title: Replanning Criteria and Timing Definition for Parotid Protection-Based Adaptive Radiation Therapy in Nasopharyngeal Carcinoma.
abstract: The goal of this study was to evaluate real-time volumetric and dosimetric changes of the parotid gland so as to determine replanning criteria and timing for parotid protection-based adaptive radiation therapy in nasopharyngeal carcinoma. Fifty NPC patients were treated with helical tomotherapy; volumetric and dosimetric (D mean, V 1, and D 50) changes of the parotid gland at the 1st, 6th, 11th, 16th, 21st, 26th, 31st, and 33rd fractions were evaluated. The clinical parameters affecting these changes were studied by analyses of variance methods for repeated measures. Factors influencing the actual parotid dose were analyzed by a multivariate logistic regression model. The cut-off values predicting parotid overdose were developed from receiver operating characteristic curves and judged by combining them with a diagnostic test consistency check. The median absolute value and percentage of parotid volume reduction were 19.51 cm(3) and 35%, respectively. The interweekly parotid volume varied significantly (p < 0.05). The parotid D mean, V 1, and D 50 increased by 22.13%, 39.42%, and 48.45%, respectively. The actual parotid dose increased by an average of 11.38% at the end of radiation therapy. Initial parotid volume, initial parotid D mean, and weight loss rate are valuable indicators for parotid protection-based replanning.
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China; Department of Oncology, People's Hospital of Jiangxi Province, 92 Aiguo Road, Nanchang 330006, China.
authors.forename: Wei-Rong
authors.initials: WR
authors.lastname: Yao
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China.
authors.forename: Shou-Ping
authors.initials: SP
authors.lastname: Xu
authors.affiliation: Image Processing Centre, Beihang University, 37 Xueyuan Road, Beijing 100191, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Medical Statistics, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China.
authors.forename: Xiu-Tang
authors.initials: XT
authors.lastname: Cao
authors.affiliation: Department of Radiation Oncology, Air Force General Hospital, 30 Fucheng Road, Beijing 100141, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Ren
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Hainan Branch, Haitang Bay, Sanya 572000, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Du
authors.affiliation: Image Processing Centre, Beihang University, 37 Xueyuan Road, Beijing 100191, China.
authors.forename: Fu-Gen
authors.initials: FG
authors.lastname: Zhou
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China; Department of Radiation Oncology, Chinese PLA General Hospital, Hainan Branch, Haitang Bay, Sanya 572000, China.
authors.forename: Lin-Chun
authors.initials: LC
authors.lastname: Feng
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China.
authors.forename: Bao-Lin
authors.initials: BL
authors.lastname: Qu
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China.
authors.forename: Chuan-Bin
authors.initials: CB
authors.lastname: Xie
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China; Department of Radiation Oncology, Chinese PLA General Hospital, Hainan Branch, Haitang Bay, Sanya 572000, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma; D002648:Child; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D010306:Parotid Gland / Q000473:pathology / Q000528:radiation effects*; D011837:Radiation-Protective Agents / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted
chemical_list: D011837:Radiation-Protective Agents