Rebecca Huke Lamoureux MS, BS, Presenter: Nothing to Disclose

Anna Mench, Abstract Co-Author: Nothing to Disclose

Izabella Lipnharski, Abstract Co-Author: Nothing to Disclose

Brian Cormack, Abstract Co-Author: Nothing to Disclose

Sharatchandra S. Bidari MD, Abstract Co-Author: Nothing to Disclose

Lynn Neitzey Rill PhD, Abstract Co-Author: Nothing to Disclose

Manuel M. Arreola PhD, Abstract Co-Author: Nothing to Disclose

To measure the effects of table positioning on dose reducing systems and organ dose in computed tomography (CT), and determine the clinical occurrence of miscentering.

The post-mortem dose measurement methodology established in house was utilized to perform organ dose measurements on varying body habitus subjects for a clinically standardized chest/abdomen/pelvis protocol on a 320-slice scanner. The table was moved in increments of 1cm for a total range of 8cm anteriorly and posteriorly and 4cm laterally. The organ dose measurements taken at each position were then compared with dose measurements from a central position for each subject. Clinical miscentering occurrence assessment includes measuring the AP and lateral miscentering of 80 CAP exams through a retrospective chart study.

Strong correlations were established between the degree of AP miscentering and the percentage difference in dose from the central position for eight out of ten organs of interest including lung, liver, stomach, small intestines, colon, ovary, uterus, and skin (R2 range: 0.7284 - 0.9888), with the percentage difference from the central position dose among all organs ranging from -22.4% to 21.8%. Reasonable correlations were established for the degree of lateral miscentering and one side of an organ, including left lung, right lung, left breast, right breast, descending colon and ascending colon (R2 range: 0.5746 – 0.9433), with the percentage difference from the central position dose among all organs ranging from -14.7% to 14.7%. Measurements for multiple post-mortem subjects present a correlation between varying body habitus and effects of table positioning on dose. Results for the occurrence of AP and lateral miscentering clinically show a range of 2.55cm posterior to 3.9cm anterior, 1.55cm left to 1.56cm right, and an average of 1.24cm posterior and 1.74cm anterior, and 0.71cm left and 1.21cm right

Table positioning has a strong correlation to optimizing system output to varying degrees for different body habitus and therefore minimizing dose to organs and miscentering occurs frequently in clinic.

Correct patient centering is rarely achieved in a clinical setting the effects of which, as seen in this study, are reduction in system optimization which negatively impacts patient outcome.

Lamoureux, R, Mench, A, Lipnharski, I, Cormack, B, Bidari, S, Rill, L, Arreola, M, Impact of Table Positioning on Dose Reduction Systems and Organ Doses within Cadaveric Subjects.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018839.html