{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T14:51:21Z","timestamp":1786978281838,"version":"build-2736575974"},"reference-count":31,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2025,12,21]],"date-time":"2025-12-21T00:00:00Z","timestamp":1766275200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2025,12,21]],"date-time":"2025-12-21T00:00:00Z","timestamp":1766275200000},"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":[[2026,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Fluoroscopic\u2010gated proton therapy (FGPT) enables precise dose delivery to tumors affected by respiratory motion by tracking internal fiducial markers and delivering the proton beam when the marker is within a gating window. However, scatter radiation from fluoroscopic x\u2010rays may be detected by the dose monitor (DM) and mistakenly counted as proton monitor units (MU). To mitigate this issue, proton beam delivery is typically interrupted during the fluoroscopy pulse, a method known as interrupted continuous delivery (ICD). If the contamination from scattered fluoroscopic x\u2010rays is sufficiently low compared to the proton beam current, uninterrupted continuous delivery (UCD), in which fluoroscopic x\u2010rays are delivered concurrently with proton beams, may be feasible. UCD can enhance beam stability and improve treatment efficiency in particular for synchrotron\u2010based proton therapy systems using continuous beams.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aimed to measure the contamination of scattered fluoroscopic x\u2010rays in DM and to evaluate the dose distribution when fluoroscopic x\u2010rays and proton beams are delivered simultaneously in FGPT.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>x\u2010ray contamination was measured using a proton therapy system equipped with the FGPT system. Fluoroscopic x\u2010rays were delivered for 30 s under both in\u2010air and solid phantom conditions, with thicknesses of 10 and 30\u00a0cm, and DM counts were recorded. The dose rate was evaluated under various fluoroscopic conditions, both with and without the range shifter and mini ridge filter. To assess the dosimetric impact, six virtual treatment plans were created using anthropomorphic phantoms for cases involving the prostate, lung (both superficial and deep), liver (both superficial and deep), and pancreas. Scatter fluoroscopic x\u2010ray contamination was measured at the beam angles specified in the treatment plans under clinical setup conditions. Dose distributions were recalculated assuming simultaneous delivery with proton beam currents of 0.1, 1, 2, 4, 8, and 40 MU\/s, and these were compared to the treatment plans.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The scattered fluoroscopic x\u2010ray contamination in the DM increased with higher tube voltage, tube current, frame rate, and field size. The maximum dose rate was 0.247 MU\/s with 125\u00a0kV tube voltage, 80\u00a0mA tube current, 30\u00a0s\n                      <jats:sup>\u22121<\/jats:sup>\n                      frame rate, 19 \u00d7 19\u00a0cm\n                      <jats:sup>2<\/jats:sup>\n                      field size, and solid phantom of 10\u00a0cm. The dose rate of scattered fluoroscopic x\u2010rays peaked at a solid phantom thickness of approximately 5\u00a0cm. In an anthropomorphic phantom, scattered fluoroscopic x\u2010ray contamination varies based on anatomical site and beam angle. Dose evaluations indicated that if the proton beam current was \u22652\u00a0MU\/s at the target and \u22651\u00a0MU\/s at organs at risk, the differences in dose metrics were within 1% compared to the treatment plans. These beam currents are achievable with clinical systems.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Scattered fluoroscopic x\u2010rays were confirmed to contaminate the DM and be counted as proton MUs. However, under clinically realistic beam current conditions, their impact on dose distribution in UCD FGPT was negligible. These findings support the feasibility of implementing UCD FGPT.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70227","type":"journal-article","created":{"date-parts":[[2025,12,22]],"date-time":"2025-12-22T04:37:34Z","timestamp":1766378254000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Dosimetric impact and safety of uninterrupted fluoroscopic\u2010gated proton therapy"],"prefix":"10.1002","volume":"53","author":[{"given":"Masashi","family":"Yamanaka","sequence":"first","affiliation":[{"name":"Department of Medical Physics Shonan Kamakura General Hospital  Kamakura Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keith M.","family":"Furutani","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Division of Medical Physics Mayo Clinic Florida  Jacksonville Florida 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