AMIT cyclotron

28 Pages·2015·14.36 MB·English

COMPACT WEAK FOCUSING CYCLOTRONS FOR
ISOTOPE PRODUCTION: STATUS OF AMIT
PROJECT

Concepción Oliver
[email protected]

On behalf of
Accelerator Unit, Division of Electric Engineering
CIEMAT (Spain)
Compact accelerators for isotope production 26-March-2015
INTRODUCTION

Stable nuclide
Ø  PET technique is broadly used
γ
around the world as a diagnostic tool
e-
β- decay
and for treatment planning and
e+ γ
follow-up.
Positron
emitting Whole-body PET scan
isotope using 18F-FDG
Ø  Cyclotrons are the most widely used accelerators for the production of
positron emitter isotopes
In Spain…
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Workshop on compact accelerators for isotope production C. Oliver
AMIT project: Advanced Molecular Imaging Technologies

N
O
Work supported by the Spanish Ministry of Science and Innovation
I
T
C
Center for Industrial
U
Funded by:
D Technology development
O
R
Led by:
T
N
I
Partners: 10 companies, 14 research labs
Ø Target: Development of the core technology for molecular
imaging in Medicine and Biomedicine with special focus in the
human brain and in particular in mental diseases
WP1. Development of a compact cyclotron for 11C y 18F single doses production
Ø  CIEMAT is the scientific leader of this cyclotron project
q  Close collaboration with Spanish industry
q  External collaborations as CERN, MIT
v Funding for beam dynamics and diagnostics: OPTIMHAC, by the Spanish
Ministry of Economy and Competitiveness under the project FIS2013-40860-R
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THE AMIT CYCLOTRON: SPECIFICATIONS
AMIT cyclotron specifications: to produce one dose of 11C or 18F

N
O
Isotope Dose Target Reaction
I
T
C 18F 40 mCi Water enriched in
U 18O+1H+ →n+ 18F
D 18O 8 1 9
O
R
T 11C 100 mCi Nitrogen gas 14N+1H+→4He+++11C
7 1 2 6
N
I
àà BBeeaamm rreeqquuiirreemmeennttss:? ?E >8.5 MeV I>10µA
Ø  Very compact on-site cyclotron promises to:
-  reduce cost of cyclotron (more adjustable to on-site needs)
Cross sections of 11C and 18F from incident
-  reduce high cost of isotope transportation to remote PET machines
protons (IAEA medical database)
-  possibility to produce new markers with short half- life (11C, 20 min)
Ø Technology requirements for radiopharmaceuticals production:
§ To minimize building requirements:
à compact machine
- cyclotron with the minimal weight/size
- Reduced shielding
§ Low power consumption
§  Minimal maintenance
Context: Experienced group in accelerator component design and fabrication but not in a complete machine
development, integration and operation → Limitation of the complexity of the accelerator and its challenges.
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Workshop on compact accelerators for isotope production C. Oliver
THE AMIT CYCLOTRON: SPECIFICATIONS
⎡Q2⎤
T ≈ 48.24 B2R2(MeV)
⎢ ⎥
N A
R SC ⎣ ⎦
O Compact ext High B 4 T
I limitation magnet
T
C
U
D
O
R
Resistive Magnets
Superconducting Magnets
T
N
< 2T
I > 2T
à superconducting
J Cheap and robust
J Low power consumption
J Easy maintenance
J No field limit
J No risk of quench magnet
J Only alternative for really
L Field limited to iron saturation
compact cyclotrons
level (1.8 T).
L Higher power consumption. L Needs for cryogenics
L Limits the minimum size of L Specific maintenance
the cyclotron
Simple model
NbTi Technology

B Biot &
Savart Law Bc 3000 SC Price

h 2500
Amptere´s Law H p ht (kg) 12500000 POT 2205000000
Weig 1000 E uros 15000 SC
 Price
z Bs E 10000
c Bo g 500
re 5000
r 0 0
rpi 0 2 4 6 8 0 2 4 6 8
B (T)
re B (T)

o
à 4 Tesla for NbTi
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Workshop on compact accelerators for isotope production C. Oliver
Why classical machines (again)?
E. Lawrence
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Workshop on compact accelerators for isotope production C. Oliver
AMIT CYCLOTRON
BB
zz
Beam focusing in cyclotrons: BB
OO

N
O rr o  Focusing by radially
I 000 rrreee
T decreasing magnetic field
C
BB
U OO
o  Non synchronism
D
θθ
O
000 222πππ
R
T
N
I BBB
zzz
o  Focusing by an
rrr
0000 rrrreeee alternating field (flutter) in
BB00++ΔΔBB
BB00 azimuthal direction F= 1 2∫π⎢⎡B(r)−B0⎥⎤2dθ
BB00--ΔΔBB 2π B
θθθ 0⎣ 0 ⎦
o  Synchronism
0000 2222ππππ
q  In our 4T cyclotron, the magnetic field is so high that iron will be saturated and the magnetic field difference between
valleys and hills is small, resulting in a small flutter (even with spiralized sectors)
q  Other solutions (magnetic elements with higher saturation level, additional SC coils) will result in expensive or
more complicated machines
q  Classical cyclotron becomes a good option for compact machine, given its simplicity
Focusing forces:
Compact low flutter for a Classical
Machine: 4 T 4 T isochronous Cyclotron
machine
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N
O
I
T Classical
AMIT Requirements
C
U cyclotron
D
O
R
T
N
I Iterative
process
Beam Dynamics
Vacuum
system &
diagnostics
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Workshop on compact accelerators for isotope production C. Oliver
AMIT BEAM DYNAMICS IN A CLASSICAL CYCLOTRON
Non particle-RF isochronism
q  The energy gain will be lower than the maximum one (qV )
peak
q  The time that the particle can be accelerated is limited–> limitation
on the maximum energy at extraction in a classical cyclotron
To optimize the AMIT radioisotope production ß I, E
I extracted by puller
q  High accelerating voltages à higher energy gain & higher extracted current by pullerà 60 kV
q  Limited field gradient of magnetic field à balance between beam focusing and phase shift
Relative Radioisotope production

q  Optimum phase excursion: maximum excursion for
60.3 0.9
0.8
60.25
max. energy but limited to avoid losses by vacuum stripping 0.7
60.2
z) 0.6
H 60.15
and by electric defocusing forces à Beam tuning with RF M 0.5
F (
R 60.1 0.4
0.3
frequency (B field) and stripping foil location 60.05
0.2
60
0.1
59.95
0
q  Careful design of central region à given the internal 0.08 0.09 0.1 0.11
Stripper radial position (m)
ion source, high B & V and weak focusing magnetic forces
Workshop on compact accelerators for isotope production C. Oliver
AMIT cyclotron: main specifications

N
O
I GENERAL
T
C Cyclotron Type Classical
U
Energy >8.5 MeV
D
O Current >10 µA
R
MAGNET
T
N
Type Low Tc Superconductor
I
Configuration Warm Iron
Superconductor NbTi
Central Field 4 T
Radially decreasing (1.5%@extraction
Focusing type
radius)
RF SYSTEM
Configuration One 180º Dee
Peak Voltage 60 kV
RF frequency ∼ 60 MHz
ION SOURCE
Type Internal
Ions H-
EXTRACTION
Extraction Stripping foil at 110 mm
Nitrogen gas (11C) , 18O enriched water
Target
(18F)
Position External
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Workshop on compact accelerators for isotope production C. Oliver