Pediatric Urology Fall Congress, Sept 9-11 2016, Fairmont The Queen Elizabeth
 Montréal, Canada



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Prospective Evaluation of Radiation Dose with Conventional Fluoroscopic Voiding Cystourethrogram in Pediatric Patients
Pankaj P. Dangle, MD,MCh, Rajeev Chaudhry, MD, Wael Abdalla, MD, Michael Sheetz, MD, Helen Bradley, BSN, Glenn Cannon, MD, Francis X. Schneck, MD, Michael C. Ost, MD, Heidi Stephany, MD.
Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.

Background: A voiding cystourethrogram (VCUG) remains the gold standard for evaluation of febrile urinary tract infections in pediatric patients. Children are more sensitive to ionizing radiation and the risk of cumulative radiation is a growing concern. We prospectively evaluated children undergoing single VCUG using dosimeters to assess the amount of radiation.
Material and Methods: All patients undergoing a VCUG were prospectively enrolled in the study. Dosimeters [nanoDot™OSL(optically stimulated luminescence)] were affixed to the patient’s skin using a standardized clear adhesive patch overlying the sacrum, at the point of maximum radiation exposure to record dosimetry data. Fluoroscopy was performed with a Siemen Axiom Luminos fluoroscopic unit, with an integral device to compare emitted radiation dose with the returned dose. Fluoroscopy time and dose mode were recorded. Skin to source distance was fixed at 60 cm for all patients with the beam collimated to the smallest area possible with a low dose setting and pulsed fluoroscopy at 3 frames per second. Dosimeters were processed with a MicroStar® InLight® Reader. Demographic data, indications for VCUG, fluoroscopic settings and dosimeter readings were collected. We used Pearson’s correlations coefficient to establish correlation between dosimeter skin dose, fluoroscopic time, body mass index, BMI percentile. Statistical significance was considered with p -0.05 obtained with Microsoft Excel 2016.
Results: A total of 19 patients were enrolled with a median age of 12 months (1-280). Twelve patients were female and the indication for a VCUG in the majority of patients (13/19) was a febrile urinary tract infection. The median body mass index (BMI) was 17.7 (14.3 - 23.4) and the median BMI percentile was 77.7 (57.2 - 99.7) based on age.
Median fluoroscopic time was 54 seconds (12-132). The mean dose area product (DAP) was 18.7 mGy*m2 (0.1-119) and the mean dose measured at the skin entrance received per dosimeter was 0.68 mGy (0.08-2.7) (p = 0.01). There was no linear correlation between the dosimeter skin entrance dose and BMI (r = 0.05, p = 0.86) and BMI percentile (r = 0.49, p = 0.26) as well as no correlation between skin entrance dose at the source dose and BMI (r = 0.06 p = 0.80) and BMI percentile (r = 0.52, p = 0.22). There was no correlation between fluoroscopic time in seconds to BMI (r = 0.10, p = 0.75) and BMI percentile (r = 0.30, p = 0.50).
Conclusion: There was a significant difference between the mean dose of radiation recorded by the fluoroscopy unit compared to the amount of radiation at the skin entrance in children undergoing a VCUG. Overall, the amount of radiation at the skin entrance is low with modifications including tight collimation, low dose setting, and pulsed fluoroscopy without compromising the quality of image.


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