Development of a palpation system to help provide accurate robotic needle insertion during the treatment of breast cancer

There are various medical treatments for breast cancer. One of the most minimally invasive and promising medical treatments for early-stage noninvasive breast cancer is radiofrequency ablation (RFA). RFA can reduce both mental and physical damage to women with breast cancer. However, it is very difficult to accurately insert diagnosis and treatment needles in cases of early-stage breast cancer, because the cancer is a minimal target in soft tissues. Therefore, we have developed a robotic system to make needle insertion more accurate. Our system is comprised of two main components: a breast deformation simulation system for determining a needle approach path and a palpation system that uses force information to search for the cancer. This paper focuses on our palpation system. We performed three experiments to verify the efficiency of our palpation system's control algorithm, based on the hypothesis that force information from multiple-axes is necessary to search for a hard body in soft tissue. Based on the results of the experiments, we conclude that our approach is useful to pinpoint the center of a spherical hard body in soft tissue.