RBE and OER of π−mesons for damage to cultured T−1 cells of human kidney origin

Cultured cells of human kidney origin (T−1 cells) have been used to measure the oxygen-enhancement ratio of π− mesons at the peak of the depth-dose distribution and the biological effectiveness of π− mesons was compared with that of 60Co γ rays. The OER appears to be dose dependent, and has values of 1·9 and 1·5 at survival levels of 50 and 10 per cent respectively. The relative biological effectiveness of π− mesons was found to be between 2·2 and 2·4 for oxygenated cells. The OER of 60Co γ rays (240 R/hour) was 2·6 and 2·3 measured at 50 and 10 per cent survival, respectively. Similar measurements with Chang liver cells yielded identical values for the OER of π− mesons.