http:// www.adams -institute.ac.uk [email protected].uk A new accelerator for advanced research and cancer therapy Ken Peach John Adams Institute for Accelerator Science University of Oxford and Royal Holloway University of London Princeton 11 th October 2007
56
Embed
Http:// [email protected] A new accelerator for advanced research and cancer therapy Ken Peach John Adams Institute.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
• Why?… the magnets are LARGE LARGE and COMPLICATEDCOMPLICATED
• Why does k have to be so large?1. Larger k means stronger focussing
2. k > 0 means horizontal focussing– This means that the average field increases with radius
3. The momentum compaction 1/(k+1)– Large momentum bite small orbit excursion p
pRR
Orbit excursion ~ 0.9m
+ k
r
rBB
00
where k >> 1
1 krp
Ken Peach John Adams Institute 11 x 07 21
Scaling and non-scaling FFAGs
k
r
rBB
00
where k >> 1
1 krp
k
r
rBB
00
where k = 1
LinearLinear magnets!
i.e. quadrupoles
Invented in 1999
Ken Peach John Adams Institute 11 x 07 22
Simpler Magnets
… the magnets are LARGE LARGE and COMPLICATEDCOMPLICATED … to something SMALLSMALL and SIMPLESIMPLE
r
B (r)
Ken Peach John Adams Institute 11 x 07 23
The ns-FFAG
• Should combine the advantages of FFAGs – Fixed Field
• Fast cycling (limited essentially by RF)• Simpler, cheaper power supplies• No eddy-currents• High intensity (pulsed, ~continuous)• Low beam losses• Easier maintenance and operation• Lower stresses
– Strong Focussing• Magnetic ring• Variable energy extraction• Higher energies (than cyclotrons)• Different ion species possible
• with relative ease of construction
Ken Peach John Adams Institute 11 x 07 24
… so … where is the catch?
• Variable tune!
Tune ~ c
Must crossresonances
Ken Peach John Adams Institute 11 x 07 25
Beam Acceleration
• Resonance is a coherentcoherent effect– Can fast acceleration circumvent the
resonances?• If the momentum changes by a large
amount during a single turns, is it possible to leap-frog over the resonance?
– Small variation of the path length with momentum (small momentum compaction)
• Fixed radio-frequency cavities?
10MeV
20MeV
|df/f|~0.1%
0.1ns
Plots for EMMA
Ken Peach John Adams Institute 11 x 07 26
Does it work?
• We do not know!– There is no “no-go” theorem
• Need for a “proof of principle” demonstrator– EMMA
• Electron Model for Many Applications– Originally Electron Model for Muon Acceleration
• Funding obtained in the UK to design and build a EMMA – the world’s first non-scaling FFAG accelerator!
Ken Peach John Adams Institute 11 x 07 27
Objectives of the CONFORM Project
1. Show the non-Scaling Fixed-Field Alternating Gradient Accelerators work
• Build an Electron Model (EMMA)• Design a prototype Charged Particle
Therapy machine based on ns-FFAGs• Protons and carbon ions
2. Develop applications of ns-FFAGs
Ken Peach John Adams Institute 11 x 07 28
EMMA Parameters
42 identical straight length 394.481 mm
Long drift 210.000 mm
F Quad 58.782 mm
Short drift 50.000 mm
D Quad 75.699 mm
Ken Peach John Adams Institute 11 x 07 29
Location of EMMA
Daresb
ury
Daresb
ury
Ken Peach John Adams Institute 11 x 07 30
EMMA at the ERLP@Daresbury
After Neil Bliss
ERLP Parameters
Ken Peach John Adams Institute 11 x 07 31
EMMA: Lattice & Magnets
B0 xB1
B0
xMagnet linear slide
After Neil Bliss
Ken Peach John Adams Institute 11 x 07 32
Diagnostics, injection & extraction
After Rob Edgecock
Ken Peach John Adams Institute 11 x 07 33
Status of EMMA
• Funded! (~$10M)– Started 1st April 2007
• Lattice - fixed
• Component design - ongoing– Prototype quads being measured now
• 13.5% probability, all types (except skin cancer)– Around half are associated with specific risks– Statistically, some will be close to sensitive tissue
• and difficult to treat surgically or chemically
Source: Cancer Research UK
Ken Peach John Adams Institute 11 x 07 37
Why use protons?
After Bleddyn Jones
X-Rays100
80 80150
60
Protons
30050 50
60
0
Ken Peach John Adams Institute 11 x 07 38
Why use Carbon?
