High-Performance and Cost-Effective Detector Using Microcolumnar CsI:Tl and SiPM

Abstract

We are developing a technique to fabricate high spatial resolution and cost-effective photon counting detectors using silicon photomultipliers (SiPMs) and microcolumnar structured scintillator. Photon counting detectors using SiPMs are of much interest to the gamma-and X-ray detector community, but they have limitations at low energy due to their dark noise. In this paper, we report on vapor deposition of CsI:Tl directly onto a SiPM, a technique that improves optical coupling and allows for detection of low energy gamma-and X-rays. It simultaneously addresses related issues of light loss and light spread in the scintillator, thereby improving the performance of the detector. Devices made by this technique may be used for both photon counting and gamma-and X-ray imaging.The SiPM used in this study comprises a 4 4 array of macropixels, each of which is 3.0 mm 3.0 mm, with 3.36 mm pitch. This SiPM was placed inside a physical vapor deposition chamber and a 0.75 mm thick layer of microcolumnar CsI:Tl was grown on its surface without any damage. Scanning Electron micrographs (SEM) show highly oriented microcolumnar CsI:Tl structure orthogonal to the SiPM surface. These microcolumnar structures are excellent for channeling scintillation light to the SiPM and provide sub-macro-pixel resolution, which is now limited to the size of the macro-pixels. In this study, we report the performance characteristics of the resultant detector in terms of position sensitivity, energy discrimination, optical crosstalk, and signal-to-noise ratio. The performance of the detector is evaluated against that of other CsI:Tl/SiPM combinations, such as mechanically coupled monolithic and laser-pixelated CsI:Tl scintillators. Success of the technique may be gauged by the fact that the photopeak can be realized for a wide range of energies, including those of (60 keV) and(122 keV).

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout

“…We first simulated the monolithic and the pixelated array detector types in DETECT2000, as these constitute the mainstay in imaging applications and have been in use for decades. Even though other structured scintillator types have been developed, such as microcolumnar detectors (Nagarkar et al 1998, Sabet et al 2012b, and scintillators that are grown into pixel shapes (Sabet et al 2013, Zhao et al 2015, we focused this study on the most common detector types for nuclear medicine applications. These initial simulations helped us debug our code and setup baselines for the new detector designs fabricated using the LIOB technique.…”

Direct and indirect detectors for X-ray photon counting systems

“…The experimental methods, materials and samples used for studying the performance of the detector array have been described in detail elsewhere [27,28]. In this paper we will discuss the highlights and summarize the advantages and disadvantages that rrticrocolumnar films possess over the traditionally used monolithic and/or mechanically structured (pixelated) scintillators, when coupled to an imaging photodetector -in this case, a solid state photomultiplier.…”

Novel laser-processed CsI:Tl detector for SPECT

“…Most notable is thin film scintillator fabrication using physical vapor deposition (PVD), 6,7 which also can be used to force the deposited film to follow a pixelated pattern. 8 In these scintillators, the material is deposited in the form of microcolumns where the size, packing fraction, and thickness of the microcolumns can be controlled by optimizing the deposition parameters.…”