Clinically accessible oral cavity cancers may be treated with interstitial radiation therapy, external beam, or a combination of both. Interstitial treatments (brachytherapy) may include radioactive needles (radium 226, cesium 137), wires (iridium 192), or seeds (iridium 192).

High dose radiation therapy to the primary site and regional lymph nodes is also the treatment of choice for cancer of the nasopharynx. High dose radiation therapy is necessary to treat cancers of the paranasal sinuses and nasal cavity, which frequently invade adjacent bony structures.

Radiation therapy for salivary gland tumors is usually reserved for tumors that are inoperable, unresectable or recurrent. However, neutron beam radiation has been proven to be effective for salivary gland cancers in clinical trials.

Radiation therapy alone is a treatment option for low stage laryngeal cancers, in order to preserve the voice.

Hyperfractionated radiation therapy is under clinical investigation for many head and neck sites.

Radiation modifiers, such as chemosensitizers, are under clinical investigation for treatment of large or bulky lesions.

Iodine isotope (iodine 131) is used in thyroid cancer cases to decrease the recurrence rate for follicular and papillary carcinomas.