Acute Radiation Syndrome (ARS)-
Also Known as Radiation Sickness
People exposed to radiation will develop ARS only if all the following are true:
The radiation dose was high
The radiation was penetrating (i.e., able to reach internal organs, as with x-rays or gamma rays)
The person's entire body, or most of it, received the dose
The radiation was received in a short time, usually within minutes
Clinical severity of the four ARS subsyndromes will vary with dose and host factors:
High dose whole body radiation exposure will also produce clinically detectable effects in the lung, liver and kidneys, among other organs. Usually, injury to these organs is detected well after those from the standard four ARS subsyndromes, and individuals would have to survive the earlier-onset injuries to blood, the GI tract, skin and and neurovascular system, for these to become clinically life-threatening.
Immune dysfunction, as part of hematopoetic system injury, is also clinically important, if the dose from exposure is high enough.