{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T19:48:10Z","timestamp":1792612090280,"version":"4.5.0"},"reference-count":24,"publisher":"Wiley","issue":"11","license":[{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"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":[[2026,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Temporal mismatches between gating signals and beam activation\u2014beam\u2010on and beam\u2010off latencies\u2014in gated particle beam therapy can compromise dose integrity. Yet standardized measurement techniques are lacking, and system\u2010specific characterization, particularly for synchrotron\u2010based proton systems, remains limited.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>To implement a novel strategy for precise end\u2010to\u2010end gating latency measurements of a spot\u2010scanned proton beam using Gafchromic\u00a0film.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Gating latencies have been measured for a Hitachi ProBeat accelerator equipped with a Varian RPM gating system. EBT4 films were positioned within a stack of acrylic blocks on a QUASAR respiratory motion platform operated with a 1.5 cm amplitude and 12 bpm sinusoidal pattern. A stainless\u2010steel ball bearing (BB), positioned atop the film, facilitated localization. During irradiation, the BB produced a dose shadow on the film that indicated the phantom position. A proton plan consisting of a single 85.3 MeV spot was delivered to isocenter during a single gate\u2010on\/off interval initiated near the 25% phase, to maximize phantom velocity. Fifty\u2010one measurements were made with a variety of gating intervals. Beam\u2010on latency and delivery time produced a separation between the BB\u2010shadow and the centroid of the Gaussian proton spot. Spot duration information was extracted from accelerator log files. BB\u2010shadow\/spot separation is modeled analytically based on phantom motion enabling the direct calculation of the total beam\u2010on and beam\u2010off latencies. Accelerator latency was measured directly with an oscilloscope, enabling isolation of the relative contributions of the RPM gating system.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>An average beam\u2010on latency of  ms is observed for the RPM+ProBeat system for the first gate of a delivery, which includes a known 69\u00a0ms beam extraction judgment time for the first proton spot in a spill from the Hitachi synchrotron. The corresponding average beam\u2010off latency is . The average gate\u2010on and gate\u2010off latencies of the RPM system are calculated as  and , respectively. The associated average contributions of the accelerator to the beam\u2010on latencies are measured as  (first gate in new spill) and  (subsequent gates in existing spill) and similarly  for beam\u2010off latency.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>A novel, high\u2010precision method for gating\u2010latency measurements has been implemented using film to characterize gating latencies in a spot\u2010scanned particle beam. Commissioning and regular quality assurance methods to precisely characterize the temporal accuracy of a gating system ensure treatment accuracy and will become increasingly vital to consider for higher\u2010frequency applications, such as cardiac gating or FLASH\u2010capable\u00a0systems.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/acm2.70826","type":"journal-article","created":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T19:23:52Z","timestamp":1792610632000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["End\u2010to\u2010end film\u2010based characterization of gated delivery latencies in a spot\u2010scanned synchrotron\u2010based proton therapy system"],"prefix":"10.1002","volume":"27","author":[{"given":"Z. S.","family":"Stottler","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology Mayo Clinic Rochester Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. J.","family":"Kruse","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Mayo Clinic Rochester Minnesota USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. 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