الفهرس 
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Abstract
Head and neck cancer accounts for more than 650,000 cases annually worldwide.
The main risk factors include tobacco and alcohol use, and HPV infection.
Most of patients present with locally advanced disease with cure rates reach only 30.
Oncologic imaging plays an important role in head and neck cancers as imaging findings can aid significantly detection, staging, restaging, and therapy response assessment of these tumors.
Treatment is complex for head and neck cancer. Combined modality therapy is generally recommended for the approximately 60% of the patients with locally or regionally advanced disease at diagnosis.
The therapeutic index in radiation therapy can be improved with better target volume delineation especially in head and neck cancers where organs at risk are in close proximity to these targets and highly conformal therapies are often needed to minimize morbidity.
PET has found its role in the diagnosis, staging, prognosis, treatment planning and evaluation of treatment response. The incorporation of PET in radiotherapy treatment planning has revolutionized the field of radiation oncology.
Combined PET/CT imaging -utilizing anatomical and biological data- could improve target volume delineation and RT dosimetry and, likely, provide better locoregional control in head-and-neck cancer while sparing the surrounding normal tissues.
The present study was undertaken to evaluate the role of combined PET/CT in pretreatment staging, radiotherapy planning and in response evaluation. It shows that FDG-PET/CT images for primary head and neck carcinoma had a potential impact on both tumor staging and treatment planning.
A clinical stage variation was observed in 10% of cases. (PET-GTV) of the primary tumor was smaller than (C-GTV) by a mean of 15.5 cc which represents 47.3% reduction in the gross tumor volume and a statistical significant difference using PET/CT versus CT. Yet PET/CT failed to demonstrate statistically significant change in evaluating response to therapy.
Toxicity profile was comparable to patients received concurrent cisplatin versus cetuximab with higher incidence of hematological toxicity in cisplatin group and higher incidence of skin rash in cetuximab patients.