Inclusion Criteria:  Patient has lateralized oropharyngeal carcinoma (tonsil or tongue base) not involving midline Has squamous cell carcinoma, T1-3 tumours, with no contralateral nodes on clinical exam or axial imaging Human papillomavirus (HPV) positive or negative Patient should have normal organ function as per Investigator judgement Patient is planned for definitive or adjuvant radiotherapy (RT) or chemo radiotherapy (CRT) with bilateral neck RT, or surgery Eastern Cooperative Oncology Group (ECOG) performance status 0-1  Exclusion Criteria:  T4 tumours Contralateral/bilateral nodal disease or node(s) > 6cm on clinical exam or axial imaging or positron emission tomography (PET) Primary tumour involving or crossing midline Soft palate or posterior pharyngeal wall tumour subsites Previous head and neck cancer Previous radiotherapy (RT) to the head and neck Previous neck dissection Distant metastases Prior invasive malignancy (except non-melanoma skin cancer) unless disease free for 3 years Prior radiotracer allergy Multiple primary head and neck cancers Pregnancy