Biomedical Engineering Reference
In-Depth Information
children and adolescents is a major effect from the Chernobyl accident. Figure 13.7
shows an example of findings from one study.
Additional information on what has been learned from radiation accidents can
be found in several of the references listed in Section 13.15 and on the World Wide
Web. Experience with the medical and logistic management of radiation accidents
also has important lessons for dealing with potential terrorist attacks that might
involve radiation.
5)
13.8
The Acute Radiation Syndrome
If a person receives a single, large, short-term, whole-body dose of radiation, a
number of vital tissues and organs are damaged simultaneously. Radiosensitive
cells become depleted because their reproduction is impeded. The effects and their
severity will depend on the dose and the particular conditions of the exposure. Also,
specific responses can be expected to differ from person to person. The complex of
clinical symptoms that develop in an individual plus the results of laboratory and
bioassay findings are known, collectively, as the acute radiation syndrome.
The acute radiation syndrome can be characterized by four sequential stages. In
the initial, or prodromal, period, which lasts until about 48 h after the exposure,
an individual is apt to feel tired and nauseous, with loss of appetite (anorexia) and
sweating. The remission of these symptoms marks the beginning of the second,
or latent, stage. This period, from about 48 h to 2 or 3 wk postexposure, is char-
acterized by a general feeling of well being. Then in the third, or manifest illness,
stage, which lasts until 6 or 8 wk postexposure, a number of symptoms develop
within a short time. Damage to the radiosensitive hematologic system will be ev-
ident through hemorrhaging and infection. At high doses, gastrointestinal symp-
toms will occur. Other symptoms include fever, loss of hair (epilation), lethargy,
and disturbances in perception. If the individual survives, then a fourth, or recov-
ery, stage lasts several additional weeks or months.
Depending on the dose received, the acute radiation syndrome can appear in
a mild to very severe form. Table 13.6 summarizes typical expectations for differ-
ent doses of gamma radiation, which, because of its penetrating power, gives an
approximately uniform whole-body dose.
An acute, whole-body, gamma-ray dose of about 4 Gy without treatment would
probably be fatal to about 50% of the persons exposed. This dose is known as the
LD50—that is, the dose that is lethal to 50% of a population. More specifically, it
is also sometimes called the LD50/30, indicating that the fatalities occur within 30
days.
5
See the Proceedings of the 40th Annual
Meeting of the NCRP: Advances in
Consequence Management for Radiological
Terrorism Events,
Health Phys.
89
, 415-588
(2005).
