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contamination. Typically, the patient or someone else provides the important information
that an exposure occurred. To quote the experts, “How does a physician become aware
that his patient(s) may have an external exposure to radioactive material? Usually,
someone tells her.”
After a radiological attack, the history provides the best initial indicator of the likelihood
of internal exposure. The history should include the exposure setting (e.g., enclosed
space, open air in fallout field, etc.) and the protection status of the patient (e.g., wearing
a mask). The patient or a fellow worker may know which isotope was used, or this may
need to be determined by a health physicist in the laboratory.
Initial patient survey and nasal swabs. The initial external survey of the body can be
performed using standard RADIACs with both beta-gamma and alpha probes. Nasal
swabs collected before decontamination can help diagnose, but cannot exclude, a
significant inhalation injury (because the nares are self-cleaning). These swabs should be
collected early, in the first hour and before the patient is washed off or showered, but
decontamination should not be delayed just to obtain nasal samples.
Each nostril should be swabbed separately, and the radioactivity on each swab measured
using a RADIAC. The swabs should be saved. Activity measured by a RADIAC on a
nasal swab reflects lung deposition. Health physicists can calculate the lung burden of the
contaminant using standard equations and extrapolation curves. If both nostrils are “hot,”
the patient probably inhaled contamination. If only one nostril is hot, the patient either
has touched his nose with a contaminated finger (suggesting no lung contamination), or
there is unilateral nasal obstruction.
Measuring internal contamination. The laboratory tests most familiar to medical
personnel (e.g., CBC and chemistry panels) are not helpful in diagnosing internal
contamination. Instead, internal contamination is measured either directly with RADIACs
or indirectly using samples of body fluids and excreta.
Direct measurement. Machines such as RADIACs and larger stationary units such as
whole-body counters directly measure radioactivity of the body. The operator sweeps the
RADIAC slowly over the body, maintaining a constant distance above the skin. A wholebody
counter is a large fixed device, associated with a heavily shielded walk-in or liedown
chamber. This is the most reliable diagnostic instrument, although availability is
limited.
Indirect measurement. Body fluids (obtained by swabs), tissue samples, and excreta can
be directly examined for radioactivity and for the specific radioactive isotopes involved.
A health physicist can then estimate the patient’s “body burden” using extrapolation
curves.
Nasal swabs should be obtained as soon as possible after contamination, as noted above.
These are sent with the patient to the medical facility. Medical or health physics
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