Inclusion Criteria:

          -  Pathologically (histologically or cytologically) proven diagnosis of squamous cell
             carcinoma of the oropharynx, which include the sites tonsil, base of tongue, soft
             palate, or posterior oropharyngeal wall. Histologic variants will be included
             (papillary squamous cell carcinoma and basaloid squamous cell carcinoma). Cytologic
             diagnosis from a cervical lymph node is sufficient in the presence of clinical
             evidence of a primary tumor in the oropharynx.

          -  Patient's tissue must be positive for p16 by immunohistochemical staining (>70%
             staining). Fine needle aspiration (FNA) biopsy specimens may be used as the sole
             diagnostic tissue if formalin-fixed paraffin-embedded cell block material is available
             for p16 immunohistochemistry.

          -  Clinical stage T1-T2, N1-N2b or T3, N1-N2b (AJCC 7th Edition) with no distant
             metastases based on the following diagnostic workup:

          -  Fiberoptic exam with laryngopharyngoscopy (mirror and/or fiberoptic and/or direct
             procedure) within 8 weeks prior to registration.

          -  One of the following combinations of imaging is required within 8 weeks of
             registration:

               1. Or a CT scan of the neck (with contrast) and a PET/CT of neck and chest (with or
                  without contrast);

               2. Or an MRI of the neck (with contrast) and a PET/CT of neck and chest (with or
                  without contrast)

               3. Note: A CT scan of the neck and/or a PET/CT performed for the purposes of
                  radiation planning may serve as both staging and planning tools.

          -  Patients must provide their personal smoking history prior to registration. Patients
             cannot have a cumulative personal smoking history that exceeds 10 pack-years.

               1. Number of pack-years = [Frequency of smoking (number of cigarettes per day) x
                  duration of cigarette smoking (years)] / 20

               2. Note: Twenty cigarettes is considered equivalent to one pack. Cigar and pipe
                  tobacco consumption is not included in calculating lifetime pack-years.

          -  Zubrod Performance Status of 0-1 within 8 weeks prior to registration;

          -  Adequate hematologic function within 2 weeks prior to registration, defined as
             follows:

        Absolute neutrophil count (ANC) ≥ 1,500 cells/mm3; Platelets ≥ 100,000 cells/mm3;
        Hemoglobin ≥ 8.0 g/dl; Note: the use of transfusion or other intervention to achieve Hgb ≥
        8.0 g/dl is acceptable.

          -  Adequate renal function within 2 weeks prior to registration, defined as follows:

             a.Serum creatinine ≤ mg/dl or creatinine clearance (CC) ≥ 50 ml/min determined by 24
             hour collection or estimated by Cockcorft-Gault formula: i.CCr male = [(140 - age) x
             (wt in kg)] [(Serum Cr mg/dl) x (72)] ii.CCr female = 0.85 x (CrCl male)

          -  Negative serum pregnancy test within 14 days prior to registration for women of
             childbearing potential;

          -  Patients who are HIV positive but who have no prior AIDS-defining illness and have CD4
             cells of at least 350/mm3 are eligible. HIV-positive patients must not have multi-drug
             resistant HIV infection or other concurrent AIDS-defining conditions. Patients must
             not be sero-positive for Hepatitis B (Hepatitis B surface antigen positive or
             anti-hepatitis B core antigen positive) or sero-positive for Hepatitis C
             (anti-Hepatitis C antibody positive). However, patients who are immune to hepatitis B
             (anti-Hepatitis B surface antibody positive) are eligible (e.g. patients immunized
             against hepatitis B).

          -  The patient must provide study-specific informed consent prior to study entry.

        Exclusion Criteria:

          -  Cancers considered to be from an oral cavity site (oral tongue, floor of mouth,
             alveolar ridge, buccal or lip), or the nasopharynx, hypopharynx, or larynx, even if
             p16 positive;

          -  Carcinoma of the neck of unknown primary site origin (even if p16 positive);

          -  Distant metastasis or adenopathy below the clavicles;

          -  Gross total excision of both primary and nodal disease; this includes tonsillectomy,
             local excision of primary site, and nodal excision that removes all clinically and
             radiographically evident disease.

          -  Simultaneous primary cancers or separate bilateral primary tumor sites;

          -  Prior invasive malignancy malignancy (except non-melanomatous skin cancer) unless
             disease free for a minimum of 1095 days (3 years) (for example, carcinoma in situ of
             the breast, oral cavity, or cervix are all permissible);

          -  Prior systemic chemotherapy for the study cancer; note that prior chemotherapy for a
             different cancer is allowable;

          -  Prior radiotherapy to the region of the study cancer that would result in overlap of
             radiation therapy fields;

          -  Severe, active co-morbidity defined as follows:

               1. Unstable angina and/or congestive heart failure requiring hospitalization within
                  the last 6 months;

               2. Transmural myocardial infarction within the last 6 months;

               3. Acute bacterial or fungal infection intravenous antibiotics at the time of
                  registration;

               4. Chronic obstructive pulmonary disease exacerbation or other respiratory illness
                  requiring hospitalization or precluding study therapy within 30 days of
                  registration;

               5. Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects;
                  note, however, that laboratory tests for liver function and coagulation
                  parameters are not required for entry into this protocol other than those listed
                  in 4.1.10.

               6. Acquired immune deficiency syndrome (AIDS) based upon the current CDC definition
                  with immune compromise greater than that noted in section 4.1.12; note, however,
                  that HIV testing is not required for entry into this protocol. The need to
                  exclude patients with AIDS from this protocol is necessary because the treatments
                  involved in this protocol may be significantly immunosuppressive.
                  Protocol-specific requirements may also exclude immune-compromised patients.

          -  Pregnancy; this exclusion is necessary because the treatment in this study may be
             significantly teratogenic

          -  Prior allergic reaction to cisplatin.

          -  Exclusion Criteria for MRI: Normal MRI exclusion criteria will apply, including those
             on the following list. A standard MRI safety form will be used to identify potential
             conditions warranting exclusion.

          -  Electrical implants such as cardiac pacemakers or perfusion pumps

          -  Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial
             heart, valves with steel parts, metal fragments, shrapnel, bullets, tattoos near the
             eye, or steel implants

          -  Ferromagnetic objects such as jewelry or metal clips in clothing

          -  Claustrophobia

          -  History of seizures

          -  Diabetes a.In addition, patients with GFR < 15 ml/min/1.73m2 or who are on dialysis
             will not have DCE-MRI scan. These patients will have conventional anatomical MRI
             without contrast and DW-MRI,