Serial Radiography to Assist Irradiation of Carcinoma of the Nasopharynx

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Abstract
Few tumors with so characteristic a clinical course are diagnosed as late as nasopharyngeal carcinoma, which often goes unrecognized until cervical metastases are present. Yet there are few regions in the head and neck which lend themselves better to radiographic examination. The nasopharynx is an air-filled cavity with boundaries that can be readily delineated on the roentgenogram. A systematic study with emphasis on serial films is a valuable tool in the management of patients undergoing irradiation for nasopharyngeal tumors. Such an examination delineates the soft-tissue mass, is simple to perform, causes little or no patient discomfort, and may be repeated at frequent intervals, as required. The importance of roentgenography, with or without opacification of the nasopharynx, was recognized many years ago by Zuppinger (6). A sizable literature, mainly European, has accumulated (1). Baclesse, in his book Tumeurs malignes du pharynx et du larynx (1), devotes an entire chapter to the x-ray examination of the nasopharynx and to the demonstration of representative tumors. Reference should be made to this treatise for a detailed analysis of the normal and abnormal roentgenogram. Radiography limited to a pretreatment study is not without value, demonstrating the size and location of the tumor. It is, however, by analysis of serial radiographic studies, with the pretreatment film as a point of reference, that it has been possible to evaluate regression during irradiation and thus to classify tumors according to their site of origin. We have performed serial studies routinely during irradiation of most cases of carcinoma of the nasopharynx. Ideally, a comprehensive pretreatment study is performed. This includes (a) a lateral radiograph of the nasopharynx, soft-tissue technic (a 6-foot tube-target focal distance with horizontal x-ray beam minimizes distortion), (b) lateral skull tomograms, and (c) contrast nasopharyngograms (lateral and axial views). One or more of these studies were repeated during treatment, at the conclusion of treatment, and as part of the follow-up examination. Lateral soft-tissue roentgenography, which is the simplest of the procedures to perform, may suffice to demonstrate the soft-tissue tumor (3–5). The addition of lateral midline tomograms eliminates confusing extraneous shadows. The mass is silhouetted against the air-filled nasopharyngeal cavity. It has been possible to follow the progress of tumor regression with tomograms alone (Fig. 4), but the examination cannot be considered complete without contrast nasopharyngography. Examination in the lateral and axial projections delineates the tumor in its three dimensions, permitting precise localization and accurate estimate of size and extent. In addition, the integrity of the base of the skull can be evaluated from the axial view.

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