A technique for treatment of advanced carcinomas of the larynx and hypopharynx using low-megavoltage X-rays.
An isocentric three-field technique is described for irradiation of advanced lesions of the larynx and hypopharynx with low-megavoltage (less than or equal to 6 MV) X-rays. The technique has been designed to eliminate field junctures. Two anterior oblique fields and a single posterior field with central spinal cord block are used. With Ellis filters to compensate for tissue deficits, dose homogeneity is assured throughout the upper and lower neck; in particular, the dose at the anterior aspect of the spinal cord is seen to vary by less than 5%. Using this technique, it is possible to deliver 52 Gy to the primary tumor and regional nodes, while restricting the maximum spinal cord dose to 45 Gy. Computed dose distributions are presented and compared with point-dose thermoluminescent measurements made on a humanoid phantom.
D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000532:radiotherapy*; D007822:Laryngeal Neoplasms / Q000532:radiotherapy*; D008953:Models, Anatomic; D010610:Pharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy / Q000295:instrumentation; D013116:Spinal Cord / Q000528:radiation effects; D013819:Thermoluminescent Dosimetry