{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,29]],"date-time":"2026-10-29T13:33:28Z","timestamp":1793280808063,"version":"4.5.0"},"reference-count":31,"publisher":"IOP Publishing","issue":"1","license":[{"start":{"date-parts":[[2018,12,19]],"date-time":"2018-12-19T00:00:00Z","timestamp":1545177600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/iop-standard\/v1"},{"start":{"date-parts":[[2018,12,19]],"date-time":"2018-12-19T00:00:00Z","timestamp":1545177600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"}],"funder":[{"name":"Research grant from Varian Medical Systems\u2014Particle Therapy, Germany"}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Phys. Med. Biol."],"published-print":{"date-parts":[[2019,1,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>In proton therapy, the lateral fall-off is often used to spare critical organs. It is therefore crucial to improve the penumbra for proton pencil beam scanning. However, previous work has shown that collimation may not be necessary for depths of\u2009\u2009&gt;15 cm in water. As such, in this work we investigate the effectiveness of a thin multi leaf collimator (just thick enough to completely stop protons with ranges of\u2009\u2009&lt;15 cm in water) for energy layer specific collimation in patient geometries, when applied in combination with both grid and contour scanned PBS proton therapy. For this, an analytical model of collimated beam shapes, based solely on data available in the treatment planning system, has been included in the optimization, with the resulting optimised plans then being recalculated using Monte Carlo in order to most accurately simulate the full physics effects of the collimator. For grid based scanning, energy specific collimation has been found to reduce the V30 outside the PTV by 19.8% for an example patient when compared to the same pencil beam placement without collimation. V30 could be even reduced by a further 5.6% when combining collimation and contour scanning. In addition, mixed plans, consisting of contour scanning for deep fields (max range\u2009\u2009&gt;15 cm WER) and collimated contour scanning for superficial fields (&lt;15 cm), have been created for four patients, by which V30 could be reduced by 0.8% to 8.0% and the mean dose to the brain stem by 1.5% to 3.3%. Target dose homogeneity however is not substantially different when compared to the best un-collimated scenario. In conclusion, we demonstrate the potential advantages of a thin, multi leaf collimator in combination with contour scanning for energy layer specific collimation in PBS proton therapy.<\/jats:p>","DOI":"10.1088\/1361-6560\/aaf2e8","type":"journal-article","created":{"date-parts":[[2018,11,22]],"date-time":"2018-11-22T17:15:29Z","timestamp":1542906929000},"page":"015002","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":19,"title":["Contour scanning, multi-leaf collimation and the combination thereof for proton pencil beam scanning"],"prefix":"10.1088","volume":"64","author":[{"given":"Carla","family":"Winterhalter","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabriel","family":"Meier","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Oxley","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Damien C","family":"Weber","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antony J","family":"Lomax","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sairos","family":"Safai","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2018,12,19]]},"reference":[{"key":"pmbaaf2e8bib001","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/aab79c","type":"journal-article","article-title":"Collimated proton pencil-beam scanning for superficial targets: impact of the order of range shifter and aperture","volume":"63","author":"B\u00e4umer","year":"2018","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib002","doi-asserted-by":"publisher","first-page":"164","DOI":"10.1093\/rpd\/nci259","type":"journal-article","article-title":"Therapeutic step and shoot proton beam spot-scanning with a multi-leaf collimator: a Monte Carlo study","volume":"115","author":"Bues","year":"2005","journal-title":"Radiat. Prot. Dosim."},{"key":"pmbaaf2e8bib003","doi-asserted-by":"publisher","first-page":"1462","DOI":"10.1118\/1.4941957","type":"journal-article","article-title":"A Monte Carlo study on the collimation of pencil beam scanning proton therapy beams","volume":"43","author":"Charlwood","year":"2016","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib004","doi-asserted-by":"publisher","first-page":"6248","DOI":"10.1118\/1.3656025","type":"journal-article","article-title":"Comparison of secondary neutron dose in proton therapy resulting from the use of a tungsten alloy MLC or a brass collimator system","volume":"38","author":"Diffenderfer","year":"2011","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib005","doi-asserted-by":"publisher","first-page":"2829","DOI":"10.1088\/0031-9155\/57\/10\/2829","type":"journal-article","article-title":"Monte Carlo study of the potential reduction in out-of-field dose using a patient-specific aperture in pencil beam scanning proton therapy","volume":"57","author":"Dowdell","year":"2012","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib006","doi-asserted-by":"publisher","first-page":"693","DOI":"10.1145\/359842.359846","type":"journal-article","article-title":"Optimal surface reconstruction from planar