Assessment of infant gonadal dose irradiated from urine-contaminated diapers during diuretic renal scintigraphy

Abstract

Objective To estimate the gonadal doses irradiated from urine- contaminated diapers during diuretic renal scintigraphy. Methods Images of 31 patients (18 males and 13 females) with urine-contaminated diapers during 99mTc-MAG3 renal scintigraphy were analyzed. The count rate of the diapers was converted into a time-activity curve based on the calibrated factor of the gamma camera system. The cumulative activity was determined from the area under the curve. By incorporating dose per unit cumulative activity pre-calculated from Monte Carlo simulation with 0-year phantom, the gonadal dose irradiated from diaper was calculated. To assess the degree of this additionally introduced dose from diapers, the calculated gonadal dose was compared to the internal gonadal dose from injected radiotracer activity. Results The cumulative activities irradiated from urine-contaminated diapers were 1.12 E04 ± 1.29E04 MBq.s in male infants, which was nearly half of the 1.94 E04 ± 1.80E04 MBq.s (P = 0.15) in female infants. However, the absorbed doses for testes in male infants were 7.37E-01 ± 8.50E-01 mGy, which was approximately 10 times the 6.38E-02 ± 5.94E-02 mGy for ovaries in female infants (P < 0.01). The diaper-introduced dose for testes and ovaries was 91.7% and 3.9% of the gonadal doses from the injected activity in patients with normal renal function, and 99.0% and 4.3% of those in patients with abnormal renal function. Conclusion Urine-contaminated diapers introduced additional radiation doses to infant patients during 99mTc-MAG3 renal scintigraphy. The gonadal doses were of significance in male infants who had nearly double the absorbed dose for the testes.