The initial characterization of the first single-photon emission computed tomography (SPECT) insert for simultaneous human brain imaging inside magnetic resonance imaging (MRI) is presented. The ...instrument features a novel multimini-slit-slat collimator and a static ring of 20 detectors. The scanner architecture is modular and represents the scale-up of a preclinical version whose MRI-compatibility has been already successfully demonstrated. The detectors are based on CsI(Tl) crystals (50 mm <inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 100 mm <inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 8 mm) coupled to arrays of silicon photomultipliers and ASIC readout for a total of 1440 channels. The transaxial field of view (FoV) is 20 cm by 9 cm in the axial direction. The experimental results show a sensitivity of 362 cps/MBq, an energy resolution of ~17% (at 140 keV), and a tomographic extrinsic resolution in the transaxial plane of ~8 mm across the whole FoV.
Within the vast panorama of multimodal systems for clinical diagnosis, PET/MRI has been receiving significant attention. In parallel, new technological solutions have been paving the way to ...simultaneous SPECT/MRI systems, whose development has been so far delayed due to the challenging compatibility between MRI, gamma-ray detectors, and collimators. This paper presents an silicon photomultiplier (SiPM)-based Anger camera designed for preclinical and clinical SPECT static inserts for standard MR scanners. The gamma-ray detector is based on a continuous CsI(Tl) scintillator readout by arrays of SiPMs and custom ASICs. The design has been adapted to fit with the limited space conditions (23 mm thickness), but also considering mutual compatibility issues. Despite these constraints and thanks to the adoption of an iterative statistical event estimation method simply requiring a flood image, the detector maintains state-of-the-art performance in terms of intrinsic spatial resolution (1.0 mm FWHM within the usable field of view) and an energy resolution below 14% FWHM at 140 keV. The experimental studies here performed show that the camera, designed to operate at 0 °C to reduce the dark current of SiPMs, can operate up to 10 °C without significant worsening of imaging performance.
A preclinical insert for small animal simultaneous SPECT and MR imaging, in particular for imaging mouse brains, is presented. It consists of ten static magnetic resonance imaging (MRI)-compatible ...gamma cameras based on tiles of silicon photomultipliers readout by a multichannel ASIC and coupled to 5 cm × 5 cm CsI(Tl) scintillators and to an MRI-compatible multipinhole collimator. Calibration and image reconstruction algorithm are illustrated. Mutual compatibility is demonstrated along with imaging performance that is comparable with other non-MR micro-SPECT systems: 0.9 mm tomographic spatial resolution across a transverse field of view of 15.6 mm, 12% energy resolution (at 140 keV), and 1105 cps/MBq sensitivity. Experimental results with phantoms (glass capillaries of 290 μm diameter and a mini Derenzo) are presented.
A clinical SPECT insert for a commercial MRI scanner has been developed within the INSERT project, allowing simultaneous SPECT/MRI studies of the human brain. Here we present preliminary experimental ...results. The reconstructed resolution was 6-11 mm and the sensitivity 280-440 s -1 /MBq. The INSERT is the first clinical SPECT prototype for simultaneous SPECT/MRI.
A SiPM-Based Clinical MRI-Compatible SPECT Insert Carminati, M.; D'Adda, I.; Morahan, A. J. ...
2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC),
2019-Oct.
Conference Proceeding
Odprti dostop
The first SiPM-based clinical SPECT ring for brain simultaneous imaging in standard MR scanners has been put into operation. Reliable operation of the instrument has been achieved by means of its ...optimization, such as the introduction of a dual-cooling system (liquid-gas) of the DAQ electronics. The static gantry is composed of 20 MRI-compatible γ-detection modules mounting 5 cm × 10 cm CsI(Tl) scintillators for a total of 1440 pixels (targeting a transaxial FoV of 20 cm). Here we present the results of a preliminary characterization showing 220 kcps max. count rate, 365cps/MBq sensitivity with the multislit-slat collimator, ~17% energy resolution and an average extrinsic spatial resolution of ~8 mm in the trans-axial plane.
The experimental characterization of a SiPM-based 10-module SPECT gamma imager suitable for insertion and operation inside unmodified MR scanners for simultaneous (and potentially multi-tracer) ...preclinical imaging is presented. The design challenges, here fulfilled, such as compactness while granting proper cooling, mutual compatibility and resilience to high (3-7 T) magnetic fields inside the bore, suitable energetic (better than 14% at 140 keV) and spatial resolution (better than 1 mm) are discussed. The carefully optimized detection module, featuring a 5\times5 cm^{2} CsI(Tl) scintillator coupled to arrays of SiPM conditioned by a 36-channel ASIC, and the digital daisy chain infrastructure are the basis for the realization of a larger (20-module ring) clinical insert. Moreover, planar image reconstruction based on advanced statistical approaches such as maximum likelihood and iteratively estimated light response function is reported.
Laser processing of flexible substrates Gordon, P.; Berenyi, R.; Nyitrai, Z.
2nd International IEEE Conference on Polymers and Adhesives in Microelectronics and Photonics. POLYTRONIC 2002. Conference Proceedings (Cat. No.02EX599),
2002
Conference Proceeding
The paper describes some results of a research project aimed at the application of CO/sub 2/ and frequency multiplied Nd:YAG lasers for drilling via holes into copper clad flexible laminates of ...polyimide and polyester based materials. We have also carried out experiments for removing the insulation layer from the copper foil to open windows, i.e. to obtain clean copper areas. This can be a key process in the production of TABs. Three wavelengths (10600 nm, 1064 nm and 355 nm) were used to find the optimal process parameters for drilling and layer removing. The samples were examined and evaluated many ways to conclude the general behaviour of the material and its interaction with different laser beams.
The results of a systematic and quantitative experimental characterization of simultaneous operation of a preclinical SPECT insert inside an unmodified standard MR scanner (Philips 3T Achieva) are ...presented. The static gantry (20 cm diameter, 15 mm field of view) is composed of 10 MRI-compatible gamma cameras based on 8-mm thick CsI(Tl) scintillator (50 mm × 50mm) coupled with arrays of SiPMs. Mutual compatibility is achieved by proper design of the SPECT system: shielding, choice of materials, design of the analog boards. The measured energy resolution is 13% at 122 keV after correction of SiPM gain variability and local crystal luminosity. The intrinsic spatial resolution, after planar image statistical reconstruction by means of maximum likelihood, is 1mm, while the extrinsic resolution is below 0.9 mm across the entire transaxial FoV, measured with capillaries of 290 pm diameter. With the custom-designed 3 × 3 multi-pinhole collimator (whose minimal perturbation of the magnetic field can be reduced below 1ppm thanks to shimming), the measured sensitivity with 99m Tc is 1100 cps/MBq. The MR image is not distorted by the operation of the SPECT, as well as SPECT performances are no degraded by MRI (T2W and gradient sequences). Simultaneous imaging of different phantoms (capillaries, Derenzo hot rods of 0.85-1.7 mm diameter) as well as a mouse brain are reported.
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