201704临沂放射工作人员职业健康培训ppt课件.ppt

* * 宫腔内受照后儿童癌症危险资料，还来自出生前接受X射线诊断照射后儿童癌症的牛津儿童癌症（OSCC）。 * While the dose in the centre of hypothenar (ulnar) side of the palm was 100 Gy, it steeply decreased with distance. At the thenar (radial) side of the palm or last phalanx of the index finger, it decreased to 2-3 Gy. Consequently, a severe large ulcer developed in the hypothenar with necrosis in the centre, while there was no permanent damage induced at the thenar side or in the fingers. * Patient OAF of the Goiania accident (1987) 17 days after exposure: Large and tense bulla in his left palm with significant swelling limiting fingers movement. * 4. Moist desquamation Severe damage to the vasculature and connective tissue is the cause of moist desquamation or exudative epithelitis. The threshold dose to provoke this type of change is between 15-25 Gy. Intracellular oedema; vesicles coalesce to form bullae exterior to the basal layer; epidermis may slough, exposing the dermal surface, coated with fibrin. It appears during the second or third week after exposure. Its onset is directly related to the intensity of exposure. 5. Blisters Hands of the person (in the slide above) were exposed to gamma rays of 200 to 400 Gy. 3 days after irradiation, his hands showed very severe blisters. 12 days after the exposure, the epidermis had diffusely sloughed. * 6. Ulceration and Necrosis Ulceration occurs between four to six weeks after irradiation with doses higher than 20 Gy. Necrosis appears days or several weeks after local exposure to over 25 Gy. The ulcer and its natural evolution, necrosis, result from an ischemic process owing to occlusion of the capillaries underlying the lession as a consequence of the hyperplasia of endothelial cells (obliterative endarteritis), which finally reduces the blood flow and favours formation of microthrombi. * This photo presents spontaneous healing 1.5 month after the exposure to 137-Cs (in Goiania). Hyper- and depigmented areas, skin atrophy, teleangiactasia and fr