Figure 8.

Quantitative evaluation of the surgical skills; (a) Preservation of the peripheral zone (${\overline{R}}_{\mathit{pres}}$) is a safety parameter related to the safety of the surgery; (b) Smoothness of resection boundary (${\overline{R}}_{\mathit{smoo}}$) describes a dexterous control of the surgical tools, which results in a smooth resection boundary; (c) Circularity of resection area $\left({\overline{R}}_{\mathit{circ}}\right)$ is about the symmetry of the resection around the urethra. The error bars represent standard deviations and the values are compared using t test (*p < 0.01); (d) The evaluated surgical skills based on the three parameters are displayed as a scoring system in a radar chart.