Synchrotron Technology for Proton Beam Therapy
Kazuo Hiramoto
Power & Industrial Systems R&D Laboratory,Hitachi, Ltd.
PTCOG 46 Educational Workshop
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Synchrotron Based System
Synchrotron:RF CavityBending andQuad. Mag.
Injector:LNAC
Beam Transport
Irradiation System: (RotatingGantry )
Synchrotron Based Proton Therapy System
Injector : LINAC or Electrostatic Accelerator
Synchrotron : Acceleration and ExtractionHigh Energy Beam TransportIrradiation System
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Classification of Synchrotrons
Rapid Cycle• Operation Period : < 0.05 s• Fast Extraction : 10-6 Sec• Energy : Variable( in Principle),
or Changed with Degrader• Energy Spread : >> 0.2%
Injection
Time
Dec.⊿
E
Accel.
Spill Length 10-6 Sec.
Slow Cycle • Operation Period : > 1s• Slow Extraction :
Variable Length and Intensity•Energy : Variable • Energy Spread: Small< 0.2%
Time
Injection
AccelelationDecel.
Spill Length
E
Variable
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Synchrotron Based System
00.10.20.30.40.50.60.70.80.9
0 50 100 150 200 250 300 350
Dose
Depth
Intrinsic Features of Slow Cycle SynchrotronAcceleration to Higher Energy for Necessary RangeVariable Energy without Degrader
- Fine Energy Resolution- with Keeping Beam Current - without Unnecessary Radiation
Small Energy Spread for all the Energy : Good Distal Fall-off
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Synchrotron Based SystemIntrinsic Features of Slow Cycle Synchrotron
After the first application to LLUMC in 1990, which was the first hospital based proton therapy system, slow cycle synchrotron have been widely applied to proton and carbon therapy systems .
Application of Synchrotrons to Particle Therapy Systems
Acceleration to Higher Energy for Necessary RangeVariable Energy without Degrader
- Fine Energy Resolution- with Keeping Beam Current - without Unnecessary Radiation
Small Energy Spread for all the Energy : Good Distal Fall-off
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Weak Focusing Synchrotron
An Example of Lattice(LLUMC)
• Use of a Trim Quadrupole- One Dimensional Control
of Betatron Tunes
• Combined Function Magnet- Bending with Focusingand Defocusing Function
- Compact Size Lattice- Large Orbit Deviation
by Energy Difference
• Application-LLUMC, Shizuoka
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
• ApplicationP: MDACC, Tsukuba,
WakasaP, C: Hyogo, HICATC : NIRS
• Use of Quads QF and QD: - Flexible Control atInjection, Accelerationand Extraction
- Small Orbit Deviationby Energy Difference
Strong Focusing Synchrotron
7m
R1.4m
Injectionfrom Linac
Extraction to Beam Transport
BM
ESD
SX
QF
QDRF-forAcc.
An Example of Lattice • Separated Function Magnets- Bending - Quadrupole
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
39m
2 TreatmentRooms with
RotatingGantries
Exp. RoomSynchrotron(70-250MeV, Slow Cycle)
Synchrotron Based System
- Wakasa Bay: P, He, C (Multi Purpose) ( 2000)
- PMRC, Univ. of Tsukuba: P (2001)
- MD Anderson Cancer Center : P (2006)
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Fixed Beam
SynchrotronLinac
MDACC SystemSynchrotron (70-250MeV)
- Wakasa Bay: P, He, C (Multi Purpose) ( 2000)
- PMRC, Univ. of Tsukuba: P (2001)
- MD Anderson Cancer Center : P (2006)
Gantries (Passive)Gantry
(Scanning)
Medical Synchrotron SystemsSynchrotron Based System
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Low-energy Beam
Irradiation Room
Medium-energy Beam Irradiation Room
Synchrotron
High-energy Beam
Irradiation Room
Medical Irradiation
RoomTandem type Electrostatic Accelerator
Injection
Extraction
Synchrotron(P: 200MeV, He,C: 55MeV/u)
- Wakasa Bay: P, He, C (Multi Purpose) ( 2000)
- PMRC, Univ. of Tsukuba: P (2001)
- MD Anderson Cancer Center : P (2006)
Synchrotron Based System
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Typical Performance
TimeInjection
AccerelationDecel.
