RESUMO
OBJECTIVE: Our aim was to develop a compensated filtration collimator for use in paediatric patients undergoing cephalometric radiography that reduces the radiation dose administered and fulfils recommendation 4F of the European guidelines on radiation protection in dental radiology. METHODS: An easy to use filtration-compensated collimator was constructed of plastic, lead and aluminium and used randomly with a group of 32 children (mean age 11 years) undergoing cephalometric radiography before receiving orthodontic treatment. The radiation doses administered to patients (eye lens and thyroid, submandibular and parotid glands) and to the chassis of the radiographic equipment were determined. RESULTS: The filtration-compensated collimator is easily fixed to the external surface of the radiographic equipment and results in (a) as collimator, a reduction of 40% in the surface irradiated in the children and of 61.4% in the dose administered to the thyroid glands (P<0.001); (b) as filtration compensator, a reduction of 32.8% administered to the eye lens (P<0.001), 31.45% to the submaxillary gland (P<0.01) and 11.4% to the parotid gland (P<0.05); there was no difference in the dose determined on the radiographic film. CONCLUSIONS: A radiographic examination can be carried out with children using only a third of the dose normally used with no increase in the time or cost involved.
