HIFUSK FUNCTIONALITIES A GUI allows the physician to visualize the US images and enable the functionality required at each step of the treatment. The functionalities are as follows: 1) Hand guidance: At the beginning of the surgical procedure, the HIFU transducer has to be positioned in contact with the patient's skin. This step is carried out by the robot-assisted hand guidance of the transducer. A button located on the HIFU transducer enables the unlocking of the robotic arm and movement of the therapeutic device. Once this coupling is completed (i.e., the coupling balloon is in contact with the patient's skin), the clinician begins visualizing the inner anatomical structures of the patient on the images from the confocal US probe. Further hand guidance enables the identification of the target where the HIFU sonication is to be performed. 2) Automatic targeting: The HIFUSK platform allows the physician to manually select the target on the echographic images visualized in the GUI. The physician can freeze the image and tap the screen to select the target, which will appear as a visual overlay (a red dot) on the image. The robot pose is computed to have a match between the focus of the HIFU transducer and the target. Before enabling robot motion, a check on the motion amplitude is conducted (see the " HIFUSK Safety Measures " section). Then, the robot automatically adjusts its pose. This adjustment is performed as a translation in the US imaging plane. This translation () rb T is computed as rb TT kt Tf rb T )) ) im = () (1) ee ee where Trb im - ee hifu ee is the robot forward kinematics; Tee im and ee Thifu are the transformations from the imaging and HIFU im t is the reference frames (RFs), respectively, to the end effector RF (both estimated from the system CAD model); hifu HIFUSK Key Components KUKA LBR Med HIFU Transducer Ultrasound Probe Coupling Device HIFU Beam Ultrasound Image User Interface Touchscreen (a) HIFU Beam Selected Target HIFU Focus Robotic Adjustment Thermal Effect at Focus HIFU Off HIFU On Hand Guidance Automatic Targeting (b) FIGURE 4. The (a) HIFUSK platform components and (b) functionalities. 84 IEEE ROBOTICS & AUTOMATION MAGAZINE SEPTEMBER 2023 Motion Compensation HIFU Sonication Platform Functionalities