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Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 1
Beam production techniques for
hadron therapy
Marco Schippers
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 2
Contents
•
Facility configuration•
Dose delivery techniques
•
Accelerators•
New accelerator developments
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 3
accelerator
fix horgantry gantry
(energy selection) beam transport
Facility configuration
modules
•
1 accelerator
•
3-5 treatment rooms (incl
2-4 gantries)
•
Beam to 1 room at the time
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 4
IBA
PSI ACCEL/Varian cyclotron
Tsukuba
Proton therapy facility: modules
accelerator
energy selection
beam transport
gantry / fixed hor. line
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 5
accelerator
fix horgantry gantry
(energy selection) beam transport
Proton therapy facility: modules
However, NOT independent….
Beam delivery => accelerator and energy selection
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 6
Dose deliverytechniques
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 7
fast degrader (PSI)
Methods:1)
Vary energy
in accelerator (synchrotron)
2)
Slow down
from fixed to desired energy
-
degrade in beam line (PSI)
-
modulate just before patient (in “nozzle”)
250 MeV
protons250 MeV
protonsSpread-out Bragg peak
Considerations:how fast ? how accurate ? effect on beam ?
Dose delivery techniques: Depth
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 8
Dose delivery techniques: Width
transversal spread:
scattering
scanning(protons only)
(all hadrons)
CollimatorScatter syst.
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 9
Proton therapy with a scattered beam
Scatter
foils
Range
compensation
Collimator
Requirements for accelerator:-
stable beam position
-
enough intensity
-
enough energy
Energy modulation
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 10
allows fast target repainting: 15-30 scans / 2 min.
Pencil beam scanning
0 time (ms) 10
inte
nsity
Continuous scanning
kHz-Intensity modulation Requirements for accelerator:-
stable beam position
-
continuous and stable beam
-
fast adjustable beam intensity
-
fast adjustable beam energy
Spot scanning: step&shoot Requirements for accelerator:-
stable beam position
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 11
Accelerators
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 12
Accelerator
Source++++
250 MeV+
+ _250 000 000
Volt
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 13
Protons in use, ∅3.5-5 m
Present accelerator choice
e.g.:
Loma Linda
Houston
Tsukuba
3.5 m
e.g:
Boston
Florida
Seoul
Wanjie
PSI
München
Orsay
in use, ∅8-10 m
Carbon ions
in design, ∅6 m
cyclotron synchrotron
in use, ∅25 m
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 14
Synchrotron (1945)
Ring:
• acceleration to desired E
• storing of the beam
Magnet to select ion source
Injection in ring at 7 MeV/nucl
2 linear accelerators in series
Ion sources for different particles
Extraction into beam line
~50
m
(DKFZ, GSI,
Siemens)+
+
+
++
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 15
Beam extraction from synchrotron
( Hitachi )
RF-driven extraction
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 16
Time 0.5-1 sec
“spill”
time •
fill ring with ~109 particles
•
accelerate to desired energy•
extract slowly during 1-10 sec
•
decelerate and dump unused particles
Bea
m in
tens
itySynchrotron beam structure: noisy & spills
1-10 sec
σ=15%
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 17
oscillating high voltageon “Dee”
electrode
Extractor:-HVVdee
~
RF-Electrodes: 2 “Dees”
At each
electrode
border:Energy gain
ΔE=Vdee
Ion source
Cyclotron (1930)
Ernest Lawrence
(1901-1958)Magnet
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 18
Extractor
Vdee
~+
Cyclotron
Circular orbits:Centripetal force = Magnetic force
=>
=> Tcircle
independent from orbit radius r
Bqvr
mv=
2
BqmTcircle.2π
=
m
= mass
v
= speed
r
= orbit radius
B
= magnetic field
q
= charge
r
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 19
230 MeV
cyclotron (IBA,1996)PSI Injector 1, 72 MeV, 1970
Cyclotron12 MeV
cyclotron (UC, 1940)80 keV
protons
10 cm
Dee
extractor
1930
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 20
superconducting coils => 2.4 -
3.8 T
Proton source
4 RF-cavities ~100 kV on 4 Dees
Closed
He system4 x 1.5 W @4K
300 kW90 tons
3.4 m
1.4 m250 MeV proton
cyclotron
(ACCEL/Varian)
ACCEL
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 21
pole
pole
Internal
proton
source
~5 cm
anodecathode
at -HV
anodecathode
at -HV
-80 kVDee
1
+
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 22
Intensity
controlMax. intensity
set
by:
Ion source
+ slits
Deflector plate:sets requested
intensity
- within 50 µs - 5% accuracy
currently only possible with a cyclotron
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 23
Extraction from cyclotron
Electrostaticextraction elements
80%
(ACCEL / Varian)
Low radioactivity
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 24
Kicker
Beam-energy adjustment
Degrader
unitAll following magnets: 1% field change in 50 ms
Steerer
Q Q Q
Carbon wedge degrader238-70 MeV 5 mm ΔRange
in 50 ms
Dipole magnets in beam line:1.1 T190 A100 A/s (1-1.4 H)
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 25
Energy scanning, Estep
~5 mm range
in water.
Degrader
50 ms
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 26
Energy scanning, Estep
~5 mm range
in water.
Degrader
Current
in Dipole
50 ms
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 27
Energy scanning, Estep
~5 mm range
in water.
