Optimization irradiation conditions for determination of LD50 in pigs

Radiation LD50/30 values were determined in 36 twelve-week-old pigs (with a mean body weigth of 21 kg) exposed to whole-body X-ray irradiation on a revolvable table rotated at a rate of 2.5 rpm using the following conditions: 180 kV, 15 mA, focal distance 79 cm, HVT 0.9 mm Cu, dose rate 2.42 X 10(-3) to 2.68 X 10(-3) C kg-1 min-1 (9.4 to 10.4 R/min) depending upon the animal size. The coefficient of mean irradiation uniformity was 1.4. Under these conditions the LD50/30 for pigs was found to be 5.89 X 10(-2) C kg-1 min-1 (228.3 R) with the biological range of effectiveness being 5.22 X 10(-2) to 6.90 X 10-(2) C kg-1 (202.4 to 267.6 R). Furthermore experiments on 77 pigs showed that LD50 determined in this study had actually the median lethal effect.