recent progress in cyclotrons for protontherapy at iba

Recent Developments

in Proton AcceleratorsAccelerators

Damien BERTRANDDomain Expert Hadrontherapy

Erice Workshop on HadrontherapyMay 20-27, 2011

C230 cyclotron for protontherapy

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C230 key specifications

� Compact isochronous cyclotron

� 235 MeV proton energy� 300 nA beam current, quasi-continuous� Typical efficiency : 55 %

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� Approx. weight: 220 T� Diameter: 4.3 m

� Conventional magnet coil: 1.7 - 2.2 T � RF Frequency: 106 MHz� Dee voltage: 55 to 150 kV peak

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A quite popular solution… ©

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4 20 facilities including IBA equipement, 64 treatment rooms in total

Evolution… ©

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… also for cyclotrons ! ©

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… just changing the logo ?

Quite robust design

� Design not changing� Improving tools and technical details for

� Increased reproducibility � Easier maintenance� Faster commissioning

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Personalized PT treatments

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Proteus 235 is not just a cyclo©

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Treatment rooms ©

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What lies inside the nice covers… ©

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Improvements on PBS

Sigma @ 230 MeV

Minimal Energy

Position Accuracy

PBS V1 (UN) PBS V6 (DN)

10 mm 3 mm

140 MeV100Mev

or60 MeV (Optionaly)

+/- 2 mm +/- 1 mm

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Position Accuracy

Commissioned Angle

Treatment Time

+/- 2 mm +/- 1 mm

0°°°° , 360°°°° All angles

Above 5 min 1 min 36 sec

Switching Time 2 min 15 s

1st patient treatedin Boston, Dec. 2008

Challenges are in the software ! ©

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PBS Quality Assurance challenges

� A number of parameters to control and validate

- Spot Size (sigma, skewness)

- Spot Position

- Complex shape size analysis

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- Complex shape size analysis

- Dose/Intensity analysis

- Range analysis

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IBA’s Solution : QA test pattern©

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Transversal 2D measurements performed using Lynx scintillator from IBA DosimetryData acquisition and processing managed by OmniPro software from IBA Dosimetry

PBS Pattern (Polygone Area)

� 226 MeV

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PBS Pattern (spot analysis)

� 226 MeV

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PBS Pattern (Beam size analysis)

� 226 MeV

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PBS Performances

� Gantry angle dependencySpec beam reproducibility ≤ ± 5%

Beam sigma in air at isocenter vs Gantry angles

2,50

3,00

3,50

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0,00

0,50

1,00

1,50

2,00

0 50 100 150 200 250 300 350

Gantry Angle (°)

Bea

m s

igm

a (m

m)

Sigma X

Sigma Y

-5%

+5%

Beam Spot for energy of 230 MeV in air @ Isocenter for various gantry angle

PBS performances

� Range AccuracySpec ± 0.1 g/cm²

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�� Better than +/- 0.2 mm

Timing performances©

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Reducing irradiation time: PBS -10s

� Objective: treat a 1-liter tumor with PBS in 10 sec .

� Idea: use patient-specific micro ridge filter

Layer 1Layer 2

Layer N

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Mono-energetic Beam

Making PT more accessible

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Towards a novel, low -cost PT accelerator

� Lower cost & standardized Proton Therapy System

� Compact treatment room and small footprint

� Shorter installation time on site

� Operator less

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� Reduced maintenance

Proteus One : low cost, smaller footprint

Smaller cyclo, integrated ESS©

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Beam Line shortening � Smaller structure � Smaller system

Towards a more compact cyclotron

� Compact machine requires higher magnetic field�Superconducting magnet

� To conserve isochronism one has to compensate relativistic mass increase�Magnetic must increase with the radius

� Increasing magnetic field is naturally defocusing�Restore focusing by alternating field gradients in hills and valleys

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�Restore focusing by alternating field gradients in hills and valleys� Further increase focusing by spiralling the poles

� … but once the pole iron is saturated, there is a limit on the field gradient between hills and valleys (flutter)

� … and there is also a limit in spiral designs

S2C2 rationale

� The only solution to increase the magnetic field while conserving the beamfocusing inside the machine is to use weak focusing

- No field gradients between hills and valleys- Decreasing field with radius

� With such design isochronism cannot be maintained- Changing RF- Pulsed beam at machine exit

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- Pulsed beam at machine exit

By definition such machine is a SynchroCyclotronWhich in our case will be Super - Conducting

S2C2

Introducing IBA’s S2C2©

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S2C2 Specifications

� Compact system: diameter 2.5 m, height 2 m, weight <50 T� Reliability: NbTi cryogen free coil, passive magnetostatic extraction…� Repeatability: Standard high quality laminated steel� Operability: Operator-free system, remote diagnostics

� 20 nA average beam current at 230 MeV for PBS; 150 nA feasible if required� Extraction efficiency >50% at 230 MeV

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� Extraction efficiency >50% at 230 MeV� 1 kHz beam pulse repetition rate for PBS� Still possible to reach 250 MeV (with some additional work)

Overall view

Size and weight within specs Easy accessibility on sub-systems

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Yoke shape compromise : sustainablestray field for ancillary equipments

Making PT more accessible

19 m – 62.3 ft

27.3 m – 89.5 ft

7.3 m 12.8 m

Approx. the size of two linacs

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7.3 m24 ft

12.8 m42 ft

Proteus ONE* Timing

Projected Product Introduction Timeline

2011 2012 2013 2014

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Design FreezeSubsystems Procurement

PrototypeTesting

FDA Filing

PatientTreatments

*Subject to review by Competent Authorities (FDA, European Notified Bodies, et al.) before being put on the market.

recent progress in cyclotrons for protontherapy at iba

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