0.5 – 5 secExtraction
E
Performance•Proton Number : 1011 / Pulse•Acceleration : 70 – 250 MeV• Variable Energy:
Resolution < 0.4 MeVControlled without Degrader
• Energy Spread: •Beam Extraction: Variable Timing and Variable Duration
⊿E/E <0.2%
Developed Technology• RF Acceleration: Digital Control and Low Power RF
• Beam Extraction : Application of Transverse RF
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
RF Acceleration Technique
Fundamental+
HarmonicsRF PowerAmplifier
B-Field Bending Injection
ExtractionBeam
MonitorFrequency
VoltageControl
RF Oscillator
(DDS)
VoltageSignal
RFControl
Beam PositionSignal
SignalProcessor
RF Cavity
70-250 MeV
Acceleration System:1. Wide-band RF Cavity
3. Digital Frequency Control2. Solid Power Amp.
•Simple and Reliable •Fine Energy Resolution•High Reproducibility
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Wideband RF Cavity
450 mm
Multiple Power FeedingImpedance matching betweenRF cavity and RF power source
accelerating gap
Multi-channel Solid-state
RF Amplifier
FINEMET Core•High complex permeability for Freq. Range 1-10 MHz •High Curie temperature
Reliable OperationReliable Operation
•Solid-sate Amp. •Air Cooling
Simple Operation• Non Resonant Freq.
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
RF Acceleration System of HICAT
RF Cavity
RF Power Amplifier
RF Control System RF Cavity Design Parameters
Frequency
Accel.Voltage > 2.5 kV
Magnetic Core FINEMETPower Feeding Each Core
Length 1.4 m1-7 MHz
RF Amp. Power 6 kW
Particles P, He, C etc.Accel. Energy P:250MeV,
C:430MeV/u
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Application to Fast Energy Change
Range modulation for scanning with pulse to pulse.
0 4 8 12 16 20t[sec]
155MeV 150MeV 145MeV 140MeV 135MeV
Pulse to pulse energy change
Synchrotronoperation
pattern
Extraction
Injection
IrradiatedBeamsignal
Fast Parameter Change for Different Patient
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Beam Extraction : Magnet Current Change
Extraction : Narrow the stability limit of betatron oscillations
Stability Limit
No Extracted Beam
Beam Duct of Synchrotron
Prior: Beam circulating with stable oscillations before extraction
Beam
Beam Extraction Line (with Electric Field)
Extracted Beam in various tracks
Time
Time
On Off
QF : QuadrupoleFocusing magnet
ESD : ElectrostaticDeflector
BMP : Bump magnetSynchrotron
NozzleNozzle
PatientPatientRotating Beam
QF ESD
BMP
Slow Beam Turn On/Off
Beam Position Fluctuation
QF
ESD
BMP
ExtractedBeam
Intensity
Beam
Stability Limit
Magnet Current Change for Narrowing the stability limit
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
RF Driven Beam Extraction
Extraction : Applying the RF to make the beam exceed the stability limit
Stability Limit
No Extracted Beam
Extracted Beam in Single Track
Stability Limit
Beam Extraction Line (with Electric Field)
Beam Duct of Synchrotron
Prior: Beam circulating with stable oscillations before extraction
Magnet Current : Constant
Sufficient Beam Position Stability
Beam Position TimeBeam
Synchrotron
NozzleNozzle
PatientPatientRotating Beam
QF ESDStable Beam Position
BMP RF forExtraction
TimeOn Off
BMPQF
ESD
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
RF
Time
Variable Spill Timing and IntensityBeam
Intensity
Sufficient Beam Position Stability
Beam Position Time
pow
er
frequency
f0±Df
RF Amp.
