{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T13:45:24Z","timestamp":1792071924807,"version":"4.4.0"},"reference-count":27,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T00:00:00Z","timestamp":1788739200000},"content-version":"vor","delay-in-days":6,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"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>Proton minibeam radiation therapy is an emerging technique that combines the tissue\u2010sparing benefits of protons with the spatial modulation used for minibeams to reduce toxicity in healthy tissue. Achieving accurate delivery of planned dose distributions depends on precise collimator\u2010to\u2010beam alignment, for which it is essential to understand the behavior of both multi\u2010slit and single\u2010slit configurations. Understanding single\u2010slit behavior is particularly important, as it also linearly affects the heterogeneity (peaks and valleys) of the overall minibeam. While several studies have investigated misalignment effects with multi\u2010slit collimators, there is limited experimental characterisation of single\u2010slit behavior and its impact on multi\u2010slit\u00a0arrays.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aims to quantify the dosimetric effects of translational and rotational collimator\u2010to\u2010beam misalignments for single\u2010slit proton minibeams using our in\u2010house automated measurement setup. Additionally, the robustness of lateral dose profiles for minibeam arrays will be investigated under varying collimator\u00a0misalignments.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A single slit collimator with  protons was used to produce a single minibeam with adjustable collimator slit widths (0.4 and ). We introduced rotational and translational misalignments using motorized stages. We developed a quick measurement setup to measure lateral profiles using a microDiamond detector. The lateral profiles were measured at depths of 1 and  using a water\u2010equivalent phantom. We validated the setup by comparing the measurements to gafchromic film measurements using local gamma analysis. A custom fitting model combining two Gaussians and a Lorentzian was developed to fit the lateral profiles. From the fitted profiles, we determined the maximum dose, the lateral position of maximum dose, the full width at half maximum, and the symmetry. Minibeam arrays were simulated via superposition of single\u2010slit profiles. Specific misalignment combinations were measured for 140, 160, and  protons, energies typically used in the clinic for deep seated tumours, to assess how misalignments affect the minibeam at different\u00a0energies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Rotational misalignments caused substantial asymmetry and peak dose reductions up to 68.4% at shallow depths, with asymmetry reducing at greater depths. Translational shifts resulted in a translation of the minibeam profile in the same direction and magnitude without changing the minibeams shape. Despite these distortions, simulated minibeam arrays achieved acceptable dose homogeneity at  depth for central 80% field\u2010widths with flatness below a 3% threshold. The proposed measurement setup enabled profile acquisition of a single minibeam in under one minute with submillimetre resolution and strong agreement with gafchromic film (3%\/ gamma pass rates of 100%).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Collimator misalignments substantially affect the minibeam dose robustness and should be considered in clinical treatment planning and quality assurance (QA). The presented measurement setup enables, rapid, high\u2010resolution profile measurements using commercially available detectors and can facilitate routine clinical\u00a0QA.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.70671","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T08:56:45Z","timestamp":1788771405000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of collimator misalignments on dosimetric robustness in proton minibeam radiotherapy using an automated measurement setup"],"prefix":"10.1002","volume":"53","author":[{"given":"Sake","family":"Salverda","sequence":"first","affiliation":[{"name":"Faculty of Mechanical Engineering Delft University of Technology Delft the Netherlands"},{"name":"Department of Research and Development Holland Proton Therapy Center Delft the Netherlands"},{"name":"Department of Medical Physics &amp; Informatics Holland Proton Therapy Center Delft the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ernst","family":"van der Wal","sequence":"additional","affiliation":[{"name":"Department of Research and Development Holland Proton Therapy Center Delft the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas","family":"Toet","sequence":"additional","affiliation":[{"name":"Department of Research and Development Holland Proton Therapy Center Delft the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mischa","family":"Hoogeman","sequence":"additional","affiliation":[{"name":"Department of Medical Physics &amp; Informatics Holland Proton Therapy Center Delft the Netherlands"},{"name":"Department of Radiotherapy Erasmus MC Cancer Institute Rotterdam the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kelvin","family":"Ng Wei Siang","sequence":"additional","affiliation":[{"name":"Department of Medical Physics &amp; Informatics Holland Proton Therapy Center Delft the Netherlands"},{"name":"Department of Radiotherapy Erasmus MC Cancer Institute Rotterdam the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,7]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.3390\/cancers16234013"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejmp.2022.06.010"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2025.111050"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/ad4192"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejmp.2015.04.014"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4791648"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41598\u2010018\u201034796\u20108"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2024.110577"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.nimb.2013.08.035"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.3390\/cancers14010026"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.15780"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/ade04b"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejmp.2024.104883"},{"key":"e_1_2_8_15_1","unstructured":"Gom\u00e0 EstadellaC.Radiation Dosimetry of Clinical Proton Beams. 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