{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T11:06:28Z","timestamp":1774004788184,"version":"3.50.1"},"reference-count":14,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T00:00:00Z","timestamp":1773964800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Shenzhen Science and Technology Program","award":["JCYJ20240813151606009"],"award-info":[{"award-number":["JCYJ20240813151606009"]}]},{"DOI":"10.13039\/501100003453","name":"Natural Science Foundation of Guangdong Province","doi-asserted-by":"crossref","award":["2023A1515011365"],"award-info":[{"award-number":["2023A1515011365"]}],"id":[{"id":"10.13039\/501100003453","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Shenzhen High-level Hospital Construction Fund"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"\n Background and Purpose<\/jats:title>\n \n Considering the limitations of current homogeneity index (HI) in multi-target plans, we have redefined the volume (V)\n PTV<\/jats:sub>\n in the formula for calculating the HI value of target volumes. This redefinition could provide a reference for clinical applications.\n <\/jats:p>\n <\/jats:sec>\n \n Methods and Material<\/jats:title>\n \n Since the three widely used HI formulas may not fully capture dose homogeneity in multi-target treatment plans, we have redefined the V\n PTV<\/jats:sub>\n in the calculation formulas, which may allow for a better assessment of HI for the multi-target radiotherapy plans. Fifteen clinically treated breast cancer (BC) with conserving surgery patients and fifteen nasopharyngeal carcinoma (NPC) patients were chosen. We calculated the V\n PTV<\/jats:sub>\n with the name of V\n PTVpro<\/jats:sub>\n and the HI\n pro1<\/jats:sub>\n , HI\n pro2<\/jats:sub>\n , HI\n pro3<\/jats:sub>\n . A paired, two-tailed non-parametric Wilcoxon signed-rank test was utilized to compare V\n PTVori<\/jats:sub>\n and V\n PTVpro<\/jats:sub>\n , HI\n ori1<\/jats:sub>\n and HI\n pro1<\/jats:sub>\n , HI\n ori2<\/jats:sub>\n and HI\n pro2<\/jats:sub>\n , HI\n ori3<\/jats:sub>\n and HI\n pro3<\/jats:sub>\n . The correlations between HI\n ori1<\/jats:sub>\n and HI\n pro1<\/jats:sub>\n , HI\n ori2<\/jats:sub>\n and HI\n pro2<\/jats:sub>\n , HI\n ori3<\/jats:sub>\n and HI\n pro3<\/jats:sub>\n were also analyzed. We conducted a questionnaire survey among a panel of six senior radiation oncologists and physicists to validate the clinical applicability of this study.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n For Planning Target Volume (PTV) of BC and PTV1 of NPC, the V\n PTVpro<\/jats:sub>\n were significantly smaller than the V\n PTVori<\/jats:sub>\n and HI\n pro<\/jats:sub>\n were significantly lower than HI\n ori<\/jats:sub>\n . The correlation coefficient values of HI\n ori1<\/jats:sub>\n -HI\n pro1<\/jats:sub>\n , HI\n ori2<\/jats:sub>\n -HI\n pro2<\/jats:sub>\n , and HI\n ori3<\/jats:sub>\n -HI\n pro3<\/jats:sub>\n showed variations, though all demonstrated positive correlations with statistically significant p-values <0.01. The results for these two target volumes revealed a consistent pattern: the HI\n ori1<\/jats:sub>\n -HI\n pro1<\/jats:sub>\n pair exhibited the highest correlation coefficient values, while HI\n ori2<\/jats:sub>\n -HI\n pro2<\/jats:sub>\n consistently showed the lowest values. Meanwhile, clinical validation by the expert panel found that the V\n PTVpro<\/jats:sub>\n and HI\n pro<\/jats:sub>\n in this study do not affect clinical plan selection. All experts agreed that, compared to V\n PTVori<\/jats:sub>\n and HI\n ori<\/jats:sub>\n , V\n PTVpro<\/jats:sub>\n and HI\n pro<\/jats:sub>\n better align with their clinical practice for evaluating multi-target radiotherapy plans.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n \n The V\n PTVpro<\/jats:sub>\n calculation subtracts the overlapping high-dose target volume from the low-dose target volume. This adjustment is intended to enable a more accurate assessment of dose HI specifically within the low-dose target. Additionally, the V\n PTVpro<\/jats:sub>\n is also applicable for HI calculation in single-target volume. We suggest using the V\n PTVpro<\/jats:sub>\n to calculate the HI of the target for multi-target plans such as BC with conserving surgery and NPC. Meanwhile, we recommend employing formula 1 for the calculation of HI among the three formulas.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.7717\/peerj.21005","type":"journal-article","created":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T08:56:39Z","timestamp":1773996999000},"page":"e21005","source":"Crossref","is-referenced-by-count":0,"title":["A modified homogeneity index for multi- target radiotherapy plans by subtracting high-dose subvolumes"],"prefix":"10.7717","volume":"14","author":[{"given":"Yong","family":"Sang","sequence":"first","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun","family":"Dang","sequence":"additional","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianan","family":"Wu","sequence":"additional","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiajun","family":"Cai","sequence":"additional","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaoye","family":"Su","sequence":"additional","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanling","family":"Wu","sequence":"additional","affiliation":[{"name":"Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"4443","published-online":{"date-parts":[[2026,3,20]]},"reference":[{"key":"10.7717\/peerj.21005\/ref-1","doi-asserted-by":"publisher","first-page":"100659","DOI":"10.1016\/j.phro.2024.100659","article-title":"Technical feasibility of delivering a simultaneous integrated boost in partial breast irradiation","volume":"32","author":"Burton","year":"2024","journal-title":"Physics and Imaging in Radiation Oncology"},{"issue":"2","key":"10.7717\/peerj.21005\/ref-2","doi-asserted-by":"publisher","first-page":"106","DOI":"10.1016\/j.meddos.2018.02.005","article-title":"Monaco treatment planning system tools and optimization processes","volume":"43","author":"Clements","year":"2018","journal-title":"Medical Dosimetry"},{"key":"10.7717\/peerj.21005\/ref-3","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1093\/jicru\/10.1.Report83","article-title":"Prescribing, recording, and reporting photon-beam intensity- modulated radiation therapy (IMRT). 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