| Summary: | The mean glandular dose (MGD) was measured for a breast phantom by using
molybdenum/molybdenum and molybdenum/rhodium target/filter combinations, at
different kVp 26, 28 and 32 kilovolts. The phantom thickness was 7.5cm and was
made of BR12 material. The change of dose was studied as a function of depth inside
the phantom at different depths from the surface, namely 3.3, 4.3 and 5.3cm, by using
TLDs. It was found that the MGD value for different combinations of beam quality
(HVL) and energy (kVp) did not exceed the recommended values given by different
protocols.
The Mo/Rh target/filter required lower doses to achieve the same or better results
compared with the Mo/Mo target/filter. The change in the surface dose as a function
of kVp was more significant for Mo/Rh than for the Mo/Mo.
Studying the change in dose within the breast, as a function of depth gives a better
understanding of the interactions between radiation and tissue inside the breast. It
should be noted that the MGD is a tool for optimization of the mammography
parameters. However, the MGD should not be used directly to estimate the risk of
determinable health effects from mammography. This will ultimately help to
determine limits for the breast surface dose and a better understanding of cancer risk.
In future work, we will try to measure the change of the dose as a function of depth by
using more kVp, HVL, different breast composition and different target/filter
combinations to give a wider picture for different situations.
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