{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T16:15:50Z","timestamp":1788538550692,"version":"build-2803163510"},"reference-count":38,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2022,6,21]],"date-time":"2022-06-21T00:00:00Z","timestamp":1655769600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2022,8]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Significant interest has been recently shown for using monolithic scintillation crystals in molecular imaging systems, such as positron emission tomography (PET) scanners. Monolithic\u2010based PET scanners result in a lower cost and higher sensitivity, in contrast to systems based on the more conventional pixellated configuration. The monolithic design allows one to retrieve depth\u2010of\u2010interaction information of the impinging 511\u00a0keV photons without the need for additional hardware materials or complex positioning algorithms. However, the so\u2010called edge\u2010effect inherent to monolithic\u2010based approaches worsens the detector performance toward the crystal borders due to the truncation of the light distribution, thus decreasing positioning accuracy.<\/jats:p><\/jats:sec><jats:sec><jats:title>Purpose<\/jats:title><jats:p>The main goal of this work is to experimentally demonstrate the detector performance improvement when machine\u2010learning artificial neural\u2010network (NN) techniques are applied for positioning estimation in multiple monolithic scintillators optically coupled side\u2010by\u2010side.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>In this work, we show the performance evaluation of two LYSO crystals of 33\u00a0\u00d7\u00a025.4\u00a0\u00d7\u00a010 mm<jats:sup>3<\/jats:sup>optically coupled by means of a high refractive index adhesive compound (Meltmount, refractive index<jats:italic>n<\/jats:italic>\u00a0=\u00a01.70). A 12\u00a0\u00d7\u00a012 silicon photomultiplier array has been used as photosensor. For comparison, the same detector configuration was tested for two additional coupling cases: (1) optical grease (<jats:italic>n<\/jats:italic>\u00a0=\u00a01.46) in between crystals, and (2) isolated crystals using black paint with an air gap at the interface (named standard configuration). Regarding 2D photon positioning (XY plane), we have tested two different methods: (1) a machine\u2010learning artificial NN algorithm and (2) a squared\u2010charge (SC) centroid technique.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>At the interface region of the detector, the SC method achieved spatial resolutions of 1.7\u00a0\u00b1\u00a00.3, 2.4\u00a0\u00b1\u00a00.3, and 2.6\u00a0\u00b1\u00a00.4\u00a0mm full\u2010width at half\u2010maximum (FWHM) for the Meltmount, grease, and standard configurations, respectively. These values improve to 1.0\u00a0\u00b1\u00a00.2, 1.2\u00a0\u00b1\u00a00.2, and 1.2\u00a0\u00b1\u00a00.3\u00a0mm FWHM when the NN algorithm was employed. Regarding energy performance, resolutions of 18\u00a0\u00b1\u00a02%, 20\u00a0\u00b1\u00a02%, and 23\u00a0\u00b1\u00a03% were obtained at the interface region of the detector for Meltmount, grease, and standard configurations, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>The results suggest that optically coupling together scintillators with a high refractive index adhesive, in combination with an NN algorithm, reduces edge\u2010effects and makes it possible to build scanners with almost no gaps in between detectors.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.15792","type":"journal-article","created":{"date-parts":[[2022,6,11]],"date-time":"2022-06-11T10:30:52Z","timestamp":1654943452000},"page":"5616-5626","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Performance evaluation of side\u2010by\u2010side optically coupled monolithic LYSO crystals"],"prefix":"10.1002","volume":"49","author":[{"given":"Marta","family":"Freire","sequence":"first","affiliation":[{"name":"Instituto de Instrumentaci\u00f3n para Imagen Molecular (I3M) Centro Mixto CSIC \u2010 Universitat Polit\u00e8cnica de Val\u00e8ncia Valencia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara","family":"Echegoyen","sequence":"additional","affiliation":[{"name":"Instituto de Instrumentaci\u00f3n para Imagen Molecular (I3M) Centro Mixto CSIC \u2010 Universitat Polit\u00e8cnica de Val\u00e8ncia Valencia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrea","family":"Gonzalez\u2010Montoro","sequence":"additional","affiliation":[{"name":"Instituto de Instrumentaci\u00f3n para Imagen Molecular (I3M) Centro Mixto CSIC \u2010 Universitat Polit\u00e8cnica de Val\u00e8ncia Valencia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Filomeno","family":"Sanchez","sequence":"additional","affiliation":[{"name":"Instituto de Instrumentaci\u00f3n para Imagen Molecular (I3M) Centro Mixto CSIC \u2010 Universitat Polit\u00e8cnica de Val\u00e8ncia Valencia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonio J.","family":"Gonzalez","sequence":"additional","affiliation":[{"name":"Instituto de Instrumentaci\u00f3n para Imagen Molecular (I3M) Centro Mixto CSIC \u2010 Universitat Polit\u00e8cnica de Val\u00e8ncia Valencia Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,6,21]]},"reference":[{"key":"e_1_2_9_2_1","first-page":"155","article-title":"Positron emission tomography: its 65 years","volume":"39","author":"Del Guerra A","year":"2016","journal-title":"La Rivista del Nuovo Cimento."},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1109\/TRPMS.2017.2692819"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.nima.2018.12.056"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/54\/11\/015"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1109\/TNS.2006.873711"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1109\/TNS.2016.2522179"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.nima.2012.08.094"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4800798"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4742850"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/aacec3"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1109\/TRPMS.2021.3059181"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/54\/7\/003"},{"key":"e_1_2_9_14_1","doi-asserted-by":"crossref","unstructured":"CondeP Gonz\u00e1lezAJ Hern\u00e1ndezL et\u00a0al.Statistical moments of scintillation light distribution analysis with dSiPMs and monolithic crystals. 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