Biomedical Engineering Reference
In-Depth Information
Figure 5.2
Radioactivity penetration.
but as an internalized radionuclide source, they
can cause significant local damage. Beta parti-
cles are very light, charged particles that are
primarily found in radiation fallout. These particles
travel a short distance in tissue; but if large
quantities are involved, they can produce radi-
ation burns that are similar to a thermal burn.
Sources of internal radiation contamination come
from radioactive particles absorbed through open
contaminated wounds or by inhaled and ingested
radioactive material. Once internalized radioactive
contaminates will cause ongoing radioactive expo-
sure and radiations poisoning.
After exposure, the radiation effects can be
grouped into acute and latent effects and are depen-
dant on the radiation dose (Table 5.1). In the
United States, the
radiation absorbed dose
(rad)
is the measure of absorbed radiation. However,
this is being replaced by the International System
unit for radiation absorbed dose, the gray (Gy)
(1 joule per kilogram); 1Gy
in the body are the skin and mucosa, hematopoi-
etic and the gastrointestinal systems. The specific
effects that occur after a variable latent phase of
days to weeks are (1) thermal burn-like effects
to skin and mucosa, (2) gastrointestinal enteritis,
(3) bone marrow suppression with immunological
dysfunction and subsequent secondary infections,
and, (4) hemorrhagic complications from thrombo-
cytopenia.
5.3 Decontamination, Diagnosis,
and Management
5.3.1 External Contamination and Injury
While information regarding the comprehensive
medical management of radiation injury is exten-
sive, there are general guidelines that apply to
decontamination, diagnosis and management of
radiological and combined injuries (Table 5.1).
Ideally, decontamination should be preformed
outside the hospital. Since this will not always
be possible, decontamination procedures should
be part of the operational plans of any treatment
facility. A radiologic survey with an appropriate
radioactivity detector (RADIAC, Geiger) should
be systematically performed on all patients before
and after decontamination (Figure 5.3). Decon-
tamination consideration for non-injured casualties
requires standard universal precaution and removal
of patient clothing. Contaminated clothing should
be carefully removed, placed in marked plastic
bags, and removed to a secure location within a
contaminated area. Removal of clothing can reduce
radiological contaminants by as much as 90%.
=
100 rad; 1 centigray
cGy
1 rad (Table 5.2). The earliest effects of
radiation exposure are limited to early transient
incapacitation (ETI) during extensive exposure and
nausea and vomiting during lesser exposures. ETI
is associated with very high acute doses of radi-
ation (20-40 Gy) and has only occurred during
fuel reprocessing accidents. This level of expo-
sure is unlikely in a terror attack. After an initial
brief loss of consciousness during ETI the patient
lapses into coma within 1-3 days and dies from
central nervous system dysfunction and vascular
instability. The severity and onset of the other
effects after radiation exposure is predictable. The
three most significant radiosensitive organ systems
=
