Dosimetric Comparison Of IMRT And VMAT Radiotherapy Techniques In Patients Undergoing Modified Radical Mastectomy Internal Mammary Lymph Node Radiotherapy

Objectiveto investigate the dosimetric differences in radiotherapy in patients undergoing internal mammary lymph node irradiation after modified radical mastectomy with fixed volume intensity modulated radiation therapy(VMAT)and fixed field dynamic intensity modulated radiation(IMRT).Methodsfrom July 20,2018 to October 2018,20 patients with modified left radical mastectomy?postoperative adjuvant radiotherapy indications and required internal lymph node irradiation were treated with radiotherapy in the Second Affiliated Hospital of Nanchang University,Jiangxi Province.The programs of VMAT and IMRT under the same dose limit were established.The target area and target organ were evaluated by dose volume histogram(D VH),calculating the PTVDmean? PTV V95%?PTV V110%?treatment time per minute? CI?HI,V5?V10?V20?V30?Dmean of both lungs,V10?V20? V30? Dmean and Dmax of the contralateral breast?spinal cord and esophagus,V30?V40?Dmean? Dmax of cardiac,Dmean,Dmax and other dosimetric parameters of the left anterior descending coronary artery.Does it has dosimetric difference in the radiotherapy of breast cancer patients after modified radical surgery on the left side using statistical methods to compare IMRT and VMAT Does the technique? ResultsAmong the two radiotherapy techniques,the HI of IMRT was higher than that of VMAT,and the difference was statistically significant(P<0.05).The differences of CI,PTVM ean,PTV V95%,PTV V110% between IMRT and VMAT were not statistically significant(P>0.05).The VMAT treatment time of each subgroup was the shortest,with an average of 5-7 minutes and IMRT of 15-25 minutes.The difference between the two groups was statistically significant(P<0.01).The V20 and V30 of the VMAT were better than the IMRT,and the difference was statistically(P<0.05),and the V30 difference was statistically significant(P<0.001).However,for the healthy side lung,IMRT was superior to VMAT between V5 and V10,and the difference was also statistically significant(P<0.05).VMAT was superior to IMRT in the left anterior descending coronary artery's Dmean and Dmax,heart's V30?V40?Dmean? Dmax,and The differences were statistically significant(P< 0.01).The mean dose of the healthy breast in the VMAT group was lower than that in the IMRT group,but the difference was not statistically different.The maximum dose of the healthy breast in the VMAT group was significantly lower than that in the IMRT group(P<0.01).The mean and maximum dose of spinal cord were significantly better in the VMAT group than in the IMRT group,and the difference was statistically significant(P<0.01).For the mean esophageal dose,the VMAT group was superior to the IMRT group,the difference was statistically significant(P<0.05).On the contrary,in the maximal esophageal dose,the IMRT group was superior to the VMAT group,the difference was statistically significant(P<0.05).ConclusionVMAT can significantly reduce the dose of the heart,contralateral lung,spinal cord,esophagus and other vital organs,reducing treatment time,For patients who need to illuminate the internal mammary lymph nodes after radical mastectomy,VMAT technology can better protect normal tissues than IMRT.