The VARIAN 250 MeV Superconducting Compact Proton Cyclotron

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2 The VARIAN 250 MeV Superconducting Compact Proton Cyclotron VARIAN Medical Systems Particle Therapy GmbH Friedrich-Ebert-Str. 1 D BERGISCH GLADBACH GERMANY

3 OUTLINE 1. Why having a Superconducting Cyclotron? 2. Machine Key Data 3. Operating VARIAN Machines Uptime Statistics Automated Operation (Startup + Optimization) 4. Production of Next Machines Production Site Factory Assembly Test Cells and Beam Testing 5. Recent Developments Solid State Amplifier Digital Low Level RF RF Commissioning Results 6. Conclusion 3

4 Why having a Superconducting Cyclotron? Why having a superconducting cyclotron? It s fascinating technology! A cyclotron is an elegant solution for efficiently generating high energy beams with a compact, reliable and cost-effective machine. There are high magnetic fields! There s superconductivity! (It s cool ) There is non-trivial RF technology! There are plasmas! It s applied relativity! Let s see if we find some quantum mechanics involved 4

5 Why having a Superconducting Cyclotron? This is what I tell my team on one hand 5

6 Why having a Superconducting Cyclotron? This is what I tell my team on one hand but on the other hand it is clear for everybody that these are unfortunately not the points that drive a business. VARIAN s commitment to this technology derives from a different approach. Timothy E. Guertin VARIAN s President and Chief Executive Officer: Varian Medical Systems mission is to explore and develop radiation technology that protects and saves lives. Our goal is to help save 100,000 more lives each year. That s enough to fill a large stadium. To meet this challenge, we equip the world with new tools for fighting cancer [ ]. The people of Varian Medical Systems share this mission and goal. Together, we are a partner for life. 6

7 Why having a Superconducting Cyclotron? We want to achieve this mission goal by providing the best tumor treatment delivery available, which currently is pencil beam scanning of energetic particles. (You will hear evidence for this in other talks during this workshop.) Technical boundary: Beam scanning requires a stable, intense cw beam, everything else makes the whole thing much more complicated. Commercial boundary: Particle therapy requires a large invest of the customer for building, technical equipment, and other infrastructure. To keep this limited to a reasonable amount we restrict ourselves to protons and small building footprints. This marks the boundary conditions for the accelerator: The machine of choice here is a compact isochronous AVF cyclotron. 7

8 Why having a Superconducting Cyclotron? Looking a bit deeper, it turns out that a superconducting cyclotron brings along even more advantages: Superconducting coil, low power consumption High magnetic field possible Small machine, high beam energy Saturated iron Larger pole gap over full radius High extraction efficiency, high beam currents Reproducible field and beam operation 8 Practically operator-free operation Low activation Fast access, easy maintenance, high uptime

9 VARIAN PT SC Cyclotron Key Data (Engineering Goals) Beam - Energy 250 MeV - Extracted current (max) 800 na - Emittance of extracted beam < 3 / 5 π mm mrad (2σ) - Momentum spread p/p ±0.04% (i.e. 250MeV) - Number of turns Extraction efficiency (multi-turn extraction mode) ~80% - Dynamic range for intensity modulation 1:800 - Fast intensity modulation via electrostatic deflector, >10% in 100 µs Iron Yoke - Outer diameter 3.1 m - Height 1.6 m - Weight <90 t SC Magnet - Stored energy 2.5 MJ - Central field 2.4 T - Max. field at the coil <4 T - Operating current 160 A - Rated power of cryocoolers 40 kw RF System - Frequency 72.8 MHz (2 nd harmonic) - Voltage source to puller extraction radius 80 kv / 130 kv - RF power 115 kw 9

10 VARIAN SC Proton Cyclotron Facility Integration 10

11 3. Operating Machines Uptime Statistics Automated Operation Morning Startup Optimization Procedures 11

12 Operating VARIAN PT SC Cyclotrons 1. Paul Scherrer Institut PSI (CH), treating patients since beginning of Rinecker Proton Therapy Center RPTC (D), treating patients since beginning of The RPTC facility is widely equipped with VARIAN technology, like superconducting compact 250 MeV proton cyclotron degrader for energy adjustment energy selection system for energy filtering beam lines for beam transportation 4 rotational isocentric gantries for 360 irradiation + 1 fixed beam for head / neck treatments delivery nozzles providing pencil beam spot scanning safety systems treatment control software 12

13 Uptime during Patient Treatment Ramp-Up RPTC presentation on PTCOG 48 conference 6 months after start of operation: Poster presented by RPTC at PTCOG 48 13

14 RPTC Operating Time / Facility Uptime User at RPTC treats patients up to 6 days/week, 8-10 hrs/day All 4 scanning gantries are clinical Upgrade of gantry / scanning nozzle functionality is still continued during nights and weekends Treatment facility including cyclotron is operated 24hrs on 6-7 days/week Service is performed every Sunday The RPTC uptime of 97% for the complete treatment facility since startup was determined by the user for daily patient treatment The Superconducting Cyclotron has of course a higher uptime (PSI > 99%) How is this achieved? Reliable Machine Reproducible Conditions Fully Automated Control System 14

