Benefit of eliminating scout abdominal radiographs in pediatric fluoroscopy procedures
Scout abdominal radiographs performed prior to common fluoroscopy procedures in pediatric patients contribute a significant portion of overall radiation exposure, researchers from the Medical University of South Carolina (MUSC) in Charleston have determined. Because scout radiographs may not be necessary for all patients having fluoroscopic procedures, their elimination could make this a safer and more beneficial exam.
The study, published in Pediatric Radiology, retrospectively evaluated data from 151 fluoroscopic procedures performed during a four-month period on children ranging in age from 2 days to 18 years. The procedures included 65 voiding cystourethography (VCUG), 63 upper gastrointestinal (UGI) studies, and 23 contrast enema studies. The purpose of the study was to assess the fractional radiation exposure contribution of the scout radiographs to that of each total procedure.
Scout radiographs are taken to detect radiopaque calculi, other types of abdominal calcification, retained contrast agent, skeletal abnormalities, and subtle pneumoperitoneum and pneumatosis. Guidelines from the American College of Radiology (ACR) and the Society of Pediatric Radiologists (SPR) state that it is appropriate to take a preliminary fluoroscopic or radiographic image if indicated with the types of fluoroscopic procedures being analyzed in the study. Based on their experiences, MUSC’s pediatric radiologists did not believe that this was necessary for every patient and wanted to determine what benefit from less exposure to radiation a child would have.
Lead author Anil G. Rao, MD, assistant professor of radiology, and colleagues, recorded the radiation exposure parameters of dose area product (DAP) in Gy-cm2 and entrance air kerma (EAK) in mGy from the abdomen radiography provided by the fluoroscopy equipment (GE Precision 500D, GE Healthcare). They made the same recordings for the entire fluoroscopic procedure using the DAP and EAK values provided by the fluoroscopy equipment. The time duration was also recorded for each procedure. The authors then estimated the fractional contribution of the radiation parameters of the scout radiograph to the total procedure as a percentage of the scout to the total procedure values.
The fluoroscopic technique used was designed to minimize radiation exposure. The technique used four frames per second, appropriate collimation, and last-image-save technique/last-image-hold technique. Geometric magnification was avoided. Procedures were terminated as soon as the clinical question requiring the exam was answered.
The 151 procedures were performed within six seconds to two minutes. VCUG studies were performed the most rapidly. Exam duration was comparable for UGI and contrast enema studies.
The fractional contribution of the DAP of the scout abdominal radiographs to the total fluoroscopic procedure ranged from 4% to 98%. Similarly, the fractional contribution of the scout radiograph to the total procedure for EAK values ranged from 6% to 97%. The shorter the duration of the fluoroscopy procedure, the higher the scout contribution was. When a grid was used with a patient to obtain a diagnostic quality radiograph, both of the radiation parameters were higher.
Based on their findings, the authors recommend eliminating scout abdominal radiograph on a case by case basis if recent prior abdominal radiographs are available for review. They recommend that scout images be ordered only when deemed necessary by the attending radiologist. An example of this would be if the entire area of interest is larger than the maximum field or size of the image intensifier, and if a patient had no prior images for reference.
The authors also recommend that additional assessments of the added value of abdominal scout radiographs be formally conducted with larger-sized patient cohorts. When scout images can be eliminated, the overall benefit-to-risk of fluoroscopic procedures would improve for these young, vulnerable patients.
REFERENCE
- Rao AG, Simmons Sr. CE, Thacker PG, et al. Radiation exposure contribution of the scout abdomen radiograph in common pediatric fluoroscopic procedures. Pediatric Radiol. 2016:46;9:1241-1248. (doi: 10.1007/s00247-016-3602-2).