18.3 Clinical Signs and Symptoms
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18.3 Clinical Signs and Symptoms
Principle: Radiation affects the body in a somewhat predictable manner and various
levels of radiation exposure cause a predictable suite of symptoms that appear in a
predictable sequence. The timing of these symptoms’ appearance and their severity
can help physicians to determine the radiation dose to which a person was exposed.
For example, if a patient begins vomiting within ten minutes of their exposure to
radiation then it is likely that the person received a dose in excess of 8 Gy and is
unlikely to survive. On the other hand, if the patient has not begun vomiting more
than two hours after exposure then they likely received a dose of less than 1 Gy and
will almost certainly survive the radiation exposure (Fig. 18.4).
Procedure: Medical caregivers will record the patient’s symptoms as they appear
and evolve with time post-exposure. These symptoms and the time and order in
which they appear are compared to standardized charts or entered into software for
evaluation [5, 12].
Sensitivity and accuracy: Doses of less than about 1 Sv cannot be estimated using
clinical symptoms as there might be no symptoms other than lymphocyte depletion
following lower levels of exposure. At higher levels of exposure the symptoms might
not manifest for several hours or days. This method is less accurate than lymphocyte
depletion in terms of estimating radiation dose received, given the normal variation
between patients.
Limitations: The studies on which these tables were derived generally involved
healthy radiation workers and citizens who were exposed to radiation but not to
physical trauma. These tables also omit the elderly and the very young, both of
whom can be expected to respond differently to various levels of radiation exposure.
Thus, the progression of symptoms in patients who were burned, injured, or who
inhaled dust and smoke might differ from what is shown in the standard tables [2, 7].
18.4 Cytogenetics
Principle: Radiation exposure can cause chromosomal abnormalities, including
dicentric chromosomes, and the number of chromosomal abnormalities is related
to the radiation exposure received. The dicentric chromosomes are caused by the
misrepair of radiation-induced single-strand DNA breaks; this type of damage is
more likely to be caused by radiation than by other agents so this method is considered to be the most specific to radiation exposure. By quantifying the number of
dicentric chromosomes in a blood sample it is possible to estimate radiation exposure
received [11].
There are additional forms of chromosomal analysis that can be used to determine radiation exposure, including using fluorescent in situ hybridization (FISH)
227
18.3 Clinical Signs and Symptoms
Principle: Radiation affects the body in a somewhat predictable manner and various
levels of radiation exposure cause a predictable suite of symptoms that appear in a
predictable sequence. The timing of these symptoms’ appearance and their severity
can help physicians to determine the radiation dose to which a person was exposed.
For example, if a patient begins vomiting within ten minutes of their exposure to
radiation then it is likely that the person received a dose in excess of 8 Gy and is
unlikely to survive. On the other hand, if the patient has not begun vomiting more
than two hours after exposure then they likely received a dose of less than 1 Gy and
will almost certainly survive the radiation exposure (Fig. 18.4).
Procedure: Medical caregivers will record the patient’s symptoms as they appear
and evolve with time post-exposure. These symptoms and the time and order in
which they appear are compared to standardized charts or entered into software for
evaluation [5, 12].
Sensitivity and accuracy: Doses of less than about 1 Sv cannot be estimated using
clinical symptoms as there might be no symptoms other than lymphocyte depletion
following lower levels of exposure. At higher levels of exposure the symptoms might
not manifest for several hours or days. This method is less accurate than lymphocyte
depletion in terms of estimating radiation dose received, given the normal variation
between patients.
Limitations: The studies on which these tables were derived generally involved
healthy radiation workers and citizens who were exposed to radiation but not to
physical trauma. These tables also omit the elderly and the very young, both of
whom can be expected to respond differently to various levels of radiation exposure.
Thus, the progression of symptoms in patients who were burned, injured, or who
inhaled dust and smoke might differ from what is shown in the standard tables [2, 7].
18.4 Cytogenetics
Principle: Radiation exposure can cause chromosomal abnormalities, including
dicentric chromosomes, and the number of chromosomal abnormalities is related
to the radiation exposure received. The dicentric chromosomes are caused by the
misrepair of radiation-induced single-strand DNA breaks; this type of damage is
more likely to be caused by radiation than by other agents so this method is considered to be the most specific to radiation exposure. By quantifying the number of
dicentric chromosomes in a blood sample it is possible to estimate radiation exposure
received [11].
There are additional forms of chromosomal analysis that can be used to determine radiation exposure, including using fluorescent in situ hybridization (FISH)