Human-machine Collaboration Modalities For Semi-automated Needle Insertion Into Soft Tissue

Needle insertion is a minimally invasive medical procedure commonly used for biopsy, ablation or deposition of therapeutic agents. In prostate brachytherapy, needles are inserted into the prostate in order to deposit multiple rice-grainsized radioactive seeds to eradicate cancerous tissue from close proximity. During insertion, the needles should remain on a straight path, such that the seeds are deposited according to their pre-planned location. The needles, however, due to their beveled tip, deflect from the straight path. In order to guide the needle back towards the straight path, the surgeon may manually rotate the needle axially or apply lateral force onto the needle near its entry point into tissue. To aid the surgeon with steering the needle more accurately towards the desired target, we propose robotic assistance where the responsibilities are assigned between the surgeon and the machine in such a way that safety is guaranteed while achieving high steering accuracy. Thus, in this work, a human-in-the-loop collaborative robotic assistant system is proposed where the aforementioned steering actions are carried out autonomously by the robotic assistant system. This collaboration modality is in agreement with safety requirements as the surgeon remains in the loop and is in charge of the most safety-critical task, which is the needle insertion itself. It is shown experimentally that using both steering commands from the machine as the surgeon inserts the needle satisfactorily achieves the goal of minimizing needle deflection with high accuracy.