Dosimetry Comparison Of IMRT And3D-CRT After Breast Conserving Surgery Of Breast Cancer

Objective: To Compare target-conformal,irradiation dose and volume of organof risk(OAR) after breast conserving surgery early breast cancer betweenintensity-modulated radiation therapy (IMRT) and three dimensional conformalradiatherapy (3D-CRT).Method： Selected10patients with breast cancer achieved postoperativeradiotherapy for the first time in our hospital during June2011to April2013, PSscore was1points or below.6cases are with left side breast cancerand the other4cases are with right side breast cancer. All patients were designed two kinds oftreatment plans. The first plan was intensity-modulated radiotherapy, tumor bedsynchronization add quantity, set whole-breast prescription dose PTV:5012cGy/28times,179cGy/times, five times per week. Tumor bed PTV2:602cGy/28times,215cGy/times, five times per week. The second plan was3D-CRT, tumor bed wasirradiated additional1000cGy with electron beams later, the whole-breast prescriptiondose: PTV:5000cGy/25times,200cGy/times, five times per week.9~12mev-Eelectronic line on part of tumor bed,dose was1000cGy/5times,200cGy/times, fivetimes per week. Compared the conformal index endanger organ dose and volume ontwo different treatment plans.Results: The conformal index of IMRT plan（0.696±0.650）was significantlyhigher than that of3D-CRT(0.608±0.759), P value is0.037<0.05, the differencewas statistically significant. The mean of Dmean, V5, V10, V20of suffering lung inIMRT group was15.10Gy,51.24%,37.45%and26.72%, in3D-CRT group was15.02Gy,34.29%,29.46%and30.20%respectively. The mean of Dmean, V5, V10,V20of the whole lung in IMRT group was8.51Gy,27.34%,21.08%and14.42%, in 3D-CRT group was8.19Gy,19.02%,15.50%and16.01%respectively. There wereno significant difference between IMRT and3D-CRT of Dmean, V10in lung andDmean, V10, V20in total lung. V20of suffering lung in IMRT group decreased by3.48%than3D-CRT group, V5of suffring lung and total lung were increased by16.95%and16.95%respectively,and the differences were statistically significant.Themean of Dmean, V5, V30of heart for left side breast cancer in IMRT group were6.49Gy,23.24%and7.08%, in3D-CRT group were7.49Gy,19.42%and9.26%respectively.There were no significant difference between IMRT and3D-CRT ofDmean of lung,V30of heart in IMRT group decreased by2.18%than3D-CRT group,V5of heart in IMRT group increased by3.72%than3D-CRT group,and thedifferences were statistically significant.The mean of Dmean, V5, V30of heart for right side breast cancer in IMRTgroup were3.25Gy,24.20%and0%, in3D-CRT group were2.15Gy,6.60%and0%respectively.There were no significant difference between IMRT and3D-CRT ofDmean of heart,V5of heart in IMRT group increased by17.60%than3D-CRT group,and the differences were statistically significant.Conclusions: IMRT has more significant advantages on improving targetconformal degree than3D-CRT, and reduced radiation dose of organs at risk such aslung and heart but added radiation volume.