Design and development of soft robot for head and neck cancer radiotherapy

In this paper, we present a new design of head immobilization system for head and neck (H and N) cancer radiotherapy. The immobilization system consists of a radio-translucent 3D printed thermoplastic, helmet-like structure open partially in the front and custom-made fluidic actuators. The system can be actuated using compressed air to induce pitch and roll rotations. The mechatronic components of the system include two valves for each chamber, a microcontroller, airflow sensor, power supply, a compressed air source, and one pump to remove air. All of these are kept away from the patient's head so as not to interfere with the radiation beams, and radiation transparent tubing are connected with the chambers to the mechatronic components. The design provides comfort to patients due to curvature fit of patient head/neck and the use of soft actuators. The material used for custom-made actuators is silicone elastomer Eco-Flex 30. The main design variables are air chamber size, air pressure, volume flow rate, number of chambers, layers of sealing and shore hardness of the elastomer. Various arrangements of actuators and designs are investigated. The fabricated new actuators specifically designed for the positioning system were characterized using a humanoid robot head that mimics an actual patient’s head. We hope that the new device will give comfort to patients due to curvature fit of patients’ head/neck and the soft compliant actuators.