{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T13:54:04Z","timestamp":1791986044855,"version":"4.4.0"},"reference-count":25,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T00:00:00Z","timestamp":1770681600000},"content-version":"vor","delay-in-days":9,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T00:00:00Z","timestamp":1769904000000},"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":[[2026,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>In the IAEA TRS\u2010483 Code of Practice (CoP), rectangular small field sizes are approximated to equivalent square small fields using the definition proposed by Cranmer\u2010Sargison et al. However, the CoP estimates the uncertainties associated with this formula only for rectangular fields with dimensions within the range .<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>The objective of the present study was to compare the accuracy of the Cranmer\u2010Sargison definition with other formulas for equivalent square small fields in the context of measuring field output factors (FOFs) for rectangular small fields, both within and outside the range covered by the\u00a0CoP.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Measurements were conducted using Gafchromic EBT4 radiochromic films. The models compared included Cranmer\u2010Sargison, Sterling, Superellipse, Sterling\u2010Partial Superellipse, Sterling\u2010Superellipse, Vadash and Bj\u00e4rngard, and Fogliata. The most accurate definition of equivalent square field size was identified as the one yielding the lowest discrepancy between measured and analytical values, with the log\u2010likelihood of the measurements selected as the metric. Analytical values were derived using the function introduced by Sauer and Wilbert, which relates FOFs to equivalent square field sizes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The best results were achieved with the Fogliata model, followed in terms of accuracy by the Sterling\u2010Partial Superellipse model. The Sterling\u2010Superellipse and Vadash and Bj\u00e4rngard models came next. It should be noted that the Sterling\u2010Partial Superellipse and Sterling\u2010Superellipse models rely solely on the geometric shape of the irradiation field size, whereas the Fogliata and Vadash and Bj\u00e4rngard models incorporate a fitting parameter. The Sterling definition, while less accurate than these models, improved upon the Cranmer\u2010Sargison definition and retained computational simplicity. Finally, the Cranmer\u2010Sargison and Superellipse models exhibited the largest\u00a0discrepancies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>This study identified several definitions of equivalent square small field size that could refine the IAEA TRS\u2010483 CoP by improving the accuracy of field output correction factors for rectangular small fields. Among these definitions, the Fogliata model obtained the best results.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/acm2.70500","type":"journal-article","created":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T12:13:13Z","timestamp":1770725593000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Evaluating equivalent square field size definitions for rectangular small fields"],"prefix":"10.1002","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0429-9145","authenticated-orcid":false,"given":"Ignasi","family":"M\u00e9ndez","sequence":"first","affiliation":[{"name":"Department of Dosimetry and Quality of Radiological Procedures Institute of Oncology Ljubljana Ljubljana Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0627-8903","authenticated-orcid":false,"given":"Mateb","family":"Al Khalifa","sequence":"additional","affiliation":[{"name":"Virginia Commonwealth University Richmond Virginia USA"},{"name":"Department of Radiation Medicine Northwell Health Lake Success New York USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-5650-3611","authenticated-orcid":false,"given":"Haya","family":"Aljuaid","sequence":"additional","affiliation":[{"name":"Virginia Commonwealth University Richmond Virginia USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bo\u017eidar","family":"Casar","sequence":"additional","affiliation":[{"name":"Department of Dosimetry and Quality of Radiological Procedures Institute of Oncology Ljubljana Ljubljana Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,2,10]]},"reference":[{"key":"e_1_2_9_2_1","volume-title":"Dosimetry of Small Static Fields Used in External Beam Radiotherapy: An IAEA\u2010AAPM International Code of Practice for Reference and Relative Dose Determination","author":"Palmans H","year":"2017"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.13208"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2013.10.002"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.16069"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.15624"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1259\/0007-1285-37-439-544"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radphyschem.2021.109775"},{"key":"e_1_2_9_9_1","first-page":"166","article-title":"Suggestion of a perimeter formula for super ellipses and their use in rectangular boundary value problems in physics","volume":"12","author":"Erba\u015f KC","year":"2022","journal-title":"Karaelmas Fen ve M\u00fchendislik Dergisi"},{"key":"e_1_2_9_10_1","volume-title":"Radiation Oncology Physics: A Handbook for Teachers and Students","author":"Podgorsak EB","year":"2005"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.597024"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.17806"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.595161"},{"key":"e_1_2_9_14_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr\/27713136"},{"key":"e_1_2_9_15_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.12201"},{"key":"e_1_2_9_16_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.14497"},{"key":"e_1_2_9_17_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/61\/21\/7704"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/61\/2\/625"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/59\/13\/3575"},{"key":"e_1_2_9_20_1","doi-asserted-by":"publisher","DOI":"10.2478\/raon-2021-0034"},{"key":"e_1_2_9_21_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/aad9c1"},{"key":"e_1_2_9_22_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.13318"},{"key":"e_1_2_9_23_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.12885"},{"key":"e_1_2_9_24_1","volume-title":"JCGM 100:2008. 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