## 3 Results
### Segmentation of the Transducer Region (TLSM Approach)

Table 6: Highest values for the F-measure median obtained in the segmentation of the gel-pad region with the DRLSE segmentation method in sagittal images. (0.9213-0.9365, IQR 0.0153). Given this maximum value, the corresponding maximum value of the F-measure median in the segmentation of the water region was 0.9609 (0.8931-0.9768, IQR 0.0837). In sagittal images the maximum was 0.9323 (0.9221-0.9402, IQR 0.0181). Given this maximum value, the corresponding maximum value of the F-measure median in the segmentation of the water region was 0.9681 (0.9627-0.9715, IQR 0.088). Segmentation with the Watershed Segmentation Algorithm with Markers (WSAM Approach) and Comparison with the Threshold, GAC and DRLSE Methods (TLSM Approach)  
In the following tables, the values for the F-measure median are reported by region of interest. Table 9 contains information of transverse images and Table 10 contains information of sagittal images. The values for the F-measure medians are shown along with the values for Q1, Q3 and IQR. \begin{table}
\begin{tabular}{c c} \hline \hline
**Region of Interest** & **Values for the F-Measure Median** \\ \hline Air & 0.9510 (0.9334–0.9608, IQR 0.0274) \\ Tissue & 0.9241 (0.8870–0.9426, IQR 0.0556) \\ Gel-Pad & 0.9553 (0.9472–0.9625, IQR 0.0154) \\ Transducer & 0.8821 (0.8617–0.9018, IQR 0.0401) \\ Water & 0.9459 (0.9338–0.9555, IQR 0.0218) \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Values for the F-measure median obtained in the segmentation of the regions of interest with the WSAM segmentation method in sagittal images. \begin{table}
\begin{tabular}{c c} \hline \hline
**Segmentation Method and Parameter Value** & **Highest Values for the F-Measure Median** \\ \hline DRLSE (\(a\_\)gelpad = \(-\)4) & **0.9305 (0.9213–0.9365, IQR 0.0153)** \\ DRLSE (\(a\_\)gelpad = \(-\)2) & 0.9226 (0.9052–0.9371, IQR 0.0319) \\ DRLSE (\(a\_\)gelpad = \(-\)3) & 0.9301 (0.9171–0.9371, IQR 0.0200) \\ DRLSE (\(a\_\)gelpad = \(-\)5) & 0.9293 (0.9212–0.9351, IQR 0.0139) \\ DRLSE (\(a\_\)gelpad = \(-\)6) & 0.9277 (0.9185–0.9364, IQR 0.0178) \\ DRLSE (\(a\_\)gelpad = \(-\)7) & 0.9252 (0.9178–0.9353, IQR 0.0175) \\ DRLSE (\(a\_\)gelpad = \(-\)8) & 0.9241 (0.9140–0.9344, IQR 0.0205) \\ GAC (\(c\_\)gelpad = \(-\)0.3) & 0.9129 (0.8924–0.9309, IQR 0.0385) \\ Threshold (\(T\_\)_\(transducer\) = 4) & 0.9240 (0.9089–0.9347, IQR 0.0257) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Highest values for the F-measure median obtained in the segmentation of the transducer region in transverse images. Maximum is shown in bold. \begin{table}
\begin{tabular}{c c} \hline \hline
**Segmentation Method and Parameter Value** & **Highest Values for the F-Measure Median** \\ \hline GAC (\(c\_\)gelpad = \(-\)0.15) & **0.9323 (0.9221–0.9402, IQR 0.0181)** \\ GAC (\(c\_\)gelpad = 0) & 0.9310 (0.9175–0.9388, IQR 0.0212) \\ GAC (\(c\_\)gelpad = \(-\)0.3) & 0.9261 (0.9076–0.9349, IQR 0.0272) \\ DRLSE (\(a\_\)gelpad = 0) & 0.9293 (0.9134–0.9392, IQR 0.0259) \\ DRLSE (\(a\_\)gelpad = \(-\)0.5) & 0.9317 (0.9188–0.9417, IQR 0.0228) \\ DRLSE (\(a\_\)gelpad = \(-\)1) & 0.9300 (0.9173–0.9393, IQR 0.0220) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Highest values for the F-measure median obtained in the segmentation of the transducer region in sagittal images. Maximum is shown in bold. \begin{table}
\begin{tabular}{c c} \hline \hline
**Region of Interest** & **Values for the F-Measure Median** \\ \hline Air & 0.9657 (0.9582–0.9699, IQR 0.0118) \\ Tissue & 0.9224 (0.8718–0.9468, IQR 0.0751) \\ Gel-Pad & 0.9553 (0.9496–0.9606, IQR 0.0109) \\ Transducer & 0.9416 (0.9330–0.9540, IQR 0.0210) \\ Water & 0.9769 (0.9741–0.9803, IQR 0.0062) \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Values for the F-measure median obtained in the segmentation of the regions of interest with the WSAM segmentation method in transverse images. After the evaluation of the segmentation quality with F-measure using the WSAM approach for each region, a comparison with the maximum results of the TLSM approach (reported in Sections 3.1-3.3) was carried out.