Symposium on the Promises 

and Perils of Proton Radiotherapy 

New Developments in Proton Therapy Delivery Systems

Eric E. Klein, Ph.D.Professor, Radiation Oncology

Washington UniversityWashington UniversitySt. Louis,  MO

Thanks to: Charlie Ma (FCCC), Jay Flanz (MGH), John Hughes (CPAC), James McDonough (Penn)

What are the (Clinical) Requirements?Jay Flanz, PTCOG 2007

• Satisfy Clinical ParametersAppropriate treatment in 1 2 minutesAppropriate treatment in 1‐2 minutes Dosimetry (It has to work !)

• Overall System Reliability > 95%Implies Accelerator Reliability of ~99%

• Fits in a “Clinical” Setting5‐8m effect of size depends on number of rooms5‐8m, effect of size depends on number of rooms.Possibly small enough to fit all equipment into one room

• Easy to OperateEasy is relative, but easier than the perception of a National

Laboratory Accelerator Operation (e.g. automatic, self diagnoses)

Promises: New DevelopmentsPromises: New Developments

• Lasers (FCCC Germany)Lasers (FCCC, Germany)

Promises: New DevelopmentsPromises: New Developments

• Lasers (FCCC Germany)Lasers (FCCC, Germany)

• CPAC

Promises: New DevelopmentsPromises: New Developments

• Lasers (FCCC Germany)Lasers (FCCC, Germany)

• CPAC

O O• PROTOM

Promises: New DevelopmentsPromises: New Developments

• Lasers (FCCC Germany)Lasers (FCCC, Germany)

• CPAC

O O• PROTOM

• MLC (U‐Penn/IBA/Varian)

Promises: New Developments:N S ifi E d S l iNo Specific Endorsement or Selection

• Lasers (FCCC, Germany)( , y)• CPAC• PROTOM• MLC (U‐Penn/IBA/Varian)

• Still River Systems– Why We Chose this Single Gantry SolutionF di– Funding

– Integration with our Photon Clinic– The Technologygy

Promises: New Developments:N S ifi E d S l iNo Specific Endorsement or Selection

• Lasers (FCCC, Dresden)( , )• CPAC• PROTOM• MLC (U‐Penn/IBA/Varian) D

eli

• Still River Systems– Why We Chose this Single Gantry Solution– Funding

ivery

– Funding– Integration with our Photon Clinic– The Technology

Laser Ion Acceleration

Friedrich Schiller University JenaPOLARIS (Petawatt Optical Laser A lifi f R di ti I t iAmplifier for Radiation Intensive Experiments): 1 PW, > 100 J, 120 fs, 0.03 Hz

The FCCC (Fox Chase, Phil, PA)100TW High-Power Laser

Energy per pulse (E) = 5~21 Joule Energy per pulse (E) = 5~21 Joule 

Pulse duration (T) = 35~50  10‐15 second (10‐15 m)

T

Focal spot size (A) = 15~75 m2  ~ 20μm2

Power (P) = E/T = 5/50~21/35  1015 = 100~600 TW 

Intensity (I) = P/A = 100/75~600/15  1019 = 0.13~4  1020 W/cm2 

Ion max. energy vs. laser energy and power

[T.Esirkepov et al., PRL 96, 105001, 2006]

Energy Selection and Beam Collimation

Movable aperture to select protons of desired energywith sharp beam penumbra

4

30

30

44irIdlrIdlB

Nb3Ti superconducting coils can 33 44 i irr Nb3Ti superconducting coils can provide I = 85 A per loop with magnetic field to 4.4 Tesla by Biot-Savart law:

mirror

Adjustable distanceAdjustable distance for scanning along yAdjustable distance

for scanning along xfor scanning along y

Gantry Target and beam selection system

yrotation

system

Main laser beam liney

Proton beam

x

Couch

CPAC (Compact Particle Accelerator Corporation):TomoProAccelerator Corporation):TomoPro

2 meters = 200MeV

One section of DWA technology

Dielectric Wall Accelerator* (DWA)

*Lawrence Livermore National Laboratory, Livermore CA

The DWA enables protons to beprotons to be accelerated to energies ~ 100 MeV per meter –

2 meters = 200MeV

100 MeV per meter without using bending magnets.gThe dielectric wall uses a high-voltage-gradient g g ginsulator to handle high electric-field stresses,

Dielectric Wall Accelerator* (DWA)enabling a proton therapy accelerator to operate without being short

*Lawrence Livermore National Laboratory, Livermore CA

without being short-circuited.

