Sunram 5: A Magnetic Resonance-Safe Robotic System for Breast Biopsy, Driven by Pneumatic Stepper Motors

Sunram 5 is the fifth-generation magnetic resonance (MR)-safe robotic system for breast biopsy. It has five degrees of freedom and is driven by six linear and curved pneumatic stepper motors plus three singular cylinders, all constructed by rapid prototyping techniques. The design, production, and evaluation of both single pneumatic cylinders and various type of stepper motors are described in detail in this chapter. Control strategies are also discussed such as how multiple motors can work together in order to achieve both high speed and high accuracy, despite the relatively low stepping frequencies associated with long pneumatic lines between controller and motor. Sunram 5 also includes a breast fixation system, an emergency needle ejection mechanism, and fast and precise needle insertions under near-realtime MR imaging (MRI) guidance, giving potential to improve accuracy and efficiency in MRI-guided breast biopsy procedures.