Inclusion Criteria:

• Ability to understand and willingness to sign a written informed consent document.
• Subject must have histologically confirmed stage III or IV squamous cell carcinoma of the head and neck, whose primary origin was from the oral cavity, oropharynx, hypopharynx, or larynx. Carcinoma must be staged using the American Joint Committee on Cancer (AJCC) staging criteria version 6.
• Subject must be scheduled to receive combined chemo-radiotherapy treatment for their standard cancer care. Treatment decisions will be made by the treating otolaryngologist, radiation, and medical oncologists.
• Male or females ≥ 18 years of age. Squamous cell cancer of the head and neck is exceedingly rare in children and not generally applicable to the pediatric population.
• Karnofsky greater than or equal to 60% at time of screening.
• Life expectancy of greater than 6 months.
• Subject must have normal organ and marrow function (as defined below) within 30 days of study enrollment:
• leukocytes ≥ 3,000/μL
• absolute neutrophil count ≥1,500/μL
• platelets ≥ 100,000/μL
• total bilirubin ≤ 1.0 mg/dl*
• AST(SGOT) ≤ 2.5 X institutional upper limit of normal
• ALT (SGPT) ≤ 2.5 X institutional upper limit of normal
• creatinine ≤ 1.4 mg/dl*
• BUN ≤ 20 mg /dl*
• PT and PTT (if biopsy is to be performed) < 2.0 X upper normal limits
• The effects of FLT on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. A screening urine hCG will be administered in the Nuclear Medicine to women of childbearing potential before each FLT scan and pregnant women will not be accepted as subjects in this study.

Exclusion Criteria:

• Subjects who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier.
• Subject may not be receiving any other investigational agents.
• Subject with a Karnofsky score of below 60.
• Pregnant women are excluded from this study. FLT PET has potential for teratogenic effects. Because there are potentially unknown risks for adverse events in nursing infants secondary to treatment of the mother with FLT, breastfeeding should be discontinued if the mother is imaged with FLT and may not resume for 48 hours after the FLT imaging.
• Subjects taking nucleoside analog medications such as those used as antiretroviral agents.