Measuring the Mean Lethal Dose (LD50) of 6 MV X-rays in Wistar Rats

There is a risk of genetic mutations and damage to the bodies of the patients and employees who are exposed to ionizing radiation. Utilizing substances that neutralize the produced free radicals by ionizing radiation is one solution to overcome this problem. To study the radioprotective role of these compounds, the mean lethal dose that kills 50% of animals exposed to radiation within 30 days (LD50/30) should be determined. This value is the basis for studying radioprotectors effects on animals. The present study aimed to evaluate the survival or death rate in irradiated rats with different doses of X-rays to determine the mean lethal dose of 6 MV X-rays.

A total of 42 male and female Wistar rats with an approximate weight of 160 ± 10 g were examined. The animals were kept in the pet house at a temperature of 25°C and a light-dark cycle of 12 hours, and water and food were provided freely. The animals were randomly divided into seven groups. Six groups received X-rays with doses of 6.4, 6.5, 6.6, 6.7, 6.8, and 6.9 Gy, respectively. The seventh group (control group) received no radiation dose. The rats were examined for 60 days, and their mortality results were recorded.

Based on the obtained results, LD50/30 was 6.641 Gy for Wistar rats weighing 160 ± 10 g and 16 weeks’ old calculated by Probit Analysis.

This finding can be used to investigate the protective effects of natural substances and chemical drugs on the effects of X-rays on the body.