{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T13:59:20Z","timestamp":1791381560434,"version":"4.3.3"},"reference-count":26,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T00:00:00Z","timestamp":1754870400000},"content-version":"vor","delay-in-days":10,"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"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R37CA250921"],"award-info":[{"award-number":["R37CA250921"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01CA261964"],"award-info":[{"award-number":["R01CA261964"]}],"id":[{"id":"10.13039\/100000002","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":[[2025,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Efficient delivery of intensity\u2010modulated proton therapy (IMPT) plays a pivotal role in improving the effectiveness of proton therapy. Accelerating delivery not only increases patient throughput but also improves the ability to manage dynamic target motion and reduces uncertainties, thereby enhancing treatment accuracy. Additionally, rapid delivery enables the effective use of breath\u2010hold techniques, allowing for smaller target margins and providing better protection for healthy tissues. Since energy layer switching time constitute the majority of delivery time, reducing the number of energy layers can be highly beneficial for improving delivery efficiency.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This work proposes a novel energy layer reduction method for rapid IMPT using a ridge filter.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The width of the Bragg peak (BP) is extended using a ridge filter, referred to as the extended Bragg peak (EBP). The machine file of the generated EBP is subsequently incorporated in our in\u2010house treatment planning system for inverse planning. The extended peak width reduces the number of energy layers required for target coverage. However, relying solely on EBP can compromise the accuracy of energy modulation. To address this limitation, pristine BP is utilized to fill small gaps left by EBP and ensure rapid dose fall\u2010off at the distal and proximal edges of the target. To optimize the selection of BP and EBP energies, the problem is formulated as a mathematical model incorporating a group sparsity constraint. The model is then solved by a variant of block orthogonal matching pursuit algorithm, which selects BP and EBP energies in a greedy manner.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The combined use of BP and EBP, referred to as the BP\u2010EBP, considerably reduced the number of energy layers required compared to conventional IMPT. For example, in an abdomen case, the BP\u2010EBP method decreased the energy layers from 79 to 28 (11 for BP and 17 for EBP) while maintaining comparable plan quality. Similarly, in a lung case, it reduced the energy layers from 70 to 30 (9 for BP and 21 for EBP), achieving slightly better plan quality than the conventional approach. Moreover, the BP\u2010EBP reduced delivery time by more than 50% in both cases compared to conventional IMPT. Furthermore, the feasibility of BP\u2010EBP was experimentally demonstrated on the ProteusONE proton therapy system.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>A novel energy reduction method is proposed and experimentally demonstrated that leverages BP and EBP generated by a ridge filter that significantly decreases the number of energy levels required in IMPT, thereby enhancing delivery efficiency.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.18031","type":"journal-article","created":{"date-parts":[[2025,8,12]],"date-time":"2025-08-12T06:15:16Z","timestamp":1754979316000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["New energy layer reduction method for rapid intensity\u2010modulated proton therapy (IMPT) using a ridge filter"],"prefix":"10.1002","volume":"52","author":[{"given":"Aoxiang","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering Huazhong University of Science and Technology  Wuhan China"},{"name":"Department of Radiation Oncology University of Kansas Medical Center  Kansas City USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ya\u2010Nan","family":"Zhu","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Kansas Medical Center  Kansas City USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jufri","family":"Setianegara","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Kansas Medical Center  Kansas City USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuting","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Kansas Medical Center  Kansas City USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valentin","family":"Hamaide","sequence":"additional","affiliation":[{"name":"Ion Beam Applications (IBA)  Louvain\u2010la\u2010Neuve Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arnaud","family":"Pin","sequence":"additional","affiliation":[{"name":"Ion Beam Applications (IBA)  Louvain\u2010la\u2010Neuve Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peng","family":"Xiao","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering Huazhong University of Science and Technology  Wuhan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qingguo","family":"Xie","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering Huazhong University of Science and Technology  Wuhan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao","family":"Gao","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Kansas Medical Center  Kansas City USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,8,11]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-8140(99)00036-5"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/53\/4\/014"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/53\/4\/015"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2015.06.019"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4952731"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/ac431c"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1186\/s13014-022-02055-w"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/44\/11\/306"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.598840"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/48\/22\/N01"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/54\/10\/009"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/61\/4\/1515"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/ac9d1f"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/41\/8\/005"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3314073"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/61\/12\/4665"},{"key":"e_1_2_8_18_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/ab2133"},{"key":"e_1_2_8_19_1","volume-title":"XII International Conference on the Use of Computers in Radiation Therapy","author":"Bortfeld T","year":"1997"},{"key":"e_1_2_8_20_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.598932"},{"key":"e_1_2_8_21_1","unstructured":"WangA ZhuYN SetianegaraJ et\u00a0al. 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