Accelerator Seminar, April 2013

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2 H. Röcken VARIAN Medical Systems Particle Therapy GmbH Friedrich-Ebert-Str. 1 D BERGISCH GLADBACH GERMANY

3 OUTLINE Why having a Superconducting Cyclotron? Some Basics VARIAN PT Cyclotrons: ProBeam Name, Key Data, Different Views Operating ProBeam Machines Uptimes, Automated Operation (Startup & Optimization) Production Site Test Cells, Machines Under Assembly and Commissioning Magnet Testing, RF Technology, Beam Operation Solid State Amplifier, Digital Low Level RF, RF Commissioning Results Status of Machines #3 to #6 Production, Status, Transport of #3, On-Site Commissioning Conclusion / Outlook 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! 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

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.

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 former 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 radiation treatment delivery available, which currently is pencil beam scanning of energetic particles. (as is done at PSI) 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 From Cyclotron Basics to Relativistic Machines The original sketch from Lawrence s patent in 1930 looked like this: 9

10 From Cyclotron Basics to Relativistic Machines The centripetal force that keeps the particle in the cyclotron on a circular arc path equals the magnetic part of the Lorentz force F Z m v r 2 q v B F mag where r is the track radius. If T is the time for one turn, then the angular velocity w becomes v 2 r T w r and thus w q B m For a constant magnetic field the orbital frequency is constant, every turn takes the same time, the cyclotron is isochronous. 10

From Cyclotron Basics to Relativistic Machines Non-Relativistic Cyclotrons The maximum particle energy of non-relativistic cyclotrons is about 100 MeV.

11 From Cyclotron Basics to Relativistic Machines Non-Relativistic Cyclotrons The maximum particle energy of non-relativistic cyclotrons is about 100 MeV. In the classical cyclotron the azimuthally homogeneous magnetic field decreases towards the edge. Thus, the field has a radial component which ensures that the ions are focused in the center plane between the magnetic poles. With radially decreasing field (B const), however, the ions run behind the high frequency (out of phase) and gain less and less energy per orbit. And 11

12 From Cyclotron Basics to Relativistic Machines Relativistic Cyclotrons due to Einstein it becomes even worse! In the relativistic case (high energy = high velocity) masses increase, i.e. the rest mass m 0 of a particle has to be multiplied by the factor g g 1 1 v c 2 2 Thus w q B g m MeV protons travel at 0.6c g =

13 From Cyclotron Basics to Relativistic Machines Relativistic Cyclotrons In order to maintain a constant orbital frequency (isochronous cyclotron), the magnetic field must therefore increase over the radius (with increasing particle velocity): w e B( r) m g 0 const. A compact relativistic cyclotron solves this problem by using magnetic poles with several sectors (azimuthally varying field, AVF), in which the average field for the respective particle trajectories increases with the energy; in addition, azimuthal and radial magnetic field components are present that focus the particle beam vertically ( axial ) and thus keep it on the median plane. With this technology, significantly higher energies of several hundred MeV up to 12 GeV are possible. 13

14 Relativistic Cyclotrons Average field in the Varian ProBeam cyclotron: B B maxrad center 3.0T 2.4T

15 Relativistic Cyclotrons PSI 590 MeV separated sector cyclotron 15

16 Relativistic Cyclotrons Four sector AVF iron pole of the Varian ProBeam compact cyclotron 16

17 Relativistic Cyclotrons Four sector AVF iron pole of the Varian ProBeam compact cyclotron and the four Dees between them: 17

18 PSI COMET COMET (COmpact MEdical Therapy cyclotron) is the first machine of the Varian ProBeam cyclotrons, here during installation at PSI: 18

19 The Name of the Game Single Particle Isochronous Fixed Energy Four Sector Superconducting Compact Azimuthally Varying Field Medical Cyclotron SPFEFSAVFISCMC 19

