{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T16:33:41Z","timestamp":1790354021239,"version":"4.1.0"},"reference-count":27,"publisher":"Wiley","issue":"12","license":[{"start":{"date-parts":[[2025,12,10]],"date-time":"2025-12-10T00:00:00Z","timestamp":1765324800000},"content-version":"vor","delay-in-days":9,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2025,12]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The helical tomotherapy (HT) system can expose more normal lung tissue to low radiation doses, resulting in extensive low\u2010dose distribution in both lungs which may induce radiation pneumonitis (RP).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aims to optimize dosimetric parameters and identify a clinically feasible treatment plan by analyzing the impact of different block settings and modulation factor (MF) combinations on HT plans for lung cancer to reduce the low\u2010dose exposure volumes in normal lung tissue.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We retrospectively reviewed 14 lung cancer patients who received radiotherapy. These cases were optimized using different modulation factors (MFs: 3, 4, 5) and block techniques (Unblocked, Directional, Complete). The impact of MF and block combinations on reducing low\u2010dose bath (e.g., V5, V10) in lung tissue was evaluated by analyzing dose distribution maps, dose\u2013volume histograms (DVH), homogeneity index (HI), conformity index (CI), and treatment time for each optimized HT plan combination.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Block settings and higher MF exerted minimal influence on the average dose to the target volume. With stricter block constraints and higher MF, HI increased (range: 17.39%\u201327.54%) and CI decreased (range: 2.76%\u201317.43%); although both indices showed slight deterioration, they remained within acceptable clinical limits. Treatment time increased substantially (range: 15.77%\u2013131.58%). The block technique significantly reduced V5 in the bilateral lungs and the contralateral (healthy) lung, with less impact on the ipsilateral (affected) lung. The combination of block and high MF effectively reduced V5.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>To balance target volume coverage (high dose), dose distribution uniformity, and treatment duration while reducing low\u2010dose irradiation to normal lung tissue, we recommend implementing Directional block with an MF range of 3\u20134 to optimize the HT plan for patients with unilateral lung cancer.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/acm2.70372","type":"journal-article","created":{"date-parts":[[2025,12,11]],"date-time":"2025-12-11T04:56:41Z","timestamp":1765429001000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Combined application of block and modulation factors to reduce the volume of the low dose area in helical tomotherapy plans for lung cancer"],"prefix":"10.1002","volume":"26","author":[{"given":"Sijin","family":"Zhu","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tianwen","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yutao","family":"Zhao","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinli","family":"Peng","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingyan","family":"Gao","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yunyan","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Yunnan Cancer Hospital The Third Affiliated Hospital of Kunming Medical University Peking University Cancer Hospital Yunnan  Kunming Yunnan 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