1. Copyright © 2015 Lippincott Williams & Wilkins. Unauthorized commercial reproduction of this slide is prohibited Supplemental PowerPoint Slides Spine CT Radiation Dose Reduction: Protocol Refinement Based On Measurement Variation At Simulated Lower Radiation Acquisitions Jonathan O. Swanson, MD1, Adam M. Alessio, PhD2, Klane K. White, MD, MSc3, Walter F. Krengel, MD3, Seth D. Friedman, PhD4, Neil C. Vining, MD5 Kit M. Song, MD, MHA6 1Corresponding Author: Seattle Children’s Hospital and University of Washington 2University of Washington, Department of Radiology 3Seattle Children’s Hospital, University of Washington, Department of Orthopedics 4Seattle Children’s Hospital, Department of Radiology 5Raleigh Orthopaedic Clinic 6Shriners Hospitals for Children, Los Angeles, Department of Orthopaedic Surgery

2. Introduction CT is a preoperative planning tool for spinal surgery Pediatric population at high risk for radiation effects of CT Hypothesis: Preoperative measurement accuracy for pediatric spinal surgery would not be compromised by lower dose of CT

3. 50 % of Standard DoseStandard Dose25% of Standard Dose Validated noise introduction software used to simulate lower dose CT scans Validated noise introduction software used to simulate lower dose CT scans ICC calculated to evaluate variation of measurements between doses and readers ICC calculated to evaluate variation of measurements between doses and readers Methods

4. Conclusions This study suggests that the measurement accuracy and precision does not significantly change when comparing 100% dose images to those having simulated reduced doses down to 25% of standard CT doses. This could lead to significant dose reductions in situations where vertebral anatomic measurements are important for preoperative planning of instrumentation placement. Further study is necessary to confirm low dose measurement accuracy in deformed spines as well as the utility of 3-D and multiplanar reconstructions at low dose.