A soft robotic device for patient immobilization in sitting and reclined positions for a compact proton therapy system

Proton therapy has a substantial physical advantage over conventional cancer radiation treatment with X-rays. Proton therapy reduces the radiation dose to healthy tissues and therefore the toxicity and side effects to the patients. However, the current high capital cost and required space make proton therapy a very limited resource. In current proton therapy, the patient is fixed on a table and a gantry is used to bend the proton beam for treatment. We propose to change the model by precisely moving a patient relative to a fixed proton beam rather than moving the beam relative to the patient. This requires a robot to move the patient and a strong immobilization device to ensure that the patient's body position remains accurate during movement. We introduce a solution to enable compact and affordable proton therapy using a parallel robot with real-time surface positioning feedback and an immobilization system made of soft robotic actuators. Immobilization experiments with healthy volunteers demonstrate that our prototype device can position and immobilize healthy volunteers in sitting position to clinical standards and correct slouching through a feedback loop. The soft robotic immobilization device is strong but soft and comfortable as well as adaptive to the body shape. The force that the immobilization device can exert on the body using negative pneumatic pressure was characterized. This new immobilization device and the robotic positioning system have great potential to significantly reduce the cost of proton radiation cancer treatment.