IN DECEMBER 1944, Andrews, Braestrup and Heisel1 published a study of the exit dose in dermatologic roentgen therapy. This factor was defined as the amount of radiation received by the skin opposite an irradiated surface. Their work suggested that the exit dose was an important reason for the localization of radiodermatitis on the middle part of the face, hands and feet following low voltage roentgen therapy. Since this paper was presented chiefly from an experimental point of view, the purpose of the present study is to show the clinical significance of the exit dose. Tables are included which set forth the exit dose values at various kilovoltages commonly used in the treatment of simple inflammatory dermatoses. It is in these diseases that fractional dosage is repeated on extensive areas. When this radiation is used on the face and extremities the exit dose becomes an important consideration.
Numerous reviews of