{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T13:45:25Z","timestamp":1792071925934,"version":"4.4.0"},"reference-count":14,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"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":[[2026,9]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>While pencil beam scanning (PBS) with motion mitigation such as re\u2010scanning, breath hold, or gating is well established for treating moving targets in clinical practice, the precision for Spatially Fractionated Radiation Therapy (SFRT) using proton minibeams introduces presents a unique challenge. The sub\u2010millimeter precision required for SFRT cannot be achieved with typical PBS spot sizes (millimeters), necessitating multi\u2010slit beam collimation, which reduces the dose rate and reintroduces motion as a critical issue. In this study, we report on our experience with minibeam irradiations of chorioallantoic membranes (CAM) of chick embryos and discuss potential solutions to the motion problem.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The first experiment was conducted at a PBS gantry using 130 MeV protons and a 6\u00a0cm thick copper multi\u2010slit collimator with 0.3\u00a0mm wide slits and 1\u00a0mm spacing. To achieve a target peak dose of 30\u00a0Gy, CAM samples were irradiated with more than 10 re\u2010scans. Due to a 91% beam loss in the collimator, the total irradiation time extended to two min.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Post\u2010irradiation analysis using gafchromic film revealed smearing of the minibeam profiles, while biological tissue analysis uncovered unexpected and disrupted dose effects, likely caused by irregular CAM movement during irradiation. A subsequent experiment, incorporating additional setup optimizations such as reduced air gap and increased dose rate, shortened the irradiation time to below one min. This led to sharper dose profiles with negligible variation in valley dose and peak width, although a reduction in peak dose of 8%\u201313% was still observed. This variation is considered acceptable for our biological experiments.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>For clinical applications, minibeam re\u2010scanning is likely to be feasible only under ultra\u2010high dose rate conditions (e.g., those required to induce the FLASH effect), where sufficiently short irradiation times minimize motion\u2010induced dose degradation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70638","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T05:40:36Z","timestamp":1787118036000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of millimeter\u2010scale target motion on the precision of spatially fractionated radiation therapy using proton minibeams"],"prefix":"10.1002","volume":"53","author":[{"given":"Oxana","family":"Actis","sequence":"first","affiliation":[{"name":"Center for Proton Therapy Paul Scherrer Institute  Villigen PSI Aargau Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cristian","family":"Fernandez\u2010Palomo","sequence":"additional","affiliation":[{"name":"Institute of Anatomy University of Bern  Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Verdiana","family":"Trappetti","sequence":"additional","affiliation":[{"name":"Institute of Anatomy University of Bern  Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michele","family":"Togno","sequence":"additional","affiliation":[{"name":"Center for Proton Therapy Paul Scherrer Institute  Villigen PSI Aargau Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paolo","family":"Pellicioli","sequence":"additional","affiliation":[{"name":"Institute of Anatomy University of Bern  Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dominic","family":"Leiser","sequence":"additional","affiliation":[{"name":"Center for Proton Therapy Paul Scherrer Institute  Villigen PSI Aargau Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Meer","sequence":"additional","affiliation":[{"name":"Center for Proton Therapy Paul Scherrer Institute  Villigen PSI Aargau Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valentin","family":"Djonov","sequence":"additional","affiliation":[{"name":"Institute of Anatomy University of Bern  Bern Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,8,18]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2019.01.080"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598\u2010018\u201034796\u20108"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr.20180466"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ctro.2025.100932"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598\u2010020\u201068015\u20100"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.3390\/cancers14010026"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.13093"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/J.IJROBP.2015.10.020"},{"key":"e_1_2_8_10_1","unstructured":"RoussetiA et\u00a0al.Current status of MINIBEE: minibeam beamline for preclinical experiments on spatial fractionation in the FLASH regime. In:Proc. IPAC\u201924. IPAC\u201924 \u2010 15th International Particle Accelerator Conference.JACoW Publishing;2024:3663\u20133666. doi:10.18429\/JACoW\u2010IPAC2024\u2010THPR62"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/ar.10021"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1088\/1742\u20106596\/1067\/9\/092002"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/aa5131"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4758060"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2024.04.011"}],"container-title":["Medical Physics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/mp.70638","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/mp.70638","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/mp.70638","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T12:55:23Z","timestamp":1792068923000},"score":1,"resource":{"primary":{"URL":"https:\/\/aapm.onlinelibrary.wiley.com\/doi\/10.1002\/mp.70638"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,18]]},"references-count":14,"journal-issue":{"issue":"9","published-print":{"date-parts":[[2026,9]]}},"alternative-id":["10.1002\/mp.70638"],"URL":"https:\/\/doi.org\/10.1002\/mp.70638","archive":["Portico"],"relation":{},"ISSN":["0094-2405","2473-4209"],"issn-type":[{"value":"0094-2405","type":"print"},{"value":"2473-4209","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,18]]},"assertion":[{"value":"2025-10-31","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-05-22","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-08-18","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}],"article-number":"e70638"}}