Experimental evaluation of a SiPM-based scintillation detector for MR-compatible SPECT systems

In the present work we briefly describe the architecture of a photo-detection module, designed in the framework of the INSERT (INtegrated SPECT/MRI for Enhanced Stratification in Radio-chemoTherapy) project, supported by the European Community. We focus on two main elements of the module: the SiPM photo-detector unit and the multi-channel ASIC. These two components have been investigated with dedicated and independent setups to assess preliminary performance of INSERT architecture. In details, we designed a 25.30 mm x 25.85 mm tile, comprising 9 pixels, each one with an 8 mm x 8mm active area. We developed an Anger camera to characterize the tile coupled to a CsI:Tl scintillator (6 mm thick). We measured an average spatial resolution (FWHM) of 2 mm in the central region of the Field of View and a 15.3% energy resolution using a Co-57 source (122 keV), when the tile is cooled down to 0 degrees C to reduce the impact of the dark count rate. Furthermore, we developed ANGUS, a 36-channels 0.35 mu m CMOS technology ASIC designed to cope with input capacitance up to 5 nF, typical of large area SiPM pixels. The spectroscopic capability of single readout channels were evaluated by coupling an 8 mm x 8 mm pixel with a cylindrical CsI:Tl scintillator (8 mm diameter, 10 mm thickness). Energy resolution at room temperature provided values between 13% and 13.5% (FWHM) at the 122 keV line for the nine pixels

Experimental Evaluation of a SiPM-Based Scintillation Detector for MR-Compatible SPECT Systems

In the present work we briefly describe the architecture of a photo-detection module, designed in the framework of the INSERT (INtegrated SPECT/MRI for Enhanced Stratification in Radio-chemoTherapy) project, supported by the European Community. We focus on two main elements of the module: the SiPM photo-detector unit and the multi-channel ASIC. These two components have been investigated with dedicated and independent setups to assess preliminary performance of INSERT architecture. In details, we designed a 25.30mmx25.85mm tile, comprising 9 pixels, each one with an 8mmx8mm active area. We developed an Anger camera to characterize the tile coupled to a CsI:Tl scintillator (6mm thick). We measured an average spatial resolution (FWHM) of 2mm in the central region of the Field of View and a 15.3% energy resolution using a 57-Co source (122 keV), when the tile is cooled down to 0C to reduce the impact of the dark count rate. Furthermore, we developed ANGUS, a 36-channels 0.35um CMOS technology ASIC designed to cope with input capacitance up to 5 nF, typical of large area SiPM pixels. The spectroscopic capability of single readout channels were evaluated by coupling an 8mmx8mm pixel with a cylindrical CsI:Tl scintillator (8mm diameter, 10mm thickness). Energy resolution at room temperature provided values between 13% and 13.5% (FWHM) at the 122 keV line for the nine pixels

A SiPM-based detection module for SPECT/MRI systems

In the present work we present the development of a Silicon PhotoMultiplier (SiPM)-based detection module for hybrid SPECT/MRI instruments. The module is designed for preclinical SPECT systems for mouse and rat brain imaging, but can also be exploited for clinical SPECT brain scanners. The gamma-ray detection module is designed on the well established Anger architecture, with a continuous 5 cm × 5 cm CsI:Tl scintillator read by an array of SiPMs (RGB-HD with 25 μm SPAD cells) from Fondazione Bruno Kessler. The current signals are conveyed to a 36-channel ASIC realized in 0.35 μm CMOS technology and digitized by an external data acquisition system. An operative temperature of 0◦C is mandatory to reduce the dark count rate of the SiPM array and to enhance the final performance of the detector in terms of energy and spatial resolution. For this purpose, an MRI-compatible heat sink is realized with a plastic material (Coolpolymer D5506) with a glycol-water mixture as cooling fluid. Gamma-ray measurements with Co-57 (122 keV) have provided an energy resolution better than 14% and an average intrinsic spatial resolution below 1.0 mm

Development of a SiPM-based Anger camera for INSERT, a new multi-modality SPECT/MRI system for preclinical and clinical imaging

A new multi-modality imaging tool is under development in the framework of the INSERT (INtegrated SPECT/MRI for Enhanced Stratification in Radio-chemoTherapy) project, supported by the European Community. A custom SPECT apparatus, used as an insert for commercially available MRI systems, could enhance the treatment of brain tumors (primarily glioma) by offering more effective and earlier diagnosis with potentially better outcome in survival. In this work we briefly describe the architecture of the gamma-ray photo-detection module with focus on the Silicon PhotoMultiplier (SiPM) detectors and their performance with low-energy gamma-rays (57Co - 122 keV). The camera has a 50.40 mm × 51.70 mm photo-detection area, comprising of 144 SiPMs with 36 readout channels, each one composed of four short-circuited SiPMs for an 8 mm × 8 mm active area. We have developed an Anger camera to characterize and qualify the array when coupled to a CsI:Tl scintillator (8 mm thick). We have measured an intrinsic spatial resolution better than 1.35 mm and an energy resolution below 14% using a 57Co source, when the tile is cooled down to -17°C to reduce the impact of the dark count rate on the measurements