20 VARIAN ProBeam SC Cyclotron Key Data (Engineering Goals) Beam - Energy and particles 250 MeV protons - Extracted current (max) 800 na - Emittance of extracted beam < 3 / 5 mm mrad (2σ) - Momentum spread Dp/p ±0.04% (i.e. 250MeV) - Number of turns ~650 - Extraction efficiency (multi-turn extraction mode) ~80% - Dynamic range for intensity modulation 1:800 - Fast intensity modulation via electrostatic deflector, >10% in 100 ms (@PSI in ~1 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 / 105 kv - RF power 115 kw 20

21 Views of the Varian ProBeam Cyclotron This is the Designer s view: Pole Cap Supply Cryostat Magnet Pole Hill RF Dee Iron Yoke Superconducting Magnet Coil Coil Cryostat 21

22 Views of the Varian ProBeam Cyclotron This is the Marketing view: 22

23 Views of the Varian ProBeam Cyclotron This is the Engineer s view: 23

24 Views of the Varian ProBeam Cyclotron This is the Service view: 24

25 ProBeam Facility Integration 25

Operating ProBeam Cyclotrons 1. Paul Scherrer Institut PSI (CH), treating patients since beginning of 20

The RPTC facility is widely equipped with VARIAN ProBeam technology, like superconducting compact 250 MeV proton cyclotron degrader for energy adjustment energy selection

26 Operating ProBeam 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 ProBeam 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 3. Scripps Proton Therapy Center SPTC (USA), providing beam since

27 ProBeam Uptime and Reliability User at RPTC treats patients up to 6 days/week, 8-10 hrs/day All 4 scanning gantries are clinical Upgrade of 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 27

Uptime during Patient Treatment RPTC presentation on PTCOG 48 conference 6 months after start of operation: Poster presented by RPTC at PTCOG 48 PSI PROSCAN availability:

28 Uptime during Patient Treatment RPTC presentation on PTCOG 48 conference 6 months after start of operation: Poster presented by RPTC at PTCOG 48 PSI PROSCAN availability: 98% [Scientific Report 2011] The Superconducting Cyclotron has a high uptime How is this achieved? Reliable Machine Reproducible Conditions Fully Automated Control System 28

29 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 29

30 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 30

31 Automated Optimization Procedures Example: Beam Centering Parameters, e.g. start values, step widths, limits, Actual values of field bump before / after automatic optimization 31

32 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 32

33 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 33

34 VARIAN PT Production Site Overview Production site near Cologne / Germany Allows assembly of several cyclotrons in parallel 34

35 VARIAN PT Production Site Overview Production site near Cologne / Germany Allows assembly of several cyclotrons in parallel and the corresponding beamline modules. 35

36 Cyclotron and Scanning Nozzle Test Cells 36

37 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 #4 is currently operated in one of these Test Cells. 37

38 Cyclotron and Scanning Nozzle Test Cells 38

39 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. 39

40 VARIAN PT Cyclotrons under Commissioning Cyclotron production and testing is ramping up from ~1/year to ~3/year now. 40

41 VARIAN PT Cyclotrons under Commissioning Cyclotron production and testing is ramping up from ~1/year to ~3/year now. The obligatory test quenches cannot be forced by fast ramping and have to be triggered by the dedicated quench heaters. After re-cool down (5 hrs) all forces on the support links as well as the magnetic field map remain unchanged: stable, quench proof and quench tolerant system 41

42 Factory Testing of a Cyclotron Cyclotron is moved into factory test cell (before or after quench test) 42

43 Factory Testing of a Cyclotron Cyclotron is moved into factory test cell (before or after quench test) 43

44 Factory Testing of a Cyclotron Cyclotron is moved into factory test cell (before or after quench test) 44

45 Factory Testing of a Cyclotron Cyclotron is moved into factory test cell (before or after quench test) 45

46 VARIAN PT Cyclotrons under Commissioning A measured field map 46

47 VARIAN PT Cyclotrons under Commissioning A measured field map is compared to its symmetrized form to reveal deviations from perfect 4-fold symmetry. 47

48 VARIAN PT Cyclotrons under Commissioning A measured field map is compared to its symmetrized form to reveal deviations from perfect 4-fold symmetry. Here the field showed a first harmonic of ~29 Gauss. 1 st Harmonic of Initial Field Map 29 Gauss 48

VARIAN PT Cyclotrons under Commissioning A measured field map is compared to its symmetrized form to reveal deviations from perfect 4-fold symmetry.

