1. 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

2. X-ray mammography,the most sensitive method 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) Diagnosi del cancro della mammella

3. γ Imaging: Single Photon Detector Module Patient injected with radioactive drug. Drug localizes according to its metabolic properties. Gamma rays, emitted by radioactive decay, that exit the patient are imaged. 1.Collimator Only gammas that are perpendicular to imaging plane reach the detector 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

4. Le tecniche S ingle P hoton E mission C omputed T omography P ositron E mission T omography 140 keV ris. sp. ed efficienza tipiche (vedi) Ris. Sp Eff. Ris. Sp Eff.

5. 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)

6. Necessita di compressione

7. 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) Preparation of clinical trials at Dipartimento di Diagnostica per Immagini. University of Tor Vergata dual head detector 100 x 100 mm2 150 x 200 mm2

8. foto Tor Vergata con spot compression

9. 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 Lesions in the middle of the breast are seen barely seen by both detectors. Fusion: contrast increased

10. NaI(Tl) 1.2 pitch H9500 (3x3 mm2) tum 8 mm tumors: (5, 6, 7, 8,9,10,12) uptake 1:10; breast 6 cm NaI(Tl) 1.5 pitch; H8500 (6x6 mm2) NaI(Tl) 1.3 pitch; H8500(6x6 mm2) 6 mm 7 mm 8 mm X (H9500) measurements confirm simulation smaller scintillator pixel, higher SNR anode pixel has to be small measurements but 6 mm tumors visible

11. First Preliminary Clinical Trials Case 1: Positive Case 3: Positive Small Head (top)Large Head (bottom) Case 2: Negative 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