Roentgen irradiation at 200 kV of neoplasms of the nasopharynx. Technique and dose distribution.

Abstract

hlalignant tumours of the nasopharynx have usually been treated by conventional roentgen therapy. In recent years y-radiation from 6oCo sources and high energy roentgen rays from 35 MeV betatrons have also been employed; an attempt was made by SNELLING in 1954 to estimate the dose distribution for some different types of treatment techniques. This paper presents an analysis of the dose distribution in the nasopharynx and adjacent structures obtained by roentgen irradiation at 200 kV with a 4-field technique in the treatment of tumours limited to the nasopharynx. Technique. A sketch is first made of the contour of the face at the level of the nasopharynx and a lateral roentgenogram is obtained of the skull. The enlargement of the roentgenogram in the sagittal plane can be determined by means of a measuring stick fixed on the forehead and nose of the patient. The true depth of the nasopharynx and the site of the tumour are established and transferred to the previously drawn sketch.