title: Dosimetric benefits of placing dose constraints on the brachial plexus in patients with nasopharyngeal carcinoma receiving intensity-modulated radiation therapy: a comparative study.
abstract: This study aimed to evaluate whether placing dose constraints on the brachial plexus (BP) could provide dosimetric benefits in patients with nasopharyngeal carcinoma (NPC) undergoing intensity-modulated radiation therapy (IMRT). Planning CT images for 30 patients with NPC treated with definitive IMRT were retrospectively reviewed. Target volumes, the BP and other critical structures were delineated; two separate IMRT plans were designed for each patient: one set no restrictions for the BP; the other considered the BP as a critical structure for which a maximum dose limit of ≤66 Gy was set. No significant differences between the two plans were observed in the conformity index, homogeneity index, maximum dose to the planning target volumes (PTVs), minimum dose to the PTVs, percentages of the volume of the PTVnx and PTVnd receiving more than 110% of the prescribed dose, or percentages of the volume of the PTVs receiving 95% and > 93% of the prescribed dose. Dose constraints significantly reduced the maximum dose, mean dose, V45, V50, V54, V60, V66 and V70 to the BP. Dose constraints significantly reduced the maximum dose to the BP, V45, V60 and V66 in both N0-1 and N2-3 disease; however, the magnitude of the dosimetric gain for each parameter between N0-1 and N2-3 disease was not significantly different, except for the V60 and V66. In conclusion, placing dose constraints on the BP can significantly decrease the irradiated volume and dose, without compromising adequate dose delivery to the target volume.
authors.affiliation: Department of Radiation Oncology, People's Hospital of Guangxi Zhuang Autonomous Region, 6 Taoyuan Road, Nanning City, 530021, Guangxi, P. R. China.
authors.forename: Hailan
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Radiation Oncology, People's Hospital of Guangxi Zhuang Autonomous Region, 6 Taoyuan Road, Nanning City, 530021, Guangxi, P. R. China luhming3632@163.com.
authors.forename: Heming
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Otorhinolaryngology, People's Hospital of Guangxi Zhuang Autonomous Region, 6 Taoyuan Road, Nanning City, 530021, Guangxi, P. R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Department of Oncology, Liuzhou Worker's Hospital, Liuzhou 545005, P. R. China.
authors.forename: Huixian
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, People's Hospital of Guangxi Zhuang Autonomous Region, 6 Taoyuan Road, Nanning City, 530021, Guangxi, P. R. China.
authors.forename: Yinglin
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Clinical Medicine, Guangxi Medical University, Nanning 530021, P. R. China.
authors.forename: Yanxian
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Clinical Medicine, Guangxi Medical University, Nanning 530021, P. R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D001917:Brachial Plexus / Q000528:radiation effects; D020516:Brachial Plexus Neuropathies / Q000209:etiology* / Q000517:prevention & control*; D002277:Carcinoma; D006801:Humans; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D059351:Organ Sparing Treatments / Q000379:methods; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D055815:Young Adult
keywords: brachial plexus; comparative study; dose constraints; intensity-modulated radiation therapy; nasopharyngeal carcinoma; radiation injury