In percutaneous robotic IGI (Image Guided Interventions) the robot typically manipulates a needle and aligns it to a desired target prescribed in the image. Targeting errors may still occur, even if before the insertion the needle is well aligned towards the target. These errors are caused by two major components. The first source of error is mechanical, being related to deflections of the needle and soft tissue. The second relates to the motion of the target, which is normally caused by respiration.
Dealing with respiratory motion is an active IGI research topic for systems with or without robotic components. In typical IGI clinical cases, patient respiration is stopped during needle insertion. Our lab is presently investigating respiratory motion tracking using ultrasound feedback, so that a given target can be continuously aimed. The US probe is held by a robot with the US-Drive stage. If the IGI is performed within a CT scanner, the robot can be controlled to automatically aim the US probe at a target defined in the CT image. This is used to control the robot so that it continuously tracks the moving target with the needle.