Acceleration of Protons in DWA Sub scale ( / )Acceleration of Protons in DWA Sub‐scale (12/08)Insulator and source (on top)Blumlein Sections

Blumlein switching* used to Accelerate Protons

Central core is Cavity moving e- field along linac –Central core is Cavity, moving e field along linac spike produced can increase thereby accelerating protons.

Uncharged transmission lines in this gregion (not shown)

*patent pending

The Differential Amplifier circuit designed by Blumlein for small signals and performs switching functions - high gain, stability, high input impedance, large output voltage swings.

ProTom (exclusive rights for a proton therapy technology system developed at the Lebedev Physics Institute)technology system developed at the Lebedev Physics Institute)

Accelerator specificationsEquipment CapabilitiesEquipment Capabilities

Fully variable beam energy of 30‐330 MeV ± 0.15%Time of acceleration up to 330 MeV ‐ 1 secSlow, computer‐controlled extraction, range of extraction time ‐ 0.1 ‐ 10 secEfficiency of the beam extraction ~ 80%Power consumption: maximum ‐ ~ 100 kW; average ‐ ~ 50 kWTotal weight ‐ 15 tonsgExternal ring diameter ‐ less than 16 feet

Beam delivery / scanning specificationsi di i l iBi‐directional scanning:

Vertical: 100 mm amplitude and frequency up to 200 HzHorizontal: 700 mm amplitude and frequency up to 1 Hz

V i f f d b di i 2 20Variance of focused beam dimension: 2 mm to 20 mmSpeed of scanning along the beam axis: 30 ‐ 330 MeV / 1 sec

Unsure of Dose Rate (Current)

ProTom Equipment at MITProTom Equipment at MITProTom Equipment at MITProTom Equipment at MITSynchrotron

Injector

Scanning Magnets

Scintillators

Ionization Chamber

Professor Balakin, Dmitri Sivan, Anatoly  and Steve Spotts

Beam Energy Range 30Beam Energy Range 30‐‐330MeV330MeV

150 MeV, 15.8cm

190 MeV, 23.8cm

225 MeV, 31.7cm

Example of multiExample of multi‐‐field 2D Irradiationfield 2D Irradiationp fp f ff

Note that each field has a different range and scanning pattern in order to obtain the desired dose distributionpattern in order to obtain the desired dose distribution

One possible footprint with 2 beams

MLCMLCPenn‐IBA‐VarianPenn IBA Varian

Why MLC?D t l h i d l bl ki• Due to nozzle changing and large blocking an MLC is preferred for increased throughput.

• MLC greatly reduces the number of apertures that need to be machined and stored.

Potential future uses of an MLC• Possibility of using MLC to conform to the target• Possibility of using MLC to conform to the target

at each depth rather than using a RC and modulator wheel.

• Finally, the possibility to use MLC to protect OAR or sharpen a field edge for scanned beamsOAR or sharpen a field edge for scanned beams.

Di i & Fi ld i

Design Issues• Dimensions & Field size – Work with clinical colleagues

and engineering constraints to come up with acceptable compromise. (100 leaves: width = 4.4 mm; length = 98 mm; p ( ; g ;projecting to a 250 x 180 mm2 at isocenter)

• Interference – Encourage Varian mechanical engineers to g glimit interference.

• Secondary neutrons – Use GEANT4 to simulate neutronSecondary neutrons Use GEANT4 to simulate neutron production for various materials.

• Electronics survival – Perform tests at the University ofElectronics survival Perform tests at the University of Washington neutron beam.

