Cyclotron activated nanoparticles: application in PET/SPECT imaging

Introduction: Nanoparticles (NP) are widely used in everyday life. Pigments, cosmetic products, some foods, suncream, and many other products may contain NPs, and possible environmental pollution may be associated with wastes and NP release. Investigation of possible toxicological effects from exposure to NPs requires in vivo bio-distribution studies. Three frequently applied NPs: silver (Ag), zinc oxide (ZnO) and titanium dioxide (TiO2) were tested by our research group in activated form for quantification and tomographic detection using PET and SPECT. Materials and Methods: Activated NPs were produced in the JRC Cyclotron (Scanditronix MC40). Dry NP powders were placed in sample holders and activated for several hours by proton or deuterium irradiation. The resulting target material was left to decay for 2 weeks to allow irrelevant short-lived isotopes to decay away. Ag-105 (Ag-NP), Zn-65 (ZnO-NP) and V-48 (TiO2-NP) isotopic purity and radioactivity were determined precisely with gamma spectroscopy (Canberra GX2518 HPGe) using Genie 2000 software. The data were used to adjust quantification factors for imaging instruments NanoSPECT/CTPlus (Mediso Ltd.) and nanoScan PET/MRI (Mediso Ltd.). Using SPECT several peaks of the different gamma photon energies characteristic of the specific isotope spectra were applied. We detected 64.0, 280.5, 443.4 and 344.5 keV peaks for Ag-105, and the 560 keV peak for V-48 in addition to detecting the 511 keV annihilation peak of Zn-65 for PET. The HiSPECT (SciVis Gmbh, Germany) reconstruction algorithm was used to calculate volumes from multiplexing overlapping multi-pinhole SPECT while Tera-Tomo (Mediso Ltd) 2-D and 3-D iterative reconstruction algorithms were used to calculate PET volumes. Results: The specific activity of all the NP types used was between 1-1.5 MBq/mg. The radiation emission of Zn-65 was detected using PET, Ag-105 and V-48 were detected with both PET and SPECT. All nanoparticle samples have shown adequate signal-to-noise ratio in their spectral properties for SPECT (Ag-105, V-48) and PET (Ag-105, Zn-65 and V-48) imaging in durations between 40 minutes and 120 minutes of signal integration. Conclusion: All PET and SPECT imaging data were capable of determining the original radioactivity and distribution of the nanoparticles. Quantitation error was 24,3%. These findings provide the basis for the application of non-conventional long-lived isotope tracking of nanoparticles. The actual practicality and usefulness of the technique at realistic NP doses and at lower doses in various organs after biodistribution still has to be studied. Acknowledgement. This study was in part supported by EC-FP7 Transnational Access Facilities grant QNANO.

MATHE Domokos;  HORVATH I;  BUDAN F;  HOBOR S;  KONCZ P;  SIMONELLI Federica;  HOLZWARTH Uwe;  NEMETH G;  SZIGETI K;  GIBSON Peter; 

2014-01-16

SPRINGER

JRC84612

1619-7070,   

http://link.springer.com/article/10.1007%2Fs00259-013-2535-3#,    https://publications.jrc.ec.europa.eu/repository/handle/JRC84612,   

10.1007/s00259-013-2535-3,