The effective dose received by children up to 5 years of age from micturating cystourethrography (MCU) examinations was estimated in this study. The MCU examination consisted of 5 radiological views, 2 anteroposterior (AP) and three oblique (OBL) views. Entrance surface doses (ESD) were measured with thermoluminescent dosimeters for 30 children. The average ESD values per view varied from 0.34 mGy up to 0.57 mGy. In order to calculate the organ and effective doses, Monte Carlo MCNP-4A radiation transport simulation code was used. It was applied to three mathematical phantoms representing newborn, 1 and 5 year old children and all the patients were classified in those three groups. The effective dose conversion factors (C(f)) were calculated as the ratio of effective dose over the entrance dose. The C(f) factors decrease as the children's age increases. Children simulated by a newborn mathematical phantom, had C(f) factors almost double those represented by a 1-year-old mathematical phantom. For children simulated by a 5 year old phantom, the C(f) factors for AP and OBL views were almost the same. This was true for both male and female patients. The mean effective dose per view for male and female patients was found to be E=0.16 mSv. The effective dose per examination for male patients was E=0.86+/-0.31 mSv and E=0.76+/-0.28 mSv for female patients.

To assess the risk involved, an attempt was made to calculate the effective dose delivered to patients undergoing radiographic examinations. The examination parameters of 704 radiographs were used to calculate the average effective dose for each one of 40 different types of radiographic examinations and the results were tabulated. A sample of 2571 radiographs representing 1586 patients, obtained over a period of 2 weeks, was used to calculate the dose administered to this group. It was found that the average effective dose/radiograph was 549 muSv and the average effective dose/patient was 890 muSv, taking into account the fact that, on average, there were 1.62 exposures per patient. These figures were extrapolated to the total number of patients going through the radiology department giving a total dose of 59.4 Sv each year, causing an average annual risk of about three malignancies.

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