{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T13:59:26Z","timestamp":1791381566589,"version":"4.3.3"},"reference-count":35,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2025,8,13]],"date-time":"2025-08-13T00:00:00Z","timestamp":1755043200000},"content-version":"vor","delay-in-days":12,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2025,8,1]],"date-time":"2025-08-01T00:00:00Z","timestamp":1754006400000},"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":[[2025,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Intrafraction motion poses a major challenge in ultrahypofractionated prostate SBRT, where high doses and fewer sessions amplify the impact of positional shifts. Its management varies across centers due to differences in technology, protocols, and resources, and standardized clinical guidelines are still lacking despite widespread recognition of its importance.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>To provide insights into real\u2010time monitoring and margin selection by quantifying intrafraction prostate motion using two distinct monitoring systems\u2014system A (electromagnetic transmitter\u2010based) and system B (4D transperineal ultrasound\u2010based)\u2014and evaluate their impact on motion patterns in Linac\u2010based SBRT.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Intrafraction motion data were collected from 92 treatment fractions using system A (47 patients) and 100 fractions using system B (30 patients). All patients underwent SBRT (1\u20135 fractions) with strict rectum and bladder preparation. Motion was recorded at 1 Hz (system A) and 2 Hz (system B) from CBCT acquisition to treatment completion, independent of any patient repositioning. Motion trend was analyzed using a mixed\u2010effects regression model, and Kaplan\u2013Meier failure analysis estimated the time to exceed 2, 3, 4, and 5 mm motion thresholds.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Median monitoring time was 13\u00a0min for system A (range: 5.9\u201335.6) and 6.4\u00a0min for system B (range: 4.9\u201329.3). Motion increased over time in all directions (\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0&lt;\u00a00.001), predominantly in the posterior direction (time coefficient\u00a0=\u00a0\u22120.20,\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0&lt;\u00a00.001). A significant longitudinal (LNG) motion divergence was observed between systems (\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0&lt;\u00a00.001). Kaplan\u2013Meier failure curves were comparable, except for a significant difference in the LNG axis at the 2 mm threshold (log\u2010rank test,\n                      <jats:italic>p<\/jats:italic>\n                      \u00a0=\u00a00.006). The failure rates at 3\u201310\u00a0min for this threshold ranged from 7.3% to 52.4% (system A) and 4.2% to 22.4% (system B). A substantial percentage of fractions (&gt;\u00a05%) exceeded the 2 mm motion threshold at 1.8\u00a0min, the 3 mm threshold at 3.8\u00a0min, the 4 mm threshold at 6.6\u00a0min, and the 5 mm threshold at 8.1\u00a0min.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Both systems exhibited predominant posterior motion, with system B reducing small LNG prostate fluctuations, likely due to probe pressure against the perineum. For fast Linac\u2010based SBRT, intrafraction motion can be managed with 4\u20135 mm margins without continuous monitoring. However, if 2\u20133 mm margins are used, real\u2010time monitoring becomes essential.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.18060","type":"journal-article","created":{"date-parts":[[2025,8,13]],"date-time":"2025-08-13T15:35:46Z","timestamp":1755099346000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Real\u2010time monitoring and appropriate margin selection in linac\u2010based prostate SBRT: Analysis of two different intrafraction motion monitoring systems"],"prefix":"10.1002","volume":"52","author":[{"given":"Denis","family":"Panizza","sequence":"first","affiliation":[{"name":"Medical Physics Fondazione IRCCS San Gerardo dei Tintori  Monza Italy"},{"name":"School of Medicine and Surgery University of Milan Bicocca  Milan Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valeria","family":"Faccenda","sequence":"additional","affiliation":[{"name":"Medical Physics 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