Historically it has been shown repeatedly that single high doses of radiation do not allow a therapeutic differential between tumor and critical normal tissues but dose fractionation does. The purpose of conventional dose fractionation is to increase dose to the tumor while preserving normal tissue function. Tumors are generally irradiated with 2Gy dose per fraction delivered daily to a more or...

A conventional course of radiation for squamous cell carcinoma in the United States is generally 70 Gy in 7 weeks, with a once-daily dose of 1.8 to 2 Gy. This schedule has a modest success rate in curing head and neck cancer. The past several decades have seen numerous investigations into altering this schedule to optimize the results of radiation. Two approaches, founded on radiobiologic princ...

Delivery of therapeutic radiation in multiple sessions, or fractions, has been practiced since the discovery of radiation’s potential to cure malignancies. Initially, this was done out of practical necessity: Radiation was delivered at a low dose rate, and the treatment sessions had to be repeated to obtain the desired effect. Technologic improvements eventually allowed for treatments in one se...

Local control is paramount in the treatment of localized advanced head and neck cancer. Standard radiotherapy cures a high percentage of early tumors--more than 80% of the early laryngeal tumors--but fewer of the advanced tumors. Attempts have therefore been made to improve the therapeutic ratio by: A) hyperfractionation: reducing the dose per fraction to reduce late morbidity; the total dose i...

69S and a reduced field which encompasses all known tumor is treated on the same day as the large field two or three times per week (an interval of 4 + h is required between fractions) to total doses of 63-70.2 Gy in 5-5#{189}weeks, Acute and late reactions were found to be tolerated such that interruption of treatment (“split”) was avoided with HFX. Data suggest that acute reactions were more ...