49 VARIAN PT Cyclotrons under Commissioning A measured field map is compared to its symmetrized form to reveal deviations from perfect 4-fold symmetry. Here the field showed a first harmonic of ~29 Gauss. This could be compensated down to <2 Gauss by a simple lateral adjustment of the sc coil. Some remaining deviations on the extraction radius must be shimmed locally. 1 st Harmonic 1 st Harmonic of Initial After Field Compensation Map <2 Gauss 29 Gauss 49

Solid State RF Amplifier RF power amplifier used at

electrical cabinets for power transformers, high

(150kW @72MHz): transistor based 120 parallel

50 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 50

51 Solid State RF Amplifier This SSAmp was used for initial RF conditioning of ProBeam cyclotrons #3 and #4 (which is currently operated at full power in the factory). 51

Solid State RF Amplifier This SSAmp was used for initial RF conditioning of ProBeam cyclotrons #3 and #4 (which is currently operated at full power in the factory).

52 Solid State RF Amplifier This SSAmp was used for initial RF conditioning of ProBeam cyclotrons #3 and #4 (which is currently operated at full power in the factory). Via its redundancy, the design features a higher - availability, - serviceability, - cost reduction,... The digitally controlled modularized system provides extended diagnostics capabilities. RF Power Out 52

53 Digital LLRF VARIAN is using a digital LLRF. 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. 53

54 Digital LLRF Control System 54

55 Digital LLRF Control System 55

56 Digital LLRF Control System 56

57 RF Amplitude Stability ΔV/V (1σ) ΔV/V (pp) 57

58 Conventional RF Ramp-Up to 120kW ~1 minute 58

59 RF Pulsing & Ramping After an RF trip the dllrf starts pulsing the power (to bypass the multipacting regime). ~15s As soon as the resonator is matched again, the power is ramped up from ~30kW to ~115kW. 59

60 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 Cavitiy Check 60

61 RF System, Dees, Beam Dynamics T orbit 2 TRF forbit frf / 2 U RF Dee 1 out Dee 2 out Dee 3 out Dee 4 out Dee 3 Dee 2 t Dee 4 Dee 1 in Dee 2 in Dee 3 in Dee 4 in Dee 1 in Dee 1 and Dee 3 Dee 2 and Dee 4 Dee 1 61

62 2 nd Harmonic Operation 62

63 First Internal Beam on #3 in Test Cell System prepared (magnet & RF ramped up, viewer probe with video camera installed near cyclotron center) First switch-on of ion source video camera 63

64 Beam Development Already on the next day it was possible to bring the beam close to extraction radius video camera 64

65 First Extracted Beam from #3: June 29, st extracted beam: RF Deflector Beam 65

66 Beam Current / na Extraction Efficiency 10 Radial Beam Probe Scan When leaving the factory: Cyclotron Radius / mm 66

Beam Current / na Extraction Efficiency 10 Radial Beam Probe Scan 9 8 7 After

67 Beam Current / na Extraction Efficiency 10 Radial Beam Probe Scan After optimization on site: Cyclotron Radius / mm 67

Production of Next Machines There s a continuous incoming goods flow in the factory. Probeam cyclotrons #4, #5, and #6 are in production and under factory commissioning.

