Radiation exposure in pediatric videourodynamics: An evaluation of safety in comparison to voiding cystourethrogram

Abstract

Children with spina bifida (SB) undergo a videourodynamic study (VUDS) or urodynamic study and voiding cystourethrogram (VCUG). A standardized protocol for imaging during a pediatric VUDS has not been established. Our aim is to quantify radiation exposure and establish a baseline for children with spina bifida (SB) undergoing VUDS in current practice at our institution. This is a retrospective study from 2013 to 2020 of consecutive pediatric SB patients undergoing VUDS by a single provider. Patients were categorized into three groups based on age; group 1 (0-2YR), group 2 (2-10YR), group 3 (>10YR). Radiation data was reported as mean air kerma (AK), dose area product (DAP) and exposure time (seconds). Effective dose (ED) was calculated based on radiation quantity (Air Kerma, AK) and organ sensitivity. The lifetime attributable risk (LAR) was calculated based on AK and a risk coefficient. Data points calculated for patients undergoing VUDS were then compared to age matched institutional VCUG data in the same age groups. 398 patients undergoing VUDS met inclusion criteria and 262 independent patients underwent VCUG. ED increased with age in both VUDS and VCUG. All VCUG groups were found to have a higher ED than VUDS. The LAR for VUDS groups 1-3 was 0.001, 0.002, and 0.006, respectively. Reported in percentages, there is a 0.1%, 0.2%, and 0.6% chance, respectively, of age groups 1, 2 and 3 developing cancer as a result of the radiation exposure from a VUDS. Our study found that ED was low across all age groups for VUDS, comparing favorably to the VCUG groups. VCUG was selected as a benchmark comparison for its diagnostic similarities and, at times, overlapping indications. Few studies have described ED with respect to VUDS or extrapolate the ED of VUDS into LAR in the pediatric population. We recognize that we have not determined the true ED of the gonads and bladder, rather we have overestimated, as the data is based on an international reference point proximal to the exposed individual. However, LAR was calculated for each age group and revealed that patients are at a negligible increased risk of developing malignancy secondary to exposure compared to the general population. Our current practice for pediatric VUDS has exhibited consistently low radiation exposure amongst all age groups. Moving forward, we have the foundation and flexibility to create an imaging protocol for pediatric VUDS, while taking more calculated steps toward incorporating ALARA, as low as reasonably achievable, principles. A protocol adhering to the ALARA principle could provide consistency across institutions and aid in multi-institutional studies.