https://scholar.dgist.ac.kr/handle/20.500.11750/59104 2026-07-10T07:59:50Z https://scholar.dgist.ac.kr/handle/20.500.11750/60421 Title: Influence of scintillation light confinement on depth-of-interaction measurement performance in a single-ended readout PET detector Author(s): Shim, Hyeong Seok; Cho, Min Jeong; He, Wen; Lee, Min Sun; Levin, Craig S.; Lee, Jae Sung Abstract: Continuous depth-of-interaction (cDOI) detectors enable single-ended readout in positron emission tomography (PET) by encoding the interaction depth into the scintillation light distribution. This study presents a comprehensive performance optimization of a cDOI detector based on light distribution tailoring with crossed triangular-shaped reflectors by analyzing the effects of optical geometry based on various DOI decoding algorithms. Two parameters were systematically varied: the degree of light confinement through (1) optical segmentation and (2) crystal pitch adjustment. Five DOI decoding strategies-variance, max/sum ratio, Euclidean-distance classification, Gaussian and modified maximum-likelihood estimation, and artificial neural network (ANN) decoding-were adopted with 8 & times; 8 SiPM readout data. Results show that moderate segmentation (2 & times; 2 configuration) achieved the best DOI precision, yielding a 4.7 mm full width at half maximum (FWHM) and an ANN classification accuracy of 89 %. In the pitch study, 1.5 mm-pitch detector achieved better performance than 3.0 mm-pitch, indicating that increased optical interfaces allows more accurate encoding of the depth-dependent light distribution within the SiPM array. The ANN decoder consistently outperformed in DOI resolution compared to analytical and statistical methods by learning nonlinear spatial correlations among SiPM pixels. These findings highlight the coupled importance of optical geometry and data-driven decoding for achieving high DOI sensitivity in next-generation PET detector designs. 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60360 Title: Extreme-Pressure Imprint-Directed Micropatterning of Self-Assembled Nanostructures Author(s): Kim, Yu Na; Kang, Eun Bin; Kang, Yu Jin; Lee, Junghoon; Hong, Seung Sae; Kim, Sung-Dae; Jeong, Diana; Lee, Min Sun; Park, Woon Ik Abstract: Extreme pressure imprint lithography (EPIL) offers a simple route to impart microscale geometries without thermal or chemical preconditioning, yet its integration with block copolymer (BCP) self-assembly remains relatively unexplored. Here we report an EPIL-directed micro- and nanopatterning strategy that couples mold-driven microscale confinement with thickness-dependent self-assembly of sphere-forming PS-b-PDMS thin films. When a spin-cast BCP film is imprinted with a rigid Si mold, the imposed height contrast, from a few nanometers on compressed mesas to tens of nanometers inside trenches, governs whether no pattern, monolayer, or double-layer nanostructures appear after thermal annealing and RIE treatment. On ductile Al substrates, simultaneous metal deformation and pressure-driven BCP redistribution create hierarchical patterns, in which polymer accumulation on the raised microfeatures after imprint release leads to selective formation of SiO x nanostructures. This EPIL-directed self-assembly approach provides large-area and shape-versatile patterning enabled by mechanically imposed confinement across rigid and ductile substrates, suggesting a broadly applicable route for hierarchical pattern engineering across multiple length scales. 2026-03-31T15:00:00Z