Use of robots to improve patients' treatment and throughput

Reporter: Arpi Thukral, MD MPH
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 12, 2011

Presenter: Regis Ferrand
Presenter's Affiliation: Institut Curie-Centre de Protontherapie d'Orsay


  • The purpose of this presentation was to provide an overview of the 15-20 year history of the use of robotic couches at Institut Curie-Centre de Protontherapie d'Orsay (CPO).
  • In the past 15 years, use of robotic positioning has developed tremendously in radiation therapy, particularly in particle therapy.
  • The challenge of robotic positioning is that it must be fast and precise.
    • Precise:
      • Need 6 degrees of freedom, long range motion <0.5 mm, with smooth trajectories
      • Need high repeatibility for QA checks and calibration
      • Short range of motion: 0.2 mm
    • Fast:
      • Ability to load/unload patient
      • Need to use a combination of fields
      • Fast detection of unexpected motion
      • Collision avoidance/back to safe position
  • History of robots
      • Before 1990: prototypes: MGH/HCL chair or eye chairs (CPO, PSI, MGH, Nice)
      • 1995-2003 – 6 axis robot based (ex. MPRI)
      • 2003-2009 – Scara-based, hexapode based
      • 2010 – new hybrid designs (Poros PPS, Toshiba PPS)
  • Extended use of robots besides patient postioning:
    • Robotic CBCT
    • MPRI snouth changer
    • Trolleys (PSI, automated in Essen)
    • Use of robots to calibrate devices inside the treatment room
    • Chair and couch
  • The CPO modest experience of 20 years:
    • The CPO has been working on 4 different robots since 1990. These include:
      • Hexapodes (original in 1991 and new version in 2006)
        • accuracy <0.2 mm with limited range through +/- 10 degrees
        • 2006 version has 360 degree vertical rotation
        • not ideal for long range motion
      • 6 axis based (1995)
        • accuracy approx 3 mm
        • The biggest advantage of this type is repeatibility.
      • Scara based (Forte/Procure)
        • Approx 0.5 mm precision
      • New pit free prototype
        • Developed within the frame of a research project.
        • Specific architecture
        • Intrinisic high precision (+/- 0.5 mm accuracy over long range movements)
        • Ability to align patient inside and outside room
        • Water tank permanently ready to use
  • Lessons learned from 20 year experience at CPO:
    • Except for hexapode, the intrinsic precision is NOT sufficient
      • Calibration is mandatory and takes time.
    • Robot has high potential and is designed for guidance.
      • Has incredible robustness (only 3 problems in 15 years at CPO, likely due to neutrons)
  • Future directions/concepts:
    • New robotic concepts: (ex. Poros prototype, patented):
      • Increased working envelope
      • Intrinsic precision enhanced
      • Reduced cycle (20 ms) – dynamic motion
      • Hardware redundant saftely systems
    • Fluid process
      • Natural ability for: alignment inside/outside and adaptive therapy
      • Simultaneous multi-PAS guidance
      • Definition of true postioning strategy at the OIS level.

Author's Conclusions

  • To compare proton and proton treatment, we need to dramatically improve the treatment process for protons (and not only the beam).
  • Robotic patient positioners have proven their potential to play a key role in this process.
  • However, there are still many advances that need to be made in this field for proton therapy.

Clinical Implications

  • The author of this presentation clearly highlighted the history and advances made in the last 2 decades regarding the use of robotic technology to improve patient treatment and throughput in the proton arena.
  • Robots play a key role in patient positioning, which in turn translates to greater efficiency in patient throughput.
  • From this overview, we are able to assess the value and limitations of robotic patient positioning. This will help guide the development of future robotic technology for particle therapy.
  • Future studies may focus not only on improving this technology, but also advancing it in terms of image guidance, safety and dynamic motion.
  • Furthermore, efforts to adapt a global positioning process to specific clinical protocols are underway.