The VARIAN 250 MeV Superconducting Compact Proton...

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

The VARIAN 250MeV Superconducting Compact Proton CyclotronH. Röcken

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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!


This is what I tell my team on one hand …


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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.”


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.


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:


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


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



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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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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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� 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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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 …

The VARIAN 250MeV SuperconductingCompact Proton Cyclotron


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