18.4 Cytogenetics
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is compared to calibration curves that incorporate the type and energy of the radiation, and is scored. A large variability in the number of dicentrics among scored cells
can indicate a partial-body exposure.
Sensitivity and accuracy: Dicentric chromosome analysis is considered to be among
the most sensitive method for determining radiation exposure with a lower detection
level of about 1 Gy [14].
Limitations: Chromosomal aberration analysis is a complicated process that requires
a great deal of skill to perform and to interpret. Determining radiation exposure in
this manner can only be done by a handful of laboratories, which might become
overwhelmed in the aftermath of a radiological or nuclear attack. In addition, individuals will respond differently to the same dose of radiation so a dose of, say, 2 Gy
might cause different numbers of induced chromosomal abnormalities in different
patients.
18.5 Quick Assessment of Internal Radioactivity
Principle: In the immediate aftermath of a large radiological event (accident or emergency) there will be a need to quickly assess internal radiation exposure for a large
number of people; a Community Reception Center (CRC) that is expected to survey
as many as 1000 people per hour might require assessment of internal radioactivity to
determine whether the person requires decorporation therapy, requires no immediate
attention, or requires further assessment via bioassay. In such a situation there will
likely be a large number of people requiring some degree of dose assessment and a
very small number of radiation safety professionals available to perform this dose
assessment. To help to address this need, Korir and Karam [6] developed a quick
assessment methodology utilizing a scoring system that incorporated both qualitative and quantitative factors; designed to be used by personnel with a minimum of
training and to be performed in less than ten minutes per person.
Quantitative factors to be evaluated include contamination levels on the face,
external bioassay count rate from the lungs, and contamination on the skin; qualitative
factors include the presence of dust and debris, injuries, and proximity to the site of
the release. In the event of an attack involving alpha or beta-emitting radionuclides
the qualitative factors might be the only factors that can be scored.
Procedure: If a person passing through the CRC is found to have elevated count rates
they will be sent for decontamination; if the elevated count rates persist then they
are sent for assessment, where the person at the assessment station will complete a
scoring sheet. Each of the qualitative and quantitative criteria is assigned a score; these
scores are summed and the final score determines the person’s disposition—a high
score warrants presumptive decorporation therapy, a low score warrants later followup with a family physician, and an intermediate score calls for further assessment
229
is compared to calibration curves that incorporate the type and energy of the radiation, and is scored. A large variability in the number of dicentrics among scored cells
can indicate a partial-body exposure.
Sensitivity and accuracy: Dicentric chromosome analysis is considered to be among
the most sensitive method for determining radiation exposure with a lower detection
level of about 1 Gy [14].
Limitations: Chromosomal aberration analysis is a complicated process that requires
a great deal of skill to perform and to interpret. Determining radiation exposure in
this manner can only be done by a handful of laboratories, which might become
overwhelmed in the aftermath of a radiological or nuclear attack. In addition, individuals will respond differently to the same dose of radiation so a dose of, say, 2 Gy
might cause different numbers of induced chromosomal abnormalities in different
patients.
18.5 Quick Assessment of Internal Radioactivity
Principle: In the immediate aftermath of a large radiological event (accident or emergency) there will be a need to quickly assess internal radiation exposure for a large
number of people; a Community Reception Center (CRC) that is expected to survey
as many as 1000 people per hour might require assessment of internal radioactivity to
determine whether the person requires decorporation therapy, requires no immediate
attention, or requires further assessment via bioassay. In such a situation there will
likely be a large number of people requiring some degree of dose assessment and a
very small number of radiation safety professionals available to perform this dose
assessment. To help to address this need, Korir and Karam [6] developed a quick
assessment methodology utilizing a scoring system that incorporated both qualitative and quantitative factors; designed to be used by personnel with a minimum of
training and to be performed in less than ten minutes per person.
Quantitative factors to be evaluated include contamination levels on the face,
external bioassay count rate from the lungs, and contamination on the skin; qualitative
factors include the presence of dust and debris, injuries, and proximity to the site of
the release. In the event of an attack involving alpha or beta-emitting radionuclides
the qualitative factors might be the only factors that can be scored.
Procedure: If a person passing through the CRC is found to have elevated count rates
they will be sent for decontamination; if the elevated count rates persist then they
are sent for assessment, where the person at the assessment station will complete a
scoring sheet. Each of the qualitative and quantitative criteria is assigned a score; these
scores are summed and the final score determines the person’s disposition—a high
score warrants presumptive decorporation therapy, a low score warrants later followup with a family physician, and an intermediate score calls for further assessment