Dysphagia following chemoradiation for patients with head and neck cancers have led to a devastating impact on their quality of life, as it leads to a change in the type of diet, prolongation of meal times, or even a need for tube feeding. Although other significant toxicities have been reduced by developments in radiation techniques, dysphagia continues to be a challenge for radiation oncologists. Many phase II studies have shown that reducing the radiation dose to critical swallowing structures such as the pharyngeal constrictor muscle and supraglottic larynx can lead to better outcomes; however, there are limited prospective studies to have verified this benefit. The aim of this study is to compare the effects of standard intensity modulated radiotherapy (S-IMRT) and dysphagia-optimized intensity modulated radiotherapy (Do-IMRT) on severity of dysphagia as well as immediate treatment response in patients undergoing concurrent chemoradiation for oropharyngeal, hypopharyngeal, and supraglottic laryngeal cancer (T2-T4, N+, M0). The swallowing function will be assessed by means of a modified barium swallow technique performed six months after treatment and the treatment response will be assessed by comparing the PET-CT scan taken six months after treatment with the pre-treatment PET-CT scan.