Application of HighEnergy Physics Technologies to
PET(Positron Emission Tomography)
ChinTu Chen, Ph.D.Committee on Medical Physics & Department of RadiologyPritzker School of Medicine & Biological Sciences Division
The University of Chicago
National Science Foundation Visit, June 26, 2007
HEP & PETHEP & PET Similarities and differencesSimilarities and differences
SimilaritiesGeometry and granularity Detector (Crystals & scintillator)Sensor (PM,APD)Electronics:Fast (40 MHz), compactEvent rate & Data volume (Gbit/s)
DifferencesEnergy range (10GeV511keV)No synchronisation> free running electronics Multiple vertices
CMS
PET Scanner
BiomedicalImaging
200 400 600 800 1000
28,700 ph/MeVER = 10.1%
Cou
nts
Energy (keV)
Calorimeter
HEP
P. Le Du/Saclay
From HEP to Medical ImagingFrom HEP to Medical Imaging
New scintillating crystals and detection materials New scintillating crystals and detection materials – CMS (WPbO4) CMS (WPbO4) Luap …(Crystal Clear col) Luap …(Crystal Clear col)
Photodetectors : Photodetectors : Highly segmented and compact Highly segmented and compact PMT PMT APD APD SiPM SiPM
– APD : SSC/SDC (1991) APD : SSC/SDC (1991) CMS (1996) CMS (1996) MicroTEP MicroTEP TEP TEPElectronics & signal treatemntElectronics & signal treatemnt Highly integrated Highly integrated– Fast, low noise,low power preamp Fast, low noise,low power preamp – Digital filtering and signal analysisDigital filtering and signal analysis
Trigger/DAQ Trigger/DAQ – High level of parallelism and event filtering algorithmsHigh level of parallelism and event filtering algorithms– Pipeline and parallel readout, trigger and online treatmentPipeline and parallel readout, trigger and online treatment
Simulation & ComputingSimulation & Computing– Modern and modular simulation software using worldwide recognized standards Modern and modular simulation software using worldwide recognized standards
(GEANT)(GEANT)
Where techniquestechniques are transferred to developments in biomedical fieldMedical Imaging has so far only partially benefited from new technologies developed for High Medical Imaging has so far only partially benefited from new technologies developed for High Energy Physics detectorsEnergy Physics detectors
P Le Du/Saclay
P a t ie n t 1 P a t ie n t 2
M R P E T M R P E T
PET: Molecular Imaging of Life and Life Processes
Live Brain Dead Brain
15O
13N
11C
18F
64Cu
82Rb
124I
PET Isotopes
PET Tracers
[15O]O2 [15O]H2O
[15O]H2O [15O]CO
[13N]NH3 [18F]FDOPA
[13N]glutamate [18F–]
[11C]acetate [18F]FDG
[11C]palmitate
[11C]methionine
18Fluoro2deoxyDglucose
H O
O
O H
O H
1 8F
O H
P L A S M A T I S S U E
F D G F D G F D G – 6 – P
g lu c o s e g l u c o s e g l u c o s e – 6 – P
C O2 + H
2O[1 8F ] – F D G
0
0.05
0.1
0.15
0.2
0 10 20 30 40 50
striatum
cerebellum
cps
Time(min)
Biochemical Imaging with Small AnimalsBiochemical Imaging with Small Animals
microPETmicroPET
[11C]WIN 35,428
N
11CH3 O
F
OCH3
Human PET: 34mm; Target: 1mmAnimal PET: 12 mm; Target: <0.5mm
Fast Dynamic Image AcquisitionHigh Resolution & High Sensitivity
HighPerformance & LowCost (HPLC)
Siemens “Molecular Imaging”
MultiModality Integrative System
PET/MRIPET/SPECT/CT
ForAnimal Imaging
PET/SPECT
MultiModalityBayesian Image Reconstruction
1. Coregistration of PET/SPECT with CT/MRI2. Incorporation of highresolution information from the co registered CT/MR images into a Bayesian image recons truction framework to enhance image quality of PET/SPECT5. Using the coregistered CT/MR images as an anatomic map in correction for attenuation and scatters in PET or SPECT
Upper Two: Filtered BackProj.Lower Two: MultiModality Image Reconstru. Chen, Kao, et al
A Benchtop Prototype for
HighThroughput
Animal Imaging
HRRT modules• LSO crystals with DOI
capability◆ good spatial resolution
– ~2.42mm crystal pitch
– ~10mm DOI resolution◆ good detection sensitivity◆ high count rate
• large detection sensitive area◆ ~25.2cm ×17.4cm◆ 72×104 crystals per layer
• offshelf, well tested, costeffective design
• adjustable energy and coincidence windows
High-Throughput Compact PET
FOV FOV
RFOV = 56.3mm
Compact Conventional57.3mm 85.9mm
True Compact,no PSF
Convent’lscanner
Compact, with PSF
DOI Detectors
✦ Phoswich detectors
✦ photodiodes (or SiPM/MPPC)
LSO GSO/LSO PMT
scintillator (BGO) PMT
photo diode/SiPM
Time-of-Flight Tomograph
• Can localize source along line of flight - depends on timing resolution of detectors
• Time of flight information can improve signal-to-noise in images - weighted back-projection along line-of-response (LOR)
D
x = uncertainty in position along LOR = c . t/2
x
Karp, et al, UPenn
Benefit of TOFno TOF 300 ps TOF
1 M
cts
5 M
cts
10 M
cts
5Mcts
1Mcts1Mcts TOF5Mcts TOF
Better image qualityFaster scan time
Karp, et al, UPenn
TOFPET DREAMPET without TOF (>99%)
One Commercial TOFPET System Available with 750 picosec TOF (11.25 cm LOR Resolution)
30 picosec TOF4.5 mm LOR Resolution
10 picosec TOF1.5 mm LOR Resolution
3 picosec TOF0.45 mm LOR Resolution
HistogrammingNo “Image Reconstruction”
Pipeline ArchitecturesPipeline Architectures
LHC Future PET
Digitisation
Pipeline
Event builder
P. Le Du/Saclay
Proposal of Proposal of Front End ArchitectureFront End Architecture
Trigger logic processes “raw fast information” Freerunning sampling ADC Digital filter used to extract pulse amplitude and
high resolution timing Pipelined processing architecture to avoid deadtimes Only one “channel” to compute either the energy and time
charge preamplifier
E,T,Q
Pipelined register
clock 50 MHz
7 bits
ADC
digital filterphotodetector
APDPMT LOCAL
BUFFER
Other ROI channels
shaper CRRC
crystal
Trigger logic
A B C
1
2
3
4
5
6
7
8
ROI Data
DataAcquisition
SiPM
Pixelised
P. Le Du/Saclay
High Energy Physics
Space and Radiation Medical
Technology Transfer
High Energy Physics
Space and Radiation
Medical Technology Transfer
Geant4 – A Common Simulation Platform
GATE Geant4 Application for
Tomographic Emission Higgs event at LHC (CMS) with Geant4