Forensic Pathology for Police - Brainshare Public Online Library

Radiation 579
radiation). Alpha particles have the least ability to penetrate tissues, are able to be
shielded by paper or clothing, but can result in serious health concerns if ingested.
Beta particles can penetrate tissues to a moderate extent, are able to be shielded by
plastic and light metals, and can induce serious health risks, including skin burns.
Neutrons can be shielded by concrete, water and oil, and large doses can be fatal.
Gamma waves are able to penetrate deeply into the body, are able to be blocked by
lead and concrete, and can be highly lethal.
There are a variety of terms used to define specific amounts of ionizing radiation.
A “roentgen” is a unit of charge produced by X-rays or gamma rays that
ionize a specific volume of air. A “rad” is the dose of radiation that will produce
absorption of 100 ergs of energy per gram of tissue. A “gray” (Gy) is the dose of
radiation that will produce absorption of 1 joule of energy per kilogram of tissue.
One Gy is equivalent to 100 rads. A “rem” is the dose of radiation that causes a
biologic effect that is equivalent to 1 rad. A “sievert” (Sv) is the dose of radiation
that causes a biologic effect that is equivalent to 1 Gy. One Sv is equivalent to
100 rem.
Ionizing radiation damage to the human body depends on the overall dose of
radiation, the duration, and the mode of exposure. The cells that are most sensitive
to ionizing radiation include the bone marrow (where blood cells are made), reproductive
cells, and the cells that line the gastrointestinal tract. The least sensitive cells
are muscle, bone, nerve, and red blood cells. In controlled settings, such as occurs in
radiation therapy for cancer treatment, the radiation “beam” is directed at the malignancy,
in the hope that the radiation will kill the cancer cells. Efforts are made to
protect the surrounding normal tissues from the damaging effects of the radiation,
but radiation injury can still occur (Disc Image 21.33). In situations where there is
chronic (long-term) or subacute excessive exposure, such as may occur in persons
working with radiation, a variety of effects can occur, including effects on growth
and development, and the induction of genetic mutations, including those that cause
cancer. When there is acute (quick), whole-body exposure, such as may occur in
nuclear reactor accidents or in atomic/nuclear bombings, the damage depends on
the overall whole-body dose.
The following effects occur with the corresponding whole-body dose: 25
rads – no effect; 100–200 rads – mild radiation sickness (“subclinical” nausea,
vomiting, destruction of some lymphocytes); 200–600 rads – definite radiation
sickness, primarily “hematopoietic” (marked reduction of white blood cell (WBC)
numbers, infection, high incidence of death); 600–1000 rads – severe radiation sickness,
primarily “gastrointestinal” (severe nausea, vomiting, diarrhea, hemorrhage,
WBC destruction, infection, electrolyte disturbances, skin burns, death within 10–
14 days); >1000 rads – very severe acute radiation sickness, with “central nervous
system” effects (as above with confusion, convulsions, somnolence, coma, death
within 2 days).
Before examination and autopsy of a person who has been exposed to ionizing
radiation, death investigators and pathologists should first make certain that proper
decontamination procedures have been instituted, such that the body (including
surroundings and personal effects) does not pose a threat.