Radiation doses from small-bowel follow-through and abdomen/pelvis MDCT in pediatric Crohn disease

Background The onset of Crohn disease (CD) can occur in childhood. Imaging, which often involves radiation, is frequent in CD both for disease diagnosis and follow-up. However, information regarding radiation dose for contemporary CT and fluoroscopy is not available for determining the cost/benefit ratio for imaging strategies. Objective To compare effective dose (ED) for small-bowel follow-through (SBFT) and abdomen/pelvis MDCT in pediatric CD. Materials and methods Average fluoroscopic time and number of radiographs were obtained for 30 consecutive pediatric SBFTs. The numbers of SBFTs and CT scans performed per child among children with CD (1990-2005) were determined. The ED was determined (ICRP 60, 10-year-old phantom, MOSFET) for a 5-min fluoroscopy examination of the central abdomen and right lower quadrant (110 kVp, 0.3 mA) and pelvis (110 kVp, 0.35 mA). The ED for a 16-slice abdomen/pelvis MDCT scan was determined using the 10-year-old protocol: 16x1.25 mm, pitch 1.375, 27.5 mm/rotation, 0.5 s, 140 kVp, 85 mA. Results A total of 176 children with CD underwent imaging, averaging 1.2 SBFTs and 1.1 CT scans. On average SBFT took 5.1 min with 3.3 abdominal radiographs. The EDs (mSv) for a 5-min fluoroscopy were 0.15 for the central abdomen, 0.35 for the right lower quadrant, and 0.56 for the pelvis, yielding an average ED for SBFT (5-min fluoroscopy, 3.3 abdominal radiographs) of 1.8-2.2 mSv. The ED for MDCT was 3.48 mSv. Conclusion Although the ED for MDCT might be up to twice that for SBFT, excessive fluoroscopy time and number of abdominal radiographs can result in actual EDs that are equivalent. Attention must be paid to SBFT technique to minimize radiation dose and to the indication to determine the appropriate examination.