Ex vivo conformal RFA under the guidance of ultrasound imaging
An ex vivo ultrasound-guided RFA is conducted in accordance with the protocol of in vivo RFA, Figure 17A. Based on the morphologic information of target tissue, preoperative planning of electrode is done for our experiments. Following our planning, in-plane operation of our electrode is subsequently conducted to ensure the total visibility of the entire procedure, Figure 17B and C. Under the guidance of ultrasound imaging, our electrode accurately targets a small target tissue with an oval sectional view (major axis of 14 mm, and minor axis of 7 mm), and ablates the targets tissue conformally, Figure 17B. With rational energy control, the ablated area is controlled to encompass the target tissue including a circumferential safety margin (the brightened area covers the dark region with a margin of 5-10 mm).\cite{Zhang_2016} Apart from the small target tissue, an elongated bigger one (major axis of 24 mm, and minor axis of 5 mm) is also successfully ablated with an ensured safety margin, Figure 17C and Movie S3. It can be clearly observed that the ablation region starts from the tip of electrode, which agrees well with previous simulation results (Figure 11).