DOSE REFERENCE LEVELS IN SPANISH INTRAORAL DENTAL RADIOLOGY: STABILISATION OF THE INCORPORATION OF DIGITAL SYSTEMS IN DENTAL CLINICAL PRACTICES

Backscatter factors calculation for intraoral dental radiology

The dosimetry of intraoral radiography procedures is of great interest since dental examinations are among the most numerous radiological procedures. Usually, the surveys are performed using measurements free in air. The entrance surface air kerma (K_e) can be estimated from measurements of incident air kerma and the use of backscatter factors (BSF). The purpose of this work is to calculate BSF values suitable for intraoral radiography. In addition to specific intraoral radiography, a comprehensive reassessment of internationally recommended BSF values was performed through Monte Carlo simulations. Moreover, theK_ewas estimated using the calculated BSF values for a sample of 44 intraoral radiography systems. The interpolation of intraoral radiography BSF values from reference data can lead to an overestimation of up to 10% and 6% in comparison with the values calculated in this work for monoenergetic photons and x-ray spectra, respectively. Such discrepancy may be relevant when defining diagnostic reference levels (DRLs) or performing quality control tests. The calculations for a sample of 44 intraoral radiography systems showed that the majority of the equipment operates with an entrance surface air kerma higher than 3.5 mGy. In the case of adopting a single value to estimateK_e, the use of BSF equal to 1.2 results in less dispersion compared to calculated values in this work and the use of 1.1 can underestimateK_evalues up to 12%.

ASSESSMENT OF ADULT DIAGNOSTIC REFERENCE LEVELS IN INTRAORAL RADIOGRAPHY IN TAMIL NADU REGION, INDIA

In the present study, incident air kerma has been measured, for six intraoral examinations, for establishing regional adult diagnostic reference levels (DRLs), in intraoral radiography, in Tamil Nadu, India. A total of 131 units, both digital (semiconductor-based) and analog (film-based) radiography systems, were selected for the study. The third quartile values, for the six intraoral examinations selected for the present study, ranged from 1.2 to 2.0 mGy, for the adult settings. The results showed a wide range of patient doses existing across the clinics or hospitals studied. This is the primary study for the establishment of adult intraoral DRL, in Tamil Nadu, one of the major states of the country. Similar studies will be undertaken in other major states across the country to establish national DRLs in intraoral radiography in the country.

DENTAL INTRAORAL EXPOSURES IN PORTUGAL: FROM 1990 TO 2018

Data from dental intraoral radiography quality controls was gathered from 1201 units (22% of the licensed X-ray units existing in Portugal), using film and digital image systems, between 2016 and 2018. The median incident air KERMA for standard superior molar tooth was evaluated in 0.9 mGy with the value of 1.3 mGy as the upper quartile. Comparisons with a 1990 published survey from dental exposures in Portugal were made. A 85% reduction for incident air KERMA per exposure was observed (6.0 mGy for the 1990 survey), which can be attributed to technical advances in the X-ray image receptors, as well as the implementation of legal requirements for technical acceptability of radiological units. It was also observed an increase of X-ray exams, which is related to an increase of dental practitioners, available radiological equipment and the level of dental healthcare.