Compare a Brass Aperture to a Tungsten MLCNeutron Leakage

•Penn compared leakage through 8.2 cm tungsten (1.2 mGy/Gy) and 6.5 cm brass (1.8 mGy/Gy): PDD very similar. •Leaves has stepped sides with minimal gaps, hence the thickness•Although tungsten creates more secondary neutrons & x-rays than brass, there is self-shielding because the tungsten is twice as thick as the range of the protons making the neutron dose to the patient lower for tungsten.

D thD h DepthDepth

MLC design variations modeled using GEANT4 to provide sufficient shielding to stop primary protons

Still RiverStill River SystemsSystems

SRS + BJH/WU: History• 1990s: Discussions on Bringing Protons to St. Louis: Barnes‐Jewish Hospital/ WashingtonLouis: Barnes Jewish Hospital/ Washington University

2005 Di i i h SRS f Si l• 2005: Discussions ensue with SRS for Single Room System

• Early 2006Expert Consultants Give Positive Outlook– Expert Consultants Give Positive Outlook Reviews

SRS + BJH/WU: HistoryWh Si l S l i ?– Why a Single Room Solution ?

• Obviously, Cost• High Selectivity of PatientsHigh Selectivity of Patients• Ease of Integration with Existing Clinic• An NCI Comprehensive Cancer Center that Provides Proton Radiotherapy as a Viable Treatment Option, rather than, a Peripheral Proton Clinic.

• Not Convinced St. Louis needs More than 1‐2 Rooms.

– Some Initial Concerns (beyond typical serial #1 concerns)• Magnetic Shielding of Stray Cyclotron Magnetic Fields• EM Shielding of Cyclotron RF Fields• Neutron Dose Contamination• Neutron Dose Contamination• Limited to Passive Scattering

Still River SystemsMonarch 250 System

• Gantry Mounted Proton Accelerator (Synchrocyclotron)• Patient Support (couch)• Radiographic Positioning systems (fixed imagers, portable CBCT)

•Superconducting magnets reduceSuperconducting magnets reduce size and cost of the system

A program to adapt a superconducting synchrocyclotron to medical use began at MSU in the early

Invited Paper, 1989 Particle Accelerator Conference, March 20-23, 1989, Chicago, ILMEDICAL ACCELERATOR PROJECTS AT MICHIGAN STATE UNIVERSITYMSU in the early

1980'sMICHIGAN STATE UNIVERSITYH. Blosser, R. Burleigh, D. Johnson, T. Kuo, F. Marti, J. Vincent, J. Wagner, & A. Zeller,

SRS + BJH/WU: HistorySRS + BJH/WU: History

• 1990s: Discussions on Bringing Protons to St.1990s: Discussions on Bringing Protons to St. Louis

• 2005: Discussions ensue with SRS2005: Discussions ensue with SRS• Early 2006

– Expert Consultants Give Positive OutlookExpert Consultants Give Positive Outlook Reviews

– Contract is Signed– Hospital Deals with Funding……..

BJH/WU: FundingBJH/WU: Funding

Based on 225 patients per yearBased on 225 patients per year

Outside Funding Required = ?

BJH/WU: FundingBJH/WU: Funding

Outside Funding Required:Outside Funding Required:

O !NONE !Based on Pro forma: Even if Billing Codes are Reduced to IMRT Levels, Break Even Interval Will Occur in Year 4 of OperationInterval Will Occur in Year 4 of Operation

Existing  Department

Proton Section

Monarch‐250 Rooms’ Eye View

Inner Gantry

Couch: Accuray-Robotic 6D

Gantry Arms + Embed

Cyclotron: 9 Tesla, 20 tons

Our 10th Vault• Adjacent Clinic with Mirrored Activities

– Within Proton facilityy• Nursing, Anesthesia

• Assigned Physics, Dosimetrist, Therapists

• TP Suite

• MD Office

• Local Engineer

– At Main Adjacent Clinicf l• Imaging for Planning

• Treatment Planning

• Initial and Follow Up Clinic• Initial and Follow‐Up Clinic

• Professional Staff

Construction April_2009