ObjectiveDerive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations.Materials and MethodsFiltered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode.ResultsCalculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%.ConclusionThe results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography.

ObjectiveTo evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms.Materials and MethodsIrradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms.ResultsConsidering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values.ConclusionThe present study contributes to verify the equipment conformity as regards dose values and image quality.

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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, the K e was 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 estimate K 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 underestimate K e values up to 12%.