# Risk Management for the Reliability of Robotic Assisted Treatment of Non-resectable Liver Tumors
## 2 Materials and Methods
### Definition of Possible Hazards and Associated Risks  
Steps 2 and 3 in the risk management process (see Figure 1) are intended to evaluate all the possible hazards and estimate their occurrence risk. The possible hazards were determined (and detailed in Table 1) with the help of nine clinicians from the \"Iuliu Hatieganu\" University of Medicine and Pharmacy, Cluj-Napoca. Furthermore, each clinician filled in a questionnaire (see Appendix A) regarding the severity and occurrence probability of each hazard, and the mean values are also presented in Table 1 (in Section 3, the risks associated with the robotic assisted procedure are reevaluated based on the proposed technical solution). The severity and probability scales were derived from a typical risk assessment matrix and the overall score definition was chosen to allow a simple yet comprehensive evaluation of the risks (which was also used in [15]).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Hazard**} & \multirow{2}{*}{**Associated Risk**} & \multirow{2}{*}{**Severity \({}^{*}\)**} & \multirow{2}{*}{**Probability**} & \multirow{2}{*}{**Overall**} \\  & & & & & **Score *** \\ \hline \multirow{2}{*}{**H1**} & \multirow{2}{*}{**Needle positioning error**} & \multirow{2}{*}{**Linear positioning error** (the error & & & \\  & beyond acceptable value & remains constant at any depth) & 85 & 60 & 150 \\ \hline \multirow{5}{*}{**H2**} & \multirow{5}{*}{**H-US entry port (RCM) is not preserved**} & \multirow{5}{*}{**H-US probe applies pressure on the abdominal wall**} & \multirow{5}{*}{90} & \multirow{5}{*}{95} & \multirow{5}{*}{195} \\  & & & & & **Insertion depth error** & 80 & 50 & 130 \\ \hline \multirow{2}{*}{**H3**} & \multirow{2}{*}{**H-US (intraroparty ultrasound probe positioning error**} & \multirow{2}{*}{I-US probe positioning does not respect the predefined trajectory} & \multirow{2}{*}{50} & \multirow{2}{*}{50} & \multirow{2}{*}{50} & \multirow{2}{*}{100} \\  & & & & & **\\  & & I-US probe is pressing too hard on the liver & 90 & 70 & 160 \\ \hline \multirow{5}{*}{**H4**} & \multirow{5}{*}{**The targeted area can be reached**} & \multirow{5}{*}{1-US carrot reach the targeted area (RCM) is the T-US probe applies pressure on the abdominal wall} & \multirow{5}{*}{100} & \multirow{5}{*}{80} & \multirow{5}{*}{180} \\  & & & & & **\\ \cline{1-1} \cline{5-5}  & & The I-US probe movements are different than intended & 90 & 80 & 170 \\ \hline \multirow{5}{*}{**H4**} & \multirow{5}{*}{**The targeted area cannot be reached**} & \multirow{5}{*}{Incapability of performing the procedure (the instruments cannot reach the specific liver area)} & \multirow{5}{*}{100} & \multirow{5}{*}{50} & \multirow{5}{*}{150} \\  & & & & & **\\ \cline{1-1} \cline{5-5}  & & Incapability of achieving the necessary orientation for the I-US probe & 60 & 45 & 105 \\ \hline \multirow{5}{*}{**H5**} & \multirow{5}{*}{**The operating table has to be repositioned to ensure**} & \multirow{5}{*}{The relative patient–robot position is changed} & \multirow{5}{*}{100} & \multirow{5}{*}{60} & \multirow{5}{*}{160} \\  & & & & & **area of the liver** & \\ \hline \multirow{2}{*}{**H6**} & \multirow{2}{*}{**The patient state deteriorates during the procedure**} & \multirow{2}{*}{The patient cannot be reuscuitated in due time**} & \multirow{2}{*}{100} & \multirow{2}{*}{40} & \multirow{2}{*}{140} \\
**H7** & & **The needle cannot be viewed inside the liver** & & & \\  & & **parenchyma** & & & \\ \hline
**H8** & **Improper sterilization** & Infection risk & 80 & 10 & 90 \\ \hline \hline \end{tabular}  
* Severity scale: (0–29) minor, (30–89) moderate, (90–99) serious, (100) catastrophic; ** Probability scale: (0–29) remote, (30–69) unlikely, (70–99) likely, (100) very likely; *** Overall score: Severity + Probability.  
\end{table}
Table 1: Identified hazards and associated risks for the targeted therapy of hepatocellular carcinoma (HCC).