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 userspecified 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 ± 0.34mm was determined for the registration system, < 1.2mm and < 3.3mm for the drive system, and 0.35mm and 0.43mm for two load cases of the structural link. The overall unloaded system achieved 1.0 ± 0.25mm and 2.6±0.7mm at 100mm and 250mm depth, respectively. The overall placement errors in air do not exceed the ≤5mm error specified as a clinical user requirement for needle placement in tissue.