The Study Of Establishing Radiation Injury Of Hippocampus Gyrus And The IMRT Dosimetric Study Of Hippocampus Gyrus In NPC Patients

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A study of radiation injury of hippocampus gyrus based on small animal radiation research platformBackground:More and more attention had been paid to cognitive impairment caused by radiotherapy.Hippocampus gyrus is the key factor for the impairment,and it is of great significance to study the radiation injury of hippocampus gyrus.Methods:Based on small animal radiation research platform(SARRP),the left brains of SD rats were irradiated with a single dose of 30 Gy or 40 Gy.HE and immunofluorescence staining was performed on the dentate gyrus of the hippocampus after irradiation.Results:The SARRP completed the precise irradiation of the left hemisphere of SD rats.Single dose of 30Gy or 40Gy could induce apoptosis of neural stem cells in dentate gyrus of hippocampus,and the apoptotic degree of 40Gy was more serious.After 40Gy irradiation,a large number of cells were stained by SOD1 in the left hippocampal gyrus,IFIH1 in the left cerebral cortex,while IFIH1 staining in the right cerebral cortex was not obvious.A lot of BCL-2 staining was observed in the left hippocampal gyrus after 40 Gy irradiation,while the staining of BCL-2 in the right hippocampal gyrus was not obvious.Conclusions:The irradiation injury model of hippocampus gyrus could be esatblished by single dose of 30Gy or 40Gy.Apoptosis of neural stem cells in dentate gyrus of hippocampus could be observed.Oxidative damage of oxygen free radicals may be one of the mechanisms of hippocampus gyrus injury induced by radiotherapy,which deserves further study.Part ? Preliminary results of the exposed dose of head body and tail of the hippocampus gyrus in nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy and preliminary analysis of cognitive functionBackground:Hippocampus gyrus(HC)plays important role in the cognitive impairment induced by radiotherapy.HC can be divided into HC head(HH),HC body(HB)and HC tail(HT),and these three parts play different functions.This study analyzed the exposed dose of head,body and tail of the HC of nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy(IMRT),and preliminarily analyzed and the cognitive function of the patients.Methods:The bilateral HCs were delineated on MRT T1 weighted image and were divided into HH,HB and HT for 10 nasopharyngeal carcinoma patients treated with IMRT.The indexes minimum dose(D99%),50%dose of irradiated volume(D50%),average dose(Dmean),maximum dose(D1%);and the percentage volume of different doses of irradiation Vn%(the percentage volume of hippocampus irradiated by nGy)of HC,HH,HB,and HT were then analyzed.The Wechsler Intelligence Scale(WAIS-CR)was tested in 5 patients before and 3 months after radiotherapy.Results:Both sides of HCs were irradiated with lots of irradiation dose.The Dmean of the left and right HC were(396+480)cGy and(389+403)cGy.The V5%,V10%,V15%,V20%,V30%,V40%,V50%of left and right HC decreased in turn.The D1%,D50%,Dmean and D99%of HH,HB and HT decreased in turn.The exposed dose of HH was significantly higher than that of HB and HT.The Dmean of HH,HB and HT of left HC was(1739±1317)cGy,(890±982)cGy,(547±688)cGy respectively,P=0.042.The Dmean of HH,HB and HT of right HC was(169±1942)cGy,(744±483)cGy,(531±603)cGy respectively,P=0.002.The volume irradiated with different doses of HH,HB and HT was different.V5%-V50%decreased in turn(except V20%of right hippocampus).The Vn%of HH was significantly higher than that of HB and HT.5 patients completed WAIS-CR test.Before and after radiotherapy,the mean score of regular order was 8.60±1.34,8.0±1.00 respectively(P=0.43);and the mean score of reverse order was 5.80±0.84,5.20±0.84(P=0.07).Conclusions:For nasopharyngeal carcinoma patients,in the IMRT plan,the exposed dose of head,body and tail of hippocampus was different,and the exposed dose of head,body and tail of hippocampus decreased in turn.The volume irradiated with different dose of the three parts of HC also decreased in turn.The highest dose of hippocampus head is particularly noteworthy.The cognitive function of patients decreased after radiotherapy,which deserved further study.Part ? Dose analysis of hippocampus gyrus in T3,T4 