Magnification mammography is a special technique used in cases where breast complaints are noticed by a woman or when an abnormality is found in a screening mammogram. The carcinogenic risk in mammography is related to the dose deposited in the glandular tissue of the breast rather than the adipose, and Average Glandular Dose (AGD) is the quantity taken into consideration during a mammographic exam. Direct measurement of the AGD is not feasible during clinical practice and thus, the incident air Kinetic Energy Released per unit of MAss (KERMA) on the breast surface is used to estimate the glandular dose, with the help of proper conversion factors. Additional conversion factors adapted for magnification and tube voltage are calculated, using Monte Carlo simulation. The effect of magnification factor, tube voltage and various anode/filter material combinations on AGD, ESD and PDD is also studied. Results demonstrate that, for fixed glandularity, the estimation of AGD utilizing conversion factors depends on magnification factor, anode/filter combination and tube voltage applied. AGD was found to increase mainly with filter material’s kabsorption edge, filter’s Al thickness, anode material’s k-emission edge and tube voltage. Rh/Nb, W/Zr, W/Nb, W/Mo and Mo/Nb are combinations resulting in lower AGD and higher ESD, compared to the Mo/Mo one. / -

Breast cancer presents serious epidemiological problem, in result of which die more than 2 000 czech women every year. Screening mammography is one of the most expanded and most effective examinations for early detection of this desease but one has to take into account an inconsiderable risk connected with the procedure based on X-ray ionizing radiation. This diploma thesis deals with evaluation of the dose absorbed by the tissue. It contains the description of evaluation of the average dose in glandular tissue on PMMA phantom, as well as results of the measurements on conventional and digital mammograph. A data file with exposure parameters from mammography screening is included and interpreted. Also the Monte Carlo method was used for the dose evaluation, the thesis contains the brief description of the method, concept of analysis model in mammography and results of simulations.