{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T01:39:56Z","timestamp":1777945196625,"version":"3.51.4"},"reference-count":23,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T00:00:00Z","timestamp":1738800000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T00:00:00Z","timestamp":1738800000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/100007325","name":"American Association of Physicists in Medicine","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100007325","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006098","name":"Radiological Society of North America","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100006098","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council of Canada","doi-asserted-by":"publisher","award":["RGPAS\u20102021\u201000019"],"award-info":[{"award-number":["RGPAS\u20102021\u201000019"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001804","name":"Canada Research Chairs","doi-asserted-by":"publisher","award":["CRC\u20102019\u201000039"],"award-info":[{"award-number":["CRC\u20102019\u201000039"]}],"id":[{"id":"10.13039\/501100001804","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2025,5]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The inaccessibility of clinical linear accelerators in low\u2010 and middle\u2010income countries creates a need for low\u2010cost alternatives. Kilovoltage (kV)\u00a0x\u2010ray tubes have shown promise as a source that could meet this need. However, performing radiotherapy with a kV x\u2010ray tube has numerous difficulties, including high skin dose, rapid dose fall\u2010off, and low dose rates. These limitations create a need for highly effective beam collimation and\u00a0filtration.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>To improve the treatment potential of a novel kV x\u2010ray system by optimizing an iris collimator and beam filtration using Bayesian techniques and Monte Carlo (MC)\u00a0simulations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The Kilovoltage Optimized AcceLerated Adaptive therapy system's current beam configuration consists of a 225\u00a0kVp x\u2010ray tube, a 12\u2010leaflet tungsten iris collimator, and a 0.1\u00a0mm copper filter. A Bayesian optimization was performed for the large and small focal spot sizes of the kV x\u2010ray tube source at 220\u00a0kVp using TopasOpt, an open\u2010source library for optimization in TOPAS. Collimator thickness, copper filter thickness, source\u2010to\u2010collimator distance (SCD), and source\u2010to\u2010surface distance (SSD) were the variables considered in the optimization. The objective function was designed to maximize the dose rate and the dose at a depth of 5 cm while minimizing the beam penumbra width and the out\u2010of\u2010field dose (OFD), all evaluated in a water phantom. Post\u2010optimization, the optimal beam configuration was simulated and compared to the existing\u00a0configuration.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The optimal collimation setup consisted of 2.5\u00a0mm thick tungsten leaflets for the iris collimator and a 350\u00a0mm SSD for both focal spot sizes. The optimal copper filtration was 0.22\u00a0mm for the large focal spot and 0.15\u00a0mm for the small focal spot, with a SCD of 148.5\u00a0mm for the large focal spot and 125.8\u00a0mm for the small focal spot. For the large focal spot, the surface dose rate decreased by 9.4%, while the PDD at 5cm depth () increased by 7.7% compared to the existing iris collimator. Additionally, the surface beam penumbra width was reduced by 31.3%, and no significant changes in the OFD were observed. For the small focal spot, the surface dose rate for the new collimator increased by 3.7% and the  increased by 5.3%, with no statistically significant changes in the beam penumbra width or\u00a0OFD.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The optimal beam collimation and filtration for both x\u2010ray tube focal spot sizes of a kV radiotherapy system was determined using Bayesian optimization and MC simulations and resulted in improved dose\u00a0distributions.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.17662","type":"journal-article","created":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T07:56:22Z","timestamp":1738828582000},"page":"3204-3215","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Beam collimation and filtration optimization for a novel orthovoltage radiotherapy 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Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Magdalena","family":"Bazalova\u2010Carter","sequence":"additional","affiliation":[{"name":"Department of Physics and Astronomy University of Victoria Victoria British Columbia Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2025,2,6]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2020.01.023"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1200\/GO.21.00029"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejmp.2020.11.001"},{"key":"e_1_2_8_5_1","first-page":"12","article-title":"Superficial radiation therapy for the treatment of nonmelanoma skin cancers","volume":"8","author":"McGregor S","year":"2015","journal-title":"J Clin Aesthet 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