A video analysis technique for organ dose assessment in pediatric fluoroscopy: applications to voiding cystourethrograms (VCUG).

ABSTRACT

The time-sequence videotape-analysis methodology, originally developed by Sulieman et al. [Radiol. 178, 653-658 (1991)] for use in tissue dose estimation in adult fluoroscopy exams, has been adapted to the study of the newborn voiding cystourethrogram (VCUG). Individual frames of fluoroscopic and radiographic video were analyzed with respect to unique combinations of field size, field center, projection, tube potential, and mA or mAs, respectively. A modified version of the stylized ORNL newborn model was coupled to the MCNP4C radiation transport code to report organ doses per unit entrance air kerma (free-in-air) for each identified x-ray field. A series of urinary bladder models was additionally developed representing the organ at differing stages of contrast filling. The technique was subsequently applied to two patients, a 3-month male and a 1-month female, examined via a conventional fluoroscopy system used just prior to departmental conversion to digital systems. The effective dose to these patients was estimated as 0.47 mSv and 1.36 mSv, respectively (ratio of 2.9). Corresponding ratios of cumulative fluoroscopy time and entrance air kerma were 2.2 and 1.6, respectively. For the male patient, the mean percent dose contribution from fluoroscopy for all irradiated organs was 71 +/- 12%, while that value for the female patient was 88 +/- 4%.