contours","volume":"20","author":"Fuchs","year":"1977","journal-title":"Commun. ACM"},{"key":"pmbaaf2e8bib007","doi-asserted-by":"publisher","first-page":"1321","DOI":"10.1118\/1.4907965","type":"journal-article","article-title":"A method for modeling laterally asymmetric proton beamlets resulting from collimation","volume":"42","author":"Gelover","year":"2015","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib008","doi-asserted-by":"publisher","first-page":"12","DOI":"10.1088\/0031-9155\/61\/1\/12","type":"journal-article","article-title":"Assessing the radiation-induced second cancer risk in proton therapy for pediatric brain tumors: the impact of employing a patient-specific aperture in pencil beam scanning","volume":"61","author":"Geng","year":"2016","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib009","doi-asserted-by":"publisher","DOI":"10.1118\/1.4837155","type":"journal-article","article-title":"A dynamic collimation system for penumbra reduction in spot-scanning proton therapy: proof of concept","volume":"41","author":"Hyer","year":"2014a","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib010","doi-asserted-by":"publisher","first-page":"N187","DOI":"10.1088\/0031-9155\/59\/22\/N187","type":"journal-article","article-title":"Effects of spot size and spot spacing on lateral penumbra reduction when using a dynamic collimation system for spot scanning proton therapy","volume":"59","author":"Hyer","year":"2014b","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib011","doi-asserted-by":"publisher","first-page":"185","DOI":"10.1088\/0031-9155\/44\/1\/014","type":"journal-article","article-title":"Intensity modulation methods for proton radiotherapy","volume":"44","author":"Lomax","year":"1999","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib012","doi-asserted-by":"publisher","first-page":"S36","DOI":"10.1016\/j.ijrobp.2009.01.029","type":"journal-article","article-title":"Radiation associated brainstem injury","volume":"76","author":"Mayo","year":"2010","journal-title":"Int. J. Radiat. Oncol. Biol. Phys."},{"key":"pmbaaf2e8bib013","doi-asserted-by":"publisher","first-page":"2819","DOI":"10.1088\/0031-9155\/60\/7\/2819","type":"journal-article","article-title":"Independent dose calculations for commissioning, quality assurance and dose reconstruction of PBS proton therapy","volume":"60","author":"Meier","year":"2015","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib014","doi-asserted-by":"publisher","first-page":"2398","DOI":"10.1088\/1361-6560\/aa5dde","type":"journal-article","article-title":"Contour scanning for penumbra improvement in pencil beam scanned proton therapy","volume":"62","author":"Meier","year":"2017","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib015","doi-asserted-by":"publisher","first-page":"1421","DOI":"10.1118\/1.4942375","type":"journal-article","article-title":"Toward improved target conformity for two spot scanning proton therapy delivery systems using dynamic collimation","volume":"43","author":"Moignier","year":"2016a","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib016","doi-asserted-by":"publisher","first-page":"544","DOI":"10.14338\/IJPT-15-00026.1","type":"journal-article","article-title":"Improving head and neck cancer treatments using dynamic collimation in spot scanning proton therapy","volume":"2","author":"Moignier","year":"2016b","journal-title":"Int. J. Part. Ther."},{"key":"pmbaaf2e8bib017","doi-asserted-by":"publisher","first-page":"171","DOI":"10.1016\/j.ijrobp.2015.08.030","type":"journal-article","article-title":"Theoretical benefits of dynamic collimation in pencil beam scanning proton therapy for brain tumors: dosimetric and radiobiological metrics","volume":"95","author":"Moignier","year":"2016c","journal-title":"Int. J. Radiat. Oncol. Biol. Phys."},{"key":"pmbaaf2e8bib018","doi-asserted-by":"publisher","first-page":"190","DOI":"10.1016\/j.ijrobp.2015.12.368","type":"journal-article","article-title":"Impact of spot size and beam-shaping devices on the treatment plan quality for pencil beam scanning proton therapy","volume":"95","author":"Moteabbed","year":"2016","journal-title":"Int. J. Radiat. Oncol. Biol. Phys."},{"key":"pmbaaf2e8bib019","doi-asserted-by":"publisher","first-page":"R99","DOI":"10.1088\/0031-9155\/57\/19\/6047","type":"journal-article","article-title":"Range uncertainties in proton therapy and the role of Monte Carlo simulations","volume":"57","author":"Paganetti","year":"2012","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib020","doi-asserted-by":"publisher","first-page":"R419","DOI":"10.1088\/0031-9155\/59\/22\/R419","type":"journal-article","article-title":"Relative biological effectiveness (RBE) values for proton beam therapy. Variations as a function of biological endpoint, dose, and linear energy transfer","volume":"59","author":"Paganetti","year":"2014","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib021","doi-asserted-by":"publisher","first-page":"37","DOI":"10.1118\/1.597522","type":"journal-article","article-title":"The 200 MeV proton therapy project at the Paul Scherrer Institute: conceptual design and practical realization","volume":"22","author":"Pedroni","year":"1995","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib022","doi-asserted-by":"publisher","first-page":"6818","DOI":"10.1118\/1.4758060","type":"journal-article","article-title":"TOPAS: an innovative proton Monte Carlo platform for research and clinical