{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T16:36:24Z","timestamp":1782837384303,"version":"3.54.5"},"reference-count":30,"publisher":"Wiley","issue":"11","license":[{"start":{"date-parts":[[2025,11,8]],"date-time":"2025-11-08T00:00:00Z","timestamp":1762560000000},"content-version":"vor","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,11,1]],"date-time":"2025-11-01T00:00:00Z","timestamp":1761955200000},"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":[[2025,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Secondary\u2010radiation background (BG) generated in kilovoltage X\u2010ray flat\u2010panel detectors (FPDs) under scanning proton beam irradiation has not been thoroughly analyzed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aimed to determine and mathematically model the characteristics of secondary\u2010radiation BG in FPDs under scanning proton beam irradiation.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Using a synchrotron\u2010based proton system and two FPDs mounted on a gantry tilted at 135\u00b0 to the proton beam axis, we acquired images of two phantoms (block and thorax). The FPD images were captured during three conditions: only X\u2010ray exposure, proton irradiation, and pauses between proton irradiations. Because the FPD readout rate (30 fps) was twice the X\u2010ray exposure rate (15 pps), the images were further categorized into two types: those corresponding to with and without X\u2010ray exposure. These FPD images were analyzed to determine the characteristics of the secondary\u2010radiation BG. In addition, a Monte Carlo simulation was conducted to complement the performed measurements.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Analysis of the FPD images without X\u2010ray exposure revealed that the pure secondary\u2010radiation BG appeared as sparse spike patterns without a noticeable spatial bias across the FPD area in most images. The BG affected only 1.25% of the FPD pixels and could be modeled as an exponentially decreasing function with increasing pixel intensity. When considering typical X\u2010ray image brightness for the block and thorax phantoms, the impact of the BG on mean\u2010pixel\u2010intensity variation was\u00a0&lt;\u00a01%. Monte Carlo simulations suggested that prompt photons were the primary source reaching the FPD.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>This study demonstrates that the secondary\u2010radiation BG characteristics observed in the X\u2010ray FPD images during scanning proton beam irradiation can be quantitatively modeled. The impact of the secondary\u2010radiation BG on mean\u2010pixel\u2010intensity of FPD images was minimal.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70121","type":"journal-article","created":{"date-parts":[[2025,11,9]],"date-time":"2025-11-09T03:24:49Z","timestamp":1762658689000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Characterization of secondary\u2010radiation background in X\u2010ray flat\u2010panel detectors during scanning proton beam irradiation"],"prefix":"10.1002","volume":"52","author":[{"given":"Toshiyuki","family":"Terunuma","sequence":"first","affiliation":[{"name":"Institute of Medicine University of Tsukuba  Ibaraki Japan"},{"name":"Proton Medical Research Center University of Tsukuba Hospital  Ibaraki Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kenta","family":"Takada","sequence":"additional","affiliation":[{"name":"Graduate School of Radiological Technology Gunma Prefectural College of Health Sciences  Gunma Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seishin","family":"Takao","sequence":"additional","affiliation":[{"name":"Faculty of Engineering Hokkaido University  Hokkaido Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mayu","family":"Osugi","sequence":"additional","affiliation":[{"name":"Therapy System Business, Healthcare Business Group Hitachi High\u2010Tech Co.  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