{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T14:01:49Z","timestamp":1789740109679,"version":"4.0.1"},"reference-count":19,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2026,7,26]],"date-time":"2026-07-26T00:00:00Z","timestamp":1785024000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,7,26]],"date-time":"2026-07-26T00:00:00Z","timestamp":1785024000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100008235","name":"Peking Union Medical College Hospital","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100008235","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2026,8]]},"abstract":"Abstract<\/jats:title>\n \n Background<\/jats:title>\n Radiotherapy for vulvar carcinoma often employs the \u201cfrog\u2010leg\u201d position to minimize skin toxicity, but this position is biomechanically unstable and prone to setup errors using conventional skin markings.<\/jats:p>\n <\/jats:sec>\n \n Purpose<\/jats:title>\n To evaluate the clinical efficacy of Surface\u2010Guided Radiotherapy (SGRT) for setup accuracy in vulvar cancer patients treated in the frog\u2010leg position and to quantify the biomechanical correlation between Body Mass Index (BMI) and setup errors.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n A retrospective cohort study of 20 vulvar cancer patients treated in the frog\u2010leg position was conducted. All patients were treated using a uRT\u2010linac 506c accelerator with integrated helical Fan\u2010Beam CT (FBCT). Daily image guidance was performed using a two\u2010step registration protocol (bony anatomy followed by soft\u2010tissue fine\u2010tuning). Setup errors from 500 FBCT datasets were compared between the conventional laser group (n\u00a0=\u00a010) and SGRT group (n\u00a0=\u00a010). The correlation between BMI and setup errors was analyzed using Spearman's rank correlation.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The SGRT group demonstrated significantly superior setup accuracy across multiple key dimensions (\n p<\/jats:italic>\n \u00a0<\u00a00.001). Notably, the Pitch error was reduced from 1.21\u00b0\u00a0\u00b1\u00a00.48\u00b0 in the Conventional Group to 0.07\u00b0\u00a0\u00b1\u00a00.32\u00b0 in the SGRT Group (Cohen's\n d<\/jats:italic>\n \u00a0=\u00a02.79). Longitudinal (LNG) error decreased from 0.49\u00a0\u00b1\u00a00.26\u00a0cm to 0.04\u00a0\u00b1\u00a00.24\u00a0cm (\n d<\/jats:italic>\n \u00a0=\u00a01.82), and vertical (VRT) errors were similarly reduced.\n <\/jats:p>\n <\/jats:sec>\n \n BMI correlation<\/jats:title>\n \n In the Conventional Group, BMI showed a strong significant correlation with Pitch and Yaw errors (\n \u03c1<\/jats:italic>\n \u00a0=\u00a0\u22120.81,\n P\u00a0<\/jats:italic>\n =\u00a00.005), indicating that obesity may exacerbate pelvic rotational instability. Conversely, in the SGRT Group, no statistically significant correlation was observed between BMI and setup errors in any dimension (\n p<\/jats:italic>\n \u00a0>\u00a00.05), demonstrating the system's robustness against body habitus variations.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n The frog\u2010leg position is characterized by significant biomechanical instability due to distinct anatomical factors. Traditional skin marking methods are susceptible to the \u201cskin traction effect\u201d and interference from BMI. SGRT, through real\u2010time topographical matching, effectively corrects pelvic tilt and longitudinal sliding. Crucially, it eliminates the setup uncertainty associated with BMI, providing a solid evidence\u2010based foundation for precision radiotherapy and individualized PTV margin reduction.<\/jats:p>\n <\/jats:sec>","DOI":"10.1002\/acm2.70714","type":"journal-article","created":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T03:08:09Z","timestamp":1785121689000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Surface\u2010Guided Radiotherapy for Vulvar Cancer in the Frog\u2010Leg Position: Setup Accuracy and BMI Effects"],"prefix":"10.1002","volume":"27","author":[{"given":"Hao","family":"Liang","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junfang","family":"Yan","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yongguang","family":"Liang","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiansong","family":"Sun","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hongming","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huiying","family":"Qu","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yijun","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingyu","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 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