The VARIAN 250 MeV Superconducting Compact Proton Cyclotron
H. Röcken
VARIAN Medical Systems
Particle Therapy GmbHFriedrich-Ebert-Str. 1
D-51429 BERGISCH GLADBACH
GERMANY
OUTLINE
1. Why having a Superconducting Cyclotron?
2. Machine Key Data
3. Operating VARIAN Machines3. Operating VARIAN Machines
� Uptime Statistics
� Automated Operation (Startup + Optimization)
4. Production of Next Machines
� Production Site
� Factory Assembly
� Test Cells and Beam Testing
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5. Recent Developments
� Solid State Amplifier
� Digital Low Level RF
� RF Commissioning Results
6. Conclusion
Why having a superconducting cyclotron?
Why having a Superconducting Cyclotron?
� It’s fascinating technology!� 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!
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� Let’s see if we find some quantum mechanics involved…
� There are plasmas!
� It’s applied relativity!
Why having a Superconducting Cyclotron?
This is what I tell my team on one hand …
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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 Medical Systems’ mission is to explore and develop radiation technology that protects and saves lives. Our goal is to helpsave 100,000 more lives each year.
Timothy E. Guertin — VARIAN’s President and Chief Executive Officer:
not the points that drive a business.VARIAN’s commitment to this technology derives from a different approach.
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save 100,000 more lives each year.That’s enough to fill a large stadium. To meetthis 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.”
Why having a Superconducting Cyclotron?
We want to achieve this mission goal by providing thebest tumor treatment delivery available,
which currently is
pencil beam scanning of energetic particles.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.
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complicated. 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.
Why having a Superconducting Cyclotron?
Looking a bit deeper, it turns out that a superconducting cyclotronbrings along even more advantages:
Superconducting coil, low power consumptionSuperconducting coil, low power consumption
Small machine, high beam energy
Saturated iron
High magnetic field possible
Larger pole gap over full radius
High extraction efficiency, high beam currents
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High extraction efficiency, high beam currents
Reproducible field and beam operation
Practically operator-free operation
Low activation
Fast access, easy maintenance, high uptime √
� Beam - Energy 250 MeV- Extracted current (max) 800 nA
- Emittance of extracted beam < 3 / 5 π π π π mm mrad (2σ)- Momentum spread ∆∆∆∆p/p ±0.04% (i.e. 200keV @ 250MeV)
VARIAN PT SC Cyclotron Key Data(Engineering Goals)
- Momentum spread ∆∆∆∆p/p ±0.04% (i.e. 200keV @ 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 µµµµs
� 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
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�RF System - Frequency 72.8 MHz (2nd harmonic)- Voltage source to puller / @ extraction radius 80 kV / 130 kV- RF power ≤115 kW
- Central field 2.4 T- Max. field at the coil <4 T
- Operating current 160 A- Rated power of cryocoolers 40 kW
VARIAN SC Proton Cyclotron Facility Integration
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3. Operating Machines
� Uptime Statistics
� Automated Operation
� Morning Startup
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� Morning Startup
� Optimization Procedures
Operating VARIAN PT SC Cyclotrons
1. Paul Scherrer Institut PSI (CH)
2. Rinecker Proton Therapy Center RPTC (D), treating patients since
, treating patients since beginning of 2007.
2. Rinecker Proton Therapy Center RPTC (D)
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
, treating patients sincebeginning of 2009.
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� 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� …
Uptime during Patient Treatment Ramp-Up
RPTC presentation onPTCOG 48 conferencePTCOG 48 conference6 months after
start of operation:
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Poster presented by RPTC at PTCOG 48
RPTC Operating Time / Facility Uptime
� User at RPTC treats patients up to 6 days/week, 8-10 hrs/day
� Upgrade of gantry / scanning nozzle functionality is still continued during
� 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
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� The Superconducting Cyclotron has – of course – a higher uptime(PSI > 99%)
How is this achieved?
ReliableMachine
ReproducibleConditions
Fully Automated Control System
Automated Morning Startup Procedure
Cyclotron is in overnight state(sc magnet on, RF reduced or off)
What happens after pressingand ?
Devices change their state(e.g. ramp-up of power supplies) …
... controlled by transition functions.
