Ambient dose equivalent and effective dose from scattered x-ray spectra in mammography for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations

Reassessment of structural shielding design in mammography installations

In this article, it is argued that current shielding methodologies can lead to an over-shielding of low-energy X-ray imaging facilities. Measurements of scattered air kerma rates in a mammography installation, including the effect of an anthropomorphic phantom of the patient, are presented. Detailed Monte Carlo calculations that support the measured results are also shown. Calculations for a mobile mammography installation, including the 'patient transmission factor', are presented and results are discussed.

X-ray transmission through nanostructured and microstructured CuO materials

This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 μm, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission.

Generation of calibrated tungsten target x-ray spectra: modified TBC model

In spite of the recent advances in the experimental detection of x-ray spectra, theoretical or semi-empirical approaches for determining realistic x-ray spectra in the range of diagnostic energies are important tools for planning experiments, estimating radiation doses in patients, and formulating radiation shielding models. The TBC model is one of the most useful approaches since it allows for straightforward computer implementation, and it is able to accurately reproduce the spectra generated by tungsten target x-ray tubes. However, as originally presented, the TBC model fails in situations where the determination of x-ray spectra produced by an arbitrary waveform or the calculation of realistic values of air kerma for a specific x-ray system is desired. In the present work, the authors revisited the assumptions used in the original paper published by . They proposed a complementary formulation for taking into account the waveform and the representation of the calculated spectra in a dosimetric quantity. The performance of the proposed model was evaluated by comparing values of air kerma and first and second half value layers from calculated and measured spectra by using different voltages and filtrations. For the output, the difference between experimental and calculated data was better then 5.2%. First and second half value layers presented differences of 23.8% and 25.5% in the worst case. The performance of the model in accurately calculating these data was better for lower voltage values. Comparisons were also performed with spectral data measured using a CZT detector. Another test was performed by the evaluation of the model when considering a waveform distinct of a constant potential. In all cases the model results can be considered as a good representation of the measured data. The results from the modifications to the TBC model introduced in the present work reinforce the value of the TBC model for application of quantitative evaluations in radiation physics.