Brachytherapy is one of the most effective modalities for treating early stage prostate cancer. In this procedure,
radioactive seeds are being placed in the prostate to kill the tumorous cells. Inaccurate placement of seeds can underdose
the tumor and dangerously overdose the critical structures (urethra, rectum, bladder) and adjacent healthy tissues. It is
very difficult, if not impossible, for the surgeons to compensate the needle misplacement errors while using the
conventional passive straight needles. The smart needles actuated by shape memory alloy (SMA) wires are being
developed to provide more actuation and control for the surgeons to achieve more geometric conformity. In our recent
work, a prototype of a smart needle was developed where not only the actuation of SMA wires were incorporated, but
also shape memory polymers (SMPs) were included in the design introducing a soft joint element to further assist the
flexibility of the active surgical needles. The additional actuation of shape memory polymers provided the capability of
reaching much high flexibility that was not achievable before. However, there are some disadvantages using this active
SMP component compared to a passive Nylon joint component that are discussed in this work. The utilization of a
heated SMP as a soft joint showed about 20% improvement in the final needle tip deflection. This work presents the
finite element studies of the developed prototype. A finite element model that could accurately predict the behavior of
the smart needle could be very valuable in analyzing and optimizing the future novel designs.
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