Degrader
Current
in Dipole
Beam
energy
error
50 ms
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 28
cyclotron
synchrotronCarbon ions
in development
easy
Change particle
in development
easy
Time structure
continuous dead time
Fast E-scanning
degrader
next spill
Activation degrader to be shielded
no
Intensity
“any”, adjustable
limited, per spill
Intensity stability
3-5%
15-20%
Size ∅
3.5 (p)-6 m (C)
6(p)-25 m (C)
Scattering
ok
ok
Spot scanning
ok
ok
Fast continuous scanning
ok
difficult
some differences…
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 29
The Holy Grail for proton therapy:
protons
MeV one small (cheap) accelerator
per treatment room
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 30
New accelerator types….
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 31
Small cyclotron on a gantryH. Blosser, NSCL (~1990):cyclotron
for
neutron
therapy;
30 MeV p, mounted
on a gantryUsed
in Harper Hospital, Detroit
Proposal of H.Blosser
et al.,1989:-250 MeV-52 tons, on gantry-B(0)=5.5 Tesla
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 32
—No beam extracted yet (oct
2009)—Many uncertainties on performance and reliability
( @ limit
of current
technology )—No beam
analysis
—Neutrons ?
Still River
Synchro-Cyclotron8-10 T Synchro-cyclotron on a gantry
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 33
Carbon-ion cyclotrons
25 mProton
(250 MeV)
2.43 Tm
Helium 2+ (250 MeV/nucl)
4.86 Tm
Carbon 6+ ( 450 MeV/nucl
)
6.83 Tm
Range in water =38 cm Range =33 cm
⇒
Cyclotron
radius
of is
2.8
x R proton
cyclotron
⇒
~ 2.82
= 8 x more
iron => 700-800 tons
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 34
700 tonsSC coils Ø 7 m
Carbon
ions
protons
Int. Conf. Cyclotron and appl, Tokyo 2004
IBAArchade
project
Accelerator choice
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 35
250 MeV/nucl.H2
+ α
C6+
450 MeV/nucl. C6+
250 MeV/nucl.H2
+ α
C6+
450 MeV/nucl. C6+Start with protons AND•
α
+ (up to 12.5 cm:) Carbon
•
Second step: also 450 MeV/nucl
Carbon
PSI design for 2-step approach
Accelerator choice
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 36
Proof of principle FFAG accelerator
at KEK in Japan. (Muri
et al)
Fixed Field Alternating Gradient accelerator (FFAG)
Advantage:
Fast energy
change
in accelerator
Disadvantages:
Heavy (100-200 tons)
Injector
cyclotron
needed
Pulsed
Receipe:1) inject
into
ring
2) RF until
E reached3) extract.
Accelerator choice
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 37
High gradient (100 MeV/m) Linac
(dielectric wall)
Proton-TomotherapyCaporaso
et al, Nucl
Instr
Meth B 261 (2007) 777
Dielectric material
electrode, pulsed
High Voltage
2 ns pulses
with 100mA protons
at 10 Hz
needed: reached:100 MV/m
20 MV/m
2.5 m 2 cm —
Pulsed beam
—
Low duty cycle
—
dose accuracy
?
New accelerator types
(2009)
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 38
C.M. Ma, Laser Physics, 2006, Vol. 16, No. 4, pp. 639
Lase
r bea
m lin
eprotons
Laser driven proton accelerator
—
Pulsed beam
—
Low duty cycle
—
Neutrons
New accelerator types
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 39
Amaldi
et al, Nucl
Instr
Meth A 521(2004) 512
Cyclotron driven linac
New accelerator types
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 40
Plasma wake field accelerator
Blumenfeld, et al. Nature 445, 741–744 (2007).
Nature
449 133-135 (2007)
Accelerator choice
(electron) energy doubler
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 41
Now Mañana
Time until useable
Accelerator choice (protons)C
urre
ntU
seab
ility
=> Q
ualit
ycyclotron
synchrotron
Synchro-cyclotron
FFAGDielectr. wall
linacs
cyclotron driven linac
lasersPlasma
wake field
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 42
•
Time structure: continuous/pulsed
•
Intensity (stability)
•
Beam position stability
•
(fast) E-scanning possible?
•
Control; area/mode
changes
•
Activation of components
•
Reliability, service friendliness
•
Control
system: modularity
•
Size, weight, power
Summary of accelerator specs
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 43
Concerns on new accelerators:1) at least the same quality
as we have now?
and, if yes:
2) advantages
(costs?) and when available?
Concerns on future developments:Industry is now “producing”
particle therapy.
=>however: reluctance to invest
in next steps
=>cheap
particles could be disadvantageous
conclusions
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 44
Pick your choice how to accelerate….
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 45
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 46
24 h after beam off, April 2008(extracted beam integral: 200 μA.h)
on pole: 400 -
500
μSv/h
mid plane:
250 -
400
μSv/h
10 cm unshielded degr.
500-1000 μSv/hnext to shielded degrader
10-20
μSv/h
mid
plane,
open
cap
>80% extraction
eff.=> Low dose to staff
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 47
BqmTcircle.2π
=
However, when v c:
e.g:
250 MeV
p: v/c=0.61 =>
m=1.27m0
=> Tcircle
increases with radius => particles lose pace with RF.
Remedy: increase B
with radius
220
1 cvmm−
=
Relativity in high-E cyclotrons
=>
Tcircle
constant for all radii
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 48
Conc
eptu
al de
sign
synchro- cyclotron
Energy Selection System
Gantry with integrated accelerator and ESS
8-10 T field:
250 MeV
synchro-cyclotron
⇒
pulsed beam (~1 kHz)
⇒
low duty cycle
New accelerator types
Beam delivery techniques for hadron therapy Marco Schippers, PSI Winterschool, Jan 2010 49
D.Trbojevic
et al., Proc
PAC07
FFAG optics for a Gantry