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Nuclear Medicine
Quality control
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Uniformity gamma camera
E + L + Flood correctie
Energy correctionNo correction
E + Linearity
divide by flood source image
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Uniformity PET camera
sinogram
projection
Uncorrected Corrected
Blank scan
Correction: energyuniformitydead time
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QC gamma camera
Planar• uniformity• energy resolution• linearity• spatial resolution• dead time• sensitivity• pixel size
Whole Body• bed motion• uniformity• pixel size
SPECT• center of rotation• detector position• Phantom
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dead time
• straightforward: decaying source
• two sources with (nearly) same activity
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Center of rotation
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Detector position
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well counterdose calibratorsurvey meter
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NaI(Tl)
PMT
lead
shi
eldi
ng
well counter
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NaI(Tl)
PMT
lead
shi
eldi
ng
D
H
Ra
sens =
D
sensitivity
well counter
gas filled detectors
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+
- - -
- - -
-+++
--
applied voltage
output current
ionizationchamber
proportionalcounter
Geiger-Müller
dose calibrator
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isotope selection
dose calibrator
13
+
- - -
- - -
-+++
--
output current = const x air kerma (or Ar kerma)
+-
function of isotope energy!
dose calibrator
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with Cu filter
survey meters
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ionisation detector (Xenon)
survey meters
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scintillator (NaI(Tl))
contamination monitor, spectrometer
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NaI(Tl) scintillation crystal
contamination monitor
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Image analysis
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SUV: standard uptake value
g in weighttotal / Bq in dose total
j in Bq/g in amount tracer
ionconcentrat tracer average
j in ionconcentrat tracerSUV j
•somewhat controversial•only valid if procedure is standard:
• time between injection and image• condition of patient• ...
•used all the time!
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example:analysis of heart images
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Image analysis
18F-FDG
13N-NH3
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perfusion + metabolism
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Gated PET
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Partialvolume
constantactivity
big pixels
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Partialvolume
constantconcentration
finite resolution
perfect resolution
finite resolution
Recovery
Spill-over
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Partialvolume
constantactivity
finite resolution
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Gated MIBI, thickening
7
6
5432
2 4 6 8
200400600800
1000
00
1
0
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Tracer kinetic modelling
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Dynamic PET
13N-NH3 perfusion study
20 s. 40 s.
3 min 20 min
Dynamic PET
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11C-acetate perfusion/oxidative metabolism study
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Kinetic modelling
Extra-vascular
Metabolized
K1
k2
k3
k4
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 100 200 300 400 500 0
0.05
0.1
0.15
0.2
0.25
0.3
0 100 200 300 400 500
Blood
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3 comp model
C’E C’M
K’1
k’2
k’3
k’4
Glucose:
0dt
'dC P
0'C)'k'k('C'Kdt
'dCE32P1
E
0'k 4
E3M 'C'k
dt
'dC - metabolized = 0
pp32
31E3 'C'R'C
'k'k
'k'K'C'k
metabolized
C’p
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3 comp model
CE CM
K1
k2
k3
k4
FDG:
0dt
dCP
)t(C)kk()t(CKdt
dCE32P1
E
0k4
)t(Ckdt
dCE3
M
not metabolizedbut accumulated
Cp
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Laplace transform
Cp
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3 comp model
CE CM
K1
k2
k3
FDG:
t
0p
32
31
t
0
)ut)(kk(p
32
21
MEI
du)u(Ckk
kK
due)u(Ckk
kK
)t(C)t(C)t(C
32
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3 comp model
Glucose consumption:
'LC
RR
'
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31LC1
PCkkkK
Lumped constant:
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Motion correction
12
13
14
15
16
17
11C-Acetate
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Tracer kinetic modelling: NH3
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 100 200 300 400 500
parametric modelling: acetate
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Image quality
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Bias and variance
moreregularisation
bias
variance
A
B
A is better than B!
which method is better?
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Software evaluation
• nice correct• image quality is task dependent• simulation, phantom, (animal), clinical
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Dosimetry
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Dosimetry
kgJ
Gy 11
Q(photons, electrons, positrons) = 1Q(neutrons, protons) = ..10..Q(a-particles) = 20
MIRD formalism (SNM)
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effective dose
i
BiiiAi MEBApNQBADE /)()(
A B
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R = 2 cm
L = 4 cm
D = 10 cmd = 2 cm
m = 0.15 /cm (140 keV)m = 0.095 /cm (511 keV)
1 MBq 123I: gamma: 0.84 of 159 keVelectron: 0.13 of 127 keVhalflife: 13 h
1 MBq 18F: 1 positron of 250 keV109 min
For organs with uptake:• 3D VOIs • pixelwise MBq/cc
measurement
=> Total organ activity
dosimetry
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Residence time (hr) for the thyroid: S1: 0.0017S2: 0.0017S3: 0.0013
residence times
Residence time (hr) for the liver: S1: 0.4567S2: 0.5310S3: 0.3940
evaluation of tracer for ORL-1 receptors in the brain
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Olinda: MC-based dosimetry
• MIRD Dose Estimate Report No. 19: Radiation Absorbed Dose Estimates from 18F-FDG
dosimetry
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background radiation: ..2.. mSv / year= 5.5 mSv / day= 0.2 mSv / hour
patient:
18F-FDG, 300 MBq 6 mSv
99mTc-MIBI 740 MBq 11 mSv
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the end