68 Production of Next Machines There s a continuous incoming goods flow in the factory. Probeam cyclotrons #4, #5, and #6 are in production and under factory commissioning. Long lead items (especially iron yokes) for the following machines are ordered. Build sequence is ramped up to ~3 cyclotrons per year at the moment magnetic testing coil winding machine assembly cryostat welding incoming pole caps and yoke rings 68

69 Production of Further ProBeam Systems Cyclotron Production Hall 69

70 Production of Further ProBeam Systems Other production areas: Beamline modules 70

71 Production of Further ProBeam Systems Other production areas: Scanning nozzles 71

72 Production of Further ProBeam Systems Other production areas: HW & SW test center 72

73 Status of ProBeam Cyclotrons #3, #4, #5, #6 Cyclotron #3 Installed and commissioned in San Diego, USA Currently continuously delivering beam for clinical commissioning of ProBeam equipment Cyclotron #4 Installed in the factory test cell Passed magnetic tests Passed RF commissioning Currently at the beginning of beam commissioning 73

74 Status of ProBeam Cyclotrons #3, #4, #5, #6 Cyclotron #5 Pole caps and yoke rings are being equipped with components Superconducting Coil is completed and passed quench test Currently undergoing field mapping and iron fine shimming 74

75 Status of ProBeam Cyclotrons #3, #4, #5, #6 Cyclotron #6 Coil is under manufacturing Yoke rings and pole caps passed factory incoming inspection Assembly will continue in parallel to #4 and #5 testing 75

76 Transport of #3 to the USA, 2011 Disassembly and packaging end of July Shipping August to September 76

77 Transport of #3 to the USA, 2011 Disassembly and packaging end of July Shipping August to September Installation into building October 77

78 Transport of #3 to the USA, 2011 Disassembly and packaging end of July Shipping August to September Installation into building October 78

First Beam On Site, 2012 November to December 2011: Cabling, installation of beamline January 2012: Facility powered and cyclotron cooled down February: On site

79 First Beam On Site, 2012 November to December 2011: Cabling, installation of beamline January 2012: Facility powered and cyclotron cooled down February: On site magnetic field verification after transport March: RF re-conditioning April 18: First beam on site! Without any re-tuning, all parameters known from the factory testing. 79

80 Vertical Beam Centering Tilted coil: Beam can oscillate vertically and exits the cyclotron off axis Adjusted coil: Beam is well centered vertically and exits the cyclotron on axis 80

81 Conclusion The VARIAN ProBeam Superconducting Compact Proton Cyclotrons feature superior properties that make them turn-key operational machines and predestine them for use in pencil beam scanning proton therapy. 2 of such cyclotrons are already in clinical use. #3 is commissioned at customer s site, first beam was extracted in April 2012, clinical handover planned for early summer. Several more machines are in production. All cyclotrons are/will be factory tested with beam. VARIAN is continuously developing its technology further and introducing new features. Recent product enhancements include Transistor RF Power Amplifiers and Digital Low Level RF electronics. cw proton beam high energy high current stable beam position small footprint high extraction efficiency low activation fast and easy access for maintenance high uptime operator-free operation low power consumption 81

82 Outlook Varian Medical Systems is very active in the Proton Therapy market. The 3 rd ProBeam compact superconducting cyclotron is installed and commissioned at Scripps Proton Therapy Center in San Diego, CA USA. The center is close to completion and will start patient treatment this year. In parallel Varian is continuing its production of the next machines for signed contracts for installations in Baltimore, MD USA Riyadh, Saudi Arabia St. Petersburg, Russia Atlanta, GA USA The next cyclotrons are currently under beam commissioning and magnet testing in the factory. We will equip three centers next year and are in close contact with further potential customers worldwide. 82

83 Outlook 83

84 History of Particle Treatment Patient treatment using neutrons in the 1940 s: (taken from M.K. Craddock, Proc. Cycl. 2010, Lanzhou, CN) 84

85 THANK YOU! 85

H. Röcken, M. Abdel-Bary, E. Akcöltekin, P. Budz, T. Stephani, J. Wittschen

: Medical Operation of the 2 nd Machine, Production and Commissioning Status of Machines No. 3 to 7 H. Röcken, M. Abdel-Bary, E. Akcöltekin, P. Budz, T. Stephani, J. Wittschen VARIAN Medical Systems Particle