•Beam on/off and intensity is controlled by the applied RF power.
• Applied frequency f0 is varied withthe beam energy.
Beam Duct RF
Electrode
RF Driven Beam Extraction
Synchrotron
NozzleNozzle
PatientPatientRotating Beam
QF ESDStable Beam Position
BMP RF forExtraction
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Beam Performance
200µs
(Averaged 33times)RF gate signal
Switching time(OFF)<150µs
Time [50ms/div]
Bea
m P
ositi
on[m
m]
-0.5
0.5
0.0
Hori.
Vert.Within 1 spill beam extraction
1ms Time-resolution
0 200 400 600 800time[ms]
Inte
nsity
[arb
.] Beam Gating
Time [1hour/div]
All of the operating parametersare kept constant for 10 hours.
Hori. Vert.0.5
0.0
-0.5
Bea
m P
ositi
on[m
m]
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Stability for Energy Switching
Mea
s. B
eam
Pos
ition
[mm
]
Time from G1 Beam on (min)
-0.5
0
0.5
1
0 2 4 6 8 10 12
G1200MeV
G2250MeV
Fixed225MeV
G1200MeV
G2250MeV
Fixed225MeV
- High Position Stability and Reproducibility for Energy and Course Switching
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Irradiation Scheme of Synchrotron Based System (1)
Beam
Scatterer
Wobbling Magnets
Wobbling system
Beam1st. scatterer
2nd. scatterer
Passive scattering system
collimatorcollimator
y
dose
•Tsukuba • MDACC
• Wakasa Bay• Hyogo ( Proton and Carbon )• NIRS (Carbon)
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Irradiation Scheme of Synchrotron Based System (2)
- P : MDACC - C, P : HICAT
• Lateral : Pencil Beam Scanning
Range modulation
TargetSpot
Beam
Layer
• Distal : Pulse to Pulse Energy Change by Synchrotron
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Respiration Synchronized Operation
ExtDec
InjAcc
ExtDec
Wait Wait
InjAcc
Wait Wait
Synchrotron pattern Variable Repetition Period
tInjection,Acceleration Deceleration
Extraction
Flat-top
Injection Wait for ExtractionTrigger
Inspiratory
Expiratory
ExtractionTrigger
RespirationSignal
SynchrotronPattern
ExtractedBeam
• The flat top is extended and the beam extraction is gated by therespiration signal.
• Prevention of longer treatment due to non-periodic respiration.
Operaion Cycle Length
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Respiration Synchronized Operation• The flat top is extended and the beam extraction is gated by the
respiration signal. • Prevention of longer treatment against non-periodic respiration.
Respirationsignal
Extractiongate signalSynchrotron
operationpattern
Irradiatedbeam
2sec
Wait fortrigger
Wait fortrigger
Inspiration
Extraction
Variable repetition rate Injection
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Stability for Various Repetetion Periods
Synchrotron pattern
tInjection,Acceleration Deceleration
Extraction
Flat-top
Injection Wait for ExtractionTrigger
• The flat top is extended and the beam extraction is gated by therespiration signal.
• Prevention of longer treatment against non-periodic respiration.
Repetion Period
x(Hori.)y(Vert.)
0 50 100 150 2000
5
10
-1.0
-0.5
0
+0.5
+1.0
Rep
etiti
on
Peri
od[s
ec]
Bea
mPo
sitio
n[m
m]
Time from treatment starts[sec]
Variation<±0.2mm
Repetitionperiodsvariedfrom 2.8sto 10.5s
Interval time =repetition period
May 18, 2007 PTCOG Educational WS HITACHI, Ltd.
Summary
The slow cycle synchrotron has advantages for energyand dose controllability and also small energy spread.
Slow cycle synchrotrons have been widely applied to particle therapy systems over past 17 years with highreliability and availability. For example, the MDAsystem is being operated with the availability of 98%.
New technologies for beam acceleration and extractionhave been applied to new irradiation schemes for therespiration gating and pencil beam scanning.