pet: new technologies including oncology...pet technology innovations 1953 first coincidence...
TRANSCRIPT
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
PET: New Technologies & Applications, Including Oncology
Paul Kinahan, PhD, FIEEEImaging Research LaboratoryDepartment of Radiology
University of Washington, Seattle, WA
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
DisclosuresResearch Contract, GE HealthcareAdvisory Board, Aposense Inc.
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Objectives1. Review history and uses of PET/CT2. Understand recent technology developments and challenges3. Learn the context of the potential future applications of PET/CT
imaging in clinical practiceOutline Respiratory motion compensation Time of flight imaging Advanced modeling of PET physics in image reconstruction Extended axial field of view New detector systems PET/MR scanners CT dose reduction methods Cost effective PET/CT scanners
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
PET Technology Innovations1953
First coincidence positron imaging system
1975
PETT III
1989
whole‐body imaging
1991
3D PET
1998
PET/CT
2005
respiratory gating
2006
time‐of‐flight
2008
PET/MR?
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
1998 2000 2002 2004 2006 2008
Pro
cedu
res/
yr
0%
20%
40%
60%
80%
100%
% s
cann
ers
Procedures/yr
PET/CT % ofSales
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Respiratory motion compensation
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Impact of Respiratory Motion
Breath‐hold (BH) PET SUVs are 26% greater than free breathing (FB) PET SUVs
Truth is not known
Kawano, JNM 2008
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Impact of Respiratory Motion
The SUV of the lesion goes from 2 in the static image to 6 in one phase of the respiratory‐gated image sequence
Static wholebody Single respiratory phase(1 of 7, so noisier)
1 cc lesion on CT
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
A Hierarchy of Respiratory Motion Compensation Methods
1. Breath‐hold PET2. Cine+Helical CTAC3. Respiratory‐gated PET (4D‐PET)4. Phase‐matched 4D‐PET and 4D‐CTAC5. Quiescent Period Gating6. Respiratory Aligned and Summed Phases (RASP)7. Internal‐External Correlation (INTEX)8. Dual respiratory / cardiac gating9. Reconstruction‐based methods
Increasing complexity
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Helical+CINE CTAC Acquisition to Compensating For Patient Motion
1. Standard non‐contrast helical CT (diagnostic beam) for both CT imaging correlation and for CT‐based attenuation correction (CTAC)
2. Cine CT acquired over the diaphragm region for respiratory motion (much like a PET transmission scan: based on method of Pan et al. JNM 2005)
3. Average of helical+Cine CT acquired is used for CTAC of PET data
Sum of all CT scans used for CTAC
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
lower limit of diaphragm motion
Helical+CINE CTAC Protocol
max inspiration max expiration
upper limit of diaphragm motion
Cine CT range
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Helical+CINE CTAC Protocol
area of impact
new cine+helical CTAC standard helical CTAC
reduced 'banana' artifacts
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
IR LEDs and camera
PC w/ frame grabber + trigger generator
Gating inputs
reflective block
Respiratory Gated PET/CT Imaging
Respiratory trace information
PETCT
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Wholebody Respiratory Gated PETNotes:• motion throughout
body• changes in moving
lesion intensity • apparent fixed
diaphragm location QuickTime™ and aYUV420 codec decompressor
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Single Phase CT‐based Attenuation Correction for 4D PET
CTAC Phase Image Volumes
PET EM phase sinograms
Attenuation corrected PET data
X
X
X
X
Reconstructed PET images
=
=
=
=
Resp
irato
ry p
hase
s
1
2
3
N
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Phase‐matched CT‐based Attenuation Correction
CTAC Phase Image Volumes
PET EM phase sinograms
Attenuation corrected PET data
X
X
X
X
Reconstructed PET images
=
=
=
=
1
2
3
N
Resp
irato
ry p
hase
s
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Single phase CT attenuation correction (CTAC) image(e.g. helical CT)
Phase‐matched CTAC
QuickTime™ and a decompressor
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
CT PET/CT
4D CT 4D PET/CT
Phase‐matched 4D‐PET and 4D‐CTAC