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Cyclotron reaches fully automatic the state
I = I (iron temp)
Automatic Phase
Calibration
Automatic Phase
Regulation
Beam Operation
Devices Ramp-Up
Automated Cyclotron Startup: ≤10min to Beam
Udefl = Ubeam off
Uextr.defl = std
PRF = Pfull
PRF = Preduced
I within specification
Imagnet = I0 Imagnet = I (beam phase)Imagnet = I (iron temp)
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0 1 2 3 4 5 6 7 8 9 10
IIS = stdIbeam within specification
t / min
H2flow = std
Automated Optimization Procedures
Example:
Beam CenteringBeam Centering
Parameters, e.g.
start values, step widths, limits, …
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Actual values of field bump
before / after automatic optimization
Badly centered beam� orbit precession � detected on moving head of a straight probe:
Automated Optimization Procedures
Field Bump Starting Point
Beam Centering: Graphics Output
Optimization of Phase and
Amplitude for Centering
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Amplitude for Centering
Field Bump
Optimized Field Bump
Automated Optimization Procedures
SlitOpening Offsets
BeamSuppression Measurement
Beam Current Transmission
Check
SlitPositioning
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RF PowerScan
Beam Centering
Extraction Field Bump
Optimization
Extraction Deflector
Optimization
4. Production of Next Machines
� Production Site
� Factory Assembly
� Test Cells and Beam Testing
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� Test Cells and Beam Testing
VARIAN PT Production SiteOverview
Production site near Cologne / GermanyGermany
Allows assembly of
up to 6 cyclotrons in parallel …
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VARIAN PT Production SiteOverview
Production site near Cologne / GermanyGermany
Allows assembly of
up to 6 cyclotrons in parallel …
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… and the corresponding beamline modules.
Production of Next Machines
� Fine machined iron and all major components for the next cyclotrons are ready;
next coil windings are
coil windingmagnetic testing
next coil windings are finished and assembly of pole caps is underway.
� Long lead items(especially iron yokes)for the following machines
are ordered.
cryostat welding
incoming
machine assembly
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are ordered. incomingpole caps andyoke rings� Build sequence is ramped
up from ~2 cyclotrons per year at the moment
VARIAN PT SC Cyclotrons Factory Commissioning
� Cyclotron #3 is completely pre-assembled at Varian’s PT manufacturing premises.manufacturing premises.
� It has passed the testing and shimming of the superconducting magnet and is currently tested
(with beam!) in the factory.
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� It will be shipped in summer to its destination in 2 large lots (upper / lower part).
Cyclotron and Scanning Nozzle Test Cells
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Cyclotron and Scanning Nozzle Test Cells
� Adjacent to the manufacturing hall VARIAN has built concrete bunkers for cyclotron and scanning nozzle 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”.
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Cyclotron and Scanning Nozzle Test Cells
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Cyclotron and Scanning Nozzle Test Cells
AllAll
� RF components
� Ion source
� Slit systems
� Extractors
� Diagnostics
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� Diagnostics
� etc.
are currently undergoing a system integration and beam FAT.
5. Recent Developments
� Solid State Amplifier
� Digital Low Level RF
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� RF Commissioning Results
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, � several electrical cabinets for power transformers,
high voltage supplies, and the tubes
New design in use (150kW @72MHz):
� transistor based
� 120 parallel working RF power modules in 6 cabinets
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Supplied byCryoelectra GmbH
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, ...
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� The digitally controlled modularized system provides extended diagnostics capabilities.
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.
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uptime.
� The dLLRF is faster than the previously used system and provides much more
diagnostic signals and functionality.
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
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– Cavity Check
Developments: Digital LLRF Control System
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RF Ramp-Up to 120kW
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~1 minute
Conclusion
cw beam
� 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� high current
� stable beam position� small footprint� high extraction
efficiency� low activation
them for use in pencil beam scanning therapy.
� 2 of such cyclotrons are already in clinical use.
� Several more machines are in production.
� VARIAN is continuously developing its technology
� All machines will be factory tested with beam.
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� low activation� fast and easy access
for maintenance� high uptime� operator-free operation
� low power consumption
� VARIAN is continuously developing its technology further and introducing new features.
� Recent breakthrough developments include Transistor RF Power Amplifiers andDigital Low Level RF electronics.
THANK YOU!
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Students, talk to us!Our team is continuously growing …
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