gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

The Gantry for the Heavy Ion Cancer Therapy Facility in Heidelberg, Design and Construction

Meeting Abstract

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  • E. Sust - MT Mechatronics, Mainz

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog195

DOI: 10.3205/09ptcog195, URN: urn:nbn:de:0183-09ptcog1958

Published: September 24, 2009

© 2009 Sust.
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Outline

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Introduction: The Heavy Ion Cancer Therapy Facility HICAT at the University Hospital of Heidelberg is close to start of operation. One unique feature of the treatment facility is the first heavy ion gantry in the world. The gantry will allow the patient treatment with different ion species up to 430 MeV/u and full geometrical flexibility. This functionality has to be maintained for up to 300 000 rotations over the envisaged life cycle of 15 years. The order for the design and delivery of the supporting structure as well as the integration of the main components and alignment was given to MT Mechatronics GmbH in July 2003. The gantry has been completed and accepted in August 2007.

The Heavy Ion Gantry: The gantry is an integrated system consisting of structure, mechanics and control system. Overall system performance has been achieved by optimization of all subsystems considering the overall system behaviour.

The structural optimization has been done by using the homology principle to achieve the best weight to stiffness ratio. Considering the weight of the components that had to be integrated it was necessary to perform extensive FEM – calculations to optimise the supporting structure regarding stiffness and fatigue. In order to guarantee the reliability of the system, all these deviations had to be reproducible. The security factors for the design were chosen in such a manner that more than the predicted three hundred thousand turns of the gantry over its envisaged life time can be done in an elastic manner. The design also assures the compliance to the medical law requirements with respect to mechanical stability.

Robust mechanics have been used and designed to assure minimum total error contribution and maximum reliability during Gantry lifetime. The control system consists of the servo system responsible for system performance and operation, and the safety system responsible for system safety according to the rules of the medical law requirements (Figure 1 [Fig. 1]).

Actual Status of the Gantry in Heidelberg: The gantry has been built and aligned. It was shown that it satisfies the individual requirements for position and angular stability of the relevant beam guidance components.

The maximum peak to peak fluctuations of the beam guidance components under all gantry angles with respect to the optimum position are defined in a local beamline coordinate system, rotating with the Gantry. The maximum radial deflections that were achieved for the beamline elements were in the range from 0.3 mm for steerers and 1mm for the big dipoles. The position of the beamline elements have been measured at 12 rotating angles (30° steps). The measured values were within specification at nearly all elements. The gantry has been completed and accepted in August 2007.

Conclusion: The Gantry designed for the University Hospital in Heidelberg shows that an isocentric Gantry for heavy ion therapy is feasible using conventional robust technology and standard magnets.

MT Mechatronics is prepared to supply gantries for heavy ion therapy or proton therapy. Isocentric Gantry designs for both treatment methods are existing. The design can easily be adjusted to new beamline technologies like superconducting magnets.