0
1
2
3
4
5
6
7
8
9
10
0 2 4 6 8 10 12 14
Depth in water [cm]]
effe
ctiv
e do
se [
rela
tive
units
]
photons
protons
biol. eff. dose: Carbon ions
Tumor
Daniela Schulz-Ertner, Heiddelberg
An important statisticAn important statistic
“ Radiotherapy remains a mainstay in the treatment of cancer. Comparison of the contribution towards cure by the major cancer treatment modalities shows that of those cured, 49% are cured by surgery, 40% by radiotherapy and 11% by chemotherapy”.
RCR document BFCO(03)3, (2003).
Chemotherapy provides by far the smallest contribution towards cancer cure yet is much more expensive than radiotherapy and generates a disproportionately large research and media interest.
Roger Dale, Hammersmith Hospital and Imperial College
What is RBE?RBE = Relative Biological Effectiveness.
A measure of the biological “potency” of a particular type of radiation relative to that of a reference radiation.
Reference radiation (conventional x-rays) has RBE = 1
For a given biological end-point:
Proton RBEs: ~ 1.1
Neutron RBEs: 3 - 5
Carbon ion RBEs: 3 - 5
radiationealternativwithrequiredDose
radiationreferencewithrequiredDoseRBE
Roger Dale, Hammersmith Hospital and Imperial College
The concept and definition of RBE are both straightforward. Unfortunately….
Even for a particular type of radiation, RBE is not fixed.
Its value depends on:
a) The size of the dose used at each treatment
b) The chosen biological end-point
c) The nature of the irradiated tissue
Roger Dale, Hammersmith Hospital and Imperial College
Ken Peach John Adams Institute 11 x 07 42
CPT facilities operating & planned
Ken Peach John Adams Institute 11 x 07 43
Hadron Therapy in Chiba (Japan)
Borrowed from Rob Edgecock
Ken Peach John Adams Institute 11 x 07 44
Cancer of the Kidney Stage I: TIa N0 M0 80GyE / 16fr. /4wks
Cancer of the Kidney Stage I: TIa N0 M0 80GyE / 16fr. /4wks
治療前
1 year1 year2 years2 years
3 years3 years4 years4 years
Ken Peach John Adams Institute 11 x 07 45
Prostate Cancer Results
Ken Peach John Adams Institute 11 x 07 46
We can do better
Monitoring and Control :Key issues for medical applications
time
Inte
gra
ted cu
rrent
Synchrotron & cyclotron
time
Inte
gra
ted cu
rrent
FFAG
Dose uniformity should be < ~2% To achieve the uniformity, precise intensity modulation is a must
Beam of FFAG is quantized. Active intensity control at the injection level and precise loss control are indispensable.
New approach to medical accelerator control is required in PAMELA (New postdoc is employed for the issue)
SOBP is formed by superposing Bragg peak
Gate width controls dose
Step size controls dose
intensity modulationintensity modulation
Takeichiro Yokoi
Ken Peach John Adams Institute 11 x 07 48
… much better
Ken Peach John Adams Institute 11 x 07 49
The requirements
• There are obvious potential benefits from proton/light ion therapy– Need to maximise the benefits
• Requirements– Rapid variable energy extraction– Rapid variable transverse spot scanning– Variable ion species– Accurate dose measurements
Small beam excursion of NS-FFAG makes energy variable beam extraction easier
Unique feature for fixed field accelerator However, large tune change requires phase adjustment mechanism in injection & extraction multi-kicker system
QD QD QDQF QF QF
Kicker#2Kicker#1 Septum∆p/p=+0.0
Circulating beam
@2nd kicker
@septumSeptum boundary
By changing the field strength and direction, beam position in
phase space can be adjusted Example of beam extraction (PAMELA)
Ken Peach John Adams Institute 11 x 07 54
Superconducting FFAG Gantries
Fixed field of 3.7T Transports 150-400 MeV/u
Length ~15m
D Trbojevic/BNL
Ken Peach John Adams Institute 11 x 07 55
BASROC
Ken Peach John Adams Institute 11 x 07 56
Summary
• Non-scaling FFAG accelerators are:– New– Untried– Interesting for
• Neutrino physics• Cancer therapy
– And other applications » Spallation neutron sources, muon sources» Accelerator driven reactors, nuclear waste disposal
• We will know in ~3 years if they work– Let us hope that they do … they could be