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Radiation Exposure to Children During Videourodynamics: How Low Can We Go?

Sunday, October 21, 2012: 2:30 PM
Grand Ballroom B (Hilton Riverside)
Andrew J. Combs, RPA-C, Jason P. Van Batavia, MD and Kenneth I. Glassberg, MD, Division of Pediatric Urology, Department of Urology, Columbia University College of Physicians and Surgeons, Morgan Stanley Children's Hospital of New York-Presbyterian, New York, NY

Purpose:   While videourodynamics (VUDS) are an important tool in the evaluation of children with a variety of neurogenic, anatomic or functional disorders, real concerns regarding amount of radiation exposure and potential long term cancer risks exist. These concerns are further magnified when children require repeated VUDS testing or other radiographic imaging studies over time. There are also concerns as to where these studies are performed and by whom. In recent years we have made a concerted effort to bring the dose of radiation down as low as possible and still achieve a worthwhile, informative study. We report our radiation exposure data prospectively collected for all children undergoing VUDS procedures during the past year.

Methods:  Cumulative radiation dose and total exposure time, all as a function of field of view, were analyzed, as was relation to diagnosis and bladder capacity. All fluoroscopy (OEC series 9800 C-arm) was performed in the Urology unit by urology resident or attending physicians in concert with a single experienced urodynamicist.

Results:   A total of 157 videourodynamic studies were performed (98M, 59F; mean age 8.5 yrs, range 0.1-21.5).  The most common diagnosis was anatomic abnormality (37%), followed by functional/non-neurogenic bladder dysfunction (32%) and neurogenic bladder (28%).  Mean total fluoroscopy time was 9.8 seconds (range 2.3-26.3) and mean total radiation exposure was 0.29 mGy (range 0.06-1.77 mGy).  Total fluoroscopy time and radiation exposure by diagnosis is shown in table 1.  Children with neurogenic bladder had significantly less total radiation exposure than children with either anatomic abnormalities or functional bladder disorders (0.19mGy vs. 0.35mGy and 0.31mGy, respectively, both p<0.003).  Bladder capacity influenced total radiation exposure with mean exposure 0.24 mGy for capacity <250mL vs. 0.34 mGy for capacity ≥250mL (p=0.03).  No study was deemed to have inadequate imaging quality affecting interpretation either by the attending or outside referring urologist.

Conclusions:   Radiation exposure during VUDS can be lowered to levels well below those previously reported without sacrificing study quality.  Total radiation exposure during VUDS in this study was significantly less than previously reported; on average equivalent to the radiation exposure of three chest x-rays or 1/5 of a standard VCUG and demonstrate that urologists too can adhere to the principle of ALARA (“as low as reasonably achievable”). The lower exposure times in neurogenic bladders likely reflects lesser need for multiple voiding images compared to other conditions.  Bladder capacity does appear to factor into increased radiation dosing as previously reported but this effect can be diminished by turning off the auto contrast feature once a scout image has been obtained.  The key elements to reducing radiation are attention to detail, use of low dose setting and the substitution of static images of very short duration whenever possible in place of video clips.

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