Intensity-Modulated Radiotherapy: First Results with this New Technology on Neoplasms of the Head and Neck

Abstract

Intensity-modulated beam radiotherapy (IMRT) delivers a highly conformal, three-dimensional (3-D) distribution of radiation doses that is not possible with conventional methods. When administered to patients with head and neck tumors, IMRT allows for the treatment of multiple targets with different doses, while simultaneously minimizing radiation to uninvolved critical structures such as the parotid glands, optic chiasm, and mandible. With 3-D computerized dose optimization, IMRT is a vast improvement over the customary trial-and-error method of treatment planning. We retrospectively reviewed the charts of the first 28 head and neck patients at our institution who were treated with IMRT. All had head and neck neoplasms, including squamous cell carcinoma, adenoid cystic carcinoma, paraganglioma, and angiofibroma. Total radiation doses ranged from 1,400 to 7,100 cGy, and daily doses ranged from 150 to 400 cGy/day. A quality assurance system ensured that computer-generated dosimetry matched film dosimetry in all cases. For midline tumors, this system allowed us to decrease the dose to the parotid glands to less than 3,000 cGy. The incidence of acute toxicity was drastically lower than that seen with conventional radiotherapy delivery to similar sites. This is the first report of the application of IMRT strictly to head and neck neoplasms. We discuss the indications, technique, and initial results of this promising new technology. We also introduce the concept of the Simultaneous Modulated Accelerated Radiation Therapy boost technique, which has several advantages over other altered fractionation schemes.