# Advantage of Steerable Catheter and Haptic Feedback for a 5-DOF Vascular Intervention Robot System
## 1 Introduction  
The catheter-based approach is an important and common method for treating vascular and cardiac disease. Application of the catheter-based technique has grown from simple stenting to complex aortic and valve procedures [1; 2; 3]. Vascular interventional radiology (VIR) is used to diagnose and treat diseases in the vascular system by using several vascular tools, such as catheters and guidewires. However, because angiography is frequently performed to visualize the arteries and the catheter in the body, operators are exposed to large amounts of radiation [4; 5; 6; 7; 8; 9]. Most countries regulate the radiation dose limit for occupationally exposed persons according to the recommendations of the International Commission on Radiological Protection (ICRP). As prescribed by ICRP 103 [10], the effective dose limit for radiation workers is 20 millisieverts (mSv) per year, averaged over 5 years with no more than 50 mSv in any one year. Because of the dose limit, the number of procedures for a year is restrictive. Radiation workers wear radiation protection, such as aprons, collars, glasses, and gloves, but they become stressed owing to the weight of the apron. Additionally, use of gloves is low; thus, doses to the hands are high [5]. Robotic systems are undergoing major development. They need careful clinical evaluation and should be tailored to specific clinical needs. In some cases, e.g., patients with acute coronary syndrome or high-syntax score lesions, special evaluation is needed for applying a robotic system [11; 12; 13]. Therefore, a master-slave robotic system for VIR is necessary for minimization of the radiation exposure to operators. Reducing the radiation doses to the patient and physician is important. If the curvature of the vasculature is large, vascular selection using a catheter takes a long time, and the radiation dose to thepatient is increased. Therefore, to reduce the time needed to select a vascular branch with a catheter, it is necessary to develop a steering catheter whose tip is capable of bending freely according to the curvature of the blood vessel. Because vascular intervention depends on the physician's tactile sense, haptic function is very important. The physician's movements are determined by using tactile information regarding the contact force between the VIR devices and the blood-vessel wall; thus, the haptic function significantly affects the safety of the patient. Various robot systems reflect these requirements [14]. To avoid the radiation exposure, the slave robot of the systems is installed on a surgical bed, and an operator controls the slave robot from the master console, which is separated from the bed. Hansen Medical Co. developed the Magellan robotic system and the Sensei robotic system [15; 16]. The Magellan robotic system has a robotic catheter system that controls a guidewire, a sheath, and a robotic catheter for a wide variety of endovascular procedures. The guidewire can be inserted and rotated, and the sheath and the robotic catheter can be not only inserted but also steered in four directions. The Sensei robotic system has a robotically steerable sheath for intracardiac electrophysiology procedures. It provides contact-force feedback via a visual display on the workstation and vibration feedback on the motion controller. The Corindus system [17; 18] consists of a guidewire driving system and a master console. The system controls a guidewire and a stent. The Corindus system does not offer a haptic feedback function of a guidewire but offers a visual feedback function with a navigation system. The Amigo robot system [19] consists of a remote controller and a slave robot that controls the insertion, rotation, and steering motion of the catheter. An operator manipulates the catheter using the remote controller. However, the system does not have a haptic feedback function. [PERSON] et al. [20; 21] developed a 4-degree of freedom (DOF) robotic system and a 5-DOF robotic system for vascular intervention.