15 Automated Morning Startup Procedure Cyclotron is in overnight state (sc magnet on, RF reduced or off) What happens after pressing and? Devices change their state (e.g. ramp-up of power supplies)... controlled by transition functions. Cyclotron reaches fully automatic the state 15

16 Automated Cyclotron Startup: 10min to Beam Devices Ramp-Up Automatic Phase Calibration Automatic Phase Regulation Beam Operation I magnet = I 0 I magnet = I (iron temp) I magnet = I (beam phase) P RF = P full P RF = P reduced U extr.defl = std U defl = U beam off I IS = std I beam within specification H 2 flow = std t / min 16

17 Automated Optimization Procedures Example: Beam Centering Parameters, e.g. start values, step widths, limits, Actual values of field bump before / after automatic optimization 17

18 Automated Optimization Procedures Badly centered beam orbit precession detected on moving head of a straight probe: Field Bump Starting Point Beam Centering: Graphics Output Optimization of Phase and Amplitude for Centering Field Bump Optimized Field Bump 18

19 Automated Optimization Procedures Slit Opening Offsets Slit Positioning Beam Current Transmission Check Beam Suppression Measurement RF Power Scan Beam Centering Extraction Field Bump Optimization Extraction Deflector Optimization 19

20 4. Production of Next Machines Production Site Factory Assembly Test Cells and Beam Testing 20

21 VARIAN PT Production Site Overview Production site near Cologne / Germany Allows assembly of up to 6 cyclotrons in parallel 21

22 VARIAN PT Production Site Overview Production site near Cologne / Germany Allows assembly of up to 6 cyclotrons in parallel and the corresponding beamline modules. 22

23 Production of Next Machines Fine machined iron and all major components for the next cyclotrons are ready; next coil windings are finished and assembly of pole caps is underway. Long lead items (especially iron yokes) for the following machines are ordered. Build sequence is ramped up from ~2 cyclotrons per year at the moment magnetic testing coil winding machine assembly cryostat welding incoming pole caps and yoke rings 23

24 VARIAN PT SC Cyclotrons Factory Commissioning Cyclotron #3 is completely pre-assembled at Varian s PT manufacturing premises. It has passed the testing and shimming of the superconducting magnet and is currently tested (with beam!) in the factory. It will be shipped in summer to its destination in 2 large lots (upper / lower part). 24

25 Cyclotron and Scanning Nozzle Test Cells 25

26 Cyclotron and Scanning Nozzle Test Cells Adjacent to the manufacturing hall VARIAN has built concrete bunkers for cyclotron and scanning nozzle tests. This enables the delivery of fully factory beam tested systems. Cyclotron #3 is currently operated in one of these Test Cells. 26

27 Cyclotron and Scanning Nozzle Test Cells 27

28 Cyclotron and Scanning Nozzle Test Cells All RF components Ion source Slit systems Extractors Diagnostics etc. are currently undergoing a system integration and beam FAT. 28

29 5. Recent Developments Solid State Amplifier Digital Low Level RF RF Commissioning Results 29

30 Recent Developments: Solid State RF Amplifier RF power amplifier used at PSI and RPTC: 3-stage tetrode tube based several electrical cabinets for power transformers, high voltage supplies, and the tubes New design in use transistor based 120 parallel working RF power modules in 6 cabinets Supplied by Cryoelectra GmbH 30

31 Recent Developments: Solid State RF Amplifier Test setup completed a >1000h test Allowed reflected power limit >15% Via its redundancy, the design features a higher - availability, - serviceability, - cost reduction,... The digitally controlled modularized system provides extended diagnostics capabilities. 31

32 Recent Developments: Digital LLRF VARIAN will use a digital LLRF with its future systems. The dllrf is already integrated into the cyclotron system that is currently under test. Like the SSAmp, the dllrf is designed for high redundancy. This yields a high fault tolerance and increases system uptime. The dllrf is faster than the previously used system and provides much more diagnostic signals and functionality. 32

33 Recent Developments: RF Commissioning Results Solid State Amplifier & Digital LLRF Very Fast RF Conditioning in Pulsed Mode (5% - 20% duty cycle) Work on Cyclotron Hardware, in parallel: dllrf Calibrations Cavity Check 33

34 Developments: Digital LLRF Control System 34

35 RF Ramp-Up to 120kW ~1 minute 35

36 Conclusion The VARIAN Superconducting Compact Proton Cyclotrons feature superior properties that make them turn-key operational machines and predestine them for use in pencil beam scanning therapy. cw beam high energy 2 of such cyclotrons are already in clinical use. high current stable beam position Several more machines are in production. small footprint high extraction All machines will be factory tested with beam. efficiency low activation VARIAN is continuously developing its technology fast and easy access further and introducing new features. for maintenance Recent breakthrough developments include high uptime Transistor RF Power Amplifiers and operator-free operation Digital Low Level RF electronics. low power consumption 36

37 THANK YOU! Students, talk to us! Our team is continuously growing 37

38 The VARIAN 250MeV Superconducting Compact Proton Cyclotron 38