Laser Plasma Acceleration for
Electrons and Protons
Laser-Driven Targetry:
The Road to Clinical Applications
Laser beam
1 mm
C-M Ma, Ph.D.
1 µm
Department of Radiation Oncology
Proton beam
Laser beam
Fox Chase Cancer Center
Philadelphia, PA 19111, USA
Electron beam
Ma et al Med Phys (2006) POINT/COUNTERPOINT
Laser Proton Acceleration at LLNL
Present status of the proton generation(2004)
Laser proton acceleration: intensity vs energy
Proton spectrum
Snavely et al Phys Rev Lett (2000)
Maximum Proton Energy (Mev)
1000
Proton angular distribution
Initial goal
LULI
After upgrade
VULCAN
Therapeutic energy range
LLNL
100
3D PIC Simulation
Double Target
63MeV QuasiMonochromatic
High energy sub-ps lasers
RAL
CUOS
ILE Osaka
100fs
10
LLNL
30fs
LOA
CRIEPI
50fs
1
17
10
50fs
10
18
100fs
Ultra-short pulse lasers
JAERI, Univ.Tokyo
Hiroshima
10
19
10
20
Laser Intensity (W/cm2)
10
21
10
22
CRIEPI
Theoretical Results
Proton and Electron Densities (t=100 fs)
Particle in cell (PIC) simulation results (Ueshima 1999b) on ion and
electron acceleration by laser irradiation on three thin targets. A laser
intensity of 1021 W/cm2on the target surface is applied.
Energy conversion
Ion
Electron
Peak energy H+
Peak energy Al10+
Peak energy electron
Average energy H+
Average energy Al10+
Case 1
50%
4%
48%
200 MeV
1 GeV
25 MeV
58 MeV
130 MeV
Case 2
24%
8%
16%
400 MeV
2 GeV
15 MeV
95 MeV
500 MeV
Case 3
31%
14%
17%
400 MeV
2 GeV
20 MeV
115 MeV
500 MeV
E. Fourkal et al. Medical physics (2002)
Electrons and protons expand ballistically into vacuum
Energy and Angular Distribution
Particle Selection and Beam Collimation
There is a large spread in energy and angular distribution.
E. Fourkal et al. Medical physics (2002)
V. Malka et al., Med. Phys. 31, 6 June (2004)
Combined Dose Distribution
Particle Selection and Beam Collimation
Ma (2000)
Movable aperture to select
protons of desired energy
with sharp beam penumbra
Nb3Ti superconducting coils can
provide I = 85 A per loop with
magnetic field to 4.4 Tesla by BiotSavart law:
B=
µ 0 Idl × r
=
4π r 3
4
i
µ 0 Idl × ri
3
4π ri
Luo et al Med Phys 2005
Monoenergetic Laser-driven Ion Beams
7
10
-1
Ions [MeV msrd ]
6
10
-1
Energy and Dose Rate
5
10
4
10
1
10
Energy [MeV]
Demonstration and modelling of monoenergetic carbon ions
from shortpulse driven laser acceleration.
Experiment:
30 TW LANL Trident
laser using ~20 µm
palladium targets.
10
C5+ simulated
Pd21+ simulated
8
10
C5+ meas.
Pd22+ meas.
Pd4+ meas.
7
10
Simulation:
Hybrid code BILBO
(Backside Ion
Lagrangian BlowOff),
parameters set to
match experiment.
Monoenergetic Proton Acceleration
9
6
10
5
10
4
10
0
1
2
3
4
5
Hegelich et al., Nature 439, 441 (2006)
Courtesy of S. Bulanov
B. Albright X-1, LANL
Monoenergetic proton acceleration
Future steps to improve results:
Experiments with foil targets at intensity 1018 - 1020
W/cm2 show that the ion energy depends on
PIC-Simulation for POLARIS:
• E =150 J, τ = 150 fs, dfoc = 10:m
P ~ 1 PW
• obtain peak at E = 173 MeV
with DE/E ~ 1%
• total proton number ~ 109
• Reduce dot size
- better localization of dot
within homogeneous field
- higher stability
• Increase laser power
-for sufficient thin targets cutoff
energy scales with
Ecut = 230 MeV x (Plaser/1 PW)1/2
1,0
proton counts [a.u.]
• ddot = 2,5 :m, sdot = 0,1 :m
Indications of a multi-parametric scaling law
0,5
0,0
0
155 160
165 170
proton energy [MeV]
Courtesy of R. Sauerbrey
175
model parameters
• intensity (e.g., E max∝ I 1/2)
dimensionless amplitude
a=eE/meωc
• foil thickness
• material
• pulse contrast
effective plasma density, ne
effective plasma thickness l
• focal spot size
focal spot size D
• laser polarization
fixed (p-polarized)
• target geometry
fixed (planar)
Ion max. energy vs. laser energy and power
Multistage proton acceleration
Up to 100% increase in max. proton energy with multistage stages.
[Timo.Esirkepov et al., PRL 96, 105001, 2006]
Veltchev et al 2007
Comparison of Isodose Distribution
Treatment Optimization
7 field IMRT
7 field laser protons
Fourkal et al 2003
Comparison of DVH
Comparison of Isodose Distribution
Target
Rectum
Bladder
Femur
7 field IMPT(mono-E)
7 field laser protons
Comparison of DVH
Target
Bladder
Rectum
Femur
Shielding for the Treatment Head
Secondary Sources for Shielding Considerations
Head Leakage Measurement
Fan et al 2007 Phys Med. Biol.
0.5cm steel, 10cm polyethylen, 3cm lead
Head Leakage Dose
Shielding Issues for Laser-Accelerated Protons
(5) Primary collimator shielding
Low-energy proton
(2) Low-energy proton shielding
(4) High-energy proton/neutron shielding
Electron
High-energy proton
(1)Electron shielding
(3) High-energy proton shielding
Leakage dose < 0.1% of treatment dose
Fan et al 2007 Med Phys Biol
mirror
Adjustable distance for
scanning along y
Adjustable distance for
scanning along x
System Design
Gantry rotation
Target and beam
selection system
Proton beam
Main laser beam line
y
x
Couch
The Cost of a Laser-Proton Unit
The building/shielding – $0.5million × N
The Laser-Proton Facility
Renovation completed in June
2005
An off-campus facility for
experimental studies
The high-power laser – $2-3million
The gantries - $1-2million × N
The cost of a carbon unit will be slightly higher!
SystemMaDesign
2000
Laser/target chamber/shielding
installed/commissioned in Sept
2006
Research laser-proton
accelerator license granted by
the State
The FCCC Laser System
The Experimental Setup
The FCCC Laser-Proton Team
Acknowledgments
Dr. Charlie Ma
Program director
Dr. Eugene Fourkal
Physicist, target and PIC studies
Dr. Jason Li
Physicist, dosimetry and treatment planning
Dr. Iavor Veltchev
Physicist, laser physics research
Dr. James Fan
Physicist, shielding calculations, Monte Carlo
Dr. Teh Lin
Physicist, laser-proton acceleration.
Dr. Alain Guemnie Tafo
RA, laser-proton acceleration experiments.
CM
EF
JL
IV
JF
TL
HRSA, US Dept of Health and Human Services
Strawbridge Family Foundation
Kim Family Foundation
Varian Medical Systems
AGT