Have you been diagnosed with Lateralized Oropharyngeal Cancer . If so, you may be able to take part in a research study looking at the safety by using a special imaging study called lymph node mapping (lymphatic mapping) Single Photon Emission Computed Tomography (SPECT-CT) compared to the usual treatment when radiotherapy is given . The study involves randomization (selection by 50/50 chance to assigned group), blood collection for research purposes in addition to routine blood work, diagnostic imaging scan (ex: MRI/SPET/PET/CT Scan) and study questionnaires so that there is a understanding of your care and needs as a patient.