Exploitation of SiPM technology for the developemnt of a Theranostic Imaging device

Objectives Radiolabelled magnetic nanoparticles are challenging agents in the the Theranostics field. Simultaneous nuclear imaging during hyperthermia can provide insights in the biological process that occur when they are heated and controlled drug release is performed. Buiding on the Silicon Photomlutipliers (SiPM) detector technology it is possible to design and develop small imaging systems, which are compatible with hyperthermia equipment.

Methods For the heat generation CELES MP 6kW (Fives Celes, FR) was used. The magnetic field is set by adjusting the voltage in the power supply, and the frequency with proper copper coil. We used the recent C-series of SensL SiPM with 3mm pixel size. 4x4 arrays were coupled to different scintillators and irradiated with various gamma energies. The 16 output signals of the SiPM array are further reduced to 4 position signals through a two-stage charge division resistive network and then amplified and then digitized using free running ADCs. The sampling rate was o 40 MHz. A Field Programmable Gate Array (FPGA) Spartan 6 LX150T is used for triggering and processing of the four digitized position signals. Data are transferred to a standard PC via Ethernet link.

Results The evaluation of the SiPM arrays shows that 1x1mm pixel size can be clearly resolved at PET energies for GAGG:Ce and CsI:Na and 1.5x1.5mm in SPECT imaging for CsI:Na. The best energy resolution was measured equal to 10.5% under 511keV irradiation for the 2x2mm GAGG:Ce; 16% under 511keV irradiation for the 1x1mm GAGG:Ce and 22% under 120keV irradiation for the 1x1mm CsI:Na. In parallel a larger detector with 5x10cm dimensions is under development and the placement of the imaging system in order to allow efficient mouse imaging during hyperthermia has been studied. (Fig. 1)

Conclusions We exploit for the first time the SiPM technology, in order to allow the development of PET or SPECT Theranostic detectors, which are not affected by the magnetic field of hyperthermia systems.

Research Support This research has been co-funded by the European Union (European Social Fund) and Greek national resources under the framework of the “Aristeia II” project of the “Education & Lifelong Learning” Operational Program.