Study On Dose Distribution In Target Area Under Different Radiotherapy Plan After Left Breast Conserving Surgery

BackgroundToday,female breast cancer had been the first in the world.On average,there are 1.15 millions new cases of breast cancer and 41000 deaths every year in the world.According to the data of breast cancer published by the National Cancer Center and the Ministry of health’s disease prevention and Control Bureau,the incidence rate of breast cancer in women is(42.55/10).Breast cancer has become a major public health problem.Since the1990 s,the global mortality of breast cancer has shown a downward trend.The reasons are as follows: first,the development of breast cancer screening has increased the proportion of early cases;second,the development of comprehensive treatment of breast cancer has improved the curative effect.Breast cancer has become one of the most effective solid tumors.As a local treatment,radiotherapy plays an important role in the treatment of breast cancer,especially for patients after breast conserving surgery.Radiotherapy after breast conserving surgery can reduce the local recurrence rate by 2/3.ObjectiveTo investigate the dose distribution in the target area under different radiotherapy plans after left breast cancer conserving surgery.MethodSelection in March 2019 to September 2020 to our hospital radiotherapy of the left breast cancer radiotherapy department confirmed 20 cases of postoperative patients,patients CT positioning the breast tissue and incision,philips PLNCALE plan system set up four kinds of radiotherapy,respectively 4 filed,5 filed intensity modulated radiation therapy(IMRT)and 6 filed and three-dimensional conformal radiotherapy plans.Data comparison and dose-volume histogram were used to compare the dose distribution,conformal degree and uniformity in the target area of the four radiotherapy plans,as well as the radiation dose of the heart,lung and other organs at risk,to determine the best radiotherapy plan.Results1.The results showed that there were differences in CI,HI and MU(P<0.05).Specifically,there were 6F-IMRT > 5F-IMRT > 4-IMRT > 3D-CRT,P<0.05,On the Dmin,four groups see significant differences statistically significant(P<0.05),the specific performance for 6F-IMRT>5F-IMRT>4F-IMRT>3D-CRT,two comparative differences are statistically significant(P<0.05),On the Dmax,3D-CRT > 4F-IMRT > 5F-IMRT >6F-IMRT,but there was no statistically significant difference(P>0.05);On the Dmean,both 3D-CRT and 4F-IMRT were significantly lower than 6F-IMRT and 5F-IMRT,and3D-CRT was lower than 4F-IMRT,but there was no significant difference between5F-IMRT and 6F-IMRT.There was no statistically significant difference between 3D-CRT and 4F-IMRT in V95%,but the above two groups were significantly lower than 5F-IMRT and 6F-IMRT(P<0.05).There was no statistically significant difference between 4F-IMRT,5F-IMRT and 6F-IMRT in V98%(P >0.05),but the 3D-CRT was significantly higher than the above three groups(P<0.05).On V100,there is significant difference between the four groups(P< 0.05),the specific performance for the 3D-CRT > 6F-IMRT > 5F-IMRT >4F-IMRT,two comparative differences are statistically significant(P<0.05),on the V105%,there is significant difference between the four groups(P<0.05),the specific performance for the 3D-CRT > 4 F-IMRT > 5F-IMRT > 6F-IMRT,two comparative differences are statistically significant(P<0.05).2.In the heart V5,the V10,V20,V30 and Dmean,IMRT is increased with the increase of number of vision,irradiation dose is higher(P<0.05),compared with 3D-CRT,but in the heart V5 for 6F-IMRT > 5F-IMRT > 4F-IMRT > 3D-CRT,two comparative differences are statistically significant(P< 0.05),in the heart V10,V20,V30 and Dmean,characterized by 3D-CRT > 6F-IMRT > 5F-IMRT > 4F-IMRT,two comparative differences are statistically significant(P<0.05).3.There was no significant difference in 4F-IMRT,5F-IMRT,and 6F-IMRT in V5,V10,V20,V30,and Dmean of the affected lung(P>0.05),but 5F-IMRT > 6F-IMRT and4F-IMRT 6F-IMRT >5F-IMRT and Dmean of the right lung(P<0.05).But compared with3D-CRT,on the left lung related indicators are characterized by 3D-CRT significantly higher than that of IMRT group,statistically significant difference(P<0.05),but in the right lung,V5 performance for 3D-CRT > 5F-IMRT > 6F-IMRT > 4F-IMRT,P<0.05,while on the Dmean,show the 3D-CRT > 4F-IMRT > 5F-IMRT > 6F-IMRT,P<0.05.4.In the right breast V10 and DMEAN,the four groups showed 3D-CRT >6F-IMRT > 5F-IMRT > 4F-IMRT,and the pairwise comparison showed statistically significant difference(P < 0.05).5.CD3+,CD4+,CD8+ and CD4+/CD8+ had no statistical significance before radiotherapy in the four groups of patients.After radiotherapy,CD3+,CD4+ and CD4+/CD8+ were significantly decreased compared with the first four groups,while CD8+ was increased compared with before treatment,the difference was statistically significant(P<0.05).There was no statistical significance in CD3+,CD4+,CD8+ and CD4+/CD8+ in 4F-IMRT,5F-IMRT and 6F-IMRT after radiotherapy,CD3+,CD4+ and CD4+/CD8+ in the groups were higher than 3D-CRT,while CD8+ was lower than that in3D-CRT group.The difference was statistically significant.6.Four groups in E and P,and there was no statistically significant difference in CEA,CA153 and CTNI(P>0.05),but after radiotherapy,four groups of E2 and P before radiotherapy has no obvious change,there was no statistically significant difference(P>0.05),but markedly reduced the CEA and CA153 before radiotherapy,and elevated CTNI is before radiotherapy significant,the differences were statistically significant(P<0.05),four groups of patients after radiotherapy on except CTNI index difference has no statistical significance(P>0.05),The c Tn I showed 3D-CRT > 6F-IMRT > 5F-IMRT >4F-IMRT,and the pairwise comparison showed statistically significant difference(P<0.05).7.The results showed that there was no statistical significance in the possible progression of radiation pneumonia among the four groups(P>0.05).The probability of acute skin reaction in 3D-CRT was higher than that in the other groups,P<0.05.There was no statistically significant difference in the incidence of acute skin reaction among4F-IMRT,5F-IMRT and 6F-IMRT in the other groups(P<0.05).There was no statistically significant difference in the rates of cosmetic excellence and good among the four groups(P>0.05).Only 3 patients in the 3D-CRT group had darker skin color in the irradiated area when followed up 3 months after radiotherapy.During one year,only 1 case of local recurrence was found in the 3D-CRT group,while no death,recurrence or metastasis occurred in the other groups.Conclusion1.By comparing the left breast cancer patients after breast conserving surgery treated with IMRT or 3D conformal radiotherapy.The therapeutic effect of IMRT was better than that of 3D-CRT.The conformal and homogeneity of the radiotherapy target area were better than that of 3D conformal radiotherapy,and the effects on cardiopulmonary function and immune function were small,and the safety was high.2.In different number of the radiation field,the increase in the number of radiation field of target area coverage,conformal degree and uniformity also will increase,but also associated with the lungs,the contralateral breast,heart,on average,the increase of irradiation dose and volume,so according to the condition of patients,select the appropriate number of the radiation field,such as poor cardiopulmonary function,number of low radiation field can be used for radiation therapy.