Design, calibration and evaluation of a robotic needle-positioning system for small animal imaging applications.
Waspe AC, Cakiroglu HJ, Lacefield JC, Fenster A.
Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario
Phys Med Biol. 2007 Apr 7;52(7):1863-78. Epub 2007 Mar 9.

• > A needle-positioning robot has been developed for image-guided interventions in small animal research models. The device is designed to position a needle with an error less or equal to 100 microm. The robot has two rotational axes (pitch and roll) to control needle orientation, and one linear axis to perform needle insertion. The three axes intersect at a single point to create a remote centre of motion (RCM) that acts as a fulcrum for the orientation of the needle. The RCM corresponds to the skin-entry point of the needle into the animal. The robot was calibrated to ensure that the three axes intersected at a single point defining an RCM and that the needle tip was positioned at the RCM. Needle-positioning accuracy and precision were quantified in Cartesian coordinates at ten target locations in the plane of each rotational axis. The measured needle-positioning accuracy in free space was 54 +/- 12 microm for the pitch axis plane and 91 +/- 21 microm for the roll axis plane. The measured needle-positioning precision was 15 and 17 microm for the pitch and roll axes planes, respectively. The robot's ability to insert a needle into a tumour in a euthanized mouse was demonstrated.
  
  NOTE: A Vevo 770 micro-ultrasound system was used to show the guidance of this robotic injection system in a tumor in vivo and to show the successful placement of a target bead.