Tendon-Driven Notched Needle for Robot-Assisted Prostate Interventions

Abstract

Needle insertion techniques have shown a high potential to improve the outcome of several diagnostic and therapeutic minimally invasive procedures. One example is high-dose-rate (HDR) brachytherapy (BT), a radiation therapy, in which radioactive sources are placed at cancerous tissue using needles. HDR BT offers dose conformality and sparing of clinical structures, lower operator dependency, and fewer acute irritative symptoms. However, HDR BT is limited for patients with pubic arch interference (PAI), where the transperineal path to the prostate is blocked. Active and flexible needles that can maneuver in the desired path could be a solution. Another example is targeted prostate biopsy, an effective image-guided technique that detects significant cancer via fewer cores and a lower number of unnecessary biopsies compared to traditional systematic (12-core) biopsy.This work presents two tendon-driven notched needle designs: (i) a unidirectional needle design for HDR BT patients with PAI and (ii) a bidirectional needle design for targeted prostate biopsy interventions. Compliant flexure sections of the notched needle were fabricated on a nitinol tube that enables unidirectional and bidirectional bending via actuation of internal tendon(s). Experimental evaluations with the unidirectional needle design showed the feasibility of the needle moving around the pubic arch for placement at hard-to-reach target positions. For the bidirectional needle design, kinematic and static models of the compliant flexure section have been presented and validated with experiments. The capability of the notched needle to bend, reach targeted positions inside a phantom tissue, and extract a biopsy sample is shown.