Comparison Of Dosimetry And Short-term Adverse Reactions Between VMAT Under New Optimized Function Application And DMLC Radiotherapy In Patients With Breast Cancer After Radical Mastectomy

Part Ⅰ: Dosimetric comparison of VMAT under new optimized function application and DMLC radiotherapy techniques after radical mastectomy for breast cancer ObjectiveTo compare the dosimetric diffierences between volumetric modulated are therapy(VMAT)under new optimized function application and fixed-fixed dynamic multileaf collimator(DMLC)in breast cancer after modified radical mastectomy.MethodsFiftten patients with left breast cancer after modified radical mastectomy were randomly seleced from the first affiliated hospital of Zhengzhou university between January 2018 and Febtruary 2018,VMAT and DMLC plans were designed for each patient using the Monaco5.11 system under the same dosimetric restriction,the dose-volume histogram(DVH)was used to evaluate the dose in the planned target area,the conformal index(CI),the homogeneity index(HI)and the dose for organs at risk,and paired t test was used for statistical analysis.Results1.The target area of both plans can meet the requirement of prescription dose.In terms of planning target volume(PTV),except for D98 and D50,V105、V110、CI and HI in the target area of VMAT plan were significantly better than that of DMLC plan(P < 0.05).2.The VMAT plan can significantly reduce the dose of the heart and the affected lung.The VMAT plan had significant advantages in V20、 V30、 Dmean of the affected lung and heart(P < 0.05).The DMLC plan was superior in the dose of the healthy side lung and spinal cord,except for V20 of the healthy side lung(P >0.05),the P value of V5 and Dmean of the healthy side lung and Dmax、Dmean of the spinal cord were all less than 0.05.ConclusionAmong patients who received radiotherapy after modified radical resection with left breast cancer,form the perspective of dosimetry alone,VMAT plan was significantly superior to DMLC plan in terms of target area homogeneity,conformal and protection of major organs at risk,which may become the first choice of treatment for such diseases.PartⅡ: Comparison of short-term adverse reactions between VMAT under new optimized function application and DMLC radiotherapy after radical mastectomy for breast cancerObjective To compare the short-term adverse reactions between volumetric modulated are therapy(VMAT)and the fixed-fixed dynamic multileaf collimator(DMLC)after radical mastectomy for breast cancer.Methods Retrospective analysis of 251 female breast cancer patients who received post-operative radiotherapy in the first affiliated Hospital of Zhengzhou University from September 2016 to December 2017,patients were divided into two groups: VMAT group(105 cases)and DMLC group(146 cases).The incidence of short-term adverse reactions during radiotherapy in the two groups was evaluated by chi-square test.Results1.The incidence of grade Ⅲ and Ⅳ cutaneous mucosal injury and myelosuppression in VMAT group was lower than that in DMLC group(P < 0.05).2.In terms of radiation pneumonia,there was no grade Ⅲ / Ⅳ radiation pneumonia in VMAT group,but there was only one case of grade Ⅲ radiation pneumonia in DMLC group,and there was no significant difference between them(P> 0.05).3.The incidence of upper limb edema in VMAT group was slightly higher than that in DMLC group,but the difference was not statistically significant(P > 0.05).Among them,there were 10 cases in VMAT group and 6 cases in DMLC group that presented or aggravated after radiotherapy.The difference was not statistically significant(P > 0.05).Conclusion VMAT radiotherapy technology under the new optimized function can further reduce the incidence of myelosuppression,acute skin injury and acute radiation pneumonia,which can be widely used in breast cancer patients after modified radical resection.