[Some remarks concerning the tissue-air-ratio (TAR) in the case of bilateral total body irradiation (author's transl)].

The TAR's resulting from the bilateral 60Co-irradiation of an homogeneous whole body phantom and of a quadratic phantom are measured in their midlines and at their surfaces of incidence. They are compared with measurements on a patient. The dose contributions of scattered radiation and its effective energy are determined by means of a simple water-phantom. Investigations concerning the influence of the "os ilium" on the midline dose showed that besides the former mentioned other bone structures too in the pelvic area are responsible for the low rectal dose in patients. Rectal doses therefore should not considered representative for the midline dose. The variation of the midline dose depending on the source distance is discussed.