| Objective:To explore the clinical efficacy and prognosis of different radiotherapy methods in patients with locally advanced nasopharyngeal carcinoma.Materials and Methods: 190 cases of nasopharyngeal carcinoma patients were selected to receive radiotherapy in first affiliated hospital of Guangxi Medical University,which were divided into three groups: conventional radiotherapy group(63 cases),static intensity modulated radiotherapy(62 cases),and dynamic intensity modulated radiotherapy(65cases).In the conventional radiotherapy group,CT simulation was used to locate the conventional field,and bilateral face-neck combined with field + tangential field of the lower neck was performed in the process of radiotherapy.The static intensity modulated radiotherapy group was calculated by the Pinnacle planning system and fully optimized for the patient's treatment plan.The treatment was performed by IMRT technology and treated by the Siemens Primus treatment machine.The target volume of the nasopharynx and upper neck was irradiated by IMRT technique,and the supraclavicular region of the lower neck was irradiated by single tangential field irradiation using conventional techniques.The dynamicintensit modulated radiotherapy group was calculated by the Eclipse planning system and fully optimized for the patient's treatment plan.The treatment was performed using the IMRT technique,which was treated with the Varian's clinic ix 4948 accelerator.The target volume of the nasopharyngeal and cervical targets was irradiated with IMRT.The specific investigation items were as follows: the dose uniformity,conformability and the dose to organs in the target area were evaluated by DVH diagram and isodose line distribution at all levels;RTOG standard was used to evaluate the acute response and late injury of patients in three groups.Log-rank method was used to calculate univariate analysis that might affect the prognosis.COX risk ratio model was used to calculate the multivariate analysis of prognostic factors.Brain stem dose was calculated for all patients in the three groups,and the influencing factors of brain stem dose were analyzed,including chi-square single-factor analysis?variance analysis and logistic multi-factor analysis.The survival rate of patients was analyzed by k-m method.Results: Basic feature analysis: in the statistical analysis of gender,T stage,N stage and pathological type,the P values of the three groups were 0.566,0.507,0.443,and 0.55,respectively,and the differences were not statistically significant.Dose analysis: the isodose curve of intensity-modulated radiotherapy can better surround the tumor target area of patients and give the surrounding tissues the irradiation process with the minimum dose.In the iso-dose curve distribution analysis of conventional radiotherapy,large areas of normal tissues other than tumor areas were invaded by iso-dose irradiation,and the invasion rate was higher than 95%.However,the iso-dose curve of 100% was difficult to wrap around GTV.In the analysis of dose histogram DVH in intensity modulatedradiotherapies,the target volume V95 of all patients was more than 100%,fully indicating that the average volume of patients exposed to less than 95% of the prescribed dose was less than 1%.Conformability and uniformity analysis of target volume;Standard deviation(STD),dose uniformity index(HI)and other parameters were compared,and the difference between the conventional radiotherapy group < static intensity modulation group < dynamic intensity modulation group was statistically significant(P<0.05).Dynamic radiotherapy showed higher precision,and the standard deviation,dose uniformity index and V95 of the measured data all showed higher values.The maximum dose distribution of serial organs: the analysis of brainstem showed that the dynamic group of brainstem(53.28 ± 3.03)Gy< static group(56.66 ± 3.24)<conventional radiotherapy group(59.87 ± 2.34)Gy,and the P values of statistical data was 0.038,and the difference was statistically significant.In addition,in the analysis of spinal cord,left ocular bulb,right ocular bulb,left crystal,right crystal and optic chiasm,the highest dose was compared between the dynamic group and the static group and the conventional radiotherapy group,with P values greater than 0.05,and the difference was not statistically significant.Toxicity and side effects were investigated on skin,oral mucosa,throat,salivary glands,blood and other indicators,and the data showed that P value was greater than 0.05,the difference was not statistically significant.Brain stem dose analysis: When PGTV was less than 54 Gy,the Dmax of conventional group was < static group < dynamic group,and the difference P between the groups was less than 0.05.The difference was statistically significant.All D1 cc groups showed the same law,and the difference was statistically significant.When PGTV>54Gy,Dmax and D1 cc showed the opposite law,and the comparison difference P between each group was less than0.05,the difference was statistically significant.Dynamic data analysis of 1 mm and 2 mm of outlay: data of 1 mm of outlay: Dmax,D1 cc and D01 showed that the conventional group < static group)< dynamic group,and the comparison P between the groups was less than 0.05,with statistically significant difference.Statistical analysis results of 2mm external release: the data of Dmax,D1 cc and D01 showed the same law as that of 1mm external release,effectively suggesting that the minimum organ damage dose and degree were obtained after1 mm or 2mm external release of the basic dose in the dynamic intensification group.Single factor statistical analysis of absolute brainstem Dmax: T stage,N stage,GTV dose,the volume of the invaded slope,the shortest distance between the brainstem and the normal slope,and the shortest distance between the invaded slope and the brainstem suggested that the P value of the statistical data was greater than 0.05,and the difference was not statistically significant.Dose statistical data P value of D95 on the invaded slope was 0.035,and the difference was statistically significant.Multi-factor analysis of absolute brainstem Dmax: the study indicated that the statistical data P of the two items of total invasion of the affected site and slope D95 dose were statistically significant in three groups;the statistical data P values of T stage,incomplete invasion of the affected site and volume of the invaded slope were >0.05,and the differences were not statistically significant.Survival rate analysis: Statistical analysis of 5-year overall survival rate of conventional radiotherapy group and intensity modulation groups,disease-specific survival rate,local control rate and regional control rate showed that P values were 0.041,0.038,0.040 and 0.039,respectively,with statistically significant differences.The difference between static group and dynamic group was not statistically significant.Survival rate of single factor analysis process:gender,age,T stage,N stage,clinical stage,GTV dose,Dmax,D1 cc statistical data P values were 0.890,0.877,0.744,0.498,0.455,0.371,0.575,0.668,no statistically significant difference;In the analysis of cumulative chemotherapy cycles,the P value was 0.009,and the difference was statistically significant.Survival analysis of multiple factors: gender,age,T stage,N stage,synchronous chemotherapy,GTV size and invaded slope D95 multiple factors analysis,statistical data P values were greater than 0.05,no statistically significant difference,statistical analysis of cumulative chemotherapy cycle,data P values were <0.05,the difference is statistically significant.Conclusions: Compared with conventional radiotherapy and static modulated therapy,dynamic intensity modulated therapy could improve the dose distribution in the target area,reduced the radiation dose of brainstem.It has obvious advantages in the treatment of nasopharyngeal cancer.Intensity modulated therapy could effectively improve the local vacancy rate of nasopharyngeal carcinoma radiotherapy and thus effectively improved the overall survival rate of patients compared with conventional radiotherapy.The difference between two modulated therapy was not statistically significant. |
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