SU‐D‐BRF‐06: A Brachytherapy Simulator with Realistic Haptic Force Feedback and Real‐Time Ultrasounds Image Simulation for Training and Teaching

• Published in: Medical physics (Lancaster) Vol. 41; no. 6Part3; p. 116
• Main Authors: Beaulieu, L, Carette, A, Comtois, S, Lavigueur, M, Cardou, P, Laurendeau, D
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01-06-2014
• Subjects: ANIMAL TISSUES; BENDING; BRACHYTHERAPY; Field emission displays; FINITE ELEMENT METHOD; Finite element methods; Insertion reactions; Nonlinear viscoelasticity; PROSTATE; RADIOLOGY AND NUCLEAR MEDICINE; Robotics; Sense of touch; SIMULATORS; Tissues; TRAINING; Ultrasonography
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4887892

Purpose:
Surgical procedures require dexterity, expertise and repetition to reach optimal patient outcomes. However, efficient training opportunities are usually limited. This work presents a simulator system with realistic haptic force‐feedback and full, real‐time ultrasounds image simulation.
Methods:
The simulator is composed of a custom‐made Linear‐DELTA force‐feedback robotic platform. The needle tip is mounted on a force gauge at the end effector of the robot, which responds to needle insertion by providing reaction forces. 3D geometry of the tissue is using a tetrahedral finite element mesh (FEM) mimicking tissue properties. As the needle is inserted/retracted, tissue deformation is computed using a mass‐tensor nonlinear visco‐elastic FEM. The real‐time deformation is fed to the L‐DELTA to take into account the force imparted to the needle, providing feedback to the end‐user when crossing tissue boundaries or needle bending. Real‐time 2D US image is also generated synchronously showing anatomy, needle insertion and tissue deformation. The simulator is running on an Intel I7 6‐ core CPU at 3.26 MHz. 3D tissue rendering and ultrasound display are performed on a Windows 7 computer; the FEM computation and L‐DELTA control are executed on a similar PC using the Neutrino real‐time OS. Both machines communicate through an Ethernet link.
Results:
The system runs at 500 Hz for a 8333‐tetrahedron tissue mesh and a 100‐node angular spring needle model. This frame rate ensures a relatively smooth displacement of the needle when pushed or retracted (±20 N in all directions at speeds of up to 2 m/s). Unlike commercially‐available haptic platforms, the oblong workspace of the L‐DELTA robot complies with that required for brachytherapy needle displacements of 0.1m by 0.1m by 0.25m.
Conclusion:
We have demonstrated a real‐life, realistic brachytherapy simulator developed for prostate implants (LDR/HDR). The platform could be adapted to other sites or training for other types of needle‐based procedures.