Abstract
A high energy X-ray TV have made much contribution to ensuring a field control during radiation therapy. The function of the collimeter was continuously observed on moniter TV. The more important was the fact that the TV image recorded on video-tapes during the whole couse of therapy was useful for future reference. To obtain a better TV image, some investigations performed regarding a fundamental characteristics of the luminescent screen used for this purpose, operating the linear accelator (Toshiba LMR-13). There was basical differnce between X-ray of linear accelator and gamma ray of telecobalt unit in that the former consisted a series of pulses, but the latter was continuous beam. Relation between the dose of high energy X-ray and the brightness of the luminescent screen was studied to answer a question whether the screen was saturated by X-ray or not. It was obtained results that brightness of the screen was proportional to X-ray dose.
