Development of a 3-D scintillator detector for Compton imaging based on laser engraving

Y2SiO5: Ce (YSO) scintillation with characteristics of high light yield, fast decay time, and high Compton scattering fraction shows good application potential for Compton imaging. In this article, we propose a 3-D scintillator detector, which is segmented by the YSO monolithic rods and pixelated by subsurface laser engraving (SSLE) in the depth direction. Two arrays of silicon photomultipliers are optically coupled to the YSO array at each end, in which the pixels are designed for a one-to-one match. By identifying the location number of array pixels and measuring the depth of interaction (DOI) of pixelated scintillator rods, the interaction coordinates of gamma photon can be obtained accurately. After energy-consistent calibration, the energy resolutions of the pixels in the 3-D detector were evaluated. The imaging test results indicate that the detector has the capability to locate a 0.1- $\mu $ Sv/h 137-Cs gamma-ray source within 90 s in $4\pi $ field of view (FOV). The efficiency of the imaging events is 2.2%. By using the maximum-likelihood expectation–maximization (MLEM) algorithm with ten iterations, the full width at half maximum (FWHM) of the reconstructed hotspot decreases to less than 9.0°. This configuration mainly simplifies the calculation of interaction coordinates compared to the center of the gravity method. Moreover, the higher segment precision for DOI estimation is realized due to the SSLE technique. The 3-D scintillator detector achieves $4\pi $ Compton imaging with high detection efficiency and high localization accuracy.