1. 3g Medical Imaging R&D with liquid xenon Compton telescope
Hervé Carduner, Jean-Pierre Cussonneau,
Samuel Duval, Jacob Lamblin, Eric Morteau,
Patrick Le Ray, Tugdual Oger, JS Stutzmann,
Dominique Thers
(Nantes)
Toshiaki Tauchi, Tom Haruyama et al.
(Tsukuba)
Workshop FJPPL’09, May 2007, KEK, Japan
Wednesday, 18 May 2009

2. A new medical imaging approach with liquid xenon : the 3 imaging
+  ( 44Sc) nuclide + Compton Telescope + TEP camera =
3D reconstruction event by event in counting mode
44Sc will be produced
by ARRONAX
Geant4 simulations with liquid xenon Compton telescope :
- High spatial resolution (0.1 mm)
- Light for trigger
- Charge for energy measurement
44Sc
C.Grignon, PhD Thesis
Soon published on JINST
 DL ~ 1-2 cm along the LOR targeted

3. 3g Imaging : expected plan
Scandium isotopes availability and radiolabelling : 2011
- research production on Arronax : Arronax and Subatech
- research Chemistry and radiolabelling : Inserm and Subatech
Compton telescope for small animal : 2011
- research on liquid xenon cryogenic : KEK and Subatech
- research on photodetection : WIS and Subatech
2007 – 2010 : R&D
2011 : small animal prototype
XEMIS2
XEMIS2
XEMIS1

4. XEMIS1 1st prototype

5. KEK-developed High-Power Pulse tubeCryocooler
-Cooling power up to

6. Cryogenics Since march 2007: - Liquefaction of 30 kg of Xe
→ liquefaction rate and circulation flow : ~ 1.5 kg / hour
Very stable operation !!!

7. Experimental setup
Tests with 22Na source (β+ and 3rd 1,257 MeV)

8. Signals… light photoelectric charge compton + photoelectric
Cathode : V
charge
PMT, G~1.106
Micromesh 0V
compton +
photoelectric
Single Anode : +450 V

9. 511 keV g absorption in LXe 12 cm depth 511 keV g (NIST : 3,4 cm)
Q = C*V = 3pf * 40mV/1.602e-19 = 749e3 electrons
40 mv en entree de la capa => 2000 mV mesures => 375e/mVE
chantillonnage a 500 MHz sur 80 ms
511 keV g

10. Electrons absorption by impurities in liquid xenon
12 cm drift
length
Edrift = 1.5 kV/cm
1 meter
life length
Q = C*V = 3pf * 40mV/1.602e-19 = 749e3 electrons
40 mv en entree de la capa => 2000 mV mesures => 375e/mVE
chantillonnage a 500 MHz sur 80 ms
High purity xenon achieved
after 1 month of circulation …

11. Ionization electrons collection by Micromegas
micromesh
NEW
Edrift
Egrid
 Full collection of electrons with Micromegas for field ratio > 50
 Beginning of the R&D with pixels on the anode

12. T and P tests on segmented anode (vacuum-liquid xenon windows)
Liquid xenon side
PRELIMINARY
Vacuum
Helium Pressure
Vacuum side
In progress …
Expected xenon
Maximum pressure
First results :
< 10 µm deformation in experimental conditions
No failure up to at least 4 bars at -145ºC
Validation of segmented anode ceramics and connector technology
 soon on the prototype

13. FE Electronics R&D for pixels read-out on anode with liquid xenon
IDEF-X 16 channelsAsics
Flat - connectors
Kapton feed-through
At room temperature,
Noise : 125 e e-/pF
Noise < 300 e- targeted
on anode with liquid xenon

14. 3g imaging conclusions First steps with liquid xenon technology:
First steps with liquid xenon technology
Promising for the future :
Cryogenics R&D
Low noise front-end electronics R&D
Photo detection with GPM R&D
R&D foresee until 2010 …
XEMIS1 Compton
Telescope Prototype
3 x 3 cm2
XEMIS2 Compton Telescope
for small animal imaging
Ready for end of 2011 …

15. THGEM-GPM R&D for light detectiona
THGEM
Holes diameter d = mm
Pitch a = mm
Breskin et al., NIM A 598(2009)
Principle in liquid xenon
Ehole
Edrift ~ 0
Etrans
MgF2
Liquid xenon
grid
Segmented
anode
Ne + 5%CH4
Photoelectric effect
Transfert
Signal induction
CsI
photocathode
Hit
UV photon
Gamma ray
Amplification
Goal : minimize photo-detection cost

16. Gain measurements at room T
THGEM-GPM : First tests with soft X rays
Gain measurements at room T
CsI
photocathode
THGEM g
GPM
LXe conversion volume
SegmentedAnode
MgF2 window
Next tests soon at WIS with photocathode
S. Duval, PhD Thesis