This study aims to see if using a special scan called SPECT-CT for lymph node mapping can help guide radiotherapy (a cancer treatment using high-energy rays) to just one side of the neck instead of both. This is for patients with a specific type of throat cancer called lateralized oropharyngeal cancer (OPC). The goal is to find out if this method is as effective in stopping cancer from spreading or coming back and if it leads to fewer side effects and a better quality of life.

Key Points:

• Participants will undergo a special imaging procedure before starting the treatment.
• Eligible participants should be able to start radiotherapy within 28-42 days after joining.
• Participants should be willing to complete surveys about their quality of life during the study.

To join, patients need a confirmed diagnosis of lateralized OPC and must meet specific health criteria. They should not have prior head and neck cancer treatment or severe active illnesses like heart or lung diseases. The study offers a chance to potentially receive a more targeted treatment with the possibility of fewer side effects.