Clinical examination, CT with IV contrast, and PET scan are the best modalities for the majority of cases. PET scan is helpful for small FDG-avid nodes that fall under size criteria on CT scan. Note the PET fusion may be misleading due to patient movement and should be evaluated closely for any inconsistencies without CT correlate. Ultrasound can be helpful when combined with fine-needle aspiration for staging the neck when other radiographic modalities are nondiagnostic.

MRI with contrast may be helpful in those who cannot receive CT with IV contrast and in cases where nodal adenopathy is obscured or is not easily delineated with contrast CT.

CT simulation with 3 mm slice thickness and IV contrast is preferred to ease delineation of vascular structures from lymph nodes. Supine patient positioning with rigid head cradle with the neck extended to reduce oral cavity exit dose is recommended. A custom thermoplastic mask to immobilize the nose, chin, and forehead is utilized. Shoulder pulls or other reproducible devices are used to reduce beam interference and allow adequate neck exposure. The CT simulation scan should encompass adequate superior extent of coverage of the primary disease and inferiorly to the level of the carina.

Image fusion depending upon the primary disease may include MRI and/or PET to aid in delineating involved gross disease in the neck. Attention should be paid to image fusion between primary disease and fusion to nodal disease, as patients will not have PET images in the CT simulation position (neck extended, shoulders pulled down).

Mediastinal windows should be used for contouring the neck nodal contents.

IGRT is recommended to aid in decreasing the PTV margins, depending upon patient positioning reproducibility and treatment machine considerations.

Uninvolved glottic larynx may be spared to limit RT-related speech disorders. Two possible techniques to treat the entire neck include an extended field IMRT or split field using an upper IMRT field matched to a lower anterior neck field (Fig. 1). Advantages of a split field include significantly reduced mean dose to the uninvolved larynx and inferior pharyngeal constrictors (Caudell et al. 2010). This technique is not recommended in laryngeal, hypopharyngeal, or unknown primary head and neck cases or when gross primary or nodal disease is present at the matchline or inferior to the larynx. In these cases, extended field IMRT will provide excellent coverage, whereas a split field may contribute to matchline failures or underdosage (Lee et al. 2007).

Fractionation schemes may vary between dose-painting IMRT and conventional IMRT (Table 2.) Suggested target volumes for nodal GTV and CTVs are detailed in Tables 3, 4, and 5.