Introduction

Radiation kills cells by disrupting neutral atoms. It dislodges orbital electrons to form an ion pair consisting of a dislodged electron and the residual atom. Ion pairs are highly chemically reactive.

Rapidly dividing cells are more vulnerable. The clinical outcome depends on how many and which cells die. At lower doses, cells do not die but are at risk of DNA damage and subsequent malignant change. Potential carcinogenesis can occur at lower exposures.

The effects of radiation depend not only on the type of radiation but also on time, distance and shielding – all of which must be considered when planning decontamination of the exposure areas. The absorbed dose is directly proportional to time. Only the minimal amount of time should be spent in the vicinity of a radioactive source.

Without medical management, the lethal dose to kill 50% of the population at 60 days is 4.5 sieverts (Sv). With medical management, 50% of the population would survive exposure to 5-6 Sv.