Ranish Deedar Ali Khawaja MBBS, MD, Presenter: Nothing to Disclose

Sarabjeet Singh MD, Abstract Co-Author: Nothing to Disclose

Beth Vettiyil MBBS, Abstract Co-Author: Nothing to Disclose

Sarvenaz Pourjabbar MD, Abstract Co-Author: Nothing to Disclose

Atul Padole MD, Abstract Co-Author: Nothing to Disclose

Mannudeep K. S. Kalra MD, Abstract Co-Author: Faculty, General Electric Company

Diego Alfonso Lira MD, Abstract Co-Author: Nothing to Disclose

Children are more susceptible to radiation-induced carcinogenesis because of greater organ radiosensitivity and a longer life-span. Since children have a wide variability in their body sizes and expected variations in radiation doses, we aimed to compare pediatric CT radiation doses across different body weight groups and across scanners, operators and body regions in pediatric CT.

In an IRB-approved study, 544 consecutive pediatric (≤ 18years) chest (C) and abdomen-pelvis (A) CT (nC=204; nAP=340; M:F= 309:235) were assessed with a web based dose monitoring software (Exposure, Radimetrics) from 1/2011 to 1/2013. Demographics of patient (age, sex, body weight, and body diameter); body regions; age, sex, training experience of CT technologist, scanner type (availability of Iterative Reconstruction ‘IR’), off-centering, and estimated effective dose (EED) were recorded. Corresponding EED values were also recorded for adult CT (n=14,000; nC=6,000; nAP =8,000) for comparison. Analysis of variance (ANOVA) was used to evaluate differences in ED across above variables. P <0.001 was considered statistically significant.  

Mean EED (ICRP-103) in pediatric cohort was 6.9±6.5 (EEDC: 4.7±5.3; EEDAP: 8.1±6.8; mean age:12.0±5.0 years). Compared to adults mean EED was 7.4±4.1 (EEDC: 4.6±2.7; EEDAP: 10.2±5.5). Mean EED for pediatric abdominal CT was significantly low compared corresponding adult dose (p <0.0001). Mean EED was significantly higher in scanners without IR (10.4±9.1 versus 5.1±3.6 mSv; p <0.0001). There was no difference in mean EED with age, sex, or training experience of CT technologist. 57% (309/544) patients were off-centered (±10mm) from CT gantry with mean ED 7.3±6 versus 6.9±6 mSv (centered correctly) with no significant difference. There was a strong trend in distribution of doses in children, with smaller children receiving lower doses as compared to large children.  

Mean ED varies considerably across CT scanners, body regions and with BW in pediatric patients. Mean ED varies significantly in children weighing 27-100Kg across scanners. This variability is low for lightweight (<26Kg) and heavy children (≥101Kg). 

In our experience of pediatric CT, the only modifiers that affect the radiation dose variability include CT exam performed on IR versus non-IR scanners, and body weight of patient.  

Khawaja, R, Singh, S, Vettiyil, B, Pourjabbar, S, Padole, A, Kalra, M, Lira, D, Pediatric CT Radiation Dose Variability: Affecting Factors at a Large Academic Institute.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13023171.html