title: Clinical validation and applications for CT-based atlas for contouring the lower cranial nerves for head and neck cancer radiation therapy.
abstract: OBJECTIVE
  Radiation induced cranial nerve palsy (RICNP) involving the lower cranial nerves (CNs) is a serious complication of head and neck radiotherapy (RT). Recommendations for delineating the lower CNs on RT planning studies do not exist. The aim of the current study is to develop a standardized methodology for contouring CNs IX-XII, which would help in establishing RT limiting doses for organs at risk (OAR).
  
  
  METHODS
  Using anatomic texts, radiologic data, and guidance from experts in head and neck anatomy, we developed step-by-step instructions for delineating CNs IX-XII on computed tomography (CT) imaging. These structures were then contoured on five consecutive patients who underwent definitive RT for locally-advanced head and neck cancer (LAHNC). RT doses delivered to the lower CNs were calculated.
  
  
  RESULTS
  We successfully developed a contouring atlas for CNs IX-XII. The median total dose to the planning target volume (PTV) was 70Gy (range: 66-70Gy). The median CN (IX-XI) and (XII) volumes were 10c.c (range: 8-12c.c) and 8c.c (range: 7-10c.c), respectively. The median V50, V60, V66, and V70 of the CN (IX-XI) and (XII) volumes were (85, 77, 71, 65) and (88, 80, 74, 64) respectively. The median maximal dose to the CN (IX-XI) and (XII) were 72Gy (range: 66-77) and 71Gy (range: 64-78), respectively.
  
  
  CONCLUSIONS
  We have generated simple instructions for delineating the lower CNs on RT planning imaging. Further analyses to explore the relationship between lower CN dosing and the risk of RICNP are recommended in order to establish limiting doses for these OARs.
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States; Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States. Electronic address: Waleed246@gmail.com.
authors.forename: Waleed F
authors.initials: WF
authors.lastname: Mourad
authors.affiliation: Department of Neuroradiology, Duke University Medical Center, Durham, NC, United States.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Young
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Rebekah
authors.initials: R
authors.lastname: Young
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Dukagjin M
authors.initials: DM
authors.lastname: Blakaj
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Nitin
authors.initials: N
authors.lastname: Ohri
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Rania A
authors.initials: RA
authors.lastname: Shourbaji
authors.affiliation: Department of Otolaryngology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Spiros
authors.initials: S
authors.lastname: Manolidis
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Gámez
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Department of Neuroradiology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Azita
authors.initials: A
authors.lastname: Khorsandi
authors.affiliation: Department of Neuroradiology, University of Mississippi Medical Center, Jackson, MS, United States.
authors.forename: Majid A
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Shasha
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Adriana
authors.initials: A
authors.lastname: Blakaj
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Glanzman
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Madhur K
authors.initials: MK
authors.lastname: Garg
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Hu
authors.affiliation: Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States.
authors.forename: Shalom
authors.initials: S
authors.lastname: Kalnicki
authors.affiliation: Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States.
authors.forename: Louis B
authors.initials: LB
authors.lastname: Harrison
mesh_terms: D003391:Cranial Nerves / Q000033:anatomy & histology*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Base of skull, nasopharyngeal and Paranasalsinus cancer; Contouring atlas; Intensity-modulated radiotherapy (IMRT); Locally Advanced Head-and-neck cancer (LAHNC); Lower cranial nerves IX–XII palsy; Radiotherapy (RT)