## 4 Discussion  
### Factors Affecting AGD in Mammography  
The AGD depends on several parameters, including exposure factors (kVp and mAs), beam quality (HVL), target filter/filter combination, breast composition, and breast thickness. In this study, mammography devices operate in the auto-mode, where the compressed breast thickness determines the kV and filter selection (for devices with more than one target filter combination). The required tube current exposure time was determined either via pre-exposure settings for manual systems (SF and CR) or by automatic exposure control (AEC) in digital mammography devices M2 and M8 (Table 2).  
Variations in AGD is primarily caused by differences in mAs due to differences in CBT among women. It is essential to control both parameters in mammography because the AGD values increase with mAs and CBT. Automatic exposure control in mammography adjusts mAs values based on the patient's characteristics (CBT), thereby reducing the AGD.  
Figure 2 shows a correlation between AGD and mAs in DR mammography devices that use AEC features. M2 and M8 show a correlation coefficient (R) of 0.54 and 0.84,  
Figure 1: Boxplot distributions of the average glandular dose per view (AGD).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Unit**} & \multirow{2}{*}{**N (Women)**} & \multirow{2}{*}{
\begin{tabular}{c} **HVL (mm** \\ **Aleq)** \\ \end{tabular} } & \multirow{2}{*}{**Ki (mGy)**} & \multicolumn{2}{c}{**MGD (mGy) per Projection**} & \multirow{2}{*}{**MGD (mGy)**} \\ \cline{5-6}  & & & & **CC** & & **MLO** & **per Woman** \\ \hline \multicolumn{6}{c}{SF mammography} \\ M4 & 22 & 0.47 & 2.95 \(\pm\) 1.02 & 0.98 \(\pm\) 0.26 & 1.01 \(\pm\) 0.29 & 3.98 \(\pm\) 1.10 \\ M3 & 29 & 0.42 & 7.74 \(\pm\) 1.2 & 2.45 \(\pm\) 0.49 & 2.02 \(\pm\) 0.48 & 8.94 \(\pm\) 1.94 \\ \multicolumn{6}{c}{Mean \(\pm\)\(\sigma\) (SF)} & 5.35 \(\pm\) 3.39 & 1.72 \(\pm\) 1.04 & 1.52\(\pm\)0.77 & 6.46 \(\pm\) 3.51 \\ \multicolumn{6}{c}{Digital mammography (CR \& DR)} \\ M1 & 29 & 0.38 & 8.0 \(\pm\) 0.40 & 2.89 \(\pm\) 0.82 & 2.08 \(\pm\) 0.88 & 9.94 \(\pm\) 3.4 \\ M2 & 27 & 0.42 & 5.0 \(\pm\) 1.16 & 1.10 \(\pm\) 0.24 & 1.13 \(\pm\) 0.26 & 4.46 \(\pm\) 1.00 \\ M5 & 30 & 0.41 & 2.02 \(\pm\) 0.70 & 0.56 \(\pm\) 0.21 & 0.48 \(\pm\) 0.16 & 2.08 \(\pm\) 0.74 \\ M6 & 30 & 0.36 & 3.19 \(\pm\) 0.47 & 1.02 \(\pm\) 0.21 & 0.91 \(\pm\) 0.18 & 3.86 \(\pm\) 0.78 \\ M7 & 30 & 0.39 & 5.07 \(\pm\) 0.39 & 1.13 \(\pm\) 0.09 & 1.13 \(\pm\respectively, whereas Figure 3 shows a correlation between AGD and mAs mammography devices that use manual exposure factor selection; M4 and M5 show a correlation coefficient (R) of 0.75 and 0.31, respectively. Manual exposure factors should be determined using a technical chart to avoid further dose complications. Figures 2 and 3.  
As shown in Table 2, other hospitals use fixed kVp or fixed kVp and mA values (Table 2), implying that patients can receive either a high AGD value that could increase patient risk or a low dose that could adversely affect the quality of diagnostic information. Automatic exposure control in imaging adjusts exposure factors according to patient characteristics such as breast compression thickness in mammography.  
Several authors have studied the correlation between MGD and CBT in X-ray mammography, showing a linear correlation between MGD and CBT [24,25]. Figure 4 shows a  
Figure 2: Correlation between AGD and mAs DR mammography devices: (**a**) M2; (**b**) M8.  
positive correlation between MGD and CBT because of the use of AEC to control both kV and mAs values. The correlation between MGD and CBT in other devices is significantly affected using AEC or manual settings during a particular X-ray procedure.  
Figure 3: Correlation between the AGD and mAs DR mammography devices: (**a**) M4 device and (**b**) M5 device.