[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Wed 2007-08-22 at 14:00

Location:  Auditorium          

Speaker:   Marco Schippers (Paul Scherrer Institute)

Title:     Proton therapy at PSI: from sharing the beam of the ring cyclotron to a dedicated facility with a superconducting cyclotron

Abstract: After 27 years experience with medical research and therapy at the PSI cyclotrons, a new stand-alone proton therapy facility started patient treatment last February. Previously deep seated tumours had been treated in Gantry-1 with protons “peeled off” from the beam from the large ring cyclotron. Eye tumours were being treated separately using the 70 MeV injector cyclotron. However, a thorough medical research program with Gantry-1 was in conflict with the needs of the multi-user environment and the operation routine of the cyclotrons. At the same time the reliability of the Philips injector became problematic.  A separate medical facility was therefore proposed and installed at PSI.

The heart of the new facility is a novel 250 MeV superconducting cyclotron. Originally designed at NSCL (MSU), the cyclotron was built by ACCEL instruments GmbH, in close collaboration with PSI. The collaboration ensured that the stringent medical and operational requirements could be achieved. An intensive program of beam commissioning and acceptance tests of cyclotron and beam lines confirmed that essential specifications had been met, including high extraction efficiency (>80%), fast (kHz) beam-intensity control,  reliability and efficient maintenance. The extracted beam is degraded to any energy between 235 and 70 MeV, depending on the needed proton range in a treatment. The beam is then collimated and transported either to the existing Gantry-1, or to a new Gantry-2, or to a new eye treatment room, or to a vault for experiments. To enable rapid variation of the proton range for new fast pencil-beam scanning techniques, the degrader and the beam-line magnets have been made to allow quick energy changes (2% in 50 ms). Dedicated beam diagnostics and control systems have been developed to provide high performance and safety. Patients are now being treated at Gantry-1. The facility is planned to be completed  in 2008.

Stimulants available 15 minutes before the talk.

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