Exposure: Whole Body - Animation
Radiation exposure occurs when all or part of the body absorbs
ionizing radiation from an external radiation source, as shown in the illustration above.
Exposure from an external source stops when a person leaves the area of the source, the source is shielded completely, or the process causing exposure ceases.
Radiation exposure also occurs after internal contamination, i.e., when a radionuclide is ingested, inhaled or absorbed into the blood stream.
This kind of exposure stops only if the radionuclide is totally eliminated from the body, with or without treatment.
An individual exposed only to an
of radiation, as shown above, is
NOT radioactive or contaminated
and may be approached without risk, just like after a chest x-ray or CT scan.
Radiation from external exposure alone is either absorbed without the body becoming radioactive, or it can pass through the body completely.
Therefore, if a person is scanned with a
radiation survey monitor
after external exposure alone, the device will not register radiation above the background level.
Acute Radiation Syndrome (ARS)
may result if the dose from whole or partial body exposure is high enough.
How to diagnose ARS: estimate whole body dose and clinical severity by using
Time to onset of vomiting
Lymphocyte depletion kinetics
Clinical signs and symptoms associated with ARS and its subsyndromes
Whole body exposure
: entire person receives penetrating radiation, i.e., no portion of the body is shielded
Partial body exposure
: shielding of sufficient thickness blocks a significant portion of the person from receiving penetrating radiation