# Low-Cost and Easily Fabricated Ultrasound-Guided Breast Phantom for Breast Biopsy Training
## 3 Results
### Breast Phantom Validation Workshop  
Single-layered gelatin-based phantoms (glandular tissue embedded with simulated tumors) were evaluated by six participants in the validation workshop. All the participants completed the pretraining and posttraining questionnaires. The participants ranged from trainees to experienced doctors, with varying levels of experience in ultrasound-guided biopsy: 50% (\(n=3\)) of the participants were inexperienced, 33% (\(n=2\)) were moderately experienced and the remaining 17% (\(n=1\)) were experienced. The mean preinstructional score of the participants was 17% (SD 17%). The mean postinstructional score was 83% (SD 17%), in which an overall improvement of 67% was achieved (Figure 5). Among individual groups, the experienced group performed perfectly before and after the instruction; all subjects in the moderately experienced group showed an improvement from 0% to 100%; two of the three inexperienced subjects also improved from 0% to 100%, while one remained at 0%. No chest wall hits were found in any group in the preinstructional and postinstructional tests. Overall, the confidence level of all participants in the workshop substantially increased. A comparison between the pretraining and posttraining evaluation scores is shown in Figure 6. Among individual groups, the experienced group improved the confidence level from 80% to 90%; the moderately experienced group showed an improvement from 55% (SD 5%) to 85% (SD 5%); the inexperienced group improved from 20% (SD 10%) to 47% (SD 20%). Figure 5: Pre-instructional and post-instructional test results. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Young’s Modulus (kPa)** & **Speed of Sound** & **Attenuation** & **Relative Backscatter Power** \\  & & **(m/s)** & **(dB/cm)** & **(dB)** \\ \hline Glandular tissue & 15.4 & \(1684.26\pm 36.16\) & 2.69 \(\pm\) 0.07 & 3.11 \(\pm\) 0.18 \\ Fat tissue & 2.3 & \(1534.49\pm 1.22\) & 2.34 \(\pm\) 0.03 & 0.49 \(\pm\) 0.10 \\ Rubber glove & & & & \\ with colored & - & \(1506.50\pm 6.07\) & 4.50 \(\pm\) 0.49 & \(-\)0.46 \(\pm\) 0.70 \\ solution & & & & \\ Dried sweet & & & & \\ potato & - & \(1475.50\pm 17.82\) & 4.12 \(\pm\) 0.20 & 12.62 \(\pm\) 0.48 \\ Dried agar konjac & - & \(1428.49\pm 1.81\) & 3.46 \(\pm\) 0.54 & 3.04 \(\pm\) 0.26 \\ Shallot & - & \(1503.83\pm 1.19\) & 6.98 \(\pm\) 0.11 & 7.21 \(\pm\) 0.15 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Experimental results of mechanical and acoustic properties for simulated glandular tissue, fat tissue and tumor. The results of the survey (Table 4) showed that, overall, the developed phantom satisfied the participants. Furthermore, 83% (\(n=5\)) of the participants agreed that the ultrasound image quality produced by the breast phantom was excellent or good. However, only 17% (\(n=1\)) of the participants claimed that there was room for improvement for the haptic feedback they received during the placement of the core needle into the breast phantom. In this survey, the aspects of the breast phantom that the participants valued the most were investigated. The most valuable aspects were ultrasound image quality (25%), haptic feedback (25%), ease of use (25%), cost (15%) and design (10%). A further study on the multilayered gelatin-based phantom (fat tissue, glandular tissue embedded with simulated tumors) was conducted (Table 5). Example ultrasound images of the tumors embedded in the gelatin-based phantom are shown in Figure 7a-d. All participants agreed that the ultrasound image produced by the multilayered breast phantom was similar to that of actual breast fat tissue. The artefact caused by the boundary between the fat and glandular tissues could be clearly visualized (Figure 7e). Moreover, all the participants also claimed that the haptic feedback they received during placement of the core needle into the multilayered gelatin-based phantom was more realistic than that for the single-layered phantom.