Assessment of x-ray units for intraoral radiographic techniques in Salvador, Bahia (Brasil)

The aim of this study was to assess the adequacy of x-rays units for intraoral radiographic techniques in Salvador, Bahia (Brazil). The sample was composed of 150 units randomly selected from a total of 652 units evaluated by a dosimetry kit (IRD/CNEN Institute of Radiation Protection and Dosimetry of the National Commission of Nuclear Energy - Ministry of Health). Three parametrs were considered: (a)maximum skin exposure, 500 mRem; (b)radiation field size, 5.0-6.0 cm; and (c)minimum aluminum filtration, 1.5 mm. If any of the parameters did not comply with IRD/CNEN standards, the x-ray unit was considered to be out of order. Pearson's correlation test, degree of dependence (Pearson's Qui-square test), and the degree of association between the variables (V Cramer coefficient)were used for the statistical analysis. The results showed that 59.33 porcento of the units failed to comply with at least one of the three parameters evaluated. Radiation field size was the criterion that showed the highest level of failure (40.67 porcento). Filtration and skin exposure were responsible for the failure of 30 por cento and 20.7 por cento of the x-ray units, respectively. Perarson's correlation test showed a statistically significant positive correlation between skin exposure and radiation field size, and negative correlation between skin exposure and filtration, indicating that akin exposure tends to increase with the size of the radiation field and/or decreases with filtration. The highest association was detected between skin exposure and filtration. The results show the importance of promoting an educational program about source-skin distance, exposure time, film sensitivity, film processing, film-holding devices; adopting filtration and collimation standards; and the use of rectangular collimator as mandatory. Such a program and update of the rules would stimulate increased use of the ALARA principle (as low as reasonably achievable) for patients undergoing intraoral radiography