Pediatric emergency medicine trisk 1983 1983
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dose. Local injuries are rarely life threatening, but they are difficult to manage
because they often cause a slowly progressive injury that takes months and
sometimes years to fully evolve. The injury develops slowly because the radiation
causes progressive fibrosis of the blood vessels, which, in turn, causes tissue
necrosis. The ultimate extent of the injury may not be appreciated initially.
Healing following amputation or reconstructive surgery is poor because of
deficient blood supply.
TABLE 90.15
APPROXIMATE ABSORBED DOSE TO PRODUCE SKIN CHANGES
FROM LOCAL RADIATION INJURY
Absorbed dose
(Gy)
Findings
3-6
Threshold for erythema
15
20
Moist desquamation
Skin ulceration with slow healing
>30
Gangrenous changes
The hand is the most common site for localized radiation injuries. The next
most common sites are the thighs and buttocks because individuals are likely to
put things that they find into their pockets. A patient who has undergone a
fluoroscopic procedure could have local radiation injury to the skin overlying the
region imaged. For example, the radiation source is typically positioned posterior
to a patient undergoing a cardiac catheterization and therefore a radiation burn
would be on the back. Most industrial radiography sources deliver an extremely
high radiation dose. In contrast, analytical x-ray crystallography machines, which
emit x-rays of much lower energy than the photons of 192Iridium, are not likely
to cause deep blood vessel injury.
Local radiation injuries can typically be differentiated from thermal burns. The
effects of a thermal burn appear immediately. If a patient presenting with a burnlike injury does not know the cause or time of the injury, a local radiation injury
should be suspected. Table 90.15 lists the dose-related findings expected after an
acute local radiation exposure.
If erythema is seen within the first 48 hours, ulceration may occur later. The
erythema may come in waves that appear, disappear, and then reappear. With
transepidermal injury, blister formation may occur at 1 to 2 weeks with doses in