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Time of flight imaging
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Time of Flight (TOF) PET/CTc = 3x1010cm/s, so t = 600 ps ~ d = 10 cm in resolutionSurti (JNM 2011) shows improved lesion detection in large patientsLittle information yet on effect on impact on quantitative accuracy
d = c t/2
timing resolution uncertainty
best guess about location (d)
+ + e-annihilation
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Impact of TOF PET ‐ Detection
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
75 kg patient, 120 MBq, 3 min/bed(BG = ~1kBq/cc)
0.25
0.5
0.75
1
1.25
1.5
0.1 1 10 100
Sphere volume (mL)
Rec
over
y co
effic
ient
VOI & EANM VOI & PSF+TOFMAX & EANM MAX & PSF+TOF
75 kg patient, 120 MBq, 10 min/bed(BG = ~1kBq/cc)
0.25
0.5
0.75
1
1.25
1.5
0.1 1 10 100
Sphere volume (mL)
Rec
over
y co
effic
ient
VOI & EANM VOI & PSF+TOFMAX & EANM MAX & PSF+TOF
Typical coincident count levels High coincident count levels
Courtesy Ronald Boellaard
Impact on quantitation
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Advanced modeling of PET physics in image reconstruction
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Including improved physics modeling in image reconstruction
In principle can remove detector blurring
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Phantom measurements of ringing artifact
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Bai, 2010 IEEE MIC conf record
real?
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Extended axial field of view
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Extended Axial Field of View PET scanner component has 3 rings of detector blocks.
Siemens added one more ring (they quote "extra 33 %") to extend the axial field of view
Increases scanner efficiency and/or allows for shorter scan times
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
NEMA NU‐2 2001 performance measurements
96 @ 34 kBq/ml
161 @ 31 kBq/ml
Peak NECR
Peak NECR (kcps)
Biograph
Biograph TP
Noise Equivalent Count Rate
Biograph
Biograph TP
Courtesy David Townsend PhD: University of Tennessee at Knoxville
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
New detection systems
Avalanche photodiodes Solid‐state silicon photomultipliers
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Position sensitive avalanche photodiode (PSAPD)
silicon‐based detectors Could ultimately be made cheaply
in high volumes High optical quantum efficiency
(up to 4x higher than PMTs) and wide spectral response
Insensitivity to magnetic fields (used in PET/MR)
Timing resolution of ~3 ns Lower SNR than PMTs Temperature sensitive gains
Flood histogram from coupling a 8 x 8 mm2 PSAPD to an LSO array (1 mm pixels, 20 mm tall)
Shah et al. TNS 2004
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
The silicon photomultiplier (SiPM)Combine advantages of PMTs and APDs Still very expensive High gain (like PMTs) Insensitive to magnetic fields (e.g. for PET/MR)
Excellent energy and timing resolution
Temperature sensitive gain
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Simplified structure of a SiPM composed of G‐APD cells
Roncali and Cherry, Ann Biomed Eng, 2011
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
PET/MR scanners
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
PET/CT PET/MR
Clinical PET/MR scanner Siemens mMR first
joint scanner (Philips and GE currently have 'tandem' systems) Uses APDs Expensive Attenuation correction
for bone an open problem for all systems
Clinical results from Drzezga et al, JNM June 2012
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
CT dose reduction methods
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
Iterative CT image reconstruction Can be used in CT
like it is in PET Computationally
now tractable Several approaches
under development for CT‐only scanners
Gradually move to PET/CT scanners
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
FBP
MBIR
RSD Phantom: 120 kVp100 mAs 12 mAs25 mAs
water
water+ contrast
air
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Cost effective PET/CT scanners
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AAPM 2012 Summer School on Medical Imaging using Ionizing Radiation
Paul Kinahan
'Value‐based' PET/CTRefurbished PET/CT scanners Strong market
New systems GE Optima 560 Philips Gemini LXL Siemens Excel 20 mCT Seem to be based on reduced capabilities compared to full‐featured scanners