A Precision System for Computed Tomography-Guided Needle Placement in the Thorax and Abdomen-Technical Design and Performance Analysis

A system was developed for computed tomography (CT)-guided needle placement in the thorax and abdomen, providing precise aiming of a needle guide (NG) to reach a user-specified target in a single manual insertion. The objective of this work is to present its technical design and analyze its performance in terms of placement error in air. The individual contributions to the placement error of a fiducial marker based system-to-CT registration system, a two degrees-of-freedom (2DOFs) drive system to aim the NG, and a structural link between NG and CT table were experimentally determined, in addition to the placement error of the overall system. An error contribution of 0.81 +/- 0.34 mm was determined for the registration system, <1.2 mm and <3.3 mm for the drive system, and 0.35 mm and 0.43 mm for two load cases of the structural link. The overall unloaded system achieved 1.0 +/- 0.25 mm and 2.6 +/- 0.7 mm at 100 mm and 250 mm depth, respectively. The overall placement errors in air do not exceed the <= 5 mm error specified as a clinical user requirement for needle placement in tissue.