Vana M. Derderian BS, Presenter: Nothing to Disclose

Jenifer Willmann Siegelman MD, MPH, Abstract Co-Author: Nothing to Disclose

Choonsik Lee PhD, Abstract Co-Author: Nothing to Disclose

Elizabeth C. Jones MD, Abstract Co-Author: Nothing to Disclose

Mahadevappa Mahesh MS, PhD, Abstract Co-Author: Royalties, Wolters Kluwer nv

Les Roger Folio DO, MPH, Abstract Co-Author: Nothing to Disclose

Understanding organ dose from CT in the context of age and body size is evolving. As part of efforts to balance CT radiation risk and its diagnostic benefit, we assessed the effectiveness of a BMI-based (Body Mass Index) kVp adjustment on dose in a pediatric cohort over time. We compared exposure and calculated patient-specific organ and effective dose from long z-axis exams in children before and after kVp reduction.

To evaluate the effectiveness of BMI-based kVp adjustment, we retrospectively reviewed all kVp-adjusted CT scans in children (2012; n=358). Scans with kVp-adjusted Chest, Abdomen and Pelvis (CAP) or CAP with neck with one or more scans covering the same region prior to 2011 (program implementation) were included (n=13). Technical parameters (kVp, mAs, automatic exposure control (AEC) use) as well as exposure data (CTDIvol, DLP) from four CT units extracted from Radiance/PACS were compared with SSDE (Size Specific Dose Estimate) effective diameter at the middle slice, organ and effective doses at two time points (2010 and 2012). Computational phantoms representing six different age groups (newborn to adult) and two genders were used for Monte Carlo simulation of organ dose. Radiologists and ordering physicians monitored studies for clinically relevant (subjective) reductions in quality. Repeat rate due to inadequate quality was collected.

Comparing 2012 with 2010 as baseline, CTDIvol, DLP, and SSDE in 2012 were 22% (p=0.082), 20% (p=0.2982), and 26% (p=0.012) lower on average. Organ doses in 2012 were on average 26% (p=0.012) lower than baseline, similar to the reduction seen in SSDE. Urinary bladder and active marrow showed the maximum (28%) and minimum reduction (25%), respectively. No studies were repeated; no additonal costs were incurred.

SSDE and average organ doses were, on average, 26% reduced after BMI-dependent kVp adjusted scans in 13 children.  Use of BMI-based kVp adjustment is an economical dose reduction method that can maintain quality.

Economical radiation dose reduction and organ dose estimation methods should help pediatric dose optimization efforts in hospitals and clinics without additional capital or infrastructure investment.

Derderian, V, Siegelman, J, Lee, C, Jones, E, Mahesh, M, Folio, L, Reduction of Radiation Exposure, Effective Dose and Organ Dose in Pediatric Body CT Using BMI-based kVp Adjustment.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13016826.html