{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T13:45:18Z","timestamp":1792071918342,"version":"4.4.0"},"reference-count":27,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T00:00:00Z","timestamp":1787616000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T00:00:00Z","timestamp":1787616000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>During decommissioning of positron emission tomography (PET) cyclotron facilities, metallic components\u2014including the iron yoke\u2014are typically classified as radioactive waste, incurring substantial disposal costs. In contrast to concrete, standardized decommissioning procedures for metallic components have not yet been established.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aimed to experimentally assess activation in a PET cyclotron and provide fundamental data for establishing decommissioning guidelines for metallic components. The investigation focused on residual activity in the yoke and center pole, which are among the heaviest structural parts.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A PET cyclotron that operated for 23\u00a0years at the Tokyo Metropolitan Institute for Geriatrics and Gerontology was examined 6\u00a0years after the cyclotron's complete shutdown using two complementary approaches: non\u2010destructive \u03b3\u2010ray measurements and destructive core\u2010boring analysis.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      <jats:sup>60<\/jats:sup>\n                      Co was the predominant residual radionuclide. On the outer surfaces,\n                      <jats:sup>60<\/jats:sup>\n                      Co specific activity typically ranged from 0.02 to 0.10\u00a0Bq\/g, with many locations below the 0.1\u00a0Bq\/g clearance level. Cross\u2010sectional mapping showed exponential attenuation behavior from the interior outward. Higher activation in the center pole (up to \u223c1.0\u00a0Bq\/g) was observed.\n                      <jats:sup>54<\/jats:sup>\n                      Mn was one to two orders of magnitude lower than\n                      <jats:sup>60<\/jats:sup>\n                      Co at 6\u00a0years post\u2010shutdown. Non\u2010destructive and destructive results were in close agreement, validating the quantitative use of \u03b3\u2010detectors for near\u2010surface activity. A hypothetical time\u2010dependent decay estimation, based on the non\u2010destructive\/destructive findings, was performed to project a required cooling period to meet clearance.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Activation levels in PET cyclotron components can be effectively assessed using combined non\u2010destructive and destructive approaches. The complex distribution of residual activity was observed in the yoke and center poles. Decay projections indicated that approximately half of the yoke would fall below the clearance level within 15\u00a0years and nearly all components within 23\u00a0years after shutdown. These findings provide essential benchmarks for improving simulation\u2010based activation modeling and can be broadly applied to similar PET cyclotron systems.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70649","type":"journal-article","created":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T07:14:53Z","timestamp":1787642093000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Experimental activation assessment of open\u2010type yoke in a PET cyclotron by non\u2010destructive\/destructive \u03b3\u2010ray measurement approaches"],"prefix":"10.1002","volume":"53","author":[{"given":"Go","family":"Yoshida","sequence":"first","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroshi","family":"Matsumura","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akihiro","family":"Toyoda","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hajime","family":"Nakamura","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kazuyoshi","family":"Masumoto","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Taichi","family":"Miura","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eisuke","family":"Watanabe","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kiyokazu","family":"Tsugane","sequence":"additional","affiliation":[{"name":"High Energy Accelerator Research Organization (KEK)  Tsukuba Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Katsuhiko","family":"Saito","sequence":"additional","affiliation":[{"name":"Sumitomo Heavy Industries, Ltd.  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Saijo Ehime Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Toyohara","sequence":"additional","affiliation":[{"name":"Tokyo Metropolitan Institute for Geriatrics and Gerontology  Tokyo, Itabashi\u2010ku Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kei","family":"Wagatsuma","sequence":"additional","affiliation":[{"name":"Tokyo Metropolitan Institute for Geriatrics and Gerontology  Tokyo, Itabashi\u2010ku Japan"},{"name":"Hokkaido University  Sapporo Hokkaido Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,8,25]]},"reference":[{"key":"e_1_2_9_2_1","unstructured":"Japan Radioisotope Association.Statistics on the Use of Radiation in Japan;2019."},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1088\/1742\u20106596\/1046\/1\/012016"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1039\/9781788017732\u201000135"},{"issue":"6","key":"e_1_2_9_5_1","first-page":"545","article-title":"In\u2010situ evaluation for activated concrete in accelerator facility with scintillation\u2010type gamma\u2010ray spectrometer","volume":"40","author":"Yoshida G","year":"2020","journal-title":"Radiat Prot"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.3769\/radioisotopes.69.365"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1080\/00223131.2024.2313558"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.14407\/jrpr.2023.00346"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1039\/9781788017732\u201000178"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1039\/9781788017732\u201000152"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1080\/00223131.2021.1985646"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1088\/1742\u20106596\/1046\/1\/012017"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.apradiso.2020.109446"},{"key":"e_1_2_9_14_1","unstructured":"ICRP.Nuclear Decay Data for Dosimetric Calculations. 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