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) 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, theKwas 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, 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 underestimateKvalues up to 12%.