applications","volume":"39","author":"Perl","year":"2012","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib023","doi-asserted-by":"publisher","first-page":"1729","DOI":"10.1088\/0031-9155\/53\/6\/016","type":"journal-article","article-title":"Comparison between the lateral penumbra of a collimated double-scattered beam and uncollimated scanning beam in proton radiotherapy","volume":"53","author":"Safai","year":"2008","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib024","doi-asserted-by":"publisher","first-page":"27","DOI":"10.1088\/0031-9155\/44\/1\/004","type":"journal-article","article-title":"Dose calculation models for proton treatment planning using a dynamic beam delivery system: an attempt to include density heterogeneity effects in the analytical dose calculation","volume":"44","author":"Schaffner","year":"1999","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib025","doi-asserted-by":"publisher","first-page":"4693","DOI":"10.1118\/1.4955117","type":"journal-article","article-title":"Technical note: a treatment plan comparison between dynamic collimation and a fixed aperture during spot scanning proton therapy for brain treatment","volume":"43","author":"Smith","year":"2016","journal-title":"Med. Phys."},{"key":"pmbaaf2e8bib026","doi-asserted-by":"publisher","first-page":"A15","DOI":"10.1269\/jrr.48.A15","type":"journal-article","article-title":"Irradiation system for HIMAC","volume":"48","author":"Torikoshi","year":"2007","journal-title":"J. Radiat. Res."},{"key":"pmbaaf2e8bib027","doi-asserted-by":"publisher","first-page":"N109","DOI":"10.1088\/0031-9155\/60\/7\/N109","type":"journal-article","article-title":"A method to select aperture margin in collimated spot scanning proton therapy","volume":"60","author":"Wang","year":"2015","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib029","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/aaa2ad","type":"journal-article","article-title":"A study of lateral fall-off (penumbra) optimisation for pencil beam scanning (PBS) proton therapy","volume":"63","author":"Winterhalter","year":"2018a","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib031","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/aad3ae","type":"journal-article","article-title":"Validating a Monte Carlo approach to absolute dose quality assurance for proton pencil beam scanning","volume":"63","author":"Winterhalter","year":"2018b","journal-title":"Phys. Med. Biol."},{"key":"pmbaaf2e8bib032","doi-asserted-by":"publisher","first-page":"132","DOI":"10.1002\/acm2.12231","type":"journal-article","article-title":"Evaluation of dosimetric advantages of using patient-specific aperture system with intensity-modulated proton therapy for the shallow depth tumor","volume":"19","author":"Yasui","year":"2018","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"pmbaaf2e8bib033","doi-asserted-by":"publisher","first-page":"6999","DOI":"10.1118\/1.4935528","type":"journal-article","article-title":"A patient-specific aperture system with an energy absorber for spot scanning proton beams: verification for clinical application","volume":"42","author":"Yasui","year":"2015","journal-title":"Med. Phys."}],"container-title":["Physics in Medicine &amp; Biology"],"original-title":[],"link":[{"URL":"http:\/\/stacks.iop.org\/0031-9155\/64\/i=1\/a=015002?key=crossref.5546f5f1ed6e947624fa891fa4902dee","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"text-mining"},{"URL":"http:\/\/stacks.iop.org\/0031-9155\/64\/i=1\/a=015002\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8","content-type":"text\/html","content-version":"am","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"syndication"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"http:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"am","intended-application":"similarity-checking"},{"URL":"http:\/\/stacks.iop.org\/0031-9155\/64\/i=1\/a=015002\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"},{"URL":"http:\/\/stacks.iop.org\/0031-9155\/64\/i=1\/a=015002?key=crossref.5546f5f1ed6e947624fa891fa4902dee","content-type":"text\/html","content-version":"vor","intended-application":"similarity-checking"},{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T12:09:13Z","timestamp":1770466153000},"score":1,"resource":{"primary":{"URL":"https:\/\/iopscience.iop.org\/article\/10.1088\/1361-6560\/aaf2e8"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,12,19]]},"references-count":31,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2018,12,19]]},"published-print":{"date-parts":[[2019,1,1]]}},"URL":"https:\/\/doi.org\/10.1088\/1361-6560\/aaf2e8","relation":{},"ISSN":["0031-9155","1361-6560"],"issn-type":[{"value":"0031-9155","type":"print"},{"value":"1361-6560","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,12,19]]},"assertion":[{"value":"Contour scanning, multi-leaf collimation and the combination thereof for proton pencil beam scanning","name":"article_title","label":"Article Title"},{"value":"Physics in Medicine & Biology","name":"journal_title","label":"Journal Title"},{"value":"paper","name":"article_type","label":"Article Type"},{"value":"\u00a9 2018 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.","name":"copyright_information","label":"Copyright Information"},{"value":"2018-09-05","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2018-11-22","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2018-12-19","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}