Download perche` imaging molecolare con radionuclidi come SPECT/PET

Imaging Molecolare con radionuclidi: un potente mezzo di
indagine di processi biologici in vivo
F. Garibaldi - Fisica e tecnologie Nucleari per la Salute - Dipartimento TESA
Roma 08/06/06
- perche’ imaging molecolare con radionuclidi
- come
- SPECT/PET/Compton camera
- tecniche di collimazione
-
qualche esempio
- applicazioni cliniche
- cancro della mammella
- cancro della prostata
- piccoli animali
-
rivelazione di placche aterosclerotiche vulnerabili
- monintoring della diffusione di cellule staminali
Diagnosi del cancro della mammella
X-ray
mammography,the most
sensitive method
Mechanism
but
- it shows lesions, not
cancers
-15-30% positive
predictive value
biopsy
- invasiveness
(proportional to the
risk of missing the
cancer)
- expensive
- ansiety
- false positive
(problems in successive
mammographyc controls)
- false negative
(medical problem great,
delay in operation)
Natural history of breast cancer
Diameter
1 mm.
7mm.
15 mm.
Preclinical phase
Clinical phase
Primary Prevention
Early Detection
Therapy
γ Imaging: Single Photon Detector Module
1.Collimator
Only gammas that are
perpendicular to imaging
plane reach the detector
Patient injected with
radioactive drug.
Drug localizes according
to its metabolic
properties.
Gamma rays, emitted by
radioactive decay, that
exit the patient are
imaged.
2.Scintillator
Convert gammas to
visible light
3.Photomultiplier
Convert light to
electrical signal
4.Readout Electronics
Amplify
electrical
signal and interface to
computer
5.Computer decoding
procedure
Elaborate signal and
gives image output
Le tecniche
Ris. Sp
Eff.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Single
Photon
Emission
Computed
Tomography
140 keV
ris. sp. ed efficienza “tipiche” (vedi)
Positron
Emission
Tomography
Ris. Sp
Eff.
Complementary non invasive “specific” technique is needed
Nuclear medicine:
- uptake of single radiotracer
- when the uptake due to a specific function of the tumor
or to a function specifically enhanced in the
cancer, specific tumor imaging can take place
Emission (Computed Tomography) (SPECT)
Positron Emission Tomography (PET)
Necessita’ di compressione
Molecular imaging: high resolution detectors for early diagnosis and therapy monitoring of
breast cancer (ISS, University of Rome2 and Napoli) (Project funded by Ministry of Health)
dual head detector
100 x 100 mm2
150 x 200 mm2
Preparation of clinical trials at Dipartimento di Diagnostica per Immagini. University of Tor Vergata
foto Tor Vergata con “spot compression”
Dual detector configuration
S. Majewski et al.
Combining the images taken by two detectors, an increase of lesion contrast is obtained
Lesions are not seen by the detector on the other side of the lesion. Combining the images
both lesions are visible
and a
Lesions in the middle of the breast TIFF
areQuickTime™
seen barely
seen by both detectors.
(LZW) decompressor
are needed to see this picture.
Fusion: contrast increased
tumors: (5, 6, 7, 8,9,10,12)
uptake 1:10; breast 6 cm
measurements
NaI(Tl) 1.5 pitch;
H8500 (6x6 mm2)
6 mm
SNR vs tumor dimension(10:1-breast 6cm-NaI 1.0-H8500(6x6mm2)
8 mm
20
18
Qu ickTim e™ a nd a
TIFF (Un comp resse d) de comp ress or
are need ed to see this pi cture.
16
7 mm
14
SNR
12
10
H
X (H9500)
8
6
4
2
0
4
5
6
7
8
9
10
t(mm)
11
12
6 mm tumors
13
visible
measurements confirm simulation
smaller scintillator pixel, higher SNR
NaI(Tl) 1.3 pitch;
H8500(6x6 mm2)
NaI(Tl) 1.2 pitch
H9500 (3x3 mm2)
Qu ickTi me ™ a nd a
T IFF (Uncomp resse d) de com presso r
a re ne ed ed to se e thi s pi ctu re .
but
anode pixel has to be small
tum 8 mm
First Preliminary Clinical Trials
Case 1: Positive Case 2: Negative
Small Head (top)
Small Head (top)
Case 3: Positive
Large Head (bottom)
Small Head (top)
Improvements: “dual head” software implemented, better anode sampling (NaI(Tl)
1.2 mm pitch + H9500 (3 x 3 mm2 anode) + coded aperture collimation