Clinical validation and applications for CT-based atlas for contouring the lower cranial nerves for head and neck cancer radiation therapy Waleed F. Mourad a,b,⇑ , Brett M. Young c , Rebekah Young b , Dukagjin M. Blakaj b , Nitin Orhi b , Rania A. Shourbaji a , Spiros Manolidis d , Mauricio Gámez a , Mahesh Kumar a , Azita Khorsandi e , Majid A. Khan f , Daniel Shasha a , Adriana Blakaj b , Jonathan Glanzman b , Madhur K. Garg b , Kenneth S. Hu a , Shalom Kalnicki b , Louis B. Harrison a a Department of Radiation Oncology, Beth Israel Medical Center, New York, NY, United States b Department of Radiation Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, United States c Department of Neuroradiology, Duke University Medical Center, Durham, NC, United States d Department of Otolaryngology, Beth Israel Medical Center, New York, NY, United States e Department of Neuroradiology, Beth Israel Medical Center, New York, NY, United States f Department of Neuroradiology, University of Mississippi Medical Center, Jackson, MS, United States article info Article history: Received 16 January 2013 Received in revised form 18 March 2013 Accepted 20 March 2013 Available online xxxx Keywords: Locally Advanced Head-and-neck cancer (LAHNC) Lower cranial nerves IX–XII palsy Radiotherapy (RT) Intensity-modulated radiotherapy (IMRT) Contouring atlas Base of skull, nasopharyngeal and Paranasalsinus cancer summary Objectives: 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 meth- odology 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 plan- ning target volume (PTV) was 70 Gy (range: 66–70 Gy). The median CN (IX–XI) and (XII) volumes were 10 c.c (range: 8–12 c.c) and 8 c.c (range: 7–10 c.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 max- imal dose to the CN (IX–XI) and (XII) were 72 Gy (range: 66–77) and 71 Gy (range: 64–78), respectively. Conclusions: We have generated simple instructions for delineating the lower CNs on RT planning imag- ing. Further analyses to explore the relationship between lower CN dosing and the risk of RICNP are rec- ommended in order to establish limiting doses for these OARs. Published by Elsevier Ltd. Introduction In the United States, head and neck cancer accounts for 3% of malignancies, with an estimated 52,000 Americans developing head and neck cancer (HNC) annually and 11,500 dying from the disease. 1 Radiation therapy (RT) plays a central role in the manage- ment of these patients as an effective treatment modality. How- ever, RT can be associated with serious late side effects, which can include xerostomia, dysphagia, neck fibrosis, osteoradionecro- sis, carotid vasculopathy, myelopathy, and brachial plexopathy. 2 One complication that receives relatively little attention but can significantly affect patients’ quality of life is radiation-induced cra- nial nerve palsy (RICNP). Cranial nerve palsies can be devastating to the patient. They impair quality of life and functional capacity and can even be life-threatening. 3,4 Reported rates of RICNP after RT for nasopharyngeal cancer (NPC) range from 4% to 31%, and the most commonly affected cranial nerves (CNs) are the glosso- pharyngeal nerve (IX), the vagus nerve (X), and the hypoglossal nerve (XII) nerve. 5–8 In this study, we develop a standardized methodology for con- touring the lower CNs (IX–XII) on CT imaging typically used to plan RT for HNC. We also test our contouring guidelines on imaging datasets from several HNC patients. Our aim is to demonstrate the ability to correlate lower CN RT dosing with the risk of subse- quent RICNP. Moreover, our goal is to use our atlas based dosimet- ric analysis data as pilot data for prospective studies for patients 1368-8375/$ - see front matter Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.oraloncology.2013.03.449 ⇑ Corresponding author. Address: 10 Union Square E, Suite 4G, New York, NY 10003, United States. Tel.: +1 865 385 4511; fax: +1 718 231 5064. E-mail address: Waleed246@gmail.com (W.F. Mourad). Oral Oncology xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Oral Oncology journal homepage: www.elsevier.com/locate/oraloncology Please cite this article in press as: Mourad WF et al. Clinical validation and applications for CT-based atlas for contouring the lower cranial nerves for head and neck cancer radiation therapy. Oral Oncol (2013), http://dx.doi.org/10.1016/j.oraloncology.2013.03.449