a CT chest & neck examination in the same session and same CT scanner were randomly separated into two groups. One group followed the conventional two topogram scenario with proper arm positioning while the other group kept the arms up for the combined topogram.  The first group received the divided 60/40 bolus contrast while the second group received only one contrast bolus. During scan acquisition for the second group the arms were positioned out of the scan field-of-view (FOV). Automatic Exposure Control (e.g., CareDose4D) remained on for CT scanning. Volume CT Dose Index (CTDIvol) for the chest and neck CT scans was recorded, respectively. Patient Body Mass Index (BMI) was also recorded.  

The CTDIvol and BMI of 23 patients were collected, 11 with two separate topograms and 12 with one topogram. Our preliminary comparison shows there is no significant difference in either CTDIvol of the neck (p=0.24) or BMI (p=0.51) with either topogram technique. This may be mainly due to the use of AEC (CareDose4D) which adjusts tube current in real time. CTDIvol of the chest was not compared since in either situation the arms are not included within the chest on the topogram.

One topogram with the arms up can be used for combined CT chest & neck examinations to allow the use of a single contrast bolus. With the appropriate use of AEC, there is no significant increase in the radiation dose to patient.

One topogram can be used for combined chest & neck CT examinations to enable the use of a single contrast bolus without a significantly increased patient dose.

Zhang, J, Cornett, J, Colwell, K, Broussard, G, Escott, E, Single Contrast Bolus vs Radiation Dose: Can Combined Chest & Neck CT Examinations Use One Topogram?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14014491.html