Light Spread Manipulation in Scintillators Using Laser Induced Optical Barriers

• Published in: IEEE transactions on nuclear science 2018-08, Vol.65 (8), p.2208-2215
• Main Authors: Blackberg, Lisa, Moebius, Michael, El Fakhri, Georges, Mazur, Eric, Sabet, Hamid
• Format: Article
• Language: English
• Subjects: Barriers; Cerium; Channeling; Crystals; Depth of interaction (DOI); detector fabrication; Detectors; Edge effect; Emission analysis; Fabrication; high-resolution; Image resolution; laser induced optical barriers (LIOBs); Lasers; light transport simulations; Lutetium; LYSO:Ce; Optical device fabrication; Positron emission; Positron emission tomography; positron emission tomography (PET); Refractivity; Scintillation counters; Scintillators; Sensors; Yttrium
• ISSN: 0018-9499; 1558-1578; 1558-1578
• DOI: 10.1109/TNS.2018.2809570

We are using the laser induced optical barriers (LIOBs) technique to fabricate scintillator detectors with combined performance characteristics of the two standard detector types, mechanically pixelated arrays, and monolithic crystals. This is done by incorporation of so-called OBs that have a refractive index (RI) lower than that of the crystal bulk. Such barriers can redirect the scintillation light and allow for control of the light spread in the detector. Previous work has shown that the LIOB technique has the potential to achieve detectors with high-transversal and depth of interaction (DOI) resolution simultaneously in a single-side readout configuration, suitable for high-resolution positron emission tomography imaging. However, all designs studied thus far present edge effect issues similarly as in the standard detector categories. In this paper, we take advantage of the inherent flexibility of the LIOB technique and investigate alternative barrier patterns with the aim to address this problem. Light transport simulations of barrier patterns in cerium-doped lutetium yttrium orthosilicate (LYSO:Ce), with deeper barrier walls moving toward the detector edge show great promise in reducing the edge effect, however, there is a tradeoff in terms of achievable DOI information. Furthermore, fabrication and characterization of a 20-mm-thick LYSO:Ce detector with OBs forming a pattern of 1×1×20 mm 3 pixellike structures show that light channeling in laser-processed detectors in agreement with OBs with RI between 1.2 and 1.4 is achievable.