A new adjustment proposal for determining tube output and analysis of its influence on mean glandular dose estimation
DOI:
https://doi.org/10.37004/sefm/2020.21.1.002Keywords:
Glandular dose, mammography, breast tomosynthesis, kerma, mammography dosimetersAbstract
The aim of this work is to propose a new polynomial fitting function to obtain air kerma for any kilovoltage in comparison to exponential fitting recommended by European and Spanish protocols. Kerma and half-value layer have been measured on three different mammography systems with an ionization chamber and a semiconductor dosimeter, in both digital mammography and digital breast tomosynthesis. Glandular dose has been estimated from these values using the method by Dance et al. The function proposed reveals a better agreement than the exponential one between measured and calculated kerma. Glandular dose estimation calculated from kerma by both exponential and polynomial function shows differences of less than 2.5% for all mammography systems using the ionization chamber, except for big breasts (bigger than 6 cm). Nevertheless, greater differences (~10%) are found between employed dosimeters. Therefore, knowing the dosimeters responses properly and using and accurate adjustment methodology is very important to minimize uncertainties in the glandular dose estimation.
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