{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T09:40:44Z","timestamp":1792402844224,"version":"4.4.0"},"reference-count":17,"publisher":"Wiley","issue":"10","license":[{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"vor","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T00:00:00Z","timestamp":1790812800000},"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":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2026,10]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>\n                      User\u2010derived electrometer calibration factors (\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      ) have been proposed as a practical approach for electrometer quality assurance in radiotherapy dosimetry. However, the contribution of long\u2010term stability to the uncertainty of\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      has not been quantitatively evaluated. This study aimed to assess the long\u2010term stability of\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      over a 28\u2010month period and to validate the method using different signal input techniques.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      A RAMTEC Solo electrometer was used as the reference electrometer, and three electrometers (UNIDOS\n                      <jats:sup>webline<\/jats:sup>\n                      , RAMTEC Duo, and Super MAX) were evaluated as electrometers under test. Electrometer sensitivity ratios were measured using three signal input methods: A LINAC\u2010based method, a battery\u2010powered current source (SCG002), and a servo\u2010controlled current source (EMF521R). User\u2010derived calibration factors were calculated from the sensitivity ratios and the calibration coefficient of the reference electrometer. Long\u2010term stability was evaluated from repeated measurements over 28 months using linear regression analysis, and the associated uncertainty component was estimated according to the Guide to the Expression of Uncertainty in Measurement (GUM).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The coefficients of variation for repeated measurements were \u2264 0.071% for all methods. The\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      values obtained using the LINAC method, SCG002, and EMF521R agreed within 0.1%, with a maximum relative difference of 0.06%. Over the 28\u2010month observation period, the largest estimated drift was 1.84 \u00d7 10\n                      <jats:sup>\u2212<\/jats:sup>\n                      <jats:sup>4<\/jats:sup>\n                      , corresponding to a Type B standard uncertainty of 1.06 \u00d7 10\n                      <jats:sup>\u2212<\/jats:sup>\n                      <jats:sup>4<\/jats:sup>\n                      (1.06 \u00d7 10\n                      <jats:sup>\u2212<\/jats:sup>\n                      <jats:sup>2<\/jats:sup>\n                      %). The combined standard uncertainty of\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      remained 0.20%, and the experimentally determined long\u2010term stability component had a negligible effect on the overall uncertainty.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      The influence of signal input method on\n                      <jats:italic>k<\/jats:italic>\n                      <jats:sub>elec, user<\/jats:sub>\n                      was minimal, and consistent results were obtained using LINAC\u2010based and current\u2010source\u2010based measurements. The uncertainty contribution from long\u2010term stability over 28 months was negligible compared with the reported uncertainty of electrometer calibration factors. These findings support the use of periodic in\u2010house sensitivity comparison measurements as a complementary quality assurance tool for monitoring electrometer performance between external calibrations. These findings extend previous studies by providing quantitative evidence of the relative sensitivity stability of user\u2010derived electrometer calibration factors and thereby support their application for routine in\u2010house quality assurance.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/acm2.70840","type":"journal-article","created":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T14:07:43Z","timestamp":1791468463000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Long\u2010term stability evaluation of user\u2010derived electrometer calibration factors (\n                    <i>k<\/i>\n                    <sub>elec, user<\/sub>\n                    ) for radiotherapy dosimetry"],"prefix":"10.1002","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6720-648X","authenticated-orcid":false,"given":"Hayato","family":"Tsuno","sequence":"first","affiliation":[{"name":"Gunma Prefectural College of Health Sciences  Maebashi Gunma JAPAN"},{"name":"Department of Radiation Oncology Japanese\u00a0Red\u00a0Cross Maebashi Hospital  Maebashi Gunma JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7027-9188","authenticated-orcid":false,"given":"Koji","family":"Sasaki","sequence":"additional","affiliation":[{"name":"Graduate School of Radiological Technology Gunma Prefectural College of Health Sciences  Maebashi Gunma JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruan","family":"Sasaki","sequence":"additional","affiliation":[{"name":"Department of Radiology National Hospital Organization Sendai Medical Center  Sendai Miyagi JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7022-1558","authenticated-orcid":false,"given":"Fumiyasu","family":"Matsubayashi","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Cancer Institute Hospital, Japanese Foundation for Cancer Research  Tokyo JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kohei","family":"Nishi","sequence":"additional","affiliation":[{"name":"Department of Radiology JR Tokyo General Hospital  Tokyo JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tae","family":"Ushikawa","sequence":"additional","affiliation":[{"name":"Department of Radiology JR Tokyo General Hospital  Tokyo JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daisaku","family":"Goto","sequence":"additional","affiliation":[{"name":"Department of Radiology JR Tokyo General Hospital  Tokyo JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ririko","family":"Kosugi","sequence":"additional","affiliation":[{"name":"Department of Radiology Hamamatsu University School of Medicine  Hamamatsu Shizuoka JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yasuhiro","family":"Kawashima","sequence":"additional","affiliation":[{"name":"Department of Medical Technology Japanese\u00a0Red\u00a0Cross Maebashi Hospital  Maebashi Gunma JAPAN"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,10,8]]},"reference":[{"key":"e_1_2_11_2_1","volume-title":"Determination of Absorbed Dose in a Patient Irradiated by Beams of X\u2010 or Gamma\u2010Rays in Radiotherapy Procedures","author":"Cunningham J","year":"1976"},{"key":"e_1_2_11_3_1","volume-title":"Medical electrical equipment\u2014Dosimeters with ionization chambers as used in radiotherapy","author":"International Electrotechnical Commission (IEC)","year":"2011"},{"key":"e_1_2_11_4_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4866223"},{"key":"e_1_2_11_5_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/45\/9\/301"},{"key":"e_1_2_11_6_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/43\/8\/028"},{"key":"e_1_2_11_7_1","unstructured":"MatsubayashiF TsunoH MatsumotoK et\u00a0al.Current generator for precision control of electrometer precision control system and calibration method. Japan 2021: Patent6989834."},{"key":"e_1_2_11_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.14082"},{"key":"e_1_2_11_9_1","doi-asserted-by":"publisher","DOI":"10.11323\/jjmp.44.2_21"},{"key":"e_1_2_11_10_1","doi-asserted-by":"publisher","DOI":"10.6009\/jjrt.2023\u20101216"},{"key":"e_1_2_11_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.70476"},{"key":"e_1_2_11_12_1","doi-asserted-by":"publisher","DOI":"10.1007\/s12273\u2010022\u20100935\u20107"},{"key":"e_1_2_11_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.measurement.2020.107871"},{"key":"e_1_2_11_14_1","doi-asserted-by":"publisher","DOI":"10.3390\/en15041394"},{"key":"e_1_2_11_15_1","volume-title":"Evaluation of Measurement Data\u2014Guide to the Expression of Uncertainty in Measurement (GUM)","author":"Joint Committee for Guides in Metrology (JCGM)","year":"2008"},{"key":"e_1_2_11_16_1","doi-asserted-by":"publisher","DOI":"10.1093\/rpd\/ncac262"},{"key":"e_1_2_11_17_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10967\u2010026\u201010921\u20100"},{"key":"e_1_2_11_18_1","doi-asserted-by":"publisher","DOI":"10.1120\/jacmp.v9i1.2676"}],"container-title":["Journal of Applied Clinical Medical Physics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/acm2.70840","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/acm2.70840","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/acm2.70840","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T08:53:05Z","timestamp":1792399985000},"score":1,"resource":{"primary":{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/10.1002\/acm2.70840"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,10]]},"references-count":17,"journal-issue":{"issue":"10","published-print":{"date-parts":[[2026,10]]}},"alternative-id":["10.1002\/acm2.70840"],"URL":"https:\/\/doi.org\/10.1002\/acm2.70840","archive":["Portico"],"relation":{},"ISSN":["1526-9914","1526-9914"],"issn-type":[{"value":"1526-9914","type":"print"},{"value":"1526-9914","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,10]]},"assertion":[{"value":"2026-06-22","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-09-21","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-10-08","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70840"}}