Correlation occurrence of radiation induced encephaledema with target dose and volume in stereotactic radiosurgery of epilepsy / 中华放射医学与防护杂志

ABSTRACT

Objective To study the correlation between the occurrence of encephaledema and the target dose-volume after the low dose stereotactic radiosurgery of epilepsy.Methods Totally 136 epilepsy patients treated by low dose stereotactic radiosurgery with Novalis System were analysed retrospectively.The target doses and volumes of the patients were analysed by drawing out the scatterplot and conducting the binary Logistic regression to all of the data.An equation was obtained to predict the occurrence of radiation induced encephaledema in certain range of target volume and dose.Results Among all of 136 patients,different degree of local encephaledema occurred in 19 cases after the radiosurgery.Higher occurrence of radiation induced encephaledema was observed when the target central dose (i.e.90％ isodose circling the target)was more than 18 Gy or the target volume more than 30 cm3.Moreover,in patients with multitargets the doses of different targets devoted to each other,which could lead to the occurrence of local encephaledema.The equation to predict the occurrence probability was obtained by regression analysis.By testing this equation in all of 136 patients the coincidence percentage was 94.7％.Conclusions The target dose and volume could be effective parameters in certain range to predict the occurrence probability of radiation induced encephaledema.This equation would help to establish and optimize the therapeutic planning system.So it could finally reduce the side-effect of low dose stereotactic radiosurgey in epilepsy patients.The equation has some clinical value.