Amee A. Patel MD, Presenter: Nothing to Disclose

Daniel William Maver, Abstract Co-Author: Nothing to Disclose

Eliot L. Siegel MD, Abstract Co-Author: Research grant, General Electric Company Speakers Bureau, Siemens AG Board of Directors, Carestream Health, Inc Research grant, XYBIX Systems, Inc Research grant, Steelcase, Inc Research grant, Anthro Corp Research grant, RedRick Technologies Inc Research grant, Evolved Technologies Corporation Research grant, Barco nv Research grant, Intel Corporation Research grant, Dell Inc Research grant, Herman Miller, Inc Research grant, Virtual Radiology Research grant, Anatomical Travelogue, Inc Medical Advisory Board, Fovia, Inc Medical Advisory Board, Mercury Computer Systems, Inc Medical Advisory Board, McKesson Corporation Medical Advisory Board, Carestream Health, Inc Medical Advisory Board, Bayer AG Medical Advisory Board, TeraRecon, Inc

At the beginning of each CT exam, the technologist obtains a scanogram or scout image to provide a general survey of the patient and to establish landmarks for the upper and lower boundaries of the study.  Our anecdotal experience is that most radiologists do not use the scout image while interpreting the study, and therefore its remaining purpose is to identify the region of the body that will be scanned. The radiation required for a CT scout image is equivalent to approximatly 10 chest radiographs and in some cases can represent as much as 20% or more of the total CT scan dose. We have previously established that dose reduction for the scout image as much as tenfold or more can be made with overall landmarks still well visualized.  The purpose of this study was to determine variability in dose for the scout exam and its use as a diagnostic tool for the radiologists.

Radiologists within our multi-site facility were surveyed regarding the usefulness of the scout image while interpreting CT studies.  They were asked whether they looked at the scout image while interpreting a CT scan and to select one of the following option: always, almost always, sometimes, almost never, or never.  Actual dose delivered with the scout study was also surveyed across our enterprise of facilities and multiple CT scanners.

The survey regarding how often radiologists use scout images while interpreting CT studies demonstrated that 63% of radiologist almost never looked at the scout image, while 37% never looked at the scout, and 10% looked at the scout image only sometimes. There was variability in the dose used for the scout examination by more than 50% across our own healthcare enterprise.

Our survey demonstrated that it is possible to reduce the overall radiation dose of a CT study by decreasing the dose used to create the scout image and especially to improve consistency for the dose for the scout study across our institutions.  Our radiologist survey and informal comments from the radiologists suggest little interpretave value to the scout image and therefore one could tolerate an image with greater image noise the image is utilized to determine gross anatomic landmarks.

The limited diagnostic value of the CT scout exam and ability to perceive adequate detail with major dose reduction and variability of techniques suggest major opportunity for reduced patient dose

Patel, A, Maver, D, Siegel, E, The CT Scout Exam: A Survey of Radiation Dose, Utilization, and Opportunity for Substantial Dose Reduction.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9007069.html