Breast cancer is a disease with significant worldwide impact. Many hand-operated biopsies have been performed by radiologists to treat a patient suffering from a cancer tumor. Robotic systems have been developed and demonstrated that these may increase the quality and resolution of biopsies. However, with the introduction of robotics, the radiologist's biopsy device is often replaced by a non-intuitive interface such as sliders and buttons on a control panel or a computer program. Furthermore, a biopsy performed by a biopsy robot is costly. This paper therefore proposes a design of a robotic biopsy system, which combines a rapid prototypeable biopsy end-effector with control using a hand-held smartphone.
This method uses low-cost servo motors to generate rotational motions in two dimensions of freedom, plus a stepper motor used in a screw-thread mechanism for a translational injection of the needle. All components are assembled in a 3D printed enclosure. The system uses the built-in accelerometer and gyroscope sensor of the mobile phone to retrieve the phone's orientation, which is reproduced by the robot. A mobile application is designed to retrieve the phone's sensor data and communicate wireless to a controller. In the system several modes are implemented to increase the workability: in biopsy mode, the angular movements are attenuated to enhance precision.
Results show that the designed robot had an angular accuracy of 1.034 degrees based on targeting predefined points in space using an automated program. The phone's orientation was captured with less than 0.30 degrees deviation from the real orientation in all directions. The full system was tested by targeting lesions inside a transparent phantom with 83% success rate (17 hits out of 20 attempts). Using the robotic system developed in this research, it is possible to control a biopsy needle using a handheld mobile phone, and target lesions sized 1 cm and up to 9 cm deep with 83% success rate under visual guidance.
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