# A Dosimetric Analysis of Reduction Cardiac Dose with Lead Shielding in Breast Cancer Radiotherapy
## 3 Results
### Comparison of TPS Doses with Doses Measured by OSLDs  
OSLDs were used to measure the OAR doses of different treatment techniques, so as to identify the difference between the TPS calculated dose and the actual measured dose. The results are listed in Tables 3-5. \begin{table}
\begin{tabular}{l l c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Organ (Number)**}} & \multicolumn{1}{c}{**3D-CRT**} & \multicolumn{1}{c}{**IMRT**} & \multicolumn{1}{c}{**VMAT**} & \multicolumn{1}{c}{**3D-CRT**} & \multicolumn{1}{c}{**3D-CRT**} & \multicolumn{1}{c}{**IMRT**} \\  & \multicolumn{5}{c}{**Mean Dose \(\pm\) SD (Gy)**} & \multicolumn{5}{c}{**_p-Value_**} \\ \hline Thyroid & Left (28) & 0.10 \(\pm\) 0.01 & 0.11 \(\pm\) 0.02 & 0.34 \(\pm\) 0.03 & 0.0918 & 0.0009 * & 0.0004 * \\ Heart & Right (29) & 0.18 \(\pm\) 0.02 & 0.20 \(\pm\) 0.01 & 0.38 \(\pm\) 0.01 & 0.0099 * & 0.0006 * & 0.0002 * \\  & Atrium (95) & 0.69 \(\pm\) 0.03 & 0.78 \(\pm\) 0.04 & 2.88 \(\pm\) 0.02 & 0.0622 & 0.0000 * & 0.0000 * \\ Lung & Ventricle (108) & 0.70 \(\pm\) 0.01 & 0.94 \(\pm\) 0.02 & 4.05 \(\pm\) 0.04 & 0.0004 * & 0.0000 * & 0.0000 * \\  & Left upper (97) & 6.14 \(\pm\) 0.03 & 8.22 \(\pm\) 0.01 & 8.93 \(\pm\) 0.02 & 0.0000 * & 0.0000 * & 0.0000 * \\  & Right upper (102) & 0.69 \(\pm\) 0.03 & 1.02 \(\pm\) 0.02 & 3.95 \(\pm\) 0.03 & 0.0002 * & 0.0000 * & 0.0000 * \\  & Left lower (100) & 0.24 \(\pm\) 0.03 & 0.52 \(\pm\) 0.01 & 0.83 \(\pm\) 0.03 & 0.0005 * & 0.0000 * & 0.0000 * \\  & Right lower (106) & 0.13 \(\pm\) 0.02 & 0.15 \(\pm\) 0.03 & 0.77 \(\pm\) 0.03 & 0.2627 & 0.0011 * & 0.0007 * \\ \hline \hline \end{tabular}  
* \(p\)-value < 0.05 was considered statistically significant.  
\end{table} 
Table 2: Comparison of the average OAR doses of the three techniques. \begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **Organ (Number)** & \multicolumn{2}{c}{**TPS**} & **OSLD** & \\ \cline{3-5}  & & \multicolumn{2}{c}{**Mean Dose \(\pm\) SD (Gy)**} & \multicolumn{1}{c}{\(p\)**-Value**} \\ \hline Thyroid & & & & \\ \cline{3-5} Heart & Left (28) & 0.11 \(\pm\) 0.02 & 0.25 \(\pm\) 0.04 & 0.035 * \\  & Right (29) & 0.20 \(\pm\) 0.01 & 0.21 \(\pm\) 0.03 & 0.112 \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\ \end{tabular}
\end{table} 
Table 4: Comparison of the TPS calculated doses and the doses measured by OSLDs of the IMRT plan. \begin{table}
\begin{tabular}{l c c c} \hline \hline  & **\multirow{2}{*}{**Organ (Number)**} & \multicolumn{2}{c}{**TPS**} & **OSLD** \\ \cline{3-5}  & & \multicolumn{2}{c}{**Mean Dose \(\pm\) SD (Gy)**} & \multicolumn{1}{c}{\(p\)**-Value**} \\ \hline Thyroid & & & \\ \cline{3-5} Heart & Left (28) & 0.34 \(\pm\) 0.03 & 0.40 \(\pm\) 0.07 & 0.176 \\  & Right (29) & 0.38 \(\pm\) 0.01 & 0.39 \(\pm\) 0.02 & 0.749 \\ Heart & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & \\  & & & & \\  & & & \\  & & & & \\ \end{tabular}
\end{table} 
Table 5: Comparison of the TPS calculated doses and the doses measured by OSLDs of the VMAT plan. \begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **\multirow{2}{*}{**Organ (Number)**} & \multicolumn{2}{c}{**TPS**} & **OSLD** & \\ \cline{3-5}  & & \multicolumn{2}{c}{**Mean Dose \(\pm\) SD (Gy)**} & \multicolumn{1}{c}{\(p\)**-Value**} \\ \hline Thyroid & & & \\ \cline{3-5} Heart & Left (28) & 0.10 \(\pm\) 0.01 & 0.27 \(\pm\) 0.05 & 0.024 * \\  
that the difference was statistically significant. Therefore, special attention should be paid to the thyroids when applying lead shields. In contrast, in terms of the average doses of the right thyroid, the heart, and the lungs, no significant differences were seen between the planning dose and the dose measured by OSLD. Table 4 compares the TPS calculated doses and the doses measured by OSLDs of the IMRT plan. It was noted that the TPS underestimated the average doses of both the left thyroid and the lungs (No. 100), the measurements of which were 0.25 \(\pm\) 0.04 Gy and 1.37 \(\pm\) 0.14 Gy, respectively.