Biological effects of different fractionated irradiation on pancreas after / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the damages on pancreas after different fractionated irradiation in rats.Methods Eighy healthy adult Wistar rats were randomly divided into four groups with 20 rats in each group as conventional fractionated irradiation group with 2 Gy per fraction to a dose of 12 Gy,hypofractionated radiation group with one fraction of 12 Gy,middle-dose fractionated radiation group with 6 Gy per fraction to a dose of 12 Gy in the interval of 4 days and control group without radiation.Changes in weight,fasting blood glucose and amylase were measured and morphological changes were observed in different periods.Results In the experimental groups,the reduction was observed in fasting glucose at 4 d,reached a minimum of (3.1 ±0.1 ) mmol/L,(LSD-t =20.06 -28.74,P ＜0.001 ) and the increase of amylase was found after 4th and 7th day,reached a maximum of (84.5 ±6.4) U/L(Dunnett's-t=23.10 -46.10,P ＜ 0.001 ),both more obvious in hypofractionated radiation group than those of conventional fractionated radiation group and middle-dose fractionated radiation group ( LSD-t =8.72-9.71,Dunnett's-t =7.11,P ＜ 0.05 ),however the levels in conventional fractionated radiation group was nearly to middle-dose fractionated radiation group (P ＞ 0.05 ) and became normal at 14 d.Under light microscope,the necrosis of acinarcells was observed in hypofractionated radiation group at 4th d,interstitial fibrogenesis were found at 14 d,the fibrogenesis were found in pancreatic island at 21 d,and the hyperplasia of acinarcells was observed at 42 d.The same changes were found in conventional fractionated radiation group and middle-dose fractionated radiation group,which were gently and lately than those of hypofractionated radiation group.Conclusions Radiation injury is not more serious after middle-dose fractionated radiotherapy than that after conventional fractionated irradiation,when the proper fractional dose and intervals are chosen.