{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T06:01:50Z","timestamp":1785391310977,"version":"3.55.0"},"reference-count":35,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2023,7,21]],"date-time":"2023-07-21T00:00:00Z","timestamp":1689897600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2023,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Proton arcs have shown potential to reduce the dose to organs at risks (OARs) by delivering the protons from many different directions. While most previous studies have been focused on dynamic arcs (delivery during rotation), an alternative approach is discrete arcs, where step\u2010and\u2010shoot delivery is used over a large number of beam directions. The major advantage of discrete arcs is that they can be delivered at existing proton facilities. However, this advantage comes at the expense of longer treatment times.<\/jats:p><\/jats:sec><jats:sec><jats:title>Purpose<\/jats:title><jats:p>To exploit the dosimetric advantages of proton arcs, while achieving reasonable delivery times, we propose a partitioning approach where discrete arc plans are split into subplans to be delivered over different fractions in the treatment course.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>For three oropharyngeal cancer patients, four different arc plans have been created and compared to the corresponding clinical IMPT plan. The treatment plans are all planned to be delivered in 35 fractions, but with different delivery approaches over the fractions. The first arc plan (1\u00d730) has 30 directions to be delivered every fraction, while the others are partitioned into subplans with 10 and 6 beam directions, each to be delivered every third (3\u00d710), fifth fraction (5\u00d76), or seventh fraction (7\u00d710). All plans are assessed with respect to delivery time, target robustness over the treatment course, doses to OARs and NTCP for dysphagia and xerostomia.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The delivery time (including an additional delay of 30 s between the discrete directions to simulate manual interaction with the treatment control system) is reduced from on average 25.2\u00a0min for the 1\u00d730 plan to 9.2\u00a0min for the 3\u00d710 and 7\u00d710 plans and 5.7\u00a0min for the 5\u00d76 plans. The delivery time for the IMPT plan is 7.9\u00a0min. When accounting for the combination of delivery time, target robustness, OAR sparing, and NTCP reduction, the plans with 10 directions in each fraction are the preferred choice. Both the 3\u00d710 and 7\u00d710 plans show improved target robustness compared to the 1\u00d730 plans, while keeping OAR doses and NTCP values at almost as low levels as for the 1\u00d730 plans. For all patients the NTCP values for dysphagia are lower for the partitioned plans with 10 directions compared to the IMPT plans. NTCP reduction for xerostomia compared to IMPT is seen in two of the three patients. The best results are seen for the first patient, where the NTCP reductions for the 7\u00d710 plan are 1.6 p.p. (grade 2 xerostomia) and 1.5 p.p. (grade 2 dysphagia). The corresponding NTCP reductions for the 1\u00d730 plan are 2.7 p.p. (xerostomia, grade 2) and 2.0 p.p. (dysphagia, grade 2).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Discrete proton arcs can be implemented at any proton facility with reasonable treatment times using a partitioning approach. The technique also makes the proton arc treatments more robust to changes in the patient anatomy.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.16617","type":"journal-article","created":{"date-parts":[[2023,7,22]],"date-time":"2023-07-22T05:13:45Z","timestamp":1690002825000},"page":"5723-5733","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Partitioning of discrete proton arcs into interlaced subplans can bring proton arc advances to existing proton facilities"],"prefix":"10.1002","volume":"50","author":[{"given":"Erik","family":"Engwall","sequence":"first","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Otte","family":"Marthin","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Viktor","family":"Wase","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johan","family":"Sundstr\u00f6m","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Victor","family":"Mikhalev","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bas A.","family":"de Jong","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University Medical Center Groningen University of Groningen Groningen The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johannes A.","family":"Langendijk","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University Medical Center Groningen University of Groningen Groningen The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Henrik","family":"Melb\u00e9us","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bj\u00f6rn","family":"Andersson","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erik W.","family":"Korevaar","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University Medical Center Groningen University of Groningen Groningen The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefan","family":"Both","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University Medical Center Groningen University of Groningen Groningen The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rasmus","family":"Bokrantz","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lars","family":"Glimelius","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Albin","family":"Fredriksson","sequence":"additional","affiliation":[{"name":"RaySearch Laboratories Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2023,7,21]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/61\/21\/N565"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2016.08.049"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.14083"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1080\/0284186X.2020.1765415"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/ac55a6"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.compbiomed.2022.105609"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2019.04.032"},{"key":"e_1_2_8_9_1","unstructured":"BattinelliC.Proton Arc Therapy Optimization. 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