Clinical application of PET and PET/CT in radiotherapy of head and neck cancer

Positron emission tomography (PET) is a functional imaging modality. The combined PET and CT scan provides more accurate detection of tumors and their relationship with normal tissues by providing the functional and anatomic information simultaneously. Relevant researches have been focused on the application of combined PET/CT in the radiotherapy of head and neck cancer, which includes: providing valuable information in the staging of head and neck cancer before radiotherapy; localizing a primary tumor in patients with unknown metastases in cervical lymph nodes; predicting the response of tumors to radiotherapy; providing biological target volume to radiation treatment planning, especially in intensity-modulated radiotherapy; and monitoring the residual and recurrent diseases after radiotherapy. However, its application in many aspects is still controversy, and further researches in its clinical application are still needed.