1

Nuclear Medicine

Quality control

2

Uniformity gamma camera

E + L + Flood correctie

Energy correctionNo correction

E + Linearity

divide by flood source image

3

Uniformity PET camera

sinogram

projection

Uncorrected Corrected

Blank scan

Correction: energyuniformitydead time

4

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

5

dead time

• straightforward: decaying source

• two sources with (nearly) same activity

6

Center of rotation

7

Detector position

8

well counterdose calibratorsurvey meter

9

NaI(Tl)

PMT

lead

shi

eldi

ng

well counter

10

NaI(Tl)

PMT

lead

shi

eldi

ng

D

H

Ra

sens =

D

sensitivity

well counter

gas filled detectors

11

+

- - -

- - -

-+++

--

applied voltage

output current

ionizationchamber

proportionalcounter

Geiger-Müller

dose calibrator

12

isotope selection

dose calibrator

13

+

- - -

- - -

-+++

--

output current = const x air kerma (or Ar kerma)

+-

function of isotope energy!

dose calibrator

14

with Cu filter

survey meters

15

ionisation detector (Xenon)

survey meters

16

scintillator (NaI(Tl))

contamination monitor, spectrometer

17

NaI(Tl) scintillation crystal

contamination monitor

18

19

Image analysis

20

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!

21

example:analysis of heart images

22

Image analysis

18F-FDG

13N-NH3

23

perfusion + metabolism

24

Gated PET

25

Partialvolume

constantactivity

big pixels

26

Partialvolume

constantconcentration

finite resolution

perfect resolution

finite resolution

Recovery

Spill-over

27

Partialvolume

constantactivity

finite resolution

28

Gated MIBI, thickening

7

6

5432

2 4 6 8

200400600800

1000

00

1

0

29

30

Tracer kinetic modelling

31

Dynamic PET

13N-NH3 perfusion study

20 s. 40 s.

3 min 20 min

Dynamic PET

32

11C-acetate perfusion/oxidative metabolism study

33

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

34

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

35

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

36

Laplace transform

Cp

37

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

38

3 comp model

Glucose consumption:

'LC

RR

'

32

31LC1

PCkkkK

Lumped constant:

11

Motion correction

12

13

14

15

16

17

11C-Acetate

40

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

42

Image quality

43

Bias and variance

moreregularisation

bias

variance

A

B

A is better than B!

which method is better?

44

Software evaluation

• nice correct• image quality is task dependent• simulation, phantom, (animal), clinical

45

Dosimetry

46

Dosimetry

kgJ

Gy 11

Q(photons, electrons, positrons) = 1Q(neutrons, protons) = ..10..Q(a-particles) = 20

MIRD formalism (SNM)

47

effective dose

i

BiiiAi MEBApNQBADE /)()(

A B

48

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

50

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

51

Olinda: MC-based dosimetry

• MIRD Dose Estimate Report No. 19: Radiation Absorbed Dose Estimates from 18F-FDG

dosimetry

52

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

53

the end