nasopharyngeal carcinoma patients treated with intensity modulated radiotherapy and the correlation between the exposed dose of hippocampus and the invasion of different anatomical structures in nasopharyngeal carcinoma patientsBackground:Hippocampus gyrus(HC)plays an important role in cognitive impairment caused by radiotherapy.HC can be divided into HC head(HH),HC body(HB)and HC tail(HT),and these three parts play different functions.The exposed dose of HC in advanced T stage nasopharyngeal carcinoma(NPC)patients is high.This study analyzed the exposed dose of HC of T3 and T4 NPC patients treated with intensity modulated radiotherapy(IMRT)and investigated the correlation between the exposed dose of hippocampus and different anatomical structures involved in nasopharyngeal carcinoma patients.Methods:The bilateral HCs were delineated and were divided into HH,HB and HT for 62 NPC patients(T3 stage 33 cases and T4 stage 29 cases)treated with IMRT.The dose parameters minimum dose(D99%),50%dose of irradiated volume(D50%),average dose(Dmean),maximum dose(D1%),and the percentage volume of different doses of irradiation Vn%(the percentage volume of hippocampus irradiated by nGy)of HC,HH,HB,and HT were then analyzed.Results:The Dmean of left and right HC was(1127±704)cGy,(1173±762)cGy.The exposed dose of HC and the Vn%in T4 stage patients were higher than those of T3 stage patients.The exposed dose of HH was obviously higher than that of HB and HT and the exposed dose of HH,HB and HT decreased in turn in T3 and T4 stage patients.The Dmean of left HH,HB and HT was(1732±1029)cGy,(820±632)cGy,(423±366)cGy(P=0.000):while the Dmean of right HH,HB and HT was(1985±1101)cGy,(837±531)cGy,(432±343)cGy(P=0.000).The volume exposed in different dose of HH was obviously higher than that of HB and HT.The Vn%of HH,HB and HT decreased in turn.The involvement of sphenoid sinus,ethmoid sinus and cavernous sinus correlated with high exposed dose of HC.The correlation between the involvement of right clivus,pterygoid process and the Dmean of lpsilateral HH was statistically significant.While the correlation between the involvement of the left clivus and pterygoid process and the Dmean of lpsilateral HH was not statistically significant.There was no statistical significance among other anatomical structures such as maxillary sinus,petrous apex,ruptured foramen,masticatory muscle space,orbital apex and so on and the exposed dose of HC.Conclusions:The exposed dose of HH,HB and HT was different in nasopharyngeal carcinoma patients treated with IMRT.The exposed dose of HH was the highest,which should be emphasized especially.The involvement of sphenoid sin1us,ethmoid sinus and cavernous sinus suggest high exposed dose of HC.Part ? The study of hippocampus gyrus sparing and cognitive function evaluation in nasopharyngeal carcinoma patients treated with volumetric intensity modulated arc therapyBackground:Cognitive impairment is closely related to hippocampus gyrus(HC)irradiation in nasopharyngeal carcinoma(NPC)patients.Without affecting the dose of target and organs at risk,hippocampus sparing can be completed with volumetric intensity modulated arc therapy(VMAT).In this study,VMAT was used for the HC sparing for the radiotherapy for nasopharyngeal carcinoma(NPC)patients.The cognitive function before and after VMAT of the patients was evaluated,and the significance of HC sparing for NPC patients was evaluated.Methods:Eleven NPC patients completed the hippocampus sparing VMAT plan.Before and 3 months after radiotherapy,the Montreal Cognitive Assessment(MoCA)was evaluated for the NPC patients.Results:There was relatively lots of irradiation dose in bilateral HCs.The mean exposed dose of the left and right side of HC was(1239±614)cGy and(1253±640)cGy respectively.The total scores of the MoCA before and three months after radiotherapy were(23.00±4.04),(24.43±3.99)respectively,(P=0.129).There were also no significant differences in visual space/executive function,naming,delayed recall,attention,language,ion ability and orientation test before and three months after radiotherapy.Conclusions:With VMAT HC sparing,the cognitive function evaluation of NPC patients did not decrease.There was still a lot of irradiation dose exposed to HCs,which highlighted the significance of HC sparing in NPC patients.