Background and motivation
Minimally invasive interventions such as microbrachytherapy and radioembolization have shown promising clinical outcomes for treating liver, brain, kidney, head-and-neck and prostate tumours. However, current manual and semi-manual insertion techniques lack the precision and stability required to ensure uniform dose distribution and avoid collateral damage to surrounding healthy tissues. [Project proposal: Image-Guided Robotic System for Precision Needle Insertion and Controlled Deployment of Radioactive Microspheres in various Tumours: a Platform Technology]
To overcome this challenge, RaM and RadboudUMC are making an image-guided, robotic needle insertion platform to deliver radioactive Holmium-166 microspheres intratumorally. The platform is meant for a wide variety of organs, including the liver. The liver, however, is under constant motion induced by the breathing of the patient.
Problem
This respiratory motion moves and deforms the liver and the tumour within. To still be able to insert the needle accurately, active motion compensation can be used to imitate the respiratory motion and therefore create a relatively static situation between the needle tip and the tissue around. The problem is complex, however, as the skin and tissue around the liver and even the tissue within the liver do not move equally. This can impose additional shear stress and forces on the needle during insertion. Consequently, reducing robustness and accuracy during operation. When the needle is too stiff, it can even cause damage to the tissue. Furthermore, the following of the organ is highly dependent on the accuracy of the image modalities used.
Objectives
The goal is to decouple the needle and make it back drivable using a (passive) mechanical system. As a result, the needle will move (partially) with the tissue and prevent it from being too stiff. The design should preferably be MRI compatible as well, to make sure it fits both the CT and MRI modalities within the larger scope of the project. This subsystem would be located between the needle and the roto-translational stage or the roto-translational stage and the KUKA med robot. A big plus would be for situations where coughing or other incidental movements are also (partially) resolved within the passive mechanical system.
Expected outcomes
- A (passive) mechanical (3D printed) design is developed.
- A test setup is made to be able to validate the performance on a pre-made phantom simulating respiratory motion.
- The forces on the needle and the error of the tip following the target and surrounding tissue are minimised and validated with experimental data.