Immobilization and reproducibility in radiotherapy for cancer of the larynx and pharynx using simplified shell and bite-block.

In this paper we describe the comparative study concerning the immobilization during radiotherapy for cancer of the larynx and pharynx with or without shell and fixing device. Immobilization was continuously monitored by semi-conductor detector. Reproducibility was investigated by means of verification film. The result significantly indicated that better immobilization was obtained in the patients treated with use of the shell (p much less than 0.001). Reproducibility of the field arrangement was also sufficient throughout the course of radiotherapy.