Inclusion Criteria:

          -  The participant must have squamous cell carcinoma proven by histologic diagnosis; for
             cancers of the oropharynx, p16 staining by immunohistochemistry must be negative; for
             cancers of the larynx, hypopharynx, oral cavity, nasopharynx, paranasal sinuses, p16
             staining is not required

          -  The participant must have clinical stage T1-4, N0-3, M0-1, stage II-IVC carcinoma as
             per the 7th edition of the American Joint Committee on Cancer (AJCC) staging manual;
             participants with T1N0M0 will be ineligible; participants with metastatic disease with
             a limited metastatic burden are eligible if obtaining local control is determined by
             their treating oncologist to be an important therapeutic goal

          -  The participant must have imaging documenting a primary tumor, or involved lymph node,
             ≥ 2.5 cm in greatest dimension

          -  PET/CT is required for all participants, unless contraindicated; this may be acquired
             prior to study entry or after enrollment prior to SBRT planning

          -  The participant must have a history and physical documented within four weeks of
             registration and be deemed by a medical oncologist to be ineligible for standard
             continuous course chemoradiotherapy with cisplatin

          -  Karnofsky performance status (PS) ≥ 40

          -  Female participants cannot be of childbearing age, or if they are, must have a
             negative pregnancy test prior to enrollment and be willing to use contraceptives
             during treatment and continue for 6 additional months

          -  Participants must have the ability to understand and the willingness to sign a written
             informed consent document

        Exclusion Criteria:

          -  Participants with T1N0M0 stage I disease

          -  Participants who are receiving any other investigational agents

          -  Participants with non-squamous cell histology

          -  Participants with life expectancy < 6 months

          -  Participants who cannot lie flat for 20 minutes

          -  Participants with prior history of head and neck radiotherapy (> 40 Gy) with
             significant areas of anticipated overlap