Safety_Series_025_1968 - gnssn - International Atomic Energy ...

This publication is no longer validPlease see http://www.ns-iaea.org/standards/1.3. 1.2. SkinSince radiation entering the body from external sou rces has a l­m ost in varia bly to p ass fir s t through the skin, the rea ction o f theskin to ion izin g radiation has been studied in great d eta il. B eforethe developm ent of accu rate d osim eters, erythem a of the skin fo l­low ing external irradiation by X -r a y s was taken as the basis of theb io lo g ica l unit o f d ose. A fter la rg e r d oses this erythem a changesto pigmentation, and after still greater doses, various types of radiodermatitis appear, which m ay lead to n e cro sis and u lcera tion s andmay finally becom e malignant growths. This latter case applies particularly to the form s of derm atitis resulting from chronic low -d oseX -r a y irradiation.T h ree d e g re e s of acute ra d io d e rm a titis can be distin guish ed:(1) R adioderm atitis eryth em atosa. This m an ifests its e lf in areddening of the skin beginning on the fourth to the seventh day. Onlyin the third to fourth week d oes the skin regain its n orm al a p p ea ra n ce.Hair from head and beard may fall from the areas of reddened skinwithin two or three w eeks. The skin rem ains tem porarily coloured,peels easily, and is d ry. E pilation is one o f the m ost con spicu ou sevents even after a dose of 200 rads of soft radiation. It begins 13 to17 days a fter irradiation and m ay be rep laced by a regrow th of hairafter several months depending on the dose delivered. A dose higherthan 2000 rads leads to com plete and permanent epilation.(2) R adioderm atitis bu llosa . T his o ccu rs after la rg e r d oses,and between the second and fifth days after exposure the skin becom esdark violet in colou r and water b listers, sim ilar to those occu rrin gin se con d -d e g re e burns, a re fo rm e d . The skin itch es, burns andis painful. Within two or three weeks, the hair falls out and the lossis largely perm anent. Healing is slow , and the skin th ereafter r e ­m a in s d ry , w h itish and c r o s s e d with b r ig h t-r e d b lo o d v e s s e ls .(3) R adioderm atitis e sch a rotica . The skin reddening appearsas early as the second or third day after a high radiation dose. Deepand painful u lce rs and a lso a b s c e s s e s appear on the skin, healingis slow, and sca rs, interwoven with large blood v e sse ls , rem ain onthe damaged a reas. The skin is dry, since the sebaceous and sweatglands have been com pletely destroyed.37