Robot-assisted biopsy using computed tomography-guidance -: Initial results from in vitro tests

Purpose: We sought to develop a robotic system for computed tomography (CT)-guided biopsy to validate the feasibility, accuracy, and efficacy of the system using phantom tests. Materials and Methods: Ten peas (mean diameter 9.9 +/- 0.4 mm) embedded within a gel phantom were selected for biopsy. Once the best access was defined on CT images, the position of the phantom was recorded by an optical tracking system. Positional data about the phantom and the corresponding CT image was transferred to the robot planning system (Linux-based industrial PC equipped with video capture card). Once the appropriate position, angulation, and pitch were calculated, the robotic arm moved automatically with 7 degrees-of-freedom to the planned insertion path, aiming the needle-trajectory at the center of the target. Then, the biopsy was performed manually using a coaxial technique. The length of all harvested specimens was measured and short cut pieces of a guidewire were pushed into the target to evaluate the deviation of the actual needle track from the target. Results: In all targets, biopsy specimens (mean length 5.6 +/- 1.4 mm) were harvested with only 1 needle pass required. The mean deviation of the needle tip from the center of the target in the x and z axes was 1.2 +/- 0.9 turn and 0.6 +/- 0.4 mm, respectively. Conclusions: Robotic-assisted biopsies in vitro, using CT guidance, were feasible and provided high accuracy.